Friday, January 23, 2015

Heaters.

So much of my design lately centers around heaters.

My regular gig, I build 3D printers for a living.  The printers I have spent over a year now working on utilize heaters.  

I have been using 12volt DC heaters in the form of silicone pads from China.  The downside to this arrangement is that I need a large power supply.  40 amps is a lot of juice and money adds up fast in wires, connectors, etc.

So today I started working on making my own heater.  

I purchased a length of NiChrome wire from the local heating supply company, and set to work.

First attempt turned out really bad.  

I tried to cheese it by using regular household silicone caulk.  It didn't set right and turned cuumbly.

Today's attempt was different.  

I used a sheet of Mica, taped the NiChrome wire to the sheet with kapton tape, then added silicone RTV, making a sandwich of silicone RTV, mica and heater wire, with a thermistor handling the temp reading.  

I had success...

Well kind of....

The thing works.  Draws 254 watts at 220v AC.

Heated up to 120c no problem.

Except that the silicone is not curing properly.  I think I got an old tube. It remains sticky.

So tomorrow I'll grab a tube of new silicone rtv and hope the catalyst in it will get the other stuff to cure as well with another layer on it.  

It is just a prototype and although it is the shop machine, so I do use it to make stuff.




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