Heatbed Heater Options November 26, 2014 03:24PM |
Registered: 10 years ago Posts: 42 |
Re: Heatbed Heater Options November 26, 2014 07:07PM |
Registered: 10 years ago Posts: 14,672 |
Re: Heatbed Heater Options November 26, 2014 08:26PM |
Registered: 10 years ago Posts: 42 |
Re: Heatbed Heater Options November 27, 2014 12:50AM |
Registered: 12 years ago Posts: 799 |
Re: Heatbed Heater Options November 27, 2014 04:16AM |
Registered: 10 years ago Posts: 14,672 |
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twicx
The silicone ones, although they seem to be good solutions, they seem messy between relays and using mosfets etc.
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twicx
. and it still leaves me with the problem of the awkward mounting holes on the aluminium plate.
Re: Heatbed Heater Options November 27, 2014 06:43AM |
Registered: 10 years ago Posts: 42 |
Re: Heatbed Heater Options November 27, 2014 07:22AM |
Registered: 9 years ago Posts: 1,159 |
Quote
twicx
So by the sounds of it, I'm going to need something between the Rumba, the power supply and the heater(s). This makes it tricky.
The first problem is the mounting points. Because of the design of how the bed is mounted to the z axis gantry, the mounting points for anything is going to be a tricky issue. My printer (Felix 1.5 Rev.E) uses 3 mounting points for the Heated bed. One is in the centre of the heated bed, and the other two are in the corners. However, if I move to a larger print bed, for example, 300mm x 300mm, Those two corner mounting points move up along the edge by about 1/3. So the centre mounting point would be the same, but the two other corner ones would still be on the edges, but about 40-60mm from the corner. Looking at the PCB option, I think I made an error in thinking that the holes in the middle of them are another mounting point. I think they're for the thermistor.
The next problem is the power supply. I've already gotten a new ATX power supply that puts out 58A at 12V, so I would like to try to stick with that one, rather than go to 24V.
This brings me back to the whole heater issue. By the sounds of it, I need something to manage the power (it's going to be >10A) in or around the Rumba/Heater/Powersupply. What would be my cheapest/best/easiest solution for that?
As for the heaters, I still like the convenience of the PCB one in that I can keep the weight of the heat bed down. It looks like I can drill outside of the white boundary line where the traces are, but then I still have the problem of that 3rd mounting point in the centre of the board, which I'm not so sure how to tackle. I'm still very reluctant to use the silicone ones, and I'd favor the kapton foil option over those, as they're cheaper, adhesive, and maybe 4 x foil heaters might be an option.
Edit:
[www.alibaba.com]
This is the kind of printbed I have in mind. The ideal (albeit optimistic) setup would be that, use the center hole as the 3rd mount point, drill two new mount points up from the corners (you can also see the white border), and then figure out how to manage the power supply bit. Is this possible?
Re: Heatbed Heater Options November 27, 2014 07:25AM |
Registered: 10 years ago Posts: 42 |
Quote
dougal1957
Quote
twicx
So by the sounds of it, I'm going to need something between the Rumba, the power supply and the heater(s). This makes it tricky.
The first problem is the mounting points. Because of the design of how the bed is mounted to the z axis gantry, the mounting points for anything is going to be a tricky issue. My printer (Felix 1.5 Rev.E) uses 3 mounting points for the Heated bed. One is in the centre of the heated bed, and the other two are in the corners. However, if I move to a larger print bed, for example, 300mm x 300mm, Those two corner mounting points move up along the edge by about 1/3. So the centre mounting point would be the same, but the two other corner ones would still be on the edges, but about 40-60mm from the corner. Looking at the PCB option, I think I made an error in thinking that the holes in the middle of them are another mounting point. I think they're for the thermistor.
The next problem is the power supply. I've already gotten a new ATX power supply that puts out 58A at 12V, so I would like to try to stick with that one, rather than go to 24V.
This brings me back to the whole heater issue. By the sounds of it, I need something to manage the power (it's going to be >10A) in or around the Rumba/Heater/Powersupply. What would be my cheapest/best/easiest solution for that?
As for the heaters, I still like the convenience of the PCB one in that I can keep the weight of the heat bed down. It looks like I can drill outside of the white boundary line where the traces are, but then I still have the problem of that 3rd mounting point in the centre of the board, which I'm not so sure how to tackle. I'm still very reluctant to use the silicone ones, and I'd favor the kapton foil option over those, as they're cheaper, adhesive, and maybe 4 x foil heaters might be an option.
Edit:
[www.alibaba.com]
This is the kind of printbed I have in mind. The ideal (albeit optimistic) setup would be that, use the center hole as the 3rd mount point, drill two new mount points up from the corners (you can also see the white border), and then figure out how to manage the power supply bit. Is this possible?
