CE Standard Certification for RepRaps
Posted by jamesncarter
|
Re: CE Standard Certification for RepRaps February 09, 2013 09:28PM |
Registered: 11 years ago Posts: 143 |
nophead Wrote:
-------------------------------------------------------
> The problem is that trading laws make it
> impractical for individuals to make and sell
> electrical appliances to the public. I assume that
> most if not all small companies that are selling
> complete machines are breaking the law.
What if the machines were sold the same way that Heathkit used to sell their stuff?
None of the kits they sold could have been certified because there was no inspection system, and each individual building them had different levels of skill.
-------------------------------------------------------
> The problem is that trading laws make it
> impractical for individuals to make and sell
> electrical appliances to the public. I assume that
> most if not all small companies that are selling
> complete machines are breaking the law.
What if the machines were sold the same way that Heathkit used to sell their stuff?
None of the kits they sold could have been certified because there was no inspection system, and each individual building them had different levels of skill.
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Re: CE Standard Certification for RepRaps February 10, 2013 06:23AM |
Admin Registered: 17 years ago Posts: 7,879 |
As said before kits are not a problem. This thread is about selling complete machines.
At the time Heathkit were trading these regs didn't exist. They came in around 1996, IIRC.
[www.hydraraptor.blogspot.com]
At the time Heathkit were trading these regs didn't exist. They came in around 1996, IIRC.
[www.hydraraptor.blogspot.com]
|
Re: CE Standard Certification for RepRaps February 10, 2013 07:18AM |
Registered: 11 years ago Posts: 143 |
nophead Wrote:
-------------------------------------------------------
> As said before kits are not a problem. This thread
> is about selling complete machines.
>
> At the time Heathkit were trading these regs
> didn't exist. They came in around 1996, IIRC.
Heathkit sold both kits and assembled units (complete machines). The assembled units must have been certified, at least by UL, even back then, wouldn't they? (They've been around since 1894).
The reason I'm going down this path Nohead is that I'm thinking that if one of the designs, say yours, or Prusa's were certified, then maybe all home built copies would be too, just so long as there were clear instuctions included for the exact assembly of a kit. Perhaps this is something that we as a community could contribute to getting done. At minimum, the Mendal i2, or even perhaps yours if it is an open source design. There might not be that much involved in certifying several machines, all sharing some common design concepts and software/firmware. The purpose of certification is safety, and if they are safe, they can't be rejected.
I know that you've mentioned before that a bag of parts doesn't fall under the safety laws that are responsible for certifying appliances, but some people/companies are selling assemblies, like hotends and complete heatbeds. Have you had the assemblies you sell certified? I don't think that you should have to, and given the nature and current situation with open source hardware and 3d printing, none of us should. Perhaps simply including a disclaimer with each kit or assembly stating the "experimental nature" of the systems would be adequate protection for suppliers. Since suppliers seem to be coming from all parts of the globe at the moment, the legal aspects of this situation are pretty much in the air. I do however agree that it would be a good idea for all of us, or at least you main players, to investigate options like this. Perhaps Heathkit came up with a strategy back then that could benifit all of us now.
Another reason I'm on about this is that when I first got into Repraps last fall I almost burned down my house. Seriously.
I'd bought a MK4 hotend from a company in China that used those 40 watt heater elements. They'd taped the thermistor into place with a thin strip of Kapton tape. I installed it into my machine and everything seemed to be working fine. I'd also read, from others here, that enclosing the Mendal would increase the ambient temperature and prevent warping. I was new to this technology, but I've worked servicing plotters and printers for 35 years, so this seemed simple enough. Because I was still at the tweaking stage, I put a large cardboard box around my machine with a slot in the top for the filament, and a door to access the heat bed, and I started a print. It was late at night and the print was going to take hours. I'd read about others printing throughout the night, and I'm not used to using machines that don't have all the big bugs worked out. About two hours into the print, my dog woke me to tell me there was something wrong. I went into my lab and found that the tape had come loose and the thermistor had fallen out. I quickly shoved the thermistor back into the hole and the last reading it showed before I shut everything down was about 320 degrees. Smoke was billowing from the hotend, which had of course melted, and my basement was filled with smoke from the ABS which had come very close to ignition.
The point here is that a Reprap could be very dangerous in the wrong hands. I was lucky in that I have a dog and I am calm about such things. There are however lots of people getting into this field who are naive and not very hands on. Perhaps someone more art oriented or even children who just want to check it out. If something like what happened to me were to happen to one of them, the results could be disasterous, to them, and to this Reprap community. I don't think that examining some sort of legal postion is such a bad idea. I also don't think that working toward certification is such a horrible prospect either. I don't think that it would be expensive either. All we really have to do is make the designs safe to begin with.
Heathkits setup is worth examining because it is a similar situation. They would have been liable back then, long before laws legislated in 1996. The first drunk driving liability suits happened two years after the model T came out, long before any laws about it. I think examining their strategies and position on their product would be benificial.
Edited 1 time(s). Last edit at 02/10/2013 07:21AM by Tekwizard.
-------------------------------------------------------
> As said before kits are not a problem. This thread
> is about selling complete machines.
>
> At the time Heathkit were trading these regs
> didn't exist. They came in around 1996, IIRC.
Heathkit sold both kits and assembled units (complete machines). The assembled units must have been certified, at least by UL, even back then, wouldn't they? (They've been around since 1894).
The reason I'm going down this path Nohead is that I'm thinking that if one of the designs, say yours, or Prusa's were certified, then maybe all home built copies would be too, just so long as there were clear instuctions included for the exact assembly of a kit. Perhaps this is something that we as a community could contribute to getting done. At minimum, the Mendal i2, or even perhaps yours if it is an open source design. There might not be that much involved in certifying several machines, all sharing some common design concepts and software/firmware. The purpose of certification is safety, and if they are safe, they can't be rejected.
