Peltier for hotend on emaker
July 18, 2012 08:10PM
Hi,

I just have seen the video about Adrian's attempt to cool down the hotend with water. Then I looked at ebay for a cheap peltier (e.g. [www.ebay.de]) and now I ask myself, if I can replace the fan on the emaker hotend by such a peltier.

Would it work?

I have a barrel of stainless steel. The heater block is of copper and has a airbrush nozzle (e.g. [www.ebay.de]) at the bottom.
Re: Peltier for hotend on emaker
July 18, 2012 08:50PM
Hi,

Well, I think the water cooling is probably a better way. I have not tried any of them but the peltier uses a lot of power (if it does work), it also most likely require a heatsink attached to it. The power rating is 60W max on the one you link to, that is 5A at 12V. Introducing another 5A to your power supply may effect how well it works with the rest of your setup, bed and heater block.

Regards
Jan
Re: Peltier for hotend on emaker
July 19, 2012 08:21AM
Pros: Water cooling can actually lower the temp of the device it is cooling to below ambient temp but for all practical purposes about ambient +/- 10c.
Cons: Still requires a fan, a huge heatsink, and cost.

If you had one laying around then I say go for it but honestly for a RepRap it should be overkill because water cooling is for parts (CPU/Automobile engines/etc...) that get extremely hot and if your stepper is getting so hot you really need water cooling step away from the machine and turn it off then examine everything to see why it would need so much cooling.

In the PC world water cooling is about 100 dollars and can cool a super hot CPU by 10c-30c below a stock fan so is a really nice investment but the only reason I can see it being used in a RepRap machine is to cool the plastic on the bed only.
Re: Peltier for hotend on emaker
July 19, 2012 12:26PM
They're not talking about cooling steppers, on reprap machines steppers rarely get very hot, unless you are pushing too much current through them.
Unlike mills you just don't need significant holding torque.

They are talking about cooling hot ends, the hot end obviously has to be hot enough to melt the plastic, but you ideally want that heat concentrated in a small area near the tip. What happens is that the heat soaks by a combination of conduction and convection into the usually PEEK insulator above the heating element with PLA in particular the area above the hat part can get warm enough to soften the PLA inside the feed tube, the downward feed pressure then causes it to expand and "jam" the hotend.

To prevent this people mount fans on the Hotend blowing at the area above the heater this removes the convection portion of the heating and it usually sufficient to prevent jams.
There is some claim that the water cooling can be more compact and lighter.

However, the fan increases the moving mass, which in turn limits the maximum speed of the axis, this is why you see people working on things like Bowden tubes, or the Ultimaker design that has entirely stationary steppers, or some of the more esoteric designs like the Rostok delta robot.
Re: Peltier for hotend on emaker
July 19, 2012 12:49PM
Ahhhh, that makes more sense but I have seen so many videos with people slapping a fan there, as I said, and one on the extruder stepper. Matter of fact I have seen more with a fan on the extruder stepper motor than ones that didn't and for a Nema 17 to get that hot (one guy said it blistered him) that is just beyond ludicrous and why I mentioned what I did.

The hot end fan, so I was told, is to cool the plastic so it hardens a little faster to lessen sag after it has been extruded which makes sense but to have something blowing on a hot tip to cool the hot tip that is like trying to slap ice into a pot of boiling water to cool it but you really are after the heat for the steam.

Edited 1 time(s). Last edit at 07/19/2012 12:52PM by Dark Alchemist.
Re: Peltier for hotend on emaker
July 19, 2012 03:17PM
If you pick the right motors and the right current the extruder motor runs about 20C - 25C above ambient. The trick is to use high torque NEMA17's rated for 1.65A.


[www.hydraraptor.blogspot.com]
Re: Peltier for hotend on emaker
July 19, 2012 04:37PM
> The hot end fan, so I was told, is to cool the
> plastic so it hardens a little faster to lessen
> sag after it has been extruded which makes sense
> but to have something blowing on a hot tip to cool
> the hot tip that is like trying to slap ice into a
> pot of boiling water to cool it but you really are
> after the heat for the steam.