Try looking at a Solid State Relay these can be driven by your Rumba board easily and still switch the high current dc that you need They are available in various Current rating's
Doug
Re: Heatbed Heater Options November 27, 2014 11:03AM |
Registered: 10 years ago Posts: 14,672 |
Re: Heatbed Heater Options November 27, 2014 11:09AM |
Registered: 10 years ago Posts: 42 |
Quote
dc42
Although those Fotek DC-DC SSRs are easy to wire up, unfortunately they have quite a high maximum voltage drop (1.6V, see [www.fotek.com.hk]) and hence there will be a lot of heat to get rid off. You would be better off using 2 mosfets (chosen for very low Rds(on) @ 4.5V gate voltage) wired in parallel.
Re: Heatbed Heater Options November 28, 2014 07:13PM |
Registered: 10 years ago Posts: 42 |
Re: Heatbed Heater Options November 29, 2014 03:59AM |
Registered: 10 years ago Posts: 14,672 |
Re: Heatbed Heater Options November 29, 2014 07:17AM |
Registered: 10 years ago Posts: 42 |
Re: Heatbed Heater Options November 29, 2014 01:04PM |
Registered: 10 years ago Posts: 14,672 |
Re: Heatbed Heater Options December 01, 2014 05:25AM |
Registered: 10 years ago Posts: 42 |
Re: Heatbed Heater Options December 23, 2014 10:33AM |
Registered: 10 years ago Posts: 42 |
Re: Heatbed Heater Options December 23, 2014 12:26PM |
Registered: 10 years ago Posts: 14,672 |
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twicx
1. On the RUMBA board, there's 2 terminals for HB-PWR, which normally connects to the PSU. They're right beside the HB-OUT. If I'm using a SSR Relay, what do these connect to?
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twicx
2. This was one of the diagrams I was looking at for working this out: RELAY CONFIG
The pinouts are a little confusing, as far as +/- on the board, +/- on the heat bed, and +/- on the relay. I would have thought that the +/- have to all line up. I know this sounds like a realy electrical noob question, but it's essentially just a loop from +12V on the ATX to the GND on the ATX (like in my diagram?) Is this correct?
Quote
twicx
3. I've seen a few diagrams with things like lamps and resistors and diodes across things, and others without them. I know it was mentioned earlier that I will need to test my new PSU to see if it needs a load at the 5V to power on, and if so, there's a few options like a fan or a resistor, but I'm specifically talking about the head bed/relay section. Do I need all these extra diodes and lamps?
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twicx
4. As far as the relay itself goes, my preference is to order something from this site: http://ie.rs-online.com/web/
I'm going to be ordering some stuff from them in the new year for a completely un-related project (Guitar amps) and it would save me on shipping. The only problem is, they have about 2000 different SSRs, and I have no idea what the exact one I'm looking for. They have things like zero-cross over things and I'm a bit lost. What would be the most exact description of it?
Re: Heatbed Heater Options December 23, 2014 12:36PM |
Registered: 10 years ago Posts: 42 |
Quote
dc42
No, not for the heated bed/relay section. But you will probably need a load on the 5V output from the ATX supply to keep it happy. If you will be using an LCD display, the backlight of that display may be enough load for the 5V output, and by connecting the backlight there instead of to the Rumba 5V output, you will keep the 5V regulator on the Rumba cooler.
Quote
dc42
Zero-crossing and random-fire only refer to SSRs used for switching AC loads. You cannot use an AC SSR to switch DC. This rules out most SSRs. In the parametric selector on the RS Solid State Relay page, under "Output device" deselect "triac" and "paired SCR". Of the ones left, this one [uk.rs-online.com] is the cheapest I found that can handle 20A. Check the datasheet for heat sinking requirements - the 20A rating is with a heatsink. You may be better off using an SSR rated at e.g. 40A, because at 20A it will need little or no heatsinking.
Re: Heatbed Heater Options December 23, 2014 01:16PM |
Registered: 9 years ago Posts: 1,159 |
Quote
twicx
Quote
dc42
No, not for the heated bed/relay section. But you will probably need a load on the 5V output from the ATX supply to keep it happy. If you will be using an LCD display, the backlight of that display may be enough load for the 5V output, and by connecting the backlight there instead of to the Rumba 5V output, you will keep the 5V regulator on the Rumba cooler.
Ok grand. My instinct is to run one of the always-on fans off this, as I'm not using an LCD display, or maybe something like an LED. Something simple.