I know that you've mentioned before that a bag of parts doesn't fall under the safety laws that are responsible for certifying appliances, but some people/companies are selling assemblies, like hotends and complete heatbeds. Have you had the assemblies you sell certified? I don't think that you should have to, and given the nature and current situation with open source hardware and 3d printing, none of us should. Perhaps simply including a disclaimer with each kit or assembly stating the "experimental nature" of the systems would be adequate protection for suppliers. Since suppliers seem to be coming from all parts of the globe at the moment, the legal aspects of this situation are pretty much in the air. I do however agree that it would be a good idea for all of us, or at least you main players, to investigate options like this. Perhaps Heathkit came up with a strategy back then that could benifit all of us now.
Another reason I'm on about this is that when I first got into Repraps last fall I almost burned down my house. Seriously.
I'd bought a MK4 hotend from a company in China that used those 40 watt heater elements. They'd taped the thermistor into place with a thin strip of Kapton tape. I installed it into my machine and everything seemed to be working fine. I'd also read, from others here, that enclosing the Mendal would increase the ambient temperature and prevent warping. I was new to this technology, but I've worked servicing plotters and printers for 35 years, so this seemed simple enough. Because I was still at the tweaking stage, I put a large cardboard box around my machine with a slot in the top for the filament, and a door to access the heat bed, and I started a print. It was late at night and the print was going to take hours. I'd read about others printing throughout the night, and I'm not used to using machines that don't have all the big bugs worked out. About two hours into the print, my dog woke me to tell me there was something wrong. I went into my lab and found that the tape had come loose and the thermistor had fallen out. I quickly shoved the thermistor back into the hole and the last reading it showed before I shut everything down was about 320 degrees. Smoke was billowing from the hotend, which had of course melted, and my basement was filled with smoke from the ABS which had come very close to ignition.
The point here is that a Reprap could be very dangerous in the wrong hands. I was lucky in that I have a dog and I am calm about such things. There are however lots of people getting into this field who are naive and not very hands on. Perhaps someone more art oriented or even children who just want to check it out. If something like what happened to me were to happen to one of them, the results could be disasterous, to them, and to this Reprap community. I don't think that examining some sort of legal postion is such a bad idea. I also don't think that working toward certification is such a horrible prospect either. I don't think that it would be expensive either. All we really have to do is make the designs safe to begin with.
Heathkits setup is worth examining because it is a similar situation. They would have been liable back then, long before laws legislated in 1996. The first drunk driving liability suits happened two years after the model T came out, long before any laws about it. I think examining their strategies and position on their product would be benificial.
Edited 1 time(s). Last edit at 02/10/2013 07:21AM by Tekwizard.
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Re: CE Standard Certification for RepRaps February 10, 2013 08:34AM |
Registered: 12 years ago Posts: 1,236 |
|
Re: CE Standard Certification for RepRaps February 10, 2013 08:51AM |
Admin Registered: 17 years ago Posts: 7,879 |
Tekwizard Wrote:
-------------------------------------------------------
>
> Heathkit sold both kits and assembled units
> (complete machines). The assembled units must have
> been certified, at least by UL, even back then,
> wouldn't they? (They've been around since 1894).
I only know about the UK. We only had to start CE marking for EMC around 1996 and LVD a year later. There must have been safety standards before then but it wasn't mandatory.
> The reason I'm going down this path Nohead is that
> I'm thinking that if one of the designs, say
> yours, or Prusa's were certified, then maybe all
> home built copies would be too, just so long as
> there were clear instuctions included for the
> exact assembly of a kit.
Somebody would have to sign a declaration of conformity to allow them to be CE marked and sold as complete machines. That person is then responsible for the safety and compliance. No way they are going to be responsible for something made by another company or individual.
>Perhaps this is something
> that we as a community could contribute to getting
> done. At minimum, the Mendal i2, or even perhaps
> yours if it is an open source design.
Mendel90 is completely open source: [github.com]
> There might
> not be that much involved in certifying several
> machines, all sharing some common design concepts
> and software/firmware.
My guess is all current designs would fail. There is a lot involved, I know because I was responsible for bringing it in for the company I worked for back in the 1996. We had to change a lot of our products because although they weren't blatantly unsafe the did not pass EMC and LVD regs without some modifications.
>The purpose of
> certification is safety, and if they are safe,
> they can't be rejected.
It isn't just safety. The is also EMC, ROHS and WEEE.
>
> I know that you've mentioned before that a bag of
> parts doesn't fall under the safety laws that are
> responsible for certifying appliances, but some
> people/companies are selling assemblies, like
> hotends and complete heatbeds.
Components can't be certified unless there is a standard covering them and building a system from certified components doesn't mean it is certified.
CE + CE != CE.
> Have you had the
> assemblies you sell certified? I don't think that
> you should have to, and given the nature and
> current situation with open source hardware and 3d
> printing, none of us should. Perhaps simply
> including a disclaimer with each kit or assembly
> stating the "experimental nature" of the systems
> would be adequate protection for suppliers. Since
> suppliers seem to be coming from all parts of the
> globe at the moment, the legal aspects of this
> situation are pretty much in the air. I do however
> agree that it would be a good idea for all of us,
> or at least you main players, to investigate
> options like this. Perhaps Heathkit came up with a
> strategy back then that could benifit all of us
> now.
Like I said, all this legislation wasn't in place back then. ROHS and WEEE are even more recent (this century) and ROHS has just become ROHS2, which is even more paperwork.
>
> Another reason I'm on about this is that when I
> first got into Repraps last fall I almost burned
> down my house. Seriously.
> I'd bought a MK4 hotend from a company in China
> that used those 40 watt heater elements. They'd
> taped the thermistor into place with a thin strip
> of Kapton tape. I installed it into my machine and
> everything seemed to be working fine. I'd also
> read, from others here, that enclosing the Mendal
> would increase the ambient temperature and prevent
> warping. I was new to this technology, but I've
> worked servicing plotters and printers for 35
> years, so this seemed simple enough. Because I was
> still at the tweaking stage, I put a large
> cardboard box around my machine with a slot in the
> top for the filament, and a door to access the
> heat bed, and I started a print. It was late at
> night and the print was going to take hours. I'd
> read about others printing throughout the night,
> and I'm not used to using machines that don't have
> all the big bugs worked out. About two hours into
> the print, my dog woke me to tell me there was
> something wrong. I went into my lab and found that
> the tape had come loose and the thermistor had
> fallen out. I quickly shoved the thermistor back
> into the hole and the last reading it showed
> before I shut everything down was about 320
> degrees. Smoke was billowing from the hotend,
> which had of course melted, and my basement was
> filled with smoke from the ABS which had come very
> close to ignition.