People also use fans to cool the plastic after is's extruded, it's common with PLA to run a fan all the time, but what the water cooling is intended to address is the issue I mentioned above, you need to keep the hot area of the hot end confined to the end of the hotend.
It is also sometime undesirable to run a fan while printing, because it causes some layers to cool too quickly which causes them to shrink and can crack the part, this is true of large ABS parts for example. The water cooling has the nice side effect of not blowing air on the part if you don't want it.
The Peltier is an interesting idea because it has a hot side and a cold side, but I'm not sure if they are efficient enough to use for something like a hotend.
Re: Peltier for hotend on emaker
July 19, 2012 06:42PM
Well, I didn't think a TEC could handle 200-250c since it is pretty much plastic. I just did some checking and the normal TEC is max 80c operating temp and a high temp one is max of 200c.
Re: Peltier for hotend on emaker
July 19, 2012 07:11PM
80C should be sufficient, though I'd put a 200C one on if it didn't cost much extra. It doesn't have to deal with nozzle temperatures, its cooling the top of the barrel. Theres not a lot of power - the hot end draws about 20W at full power, a portion of which will propagate upwards, and with the peltier running the temperature should never climb to dangerous levels. The limiting factor is how much energy you can dissipate from the hot side of the cooler.
Re: Peltier for hotend on emaker
July 19, 2012 07:14PM
The cooling side must be less than 100°C. Otherwise water would vaporize.

A 6R8 resistor will heat up the hot end with 21.2 watt @12V. A 60W peltier should be more than sufficient to keep the cooling side (where only a fraction of the 21W will arrive) cool, as it seems to me.

Could a peltier be run with pwm? Given we had an additional thermistor at the cooling side, wouldn't it mean we could influence the temperature gradient over the barrel?
Re: Peltier for hotend on emaker
July 19, 2012 07:22PM
I don't think PWM does much to anything on a TEC but I swear I read someone doing that for something non 3d printer related.

This might help you so search around the site -> [www.tetech.com]
Re: Peltier for hotend on emaker
July 22, 2012 09:03AM
A Peltier element allows cooling something colder than ambient, but if you just replace a heatsink with a Peltier, you then have 2 or 3 times the heat to remove right in the Peltier's hot side. Doesn't sound like a recipe for a lighter setup, considering that, for example, the Arcol V4 hot-end has full metal construction between the hot and cold ends and even that only needs a tiny 40x40 fan to cool the fairly small aluminium heatsink in the cold end. You'd have to redesign the cold end heatsink to accept a Peltier element and then bolt a much bigger heatsink to the Peltier. And where was the benefit in all that?

If you need to remove a lot of heat from a compact and light construction, liquid cooling is the way to go.
Re: Peltier for hotend on emaker
July 22, 2012 11:28AM
ttsalo Wrote:
-------------------------------------------------------
> A Peltier element allows cooling something colder
> than ambient, but if you just replace a heatsink
> with a Peltier, you then have 2 or 3 times the
> heat to remove right in the Peltier's hot side.
> Doesn't sound like a recipe for a lighter setup,
> considering that, for example, the Arcol V4
> hot-end has full metal construction between the
> hot and cold ends and even that only needs a tiny
> 40x40 fan to cool the fairly small aluminium
> heatsink in the cold end. You'd have to redesign
> the cold end heatsink to accept a Peltier element
> and then bolt a much bigger heatsink to the
> Peltier. And where was the benefit in all that?
>
> If you need to remove a lot of heat from a compact
> and light construction, liquid cooling is the way
> to go.
Like they do for the CPUs which has a reservoir where you fill it with anti-freeze (basically) that helps the system get colder than water would (transfers more heat than water alone) and helps to reduce rust.

With the different amounts of water blocks available for different electronics in a PC I would bet you could find something that would work else you would need a CNC/Lathe and some blocks of your own to make into a water cooling block.

In all honesty a water cooling system is just a reservoir, small fountain pump, a heat sink + cooling block, and a final cooling block with hoses attached to everything to complete the system. Fill the reservoir and turn the pump on to remove any air in the system then top off the reservoir and seal her up. Check the reservoir monthly and refill when needed. This is how we did it back in the stone age for computers now China got involved and can buy a water cooling system for dirt cheap but everything is made (machined) for a certain CPU so you would have to make something to attach it to.
Re: Peltier for hotend on emaker
July 23, 2012 05:58AM
theodleif Wrote:
-------------------------------------------------------
> The cooling side must be less than 100°C.
> Otherwise water would vaporize.
>
> A 6R8 resistor will heat up the hot end with 21.2
> watt @12V. A 60W peltier should be more than
> sufficient to keep the cooling side (where only a
> fraction of the 21W will arrive) cool, as it seems
> to me.
>
> Could a peltier be run with pwm? Given we had an
> additional thermistor at the cooling side,
> wouldn't it mean we could influence the
> temperature gradient over the barrel?

