Peltier heated bed

How about condesation on the cold side?

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Custom all metal CoreXY
- Duet 2 Wifi w/ PanelDue 7i
- 330mm x 360mm x 500mm
- 750w Silicon heater

Custom Mendel90
(Backup printer - Old reliable!) - Sold

@Emmanuel
What about price. How much did the peltier you are using cost?

-Nick

N314 Wrote:
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> @Emmanuel
> What about price. How much did the peltier you are
> using cost?
>
> -Nick

He already said. $5-6. I've seen them for about $3 in quantity on eBay.

Mogal Wrote:
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> How about condesation on the cold side?

The "cold" side doesn't really get cold in this type of setup. In fact, it shouldn't get below room temperature at all.

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In this use, both sides are kept at approx the same temperature meaning that it acts just like a resistor.

If you was to attach a heatsink / fan to the "cold" side, it would also operate as a form of heat pump, meaning that it would be more efficient in terms of the electrical energy used versus the heat produced on the "hot" side.

A couple of comments. My guess is that in order to enjoy the increased efficiency of heating using the peltier, you need the "cold" side to be in good thermal contact with the room ambient (a heat sink on the cold side and a fan would be good). Otherwise, the heat available to be pumped across the Peltier would be limited but what can be moved into the bare Peltier side.

If you have a source of cheap Peltiers (cheaper than power resistors) and you need to heat and you are concerned about power efficiency, it could make senses to use Peltiers. It would seem to me to make a lot of sense if you wanted to both heat and cool (very tight temp control or active cooling post print). My experience with Peltiers is that they can be fussy to use in terms of mounting them and achieving high reliabilty. They are easy to crack if torqued down too hard and they are subject to failures due to repeated thermal cycling weakening the internal solder joints. If you plan to use them, I would recommend studying the applications literature at one of the major Peltier manufacturers.

Also, per the question of stacking them to get better heating, they can be purchased that way, typically with the goal of getting the very coldest temperatures. These stacked arrangements have something like 1/3 the area peltier on each successive layer...say for example, a 1 square inch device on the bottom, next a 1/3 square inch device, next a 1/9 square inch device. Not more than three stacked usually. The 1/3 ratio relates directly to their efficiency and the need to more the heat out.

So, whatever works for you, well...works. But it is, in my experience, rare to find a heat only application (save for where *very tight* temperature regulation is needed) that doesn't use simple resistive heating.

@N314
I think I already linked it somewhere, but I'm using this one : [cgi.ebay.com]

For the peltier effect, I see it more like a pump than a "cold/hot sides", so in my setup I keep the cold side warm by having some insulation, thus, I guess, the heat is just circulating (using the heat from the bed rather than looking to pump the normal ambient heat) and you only need to compensate for the dissipation of the bed (which at 4-5mm thick have a good inertia, it take quite a long time to cool down from 53°C to 20°C)

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this is definately interesting ... i have about 30-40 peltiers lying around ...

GIven you have what I called the hot side on the bed and cold side up against insulation, my guess is that the Peltier is working like a resistor i.e. the amount of heat you are getting into the bed equals the power you are putting in...virtually no efficiency gains due to "pumping" action...not unlike running an air conditioner inside a closed room (knew someone who did this and couldn't figure out why the room was heating up...). So if you have a source of cheap peltiers, why not...they certainly have a nice form factor in terms of thermal contact with the bed. Question: how are you holding them on? Typically, they are mounted with a controlled force using thermal grease so that any difference is thermal expansion between the peltier and what is being heated or cooled won't crack the ceramic on the peltier while still getting good thermal transfer. I believe using a hard adhesive like epoxy could be trouble.

Quote

Question: how are you holding them on?

Kapton + thermal grease

The kapton is definitely held in place by the wood insulation: [reprap.org]


I couldn't resist to add this pic :

My prints were never such at the edge of the plate x)



Got a little curling this time

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about // liberapay // flickr // wiki // thingiverse - github

I mention Peltier heated cooled bed in multi development page Quad
Doug

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D. Goncz
See Also KSRM p.40 footnote
ORCID (r) is 0000-0001-5483-448X

1979 Thesis at MIT in XXV: Self-Replicating Shelter

Coined "Replikon" in 1984 to include machine tool building shelter

Built S/R 4 Axis Mill in 1997, Sold $300, 1 of 2, enough to build 2 more

Now working on RepStrap Bateson, from Unimat One to X Axis for $50 or so;
From 1 X Axis to 12 X Axes in a Cube for < $600
Groups of 4 make XYZ Inside WLO Generality
Diagonal Axis is Vertical
Arrays to Billions
Wraps in Octets
Adds/Subtracts
Also Foundry!

The signature is a pretty uncommon place to put your resumé. Are you applying for a job here?

Quote

D. Goncz
See Also KSRM p.40 footnote
ORCID (r) is 0000-0001-5483-448X

1979 Thesis at MIT in XXV: Self-Replicating Shelter

Coined "Replikon" in 1984 to include machine tool building shelter

Built S/R 4 Axis Mill in 1997, Sold $300, 1 of 2, enough to build 2 more

Now working on RepStrap Bateson, from Unimat One to X Axis for $50 or so;
From 1 X Axis to 12 X Axes in a Cube for < $600
Groups of 4 make XYZ Inside WLO Generality
Diagonal Axis is Vertical
Arrays to Billions
Wraps in Octets
Adds/Subtracts
Also Foundry!

He just woke up from a 6 years old coma, like this thread

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

Yeah

My signature ranges from null to very long and it is rather odd habit

I have an IQ of like 166 and severe brain damage

I hope the method did not trouble anyone

Dgoncz