Yes I have said before 40W heaters are dangerous. I have a couple of close shaves with wires before I switched to ribbon cable. I have a smoke alarm and a fire extinguisher in the room where my machines are. I do go out and leave them running though, so I am reasonably confident they are safe. I also don't believe in trying to live life risk free.
>
> The point here is that a Reprap could be very
> dangerous in the wrong hands. I was lucky in that
> I have a dog and I am calm about such things.
> There are however lots of people getting into this
> field who are naive and not very hands on. Perhaps
> someone more art oriented or even children who
> just want to check it out. If something like what
> happened to me were to happen to one of them, the
> results could be disasterous, to them, and to this
> Reprap community.
Yes it is almost inevitable that someone will burn their house down or electrocute themselves. I don't see how it will have much impact on the reprap community though. All DIY fields have accidents.
>I don't think that examining
> some sort of legal postion is such a bad idea. I
> also don't think that working toward certification
> is such a horrible prospect either. I don't think
> that it would be expensive either. All we really
> have to do is make the designs safe to begin with.
No they have to comply will all the other things as well. Conducted and radiated emissions need to be within limits and so does immunity to mains disturbance, radiated emissions and ESD strikes. ROHS means you need documents covering every component to show it doesn't contain banned substances like hexavalent chromium which is often found in fasteners from China.
If you think it is cheap and easy to get certification you are wrong. The company I worked for had to employ an extra full time person to handle it since CE came in and also spend thousands at external test houses for each product.
>
>
> Heathkits setup is worth examining because it is a
> similar situation. They would have been liable
> back then, long before laws legislated in 1996.
> The first drunk driving liability suits happened
> two years after the model T came out, long before
> any laws about it. I think examining their
> strategies and position on their product would be
> benificial.
I think it is too long ago and they were electrical appliances rather than machines. There is also the machinery directive, which I know nothing about, but these probably fall under that as well.
Edited 1 time(s). Last edit at 02/10/2013 08:55AM by nophead.
[www.hydraraptor.blogspot.com]
-------------------------------------------------------
>
> Heathkit sold both kits and assembled units
> (complete machines). The assembled units must have
> been certified, at least by UL, even back then,
> wouldn't they? (They've been around since 1894).
I only know about the UK. We only had to start CE marking for EMC around 1996 and LVD a year later. There must have been safety standards before then but it wasn't mandatory.
> The reason I'm going down this path Nohead is that
> I'm thinking that if one of the designs, say
> yours, or Prusa's were certified, then maybe all
> home built copies would be too, just so long as
> there were clear instuctions included for the
> exact assembly of a kit.
Somebody would have to sign a declaration of conformity to allow them to be CE marked and sold as complete machines. That person is then responsible for the safety and compliance. No way they are going to be responsible for something made by another company or individual.
>Perhaps this is something
> that we as a community could contribute to getting
> done. At minimum, the Mendal i2, or even perhaps
> yours if it is an open source design.
Mendel90 is completely open source: [github.com]
> There might
> not be that much involved in certifying several
> machines, all sharing some common design concepts
> and software/firmware.
My guess is all current designs would fail. There is a lot involved, I know because I was responsible for bringing it in for the company I worked for back in the 1996. We had to change a lot of our products because although they weren't blatantly unsafe the did not pass EMC and LVD regs without some modifications.
>The purpose of
> certification is safety, and if they are safe,
> they can't be rejected.
It isn't just safety. The is also EMC, ROHS and WEEE.
>
> I know that you've mentioned before that a bag of
> parts doesn't fall under the safety laws that are
> responsible for certifying appliances, but some
> people/companies are selling assemblies, like
> hotends and complete heatbeds.
Components can't be certified unless there is a standard covering them and building a system from certified components doesn't mean it is certified.
CE + CE != CE.
> Have you had the
> assemblies you sell certified? I don't think that
> you should have to, and given the nature and
> current situation with open source hardware and 3d
> printing, none of us should. Perhaps simply
> including a disclaimer with each kit or assembly
> stating the "experimental nature" of the systems
> would be adequate protection for suppliers. Since
> suppliers seem to be coming from all parts of the
> globe at the moment, the legal aspects of this
> situation are pretty much in the air. I do however
> agree that it would be a good idea for all of us,
> or at least you main players, to investigate
> options like this. Perhaps Heathkit came up with a
> strategy back then that could benifit all of us
> now.
Like I said, all this legislation wasn't in place back then. ROHS and WEEE are even more recent (this century) and ROHS has just become ROHS2, which is even more paperwork.
>
> Another reason I'm on about this is that when I
> first got into Repraps last fall I almost burned
> down my house. Seriously.
> I'd bought a MK4 hotend from a company in China
> that used those 40 watt heater elements. They'd
> taped the thermistor into place with a thin strip
> of Kapton tape. I installed it into my machine and
> everything seemed to be working fine. I'd also
> read, from others here, that enclosing the Mendal
> would increase the ambient temperature and prevent
> warping. I was new to this technology, but I've
> worked servicing plotters and printers for 35
> years, so this seemed simple enough. Because I was
> still at the tweaking stage, I put a large
> cardboard box around my machine with a slot in the
> top for the filament, and a door to access the
> heat bed, and I started a print. It was late at
> night and the print was going to take hours. I'd
> read about others printing throughout the night,
> and I'm not used to using machines that don't have
> all the big bugs worked out. About two hours into
> the print, my dog woke me to tell me there was
> something wrong. I went into my lab and found that
> the tape had come loose and the thermistor had
> fallen out. I quickly shoved the thermistor back
> into the hole and the last reading it showed
> before I shut everything down was about 320
> degrees. Smoke was billowing from the hotend,
> which had of course melted, and my basement was
> filled with smoke from the ABS which had come very
> close to ignition.