Depends on the pressure and how pure the water is, but you can raise the boiling point with pressure, but I doubt this system could generate significantly enough pressure to adjust it into a high temperature range.

You can also use additives to increase the boiling point as with car engine coolant.
Re: Peltier for hotend on emaker
July 23, 2012 06:24AM
There's no reason to use a peltier with water cooling. We don't gain anything from sub-ambient temperatures, all we need to do is keep the top of the hot end below the glass transition point. Even if we did use a pelt plus water, theres still not enough energy there to boil water at any reasonable flow rate.
Re: Peltier for hotend on emaker
July 23, 2012 05:51PM
I have a peltier element cooling the thermal barrier of one of my extruders. It works really well but a complex aluminum part to machine. That machine runs at 325oC no issues........I'll put up some pics to fill in the blanks when I'm back next week.

Weight: I have it installed on the first gen delta robot (Sell's version) and I didn't slow the print speed down because with the added weight, my X axis is nearly the same as Y. (2.4A stepper motors)

@Dark Alchemist: Yes you can use PWM to control a TEC. unlike a resitive load where you pick a frequency above audio frqs then determine the on/off time to regulate your load, a TEC changes resistance depending on temperature of the module so we need to adjust the frequency also.

around ambient temp will create a new problem.....water condensation, so you need to keep the taget temp just above ambient temp.
Re: Peltier for hotend on emaker
July 23, 2012 07:07PM
CdnReprap Wrote:
-------------------------------------------------------
> I have a peltier element cooling the thermal
> barrier of one of my extruders. It works really
> well but a complex aluminum part to machine. That
> machine runs at 325oC no issues........I'll put up
> some pics to fill in the blanks when I'm back next
> week.
>
> Weight: I have it installed on the first gen delta
> robot (Sell's version) and I didn't slow the print
> speed down because with the added weight, my X
> axis is nearly the same as Y. (2.4A stepper
> motors)
>
> @Dark Alchemist: Yes you can use PWM to control a
> TEC. unlike a resitive load where you pick a
> frequency above audio frqs then determine the
> on/off time to regulate your load, a TEC changes
> resistance depending on temperature of the module
> so we need to adjust the frequency also.
>
> around ambient temp will create a new
> problem.....water condensation, so you need to
> keep the taget temp just above ambient temp.

I guess you use a PWM for the TEC and less voltage to a water pump to keep the temp about 5c (for good measures) above ambient?
Re: Peltier for hotend on emaker
July 24, 2012 04:39AM
Quote

unlike a resitive load where you pick a frequency above audio frqs then determine the on/off time to regulate your load, a TEC changes resistance depending on temperature of the module so we need to adjust the frequency also.

I don't understand that statement. Does is make any noise if the PWM frequency is in the audio range?

The fact that the resistance changes with temperature would make the PWM to temperature relationship non linear but I don't see why the frequency would need to vary?


[www.hydraraptor.blogspot.com]
Re: Peltier for hotend on emaker
July 24, 2012 04:45AM
Quote

Does is make any noise if the PWM frequency is in the audio range?

Quite possible. If I set the heated bed PWM to 1024 Hz, I can hear the power supply singing. It's hearable in a quiet environment, far away from needing earplugs.


Generation 7 Electronics Teacup Firmware RepRap DIY
     
Re: Peltier for hotend on emaker
July 24, 2012 07:09AM
Dark Alchemist Wrote:
-------------------------------------------------------
> If you had one laying around then I say go for it
> but honestly for a RepRap it should be overkill
> because water cooling is for parts (CPU/Automobile
> engines/etc...) that get extremely hot and if your
> stepper is getting so hot you really need water
> cooling step away from the machine and turn it off
> then examine everything to see why it would need
> so much cooling.

Adrian mentioned daisy-chaining the cooling so it seems clear to me that the aim is to squeeze four or five water-cooled print heads into the space of one or two fan-cooled ones.

