Dicing with Delrin - A Repair Job.

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Pete W.:
Why didn't I think of that?!?! :doh: :doh: :doh:

awemawson:
... so much bullshit you should have a herd of cattle ... :lol:

Joules:
Ha ha Pete, if only shrinkage was so simple...

http://www.dupont.com/content/dam/dupont/products-and-services/plastics-polymers-and-resins/thermoplastics/documents/Delrin/Delrin®%20%20Acetal%20Homopolymer%20Resin%20–%20Molding%20Tips.pdf

I don't tend to follow convention and enjoy the challenge of coming up with my own solutions. I doubt the above outfit would approve of our methods, but at the end of the day we do what we have too to get the job done. I tend not to worry over shrinkage for small parts, if I am making something precise in house I will mould then machine to size where required. I have a small injection moulder, but it's not suitable for Delrin.

Hmmmm, for some reason I can't paste the above link as it breaks at the Copyright symbol in the URL ??? However it works if you copy and paste it. :doh:

Pete W.:
Well, I'm happy to have some more progress to report.

I've now profiled all five dominos and drilled the holes for the M2 grub-screws - they just need tapping but I intend to do that indoors and by hand.

The profiling is simple but tedious, once the saddle & vertical slide were brought into position by offering the end of the end-mill to the flank of the original mount (damaged, but not on its flank) it was just a matter of mounting each blank on the profiling fixture (see photos), traversing the cross-slide to take a small cut, turn the blank ever-so-slightly, take the next cut and so on and so on!!! Getting and maintaining a routine was important - if the mind wanders it would be too easy to forget to de-clutch the lathe while re-positioning the work-piece and those fingers would be ever so close to that cutter!!!

Once I'd finished the profiling, I re-mounted the original mount on the fixture, swapped the end-mill for a drill chuck and the M2 tapping size drill and adjusted to align the drill with the grub-screw hole. Swap the original mount for each of my efforts in turn and drill the holes, this time only the saddle moves, the cross-slide & vertical slide stay put.

I'm hoping to see my neighbour tomorrow to ask him if I can use his belt sander. Profiling with the end-mill leaves a finish not a million miles from a fine knurl but before I declare that the end result I'll see how an off-cut of Delrin responds to the sander.

I set out to 'process' five blanks in case I lost any along the way. I've currently still got five usable parts although one got bored a little over-size.
I'll just have to be careful with the M2 tap! :scratch: :scratch: :scratch:

Right, photos:

Pete49:

--- Quote from: Pete W. on November 17, 2016, 02:03:02 PM ---I thought of another reason for my not choosing the moulding approach for my project - the method I'm using uses facilities I already have and that I've had for some time. If I'd gone with the injection moulding machine plus mould approach, I would have needed another shed!!
--- End quote ---

And the problem is???? :beer:
Pete

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