Yes I have said before 40W heaters are dangerous. I have a couple of close shaves with wires before I switched to ribbon cable. I have a smoke alarm and a fire extinguisher in the room where my machines are. I do go out and leave them running though, so I am reasonably confident they are safe. I also don't believe in trying to live life risk free.
>
> The point here is that a Reprap could be very
> dangerous in the wrong hands. I was lucky in that
> I have a dog and I am calm about such things.
> There are however lots of people getting into this
> field who are naive and not very hands on. Perhaps
> someone more art oriented or even children who
> just want to check it out. If something like what
> happened to me were to happen to one of them, the
> results could be disasterous, to them, and to this
> Reprap community.
Yes it is almost inevitable that someone will burn their house down or electrocute themselves. I don't see how it will have much impact on the reprap community though. All DIY fields have accidents.
>I don't think that examining
> some sort of legal postion is such a bad idea. I
> also don't think that working toward certification
> is such a horrible prospect either. I don't think
> that it would be expensive either. All we really
> have to do is make the designs safe to begin with.
No they have to comply will all the other things as well. Conducted and radiated emissions need to be within limits and so does immunity to mains disturbance, radiated emissions and ESD strikes. ROHS means you need documents covering every component to show it doesn't contain banned substances like hexavalent chromium which is often found in fasteners from China.
If you think it is cheap and easy to get certification you are wrong. The company I worked for had to employ an extra full time person to handle it since CE came in and also spend thousands at external test houses for each product.
>
>
> Heathkits setup is worth examining because it is a
> similar situation. They would have been liable
> back then, long before laws legislated in 1996.
> The first drunk driving liability suits happened
> two years after the model T came out, long before
> any laws about it. I think examining their
> strategies and position on their product would be
> benificial.
I think it is too long ago and they were electrical appliances rather than machines. There is also the machinery directive, which I know nothing about, but these probably fall under that as well.
Edited 1 time(s). Last edit at 02/10/2013 08:55AM by nophead.
[www.hydraraptor.blogspot.com]
|
Re: CE Standard Certification for RepRaps February 11, 2013 05:32AM |
Admin Registered: 11 years ago Posts: 1,063 |
nophead Wrote:
-------------------------------------------------------
> Yes I have said before 40W heaters are dangerous.
> I have a couple of close shaves with wires before
> I switched to ribbon cable. I have a smoke alarm
> and a fire extinguisher in the room where my
> machines are. I do go out and leave them running
> though, so I am reasonably confident they are
> safe. I also don't believe in trying to live life
> risk free.
the whole thermistor falling out of the hotend hole is part of the reason i designed my hotend (aluhotend) the way i have, the thermistor hole goes all the way through so a wire-on-each-side type is thermistor can be used, physically it cannot fall out and doesn't rely on tape to hold it in, anyone who has cooked a j head can atest to the lingering nature of the smell,
the assembled printers i've got up for sale here in Australia by default i have 3 fuses 1 on the stepper drivers 1 on the heated bed and 1 on the hot end, if a dead short occurs on any of these the fuse blows,
-------------------------------------------------------
> Yes I have said before 40W heaters are dangerous.
> I have a couple of close shaves with wires before
> I switched to ribbon cable. I have a smoke alarm
> and a fire extinguisher in the room where my
> machines are. I do go out and leave them running
> though, so I am reasonably confident they are
> safe. I also don't believe in trying to live life
> risk free.
the whole thermistor falling out of the hotend hole is part of the reason i designed my hotend (aluhotend) the way i have, the thermistor hole goes all the way through so a wire-on-each-side type is thermistor can be used, physically it cannot fall out and doesn't rely on tape to hold it in, anyone who has cooked a j head can atest to the lingering nature of the smell,
the assembled printers i've got up for sale here in Australia by default i have 3 fuses 1 on the stepper drivers 1 on the heated bed and 1 on the hot end, if a dead short occurs on any of these the fuse blows,
-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-
|
Re: CE Standard Certification for RepRaps February 11, 2013 05:49AM |
Registered: 11 years ago Posts: 143 |
thejollygrimreaper Wrote:
-------------------------------------------------------
> nophead Wrote:
> --------------------------------------------------
> -----
>
> > Yes I have said before 40W heaters are
> dangerous.
> > I have a couple of close shaves with wires
> before
> > I switched to ribbon cable. I have a smoke
> alarm
> > and a fire extinguisher in the room where my
> > machines are. I do go out and leave them
> running
> > though, so I am reasonably confident they are
> > safe. I also don't believe in trying to live
> life
> > risk free.
>
>
> the whole thermistor falling out of the hotend
> hole is part of the reason i designed my hotend
> (aluhotend) the way i have, the thermistor hole
> goes all the way through so a wire-on-each-side
> type is thermistor can be used, physically it
> cannot fall out and doesn't rely on tape to hold
> it in, anyone who has cooked a j head can atest to
> the lingering nature of the smell,
>
> the assembled printers i've got up for sale here
> in Australia by default i have 3 fuses 1 on the
> stepper drivers 1 on the heated bed and 1 on the
> hot end, if a dead short occurs on any of these
> the fuse blows,
After I put the temperature back up to 300 degrees to soften the peek so that I could jam it back together, I wired the whole thing together with a heavy spring wire, epoxied the thermistor permanently into the whole with muffler cement, and sealed the thing up with high temperature auto silicon. It's been working fine for months now like that, but it sure looks a mess. If I buy a replacement, I'm going to do the same thing to that one before I even try to use it. (That thermistor will have to be drilled out to replace it). I don't know how they could have shipped something like a hot end with a thermistor held in place with a tiny bit of kapton tape....
-------------------------------------------------------
> nophead Wrote:
> --------------------------------------------------
> -----
>
> > Yes I have said before 40W heaters are
> dangerous.