Andy

Edited 1 time(s). Last edit at 07/24/2012 07:17AM by ajayre.
Re: Peltier for hotend on emaker
July 24, 2012 08:04AM
ajayre Wrote:
-------------------------------------------------------
> Dark Alchemist Wrote:
> --------------------------------------------------
> -----
> > If you had one laying around then I say go for
> it
> > but honestly for a RepRap it should be overkill
> > because water cooling is for parts
> (CPU/Automobile
> > engines/etc...) that get extremely hot and if
> your
> > stepper is getting so hot you really need water
> > cooling step away from the machine and turn it
> off
> > then examine everything to see why it would
> need
> > so much cooling.
>
> Adrian mentioned daisy-chaining the cooling so it
> seems clear to me that the aim is to squeeze four
> or five water-cooled print heads into the space of
> one or two fan-cooled ones.
>
> Andy
I suppose but if you had one head and the extruder stepper needs to be cooled something is seriously wrong. Like I mentioned one burned someone and I am sorry that is just wrong on numerous levels.
Re: Peltier for hotend on emaker
July 24, 2012 10:40PM
Dark Alchemist Wrote:
-------------------------------------------------------
> I suppose but if you had one head and the extruder
> stepper needs to be cooled something is seriously
> wrong. Like I mentioned one burned someone and I
> am sorry that is just wrong on numerous levels.

If the motors are barely powerful enough and have to be run at full current they can get to 80*C above ambient temperature, which can be over 100*C. That is why we try to use motors that are more powerful so they can be run at less than their rated current.


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Re: Peltier for hotend on emaker
July 24, 2012 10:46PM
NewPerfection Wrote:
-------------------------------------------------------
> Dark Alchemist Wrote:
> --------------------------------------------------
> -----
> > I suppose but if you had one head and the
> extruder
> > stepper needs to be cooled something is
> seriously
> > wrong. Like I mentioned one burned someone and
> I
> > am sorry that is just wrong on numerous levels.
>
> If the motors are barely powerful enough and have
> to be run at full current they can get to 80*C
> above ambient temperature, which can be over
> 100*C. That is why we try to use motors that are
> more powerful so they can be run at less than
> their rated current.
Exactly my point and if you need to cool them then it is time to step back away from the printer and go to eBay, or w/e, and buy a new bigger Stepper motor because the current one is under rated for the purpose in which you are using it.
Re: Peltier for hotend on emaker
July 26, 2012 12:06AM
Dark Alchemist Wrote:
-------------------------------------------------------
> Exactly my point and if you need to cool them then
> it is time to step back away from the printer and
> go to eBay, or w/e, and buy a new bigger Stepper
> motor because the current one is under rated for
> the purpose in which you are using it.

I was agreeing with you smiling smiley


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Just click "Edit" in the top-right corner of the page and start typing.
Anyone can edit the wiki!
Re: Peltier for hotend on emaker
July 26, 2012 03:40PM
I agree - get more powerfull motors

This might be off topic.

Cooling motors (either water cooled or peltier) could have merit if you have your machine enclosed AND you want to have a really high enclosure temp.

If they are peltier cooled they would also help heating the enclosure.

Some materials you need a really high enclosure temp to get good results. (PPSF, Ultem and PC run ....~125oC)
Re: Peltier for hotend on emaker
July 26, 2012 05:34PM
NewPerfection Wrote:
-------------------------------------------------------
> Dark Alchemist Wrote:
> --------------------------------------------------
> -----
> > Exactly my point and if you need to cool them
> then
> > it is time to step back away from the printer
> and
> > go to eBay, or w/e, and buy a new bigger
> Stepper
> > motor because the current one is under rated
> for
> > the purpose in which you are using it.
>
> I was agreeing with you smiling smiley

I was with you, lol. smiling smiley
Re: Peltier for hotend on emaker
September 08, 2014 05:33PM
Hey,how much power is your peltier cooler? do you have any pictures? My geeetech hotend is jamming due to filament expansion in the barrel and I think it's because the fan it came with is insufficient. This is the one I have, [www.geeetech.com]
Re: Peltier for hotend on emaker
September 09, 2014 07:38PM
I don't think peltiers are currently practical, but I think they may have some merit in the future as combination heating/cooling units. If small, high power, heat resistant peltiers where available, they could be used to heat the nozzle with cooling of the barrel as a byproduct of sorts.
Re: Peltier for hotend on emaker
September 09, 2014 07:49PM
Quote
Svdharma
I don't think peltiers are currently practical, but I think they may have some merit in the future as combination heating/cooling units. If small, high power, heat resistant peltiers where available, they could be used to heat the nozzle with cooling of the barrel as a byproduct of sorts.
Now that I agree with. Maybe one day but by then I am sure another, and better, technology will be here for 3d replicating, etc...

Very High Temperature (VT) modules are rated for temperatures up to 200°C So I guess Extremely High Temperature modules is what we are after. Something up to 300c, I think, would be just the ticket.

Edited 1 time(s). Last edit at 09/09/2014 07:51PM by Dark Alchemist.


_______
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