[sudo-discuss] [CCL] Tekla Labs is about to launch a DIY Lab equipment contest

[Hol Gaskill]

Hi Jake,

I haven't crunched the numbers yet, have you?  I can assure you aluminum is generally a great material for heatsinks and sheds heat very quickly.  I've done butt welds on 1/2" aluminum plate that were cool to the touch by the time I took my glove off.  It has about a quarter the heat capacity of water so will pass on heat very quickly.  I would start with aluminum strip unless you have some gold or silver you want to donate.  The tooling and the machine are both available, and it's also incredibly easy to machine and may not even require coolant depending on the cut, for the same reason noted above, and has a pretty low melting temperature easily attainable with a blowtorch.  So it's a good material for the application, can be machined easily to the desired shape, and if testing shows that the amount of material required for the machined version has too much thermal mass for the wattage we think is reasonable, going the next step and casting it will not require too much specialized equipment other than a pattern, some casting sand, a crucible, and a blowtorch.  I'm not sure what the cost would be to have these things printed in sufficient resolution, or how the 3D printing process affects the porosity and thermal properties of the part.  The presence of air between the peltier element and the wells would be more likely to insulate, probably more than offsetting your thermal mass savings.

Cheers,
Hol


Aug 21, 2013 04:44:56 PM, jake at spaz.org wrote:
I think part of the problem with that is that if you want to make your 
>openPCR do the job in a reasonable time frame, you need to be able to 
>thermally cycle your fluids rapidly.
>
>every bit of material you have that is thermally connected to the PCR 
>vials and heating/cooling apparatus is thermal mass that you need to 
>swing, which makes your energy demand greater on your heat pump, and/or 
>slows down your PCR time.
>
>that's why the best material for touching the vials will likely be a thin 
>skin of aluminum, shaped like inverted cones on one side and flat surfaces 
>on the other side, but mostly hollow.  Such a shape would be designed in 
>openSCAD, modeled with a 3D printout, and either cast at OMI or Jim's or 
>Bernards, or more likely ordered as a metal print from Pomoko or Shapeways 
>or something.
>
>unless you don't care about PCR time, in which case yes, you can make your 
>own thermal manifold out of a block of aluminum or lead.
>
>-jake
>
>Aug 21, 2013 01:58:57 PM, patrikd at gmail.com wrote:
>> Hi Hol,
>>
>> Why don't you guys use Hackteria's drill bit to drill the wells in the 
>> aluminum heat block? They designed and ordered a custom bit specifically 
>> to match the 17.5 degree cone angle used in OpenPCR, and they're willing 
>> to let other groups borrow it. Perfect example of leveraging the global 
>> DIY community!
>>
>> http://hackteria.org/wiki/index.php/Wild_OpenPCR
>>
>> Simon Field on the DIYbio list suggested a while back to cast the heat 
>> block from a lower-melt alloy. That's potentially something that anyone 
>> with a hot plate could achieve, and you could even use your own favorite 
>> PCR tubes to make a perfectly fitting mold.
>>
>>Patrik
>
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Aug 21, 2013 04:44:56 PM, jake at spaz.org wrote:
I think part of the problem with that is that if you want to make your 
>openPCR do the job in a reasonable time frame, you need to be able to 
>thermally cycle your fluids rapidly.
>
>every bit of material you have that is thermally connected to the PCR 
>vials and heating/cooling apparatus is thermal mass that you need to 
>swing, which makes your energy demand greater on your heat pump, and/or 
>slows down your PCR time.
>
>that's why the best material for touching the vials will likely be a thin 
>skin of aluminum, shaped like inverted cones on one side and flat surfaces 
>on the other side, but mostly hollow.  Such a shape would be designed in 
>openSCAD, modeled with a 3D printout, and either cast at OMI or Jim's or 
>Bernards, or more likely ordered as a metal print from Pomoko or Shapeways 
>or something.
>
>unless you don't care about PCR time, in which case yes, you can make your 
>own thermal manifold out of a block of aluminum or lead.
>
>-jake
>
>Aug 21, 2013 01:58:57 PM, patrikd at gmail.com wrote:
>> Hi Hol,
>>
>> Why don't you guys use Hackteria's drill bit to drill the wells in the 
>> aluminum heat block? They designed and ordered a custom bit specifically 
>> to match the 17.5 degree cone angle used in OpenPCR, and they're willing 
>> to let other groups borrow it. Perfect example of leveraging the global 
>> DIY community!
>>
>> http://hackteria.org/wiki/index.php/Wild_OpenPCR
>>
>> Simon Field on the DIYbio list suggested a while back to cast the heat 
>> block from a lower-melt alloy. That's potentially something that anyone 
>> with a hot plate could achieve, and you could even use your own favorite 
>> PCR tubes to make a perfectly fitting mold.
>>
>>Patrik
>
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