> > I have a couple of close shaves with wires
> before
> > I switched to ribbon cable. I have a smoke
> alarm
> > and a fire extinguisher in the room where my
> > machines are. I do go out and leave them
> running
> > though, so I am reasonably confident they are
> > safe. I also don't believe in trying to live
> life
> > risk free.
>
>
> the whole thermistor falling out of the hotend
> hole is part of the reason i designed my hotend
> (aluhotend) the way i have, the thermistor hole
> goes all the way through so a wire-on-each-side
> type is thermistor can be used, physically it
> cannot fall out and doesn't rely on tape to hold
> it in, anyone who has cooked a j head can atest to
> the lingering nature of the smell,
>
> the assembled printers i've got up for sale here
> in Australia by default i have 3 fuses 1 on the
> stepper drivers 1 on the heated bed and 1 on the
> hot end, if a dead short occurs on any of these
> the fuse blows,
After I put the temperature back up to 300 degrees to soften the peek so that I could jam it back together, I wired the whole thing together with a heavy spring wire, epoxied the thermistor permanently into the whole with muffler cement, and sealed the thing up with high temperature auto silicon. It's been working fine for months now like that, but it sure looks a mess. If I buy a replacement, I'm going to do the same thing to that one before I even try to use it. (That thermistor will have to be drilled out to replace it). I don't know how they could have shipped something like a hot end with a thermistor held in place with a tiny bit of kapton tape....
|
Re: CE Standard Certification for RepRaps February 11, 2013 06:08AM |
Admin Registered: 11 years ago Posts: 1,063 |
with the jheads i now put the thermister hole facing towards the front of the printer and i give it a paranoid poke to see if it is still secure
-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-
|
Re: CE Standard Certification for RepRaps February 11, 2013 08:30AM |
Admin Registered: 17 years ago Posts: 7,879 |
I always cement thermistors and resistors in. I don't know why people think a bit of kapton tape is OK. You want a good thermal and mechanical connection for both.
Direct shorts should shut down the PSU, so there is little point including one in series with the bed. Fuses only guarantee to blow quickly at twice their rated value and it is hard to imaging how a heated bed could take too much current without being a dead short. Also fuses drop some voltage and wear out when run at close to their max rating, especially with a load that pulses slowly. The filament expands and contracts and eventually gets metal fatigue and breaks.
I agree there should be fuses for anything were the PCB tracks or the wire gauge are not protected by the PSU current trip. It is impossible to prevent all electrical fires though as something like a small ceramic decoupling cap can develop a partial short that is not enough to blow a fuse, but is enough to burn the PCB. To make that safe you need to enclose the PCB in a fire proof box. I.e. V0 rated plastic or metal.
[www.hydraraptor.blogspot.com]
Direct shorts should shut down the PSU, so there is little point including one in series with the bed. Fuses only guarantee to blow quickly at twice their rated value and it is hard to imaging how a heated bed could take too much current without being a dead short. Also fuses drop some voltage and wear out when run at close to their max rating, especially with a load that pulses slowly. The filament expands and contracts and eventually gets metal fatigue and breaks.
I agree there should be fuses for anything were the PCB tracks or the wire gauge are not protected by the PSU current trip. It is impossible to prevent all electrical fires though as something like a small ceramic decoupling cap can develop a partial short that is not enough to blow a fuse, but is enough to burn the PCB. To make that safe you need to enclose the PCB in a fire proof box. I.e. V0 rated plastic or metal.
[www.hydraraptor.blogspot.com]
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Re: CE Standard Certification for RepRaps February 11, 2013 08:43AM |
Admin Registered: 11 years ago Posts: 1,063 |
I put the fuses on more because i don't have any faith in the short/overload features supposedly built-in to some of these power supplies, i've already had one power supply burst into flames because a fan stopped working ..... i'd rather have people replacing fuses every now and then as opposed to an entire house,
nophead Wrote:
-------------------------------------------------------
> I always cement thermistors and resistors in. I
> don't know why people think a bit of kapton tape
> is OK. You want a good thermal and mechanical
> connection for both.
>
> Direct shorts should shut down the PSU, so there
> is little point including one in series with the
> bed. Fuses only guarantee to blow quickly at twice
> their rated value and it is hard to imaging how a
> heated bed could take too much current without
> being a dead short. Also fuses drop some voltage
> and wear out when run at close to their max
> rating, especially with a load that pulses slowly.
> The filament expands and contracts and eventually
> gets metal fatigue and breaks.
>
> I agree there should be fuses for anything were
> the PCB tracks or the wire gauge are not protected
> by the PSU current trip. It is impossible to
> prevent all electrical fires though as something
> like a small ceramic decoupling cap can develop a
> partial short that is not enough to blow a fuse,
> but is enough to burn the PCB. To make that safe
> you need to enclose the PCB in a fire proof box.
> I.e. V0 rated plastic or metal.
nophead Wrote:
-------------------------------------------------------
> I always cement thermistors and resistors in. I
> don't know why people think a bit of kapton tape
> is OK. You want a good thermal and mechanical
> connection for both.
>
> Direct shorts should shut down the PSU, so there
> is little point including one in series with the
> bed. Fuses only guarantee to blow quickly at twice
> their rated value and it is hard to imaging how a
> heated bed could take too much current without
> being a dead short. Also fuses drop some voltage
> and wear out when run at close to their max
> rating, especially with a load that pulses slowly.
> The filament expands and contracts and eventually
> gets metal fatigue and breaks.
>
> I agree there should be fuses for anything were
> the PCB tracks or the wire gauge are not protected
> by the PSU current trip. It is impossible to
> prevent all electrical fires though as something
> like a small ceramic decoupling cap can develop a
> partial short that is not enough to blow a fuse,
> but is enough to burn the PCB. To make that safe
> you need to enclose the PCB in a fire proof box.
> I.e. V0 rated plastic or metal.
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Re: CE Standard Certification for RepRaps February 11, 2013 09:05AM |
Admin Registered: 17 years ago Posts: 7,879 |
Well you won't find any fuses inside a PC, but they do usually have a metal case. Theoretically they all have to comply with EN60950. The reason the 12V rail is split is so each can have a separate current limit to protect the wires, but how many actually do?
