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PI mod. coiled nichrome wire
j_allen
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Posted on 02/04/2011 10:42 AM
Just finished my first mod. of the PI; increased the size of the roasting chamber, removed the thermostat and rewired the fan.

All works fine, but...the coil only glows orange on 25%. It doesn't seem to have the same distance between the coils as it wraps around the ceramic. The hot portion of the element has very close spacing, and the rest seems rather stretched.

By probing the chamber, I have significant variation in temperature from the glowing side-440 vs. the non-glowing side-375.

A couple questions...

1. Shouldn't i be able to see it glow continuously as i look down into the roast chamber?

2.Where can i buy replacement coiled nichrome wire?
a.what are the tolerances for this machine for the coiled nichrome wire?

3. Appx. what temperatures are people getting with an empty chamber and a removed thermostat?

Awesome site! Thanks for all the help.

Jim
 
Dan
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Posted on 02/04/2011 11:45 AM
Here are some tips:

You want the space between the coils to be twice the diameter of the wire as a minimum.

Uneven heating could possibly be caused by uneven spacing and/or uneven cooling.

Get your wire from: http://www.infrar...aters.com/
Edited by seedlings on 02/04/2011 11:18 PM
 
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allenb
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Posted on 02/04/2011 7:58 PM
Another good source of nichrome wire, thermocouple wire and the design formulas needed to design your own elements is:

http://www.pelica...eform1.asp

Using their formulas and tips I was able to design and wind my own elements using a steel rod chucked into my drill press (using very slow rpm). Although a lathe would have been a whole lot easier.

Allen
1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
 
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