casting threads in aluminite

[me2cyclops]

who has tried casting threads into aluminite?
has it worked?
my idea was to turn a delrin rod to the size of hole for a FP cap with a threaded section at the base, cast around it and unscrew the delrin after it cures.
any reason this will not work?
I have taken into consideration that it will shrink away from the delrin and mold a bit and so I could cut my threads on that slightly smaller than normal, how much smaller I'm not sure yet .
how much (%) will it shrink as it cures?

 

[jthompson1995]

Alumilite does not shrink as it cures.

 

[BRobbins629]

It should work. I have done it in silver so there's no reason why it wouldn't work in alumilite. My only question is why not cut the threads directly in alumilite?

 

[me2cyclops]

why?
one , just to see if it will work
two , I'M CHEAP if it works it should save 40-50 % of resin/cap blank !, I hate to pour in material that I'm soon going to just drill back out. it would be more efficiant , less waste = greener pens :biggrin:

third if it works I could make up some extra mandrels to allow others to make kitless pens with three start threads without buying $$ tap and die sets

 

[td]

Shrinkage for Alumilite Clear is .005

Bruce is right. You're safer cutting the threads after casting.

 

[td]

Better yet... cast just as you suggest only without the threads. Therefore no waste... and better fitting threads. But then again.... this is only one opinion.

 

[workinforwood]

I like the way you think. yes, there is shrinkage with alumilite, even though it is minimal, but I still think it would work, and not only that, your threads will be very polished and clean. My theory is that the shrinkage will be from the outside in, so with the pressure on, the threads won't shrink in size, just the outside of the blank will. Othewise, when you cast something like wood, wouldn't the alumilite want to pull away from the wood the .05% or whatever it is? Just my theory...it never hurts to give it a try.

 

[me2cyclops]

I thought this stuff would not stick to delrin Grrrr....

what easily obtainable substance would make a compatable mold release for alumilite? butter flavor pam perhaps?

 

[workinforwood]

Johnson's paste wax.

Stick to delrin..well if the delrin is rough it might, but if it is smooth it won't. Try giving it a couple raps, or drop it on the floor and then it might just completely release. It sticks to the cutting boards, but sticks and adhere's are two different things. Sticking means it's stuck on but can pop off, adhering means it's stuck on for good. Alumilite is pretty flexible, and thus easy to unstick from the delrin. Drop it, rap on it, squeeze it, it will come loose.