Other than preventing wires from burning fuses do very little. For example it is virtually impossible to stop the stepper motors going up in smoke if one of the drivers fails. Even with fuse in series with every winding you can still double the current, giving four times the temperature rise before the fuse will blow. The way to protect wound components like motors and transformers is to have a thermal fuse inside the wiring. Lots of mains transformers have that but I have never seen a stepper motor with one (actually it would need two). Most steppers are driven from many times there rated voltage. A simple fault in the driver will fry the motor. How do they pass any safety regs? Big can or worms!
[www.hydraraptor.blogspot.com]
Other than preventing wires from burning fuses do very little. For example it is virtually impossible to stop the stepper motors going up in smoke if one of the drivers fails. Even with fuse in series with every winding you can still double the current, giving four times the temperature rise before the fuse will blow. The way to protect wound components like motors and transformers is to have a thermal fuse inside the wiring. Lots of mains transformers have that but I have never seen a stepper motor with one (actually it would need two). Most steppers are driven from many times there rated voltage. A simple fault in the driver will fry the motor. How do they pass any safety regs? Big can or worms!
[www.hydraraptor.blogspot.com]
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Re: CE Standard Certification for RepRaps February 11, 2013 01:28PM |
Registered: 12 years ago Posts: 153 |
While talking about fire starters, this is quite interesting reading:
[www.kodiakconsulting.com] Voltage_The Incompetent Ignition Source_Final.pdf
Cheers,
Robin.
[www.kodiakconsulting.com] Voltage_The Incompetent Ignition Source_Final.pdf
Cheers,
Robin.
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Re: CE Standard Certification for RepRaps February 11, 2013 02:47PM |
Registered: 11 years ago Posts: 477 |
The address as noted is "bad". Try this instead.
In any case, the concept that low voltage can be hazardous is effectively demonstrated by the now common suggestion in camping and disaster preparedness articles about keeping a 9V battery and a tuft of steel wool as an emergency fire starter.
Low voltage "safety" is all about electrical shock hazards. It has nothing whatsoever to do with fire safety. In fact, I can create a fire hazard with a 1.5V AAA battery, and if pressed, I could probably create one using a hearing-aid battery.
In any case, the concept that low voltage can be hazardous is effectively demonstrated by the now common suggestion in camping and disaster preparedness articles about keeping a 9V battery and a tuft of steel wool as an emergency fire starter.
Low voltage "safety" is all about electrical shock hazards. It has nothing whatsoever to do with fire safety. In fact, I can create a fire hazard with a 1.5V AAA battery, and if pressed, I could probably create one using a hearing-aid battery.
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Re: CE Standard Certification for RepRaps February 11, 2013 03:34PM |
Registered: 12 years ago Posts: 313 |
I can also offer a tale of warning...
I was using a 0.8 ohm heated bed with Sanguinololu 1.3a electronics. This draws about 15 amps. I had been printing with it at least some tens of hours total, with no problems, until a print detached from the bed before it had finished. I noticed that the bed had gone cold during the print. Closer examination revealed that the bed control FET was no longer conducting even when the controller was trying to switch it on. I had a small heatsink attached to the FETs and a small fan cooling them and the stepper drivers.
So, I decided to replace the FET. I had some IRLZ44s around , so I replaced the failed FET with with one of those. These have a maximum current rating of 50 A, logic-level gate drive and 0.028 ohm on-state resistance, so I thought that I would no longer have problems. I also bypassed the partially melted bed power connector with direct wires to a Powerpole connector (these are really nice connectors, BTW).
I hadn't been printing for long after this until noticed the familiar smell of the magic smoke (the stuff that makes all electronics work). The FET had partially disintegrated and failed in the conducting state, and the bed was heating uncontrollably. The high power bed I had heats to at least to 150C, I didn't keep the print running to see how high it really goes...
Why did the FET fail? It had cooling, the current shouldn't have been a problem, the only explanation I can think of is that the electronics were driving it on and off so slowly that it spent too much time in the partially conducting state. The beefier replacement FET I used has considerably higher gate charge at 5V than the original, so that may be why it failed much sooner.
Of the electronics I have used (Sanguinololu, RAMPS and Gen6) the Sanguinololu really seems the dodgiest. In addition to the failed FET and melted connectors I have had most problems programming it (very specific software versions needed) and I have also seen it start to drive the extruder motor backwards while programming the firmware.
I was using a 0.8 ohm heated bed with Sanguinololu 1.3a electronics. This draws about 15 amps. I had been printing with it at least some tens of hours total, with no problems, until a print detached from the bed before it had finished. I noticed that the bed had gone cold during the print. Closer examination revealed that the bed control FET was no longer conducting even when the controller was trying to switch it on. I had a small heatsink attached to the FETs and a small fan cooling them and the stepper drivers.
So, I decided to replace the FET. I had some IRLZ44s around , so I replaced the failed FET with with one of those. These have a maximum current rating of 50 A, logic-level gate drive and 0.028 ohm on-state resistance, so I thought that I would no longer have problems. I also bypassed the partially melted bed power connector with direct wires to a Powerpole connector (these are really nice connectors, BTW).
I hadn't been printing for long after this until noticed the familiar smell of the magic smoke (the stuff that makes all electronics work). The FET had partially disintegrated and failed in the conducting state, and the bed was heating uncontrollably. The high power bed I had heats to at least to 150C, I didn't keep the print running to see how high it really goes...
Why did the FET fail? It had cooling, the current shouldn't have been a problem, the only explanation I can think of is that the electronics were driving it on and off so slowly that it spent too much time in the partially conducting state. The beefier replacement FET I used has considerably higher gate charge at 5V than the original, so that may be why it failed much sooner.
