Holesaw segmenting in plastics

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skiprat

skiprat

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Here's a trick I used to make a recent pen. I wanted to have a round segment in the main body of the material. I selected two holesaws, one the next size to the other. The smaller one will make the cutout in the main body and the larger one cuts the segment that will get glued in. ( using the outside of the kerf of the small one and the inside kerf of the bigger one) Even doing this leaves a gap, so I just lightly held the matching parts in a vice and slowly heated the joint with a heat gun ( on low ) As the plastics start to get soft, gently close the vice while still warming the bits. (I also warmed up the vice and bit of steel) Leave it in the vice till it's COMPLETELY cold.



These are the two pairs of similar holesaws, 1 pair for the body and the other for the cap
2007911112432_holesaws.jpg



Here I am cutting the segment using the larger holesaw from each pair. I left the pilot bit out.


2007911112744_cutting.jpg



Here you can see that even using matching holesaws, the gap is too big


2007911112938_gap.jpg



Holding it the vice and heat it up while gently closing the vice. ( I also sanded most of the rough marks off that were caused by the holesaws) The segment was wider than the vice jaw, so I just added the chuck of metal. I concentrated the heat on this bit of metal. Leave it in the vice till it's cold.


200791111332_gapgone.jpg



Here's the pen again, no visible glueline:D


2007911113753_kimspen.jpg



I have used this method when segmenting plastics into wood too, just pre warm the plastic before putting it in the vice. Hope this is useful to someone.;)
 
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Thanks for sharing that, Steven. I had been looking at your pens and your comment about two hole-saws but I knew they didn't match and couldn't figure out that solution. Now I know!!! Thanks!!

Paul,
Get used to it, That has happened to me about 3 times so far. [:D] The truly sad thing is that each time their version is way above what I was even envisioning. [:(] (for me) [:D][:D][:D] (for them!)

GK
 
Have you thought of trying to modify the hole saws to reduce the set on the teeth. Pull in the outer teeth of the larger saw and pull out the inner teeth of the smaller one. Not even sure if you can do this but it seems you have a lot of experience with metal.
 
Wow! That's what I call creativity. The practical kind too, like Tip said. That's the kind of thing that keeps me turning. When something starts to get kind of boring, look for a new idea. You must be one of those people who's always experimenting. Keep up the good work!
 
Steven,
Very nice indeed. Regarding gluing the pieces together, is CA glue necessary or could a plastic solvent that melts the surfaces work as well? I haven't seen any comments on solvent welding but, as a noob, I am curious. Thanks for the inspiration Steven............
 
Dave, although the holesaws I used are on their last legs, I wouldn't wreck them 'just' to make pens like that. I don't think that you could ever get a perfect joint even if you modded them. It really only takes a little heat and not much time to squash them, then you know they couldn't get better. The principle work just as well with joints with corners. I made a brass and blue acrylic pen that had sharp crown like joints and it closed the gaps very nicely. I can't remember how to get the pic out of my album, or I'd show you[:I]
Bob, I use CA for everything. But your idea sounds very interesting. Perhaps acetone or some other solvent would work on Delrin?
 
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