On 14 Jul 2011, at 23:33, James wrote:
If you aren't using a PCB, get a circle of plastic, drill the hole pattern and stick the pins in it.
Or you can use a method I have found works OK for me. Take the plastic middle ring from an old roll of sticky tape or similar. Find something with an internal diameter that looks as if it will make an appropriately sized socket. If the tape is waterproof it doesn't even need to be an old roll.
Melt some polycaprolactone or PCL http://en.wikipedia.org/wiki/ Polycaprolactone, aka polymorph, and push it inside the sticky tape roll so you have a solid drum. If necessary, because it has gone hard again, whack it back into some hot water, tube ring and all, for a minute so it softens.
Push your tube into the soft polymorph which is held in your piece of tube, pushing it down onto something so it sits flat and straight. Try to get it central, you can jiggle it. If it's not right, don't force it and bust your priceless tube, pull the tube out, melt the polymorph in hot water and try again. You will soon get the idea.
When the polymorph is almost set, still a bit waxy - you have access to the bottom of the tube so you can test consistency - pull the tube out.
Push the polymorph out of the tube ring and drill out the holes to suit your pin receptacles. I find D receptacles that have a crimp type end more useful than the solder bucket type, unless you are going to mount directly onto a PCB. You can also use your drilled polymorph as a drill template for the PCB, although I prefer to drill it separately.
If you need flanges to bolt your sockets into a chassis, then you can drill your chassis, bolt your bolts through with a nut on the back and then place your tube base where it's needed. Melt and press some hot sticky polymorph around the bolts and onto your socket. If hot polymorph will bond perfectly, polymorph to polymorph. You can now unscrew the bolts and you have perfect tapped holes. The nuts will probably be captive in the polymorph but you can prise them out if you are miserly.
At no time is polymorph anything near as hot as hot glue, it melts at 60 degrees C, 140 degrees F. You heat a cup of water with polymorph in it, fish it out with a spoon and can work it with your fingers pretty much immediately, it's like soft candle wax, but not as hot. If you boil it in water, the polymorph is very sticky and will act as an adhesive until it cools a little bit.
If you want to colo(u)r polymorph, then buy some kiddies dry powder paint and work that in with your fingers.
When set polymorph is like hard nylon, very tough, useful for remaking all kinds of linkages and broken/missing bits.
I also have a big chunk of Cerrobend, aka Wood's metal or Lipowitz's alloy, http://en.wikipedia.org/wiki/Wood's_metal. Cerrobend looks like a cross between zinc and lead. It also melts in hot water, 70 degrees C or 158 degrees F.
Cerrobend is not supposed to be very environmentally friendly, having 10% cadmium in it, but it does make a very good low temperature metal casting material. It thus is useful for making press mo(u)lds into which you can cast polymorph and other materials. Of course it is reusable.
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