By Peter Twissell - 11/14/2019 1:48:32 PM
Hello,
By way of introduction, I am a professional engineer and home workshop hobbyist. For the last 6 years, I have been gradually building a 7 cylinder radial engine of my own design, manufacturing all the parts myself.
For the ignition system I need a unique distributor cap. At the time of design, I specified phenolic resin, which is what all the rest of the world uses to make distributor caps. Now that I come to make the moulds, I find I can no longer buy the resin.
I am now looking at polyester resin as an alternative (low water absorbtion, tolerable thermal stability and dielectric constant).
I have read some generalised information warning about accurate mix ratio depending on the mould depth.
I am using a heavy, machined aluminium 2 piece mould. Brass conductors will be pre-assembled and overmoulded with the resin. The part thickness is 4mm in most places, with small areas up to 8mm.
Are the warnings about excess heat generation likely to be based on light, non thermally conductive moulds (silicone etc.)?
What will be the effect of my mould drawing heat away from the resin? Will it simply slow down the curing, or will it prevent complete curing?
Alternatively, does anyone know where I could get hold of some phenolic resin?
Thanks in advance,
Pete.
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