Fastening & Attaching

Today we explored different methods of connecting pieces of Delrin.  Delrin is difficult to glue with most available glues.  Therefore we explored using heat staking and piano wire to connect the two pieces.

Heat Staking
Heat staking is where you stick part of one piece of Delrin through a hole in another and melt the Delrin so that the two pieces are melted together.
It is done on this machine:
heat stake machine

the pieces before melting

the joined piece afterwards

Heat staking makes a really stable and solid connection between two pieces of Delrin.  The connection is permanent which may be a pro or a con in this category.

One can imagine heat staking for a rigid outer wall encasing that you don't want to be rigid, and don't want other people to take apart.

Piano Wire
The idea is to make a hinge and connect the hinge with a piece of piano wire.  The finished product should look like this:
the finished,  joined pieces. 

the component parts

First you drill a hole through both parts

By using different methods of



Tight [and also not very tight] fit using slots or pegs
You can just use friction between two pieces to keep them together.

example of slots in slot holes

example of pegs bushings fitting in the holes of bushings 






pros and cons of fastening

Pros and Cons of Delrin Joining Methods

	Pros	Cons
Heat Staking	permanent  rigid you might not want a bump	permanent (making a mistake means redoing a piece) rigid planning ahead requires heat staking machine
Piano Wire Hinge	Flexible! its a hinge pieces not permanently attached secure attachment is possible	drilling a hole wrong may mean redoing the piece take time and skill to drill proper holes using drill press
Tight Fit	not permanently attached No other machines other than the delrin cutting machine is required	attachment not secure lots of planning beforehand, not only on designs, but on fitting measurements

Obviously for the tight fit method to properly connect two pieces of Delrin, the measurements of the fitted pieces must be really close to each other for there to be a tight fit.

Precise measurements is very important.  For measuring we use calipers.




one might need tight bushings to prevent things from sliding off the end
you might want loose bushings and a loose connection to

Delrin Rod and Bushing

Bushing fit type	lowest measurement	highest measurement
rod	6.34	6.34
press fit	6.23	6.39
tight	6.35	6.40
tight (snu	6.56	6.60

Delrin peg and slots

Bushing fit type	lowest measurement	highest measurement
peg	5.1	9.9
press fit	5.1	9.86
tight
tight (snu