Of the electronics I have used (Sanguinololu, RAMPS and Gen6) the Sanguinololu really seems the dodgiest. In addition to the failed FET and melted connectors I have had most problems programming it (very specific software versions needed) and I have also seen it start to drive the extruder motor backwards while programming the firmware.
|
Re: CE Standard Certification for RepRaps February 11, 2013 05:01PM |
Admin Registered: 11 years ago Posts: 1,063 |
nophead Wrote:
-------------------------------------------------------
> Well you won't find any fuses inside a PC, but
> they do usually have a metal case. Theoretically
> they all have to comply with EN60950. The reason
> the 12V rail is split is so each can have a
> separate current limit to protect the wires, but
> how many actually do?
>
> Other than preventing wires from burning fuses do
> very little. For example it is virtually
> impossible to stop the stepper motors going up in
> smoke if one of the drivers fails. Even with fuse
> in series with every winding you can still double
> the current, giving four times the temperature
> rise before the fuse will blow. The way to protect
> wound components like motors and transformers is
> to have a thermal fuse inside the wiring. Lots of
> mains transformers have that but I have never seen
> a stepper motor with one (actually it would need
> two). Most steppers are driven from many times
> there rated voltage. A simple fault in the driver
> will fry the motor. How do they pass any safety
> regs? Big can or worms!
i tend to use the big industrial power supplies so you get a single 12v line with the capability to deliver 29amps (higher if the overload protection doesn't work) the fuses just prevent shorted wiring and/or the power-supply itself from bursting into flames, i'm not really going for anything higher than that
-------------------------------------------------------
> Well you won't find any fuses inside a PC, but
> they do usually have a metal case. Theoretically
> they all have to comply with EN60950. The reason
> the 12V rail is split is so each can have a
> separate current limit to protect the wires, but
> how many actually do?
>
> Other than preventing wires from burning fuses do
> very little. For example it is virtually
> impossible to stop the stepper motors going up in
> smoke if one of the drivers fails. Even with fuse
> in series with every winding you can still double
> the current, giving four times the temperature
> rise before the fuse will blow. The way to protect
> wound components like motors and transformers is
> to have a thermal fuse inside the wiring. Lots of
> mains transformers have that but I have never seen
> a stepper motor with one (actually it would need
> two). Most steppers are driven from many times
> there rated voltage. A simple fault in the driver
> will fry the motor. How do they pass any safety
> regs? Big can or worms!
i tend to use the big industrial power supplies so you get a single 12v line with the capability to deliver 29amps (higher if the overload protection doesn't work) the fuses just prevent shorted wiring and/or the power-supply itself from bursting into flames, i'm not really going for anything higher than that
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|
Re: CE Standard Certification for RepRaps February 11, 2013 07:40PM |
Admin Registered: 17 years ago Posts: 7,879 |
0.028R is really poor for a modern MOSFET. With 15A the dissipation when fully on is 15 * 15 * 0.028 = 6.3W. The max for TO220 without a heatsink is about 2W. With a good MOSFET RDSon is 0.003R but the PCB and connectors won't handle 15A.
PCB beds are self limiting because the resistance of copper goes up rapidly with temperature. When using a constant resistance bed you need to include a thermal cut out. I use one that trips at about 140C. SSRs and MOSFETs often fail short circuit so it is essential for safety.
[www.hydraraptor.blogspot.com]
PCB beds are self limiting because the resistance of copper goes up rapidly with temperature. When using a constant resistance bed you need to include a thermal cut out. I use one that trips at about 140C. SSRs and MOSFETs often fail short circuit so it is essential for safety.
[www.hydraraptor.blogspot.com]
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Re: CE Standard Certification for RepRaps February 11, 2013 08:01PM |
Admin Registered: 17 years ago Posts: 7,879 |
In terms of starting a fire yes it isn't the voltage that is important it is power and in particular power density. Moderate power in a tiny component will generate a very high temperature. Once it gets hot enough to char a PCB the FR4 can become conductive and heat itself.
I have known fires started by tantalum capacitors wired the wrong polarity on a low current 5V rail. They explode after a random time and eject a very hot ember which will ignite plastic.
[www.hydraraptor.blogspot.com]
I have known fires started by tantalum capacitors wired the wrong polarity on a low current 5V rail. They explode after a random time and eject a very hot ember which will ignite plastic.
[www.hydraraptor.blogspot.com]
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Re: CE Standard Certification for RepRaps February 11, 2013 09:20PM |
Registered: 11 years ago Posts: 477 |
|
Re: CE Standard Certification for RepRaps February 12, 2013 06:19AM |
Admin Registered: 11 years ago Posts: 1,063 |
on the subject of fire and burning and such here's one of my aluhotend prototypes that i've recently done a thermal runaway test on
[www.dropbox.com]
562c it topped out at, the cold side was warm but not even close to intollerable goes to show how potentially hot they can get
[www.dropbox.com]
562c it topped out at, the cold side was warm but not even close to intollerable goes to show how potentially hot they can get
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Re: CE Standard Certification for RepRaps February 12, 2013 08:05AM |
Registered: 11 years ago Posts: 514 |
I would like to point out that many CE marked goods coming from China are NOT the real CE, rather a sneaky China Export marking. Therefore, unless you are using a PSU from a well known producer, it's a safe idea to use a fuse (as Nophead wisely suggests) before seeing some burning issues :-)
Bye
Davide
==============================
no toys here...sorry
Bye
Davide
==============================
no toys here...sorry
|
Re: CE Standard Certification for RepRaps April 30, 2014 03:58AM |
Registered: 10 years ago Posts: 2 |
How shoud you interpret this article [www.electronicsweekly.com]
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Re: CE Standard Certification for RepRaps April 30, 2014 05:49AM |
Registered: 10 years ago Posts: 1,381 |
interesting...
“a combination of different products and parts designed or put together by the same person is considered as one finished product which, as such, has to comply with the directive”.
Maybe there will be a challenge through the courts one day but, in the meantime, plug-in boards such as Raspberry Pi need to be compliant.
The regulatory paperwork will be a mess for the inexperienced mom and pop company, so only big biz has the ability to sell to you.
You'll have to pay for an independent company to audit you, and then the gov't audits you, you make a mistake, pay a fine, shut your business down until you fix it, then redo the audits, lots of meetings, and phone calls before you can start again.
You'll be forced to purchase software to manage the paper trail.