Quote
dc42
Zero-crossing and random-fire only refer to SSRs used for switching AC loads. You cannot use an AC SSR to switch DC. This rules out most SSRs. In the parametric selector on the RS Solid State Relay page, under "Output device" deselect "triac" and "paired SCR". Of the ones left, this one [uk.rs-online.com] is the cheapest I found that can handle 20A. Check the datasheet for heat sinking requirements - the 20A rating is with a heatsink. You may be better off using an SSR rated at e.g. 40A, because at 20A it will need little or no heatsinking.
Ah ok, well at least now I'm clear on what I'm looking for. I would be inclined to pay that bit more for the 40A one to avoid the heatsink. I think the heatbed is going to end up with a current draw of something between 10 and 15A, but i'll have to wait till it arrives to measure it exactly. At least now it's a bit clearer.
Thanks again for the help. Its top of my to-do list after my exams on the 6th.
Re: Heatbed Heater Options December 23, 2014 01:18PM |
Registered: 10 years ago Posts: 42 |
Re: Heatbed Heater Options December 23, 2014 01:21PM |
Registered: 9 years ago Posts: 1,159 |
Quote
twicx
That's a damn sight cheaper. I might go for that, or, at the very least, use it as a reference for finding what i need.
Thanks again!
Re: Heatbed Heater Options December 23, 2014 06:16PM |
Registered: 10 years ago Posts: 14,672 |
Quote
dougal1957
Quote
twicx
That's a damn sight cheaper. I might go for that, or, at the very least, use it as a reference for finding what i need.
Thanks again!
I quoted this earlier in the thread and DC42 did say that they have a high Voltsdrop across them so you may have to increase your supply Volts to it or use a slightly lower resistance on your bed to compensate for it (I am no expert on SSR's and I plan on using a AC Fed silicon heater on my large build).
Doug
Re: Heatbed Heater Options December 24, 2014 01:35AM |
Registered: 9 years ago Posts: 1,159 |
Quote
dc42
Quote
dougal1957
Quote
twicx
That's a damn sight cheaper. I might go for that, or, at the very least, use it as a reference for finding what i need.
Thanks again!
I quoted this earlier in the thread and DC42 did say that they have a high Voltsdrop across them so you may have to increase your supply Volts to it or use a slightly lower resistance on your bed to compensate for it (I am no expert on SSR's and I plan on using a AC Fed silicon heater on my large build).
Doug
Yes it does quote a relatively high voltage drop on the datasheet (1V maximum), but so does the 40A one from RS. Either of them is likely to need a heatsink to carry 15A.
Re: Heatbed Heater Options December 24, 2014 03:00AM |
Registered: 10 years ago Posts: 14,672 |
Re: Heatbed Heater Options December 24, 2014 06:20AM |
Registered: 9 years ago Posts: 1,159 |
Quote
dc42
The 100 degC or so that you need on the hot bed for printing ABS is too hot for cooling the SSR.
I am tempted to design a heat bed switch that has a much lower voltage drop than an SSR but still provides isolation. But I suspect that the demand would be too low to make it worth my while having some built.
Re: Heatbed Heater Options December 24, 2014 08:37AM |
Registered: 10 years ago Posts: 14,672 |
Quote
dougal1957
Quote
dc42
The 100 degC or so that you need on the hot bed for printing ABS is too hot for cooling the SSR.
Thought that may be the case If I was to use one it would go under my Bottom plate underneath the printer along with the rest of the Electronics PSU's and motors but as my heatpad is a 400mm x 400mm 230V AC Silicon heater it shouldn't be anywhere near the same issues (I will be using a SSR to switch it). It has an inbuilt thermocouple that I would like to use just not sure how to yet more research is needed I think!
Re: Heatbed Heater Options December 24, 2014 09:20AM |
Registered: 9 years ago Posts: 1,159 |
Quote
dc42
Quote
dougal1957
Quote
dc42
The 100 degC or so that you need on the hot bed for printing ABS is too hot for cooling the SSR.
Thought that may be the case If I was to use one it would go under my Bottom plate underneath the printer along with the rest of the Electronics PSU's and motors but as my heatpad is a 400mm x 400mm 230V AC Silicon heater it shouldn't be anywhere near the same issues (I will be using a SSR to switch it). It has an inbuilt thermocouple that I would like to use just not sure how to yet more research is needed I think!
The current drawn by your mains-voltage heatbed should be very low (I am guessing 1 to 2A), so the heat generated by your SSR will be much lower than the heat generated by twicx's DC SSR carrying 15A. You can use an inexpensive zero-crossing AC SSR.
Re: Heatbed Heater Options December 26, 2014 08:12PM |
Registered: 10 years ago Posts: 42 |
Re: Heatbed Heater Options December 27, 2014 03:44AM |
Registered: 10 years ago Posts: 14,672 |
Re: Heatbed Heater Options December 27, 2014 09:54AM |
Registered: 10 years ago Posts: 42 |