“a combination of different products and parts designed or put together by the same person is considered as one finished product which, as such, has to comply with the directive”.
Maybe there will be a challenge through the courts one day but, in the meantime, plug-in boards such as Raspberry Pi need to be compliant.
The regulatory paperwork will be a mess for the inexperienced mom and pop company, so only big biz has the ability to sell to you.
You'll have to pay for an independent company to audit you, and then the gov't audits you, you make a mistake, pay a fine, shut your business down until you fix it, then redo the audits, lots of meetings, and phone calls before you can start again.
You'll be forced to purchase software to manage the paper trail.
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Re: CE Standard Certification for RepRaps April 30, 2014 06:52AM |
Registered: 13 years ago Posts: 7,616 |
Isn't it that we all do some kind of research here? Components can be put together in so many different ways there's no practical way to test all these variations against a fixed set of rulings.
| Generation 7 Electronics | Teacup Firmware | RepRap DIY |
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Re: CE Standard Certification for RepRaps April 30, 2014 01:49PM |
Registered: 11 years ago Posts: 661 |
Don't sell the kits as a single package. For example sell the board as a separate part, then sell the components as a separate part. The Mega or Rasp Pi should already be listed and RoHS compliant so at that point you are basically selling shield kits. If it's an all in one sell the microprocessor and board separate. If they enforced it at the component level companies like Farnel wouldn't be able to operate. I see that as a pretty poor interpreation of a law.
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Re: CE Standard Certification for RepRaps May 02, 2014 08:47AM |
Registered: 10 years ago Posts: 53 |
Here's the fuller version from the 'Blue Book' P15:
"A combination of products and parts,which each comply with applicable legislation, does not always constitute a finished product
that has to comply itself as a whole with a given Union harmonisation legislation40. However, in some cases, a combination
of different products and parts designed or put together by the same person is considered as one finished product which has
to comply with the legislation as such. In particular, the manufacturer of the combination is responsible for selecting suitable
products to make up the combination, for putting the combination together in such a way that it complies with the provisions
of the laws concerned, and for fulfilling all the requirements of the legislation in relation to the assembly, the EU Declaration of
Conformity and CE marking."
Here are the bits that stood out to me.
1. "A combination of products and parts,which each comply with applicable legislation, does not always constitute a finished product"
2. "However, in some cases, a combination of different products and parts designed or put together by the same person is considered as one finished product which has to comply with the legislation"
But they do not say what those cases are.
"A combination of products and parts,which each comply with applicable legislation, does not always constitute a finished product
that has to comply itself as a whole with a given Union harmonisation legislation40. However, in some cases, a combination
of different products and parts designed or put together by the same person is considered as one finished product which has
to comply with the legislation as such. In particular, the manufacturer of the combination is responsible for selecting suitable
products to make up the combination, for putting the combination together in such a way that it complies with the provisions
of the laws concerned, and for fulfilling all the requirements of the legislation in relation to the assembly, the EU Declaration of
Conformity and CE marking."
Here are the bits that stood out to me.
1. "A combination of products and parts,which each comply with applicable legislation, does not always constitute a finished product"
2. "However, in some cases, a combination of different products and parts designed or put together by the same person is considered as one finished product which has to comply with the legislation"
But they do not say what those cases are.
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Re: CE Standard Certification for RepRaps May 02, 2014 09:23AM |
Registered: 10 years ago Posts: 474 |
Certification this talk is ridiculous this stuff was certified would cost 10 times more. If You want something that certified spend the 20 K and buy a professional machine. For the most part these machines don't even have electrical enclosures no thermal fuses or correct grounding. Getting something certified is a very expensive long drawn out thing
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Re: CE Standard Certification for RepRaps May 02, 2014 09:30AM |
Registered: 10 years ago Posts: 53 |
Quote
cnc dick
Certification this talk is ridiculous this stuff was certified would cost 10 times more. If You want something that certified spend the 20 K and buy a professional machine. For the most part these machines don't even have electrical enclosures no thermal fuses or correct grounding. Getting something certified is a very expensive long drawn out thing
I think we all appreciate that it's expensive but I believe this is more about if we need certification or not and what parts (if any) of the legislation is applicable
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Re: CE Standard Certification for RepRaps May 02, 2014 09:37AM |
Registered: 10 years ago Posts: 474 |
I would say that small companies probably breaking the law and I always wondered why they weren't worried too much about lawsuits. But if you've ever had anything to do with the certification process you'd understand why by rights it is very thorough. I used to be a prototype tech at my last job one of my jobs was to build the first pieces so that they did not invest money on tooling molds and so on. The firm I worked for had at least 15 engineers and of course I always built the first piece to be sent out for certification. With all the brainpower of the engineering department double checking everything. It was never okayed the first time it was at least five major changes that had to be done and sometimes more. And of course sent out again and sometimes again. This is a very expensive process and time-consuming
Edited 3 time(s). Last edit at 05/02/2014 09:47AM by cnc dick.
Edited 3 time(s). Last edit at 05/02/2014 09:47AM by cnc dick.
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Re: CE Standard Certification for RepRaps May 02, 2014 10:42AM |
Registered: 10 years ago Posts: 53 |
I understand what goes into certification, I had to get some of the command boards on Galileo GPS certified. What I find more interesting is the situation with people selling kits, and also what exact directives repraps both as kits and as fully assembled units fall under, hence the quote from the blue book. I know its expensive but is it needed and if so which legislation.
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Re: CE Standard Certification for RepRaps May 02, 2014 04:58PM |
Registered: 13 years ago Posts: 7,616 |
Quote
cnc dick
I would say that small companies probably breaking the law and I always wondered why they weren't worried too much about lawsuits.
Probably because there is no choice. Either they sell without CE label or they don't sell at all. Another one is, with home manufacturing you never get the exactly same result twice, so there's always an opportunity to show where the customer did something wrong.
That said, this CE thing is the reason why I never sold soldered Gen7s. CE is written with ready-to-use, mass manufactured devices in mind which simply isn't applicable to homebrew experimental machines.
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