Cutting PLA Cleanly - Finishing toneholes on instruments  

RE: Cutting PLA Cleanly - Finishing toneholes on instruments

I try to use a scalpel or even a sharp chisel for general cleaning of prints if needed.    However, I was making pvc pipe penny whistles for a while maybe 20 years ago, and I made a set of three (or four - I can't actually remember) reamers, by tapering old twist drills on a grinder - I'm pretty sure that PLA will behave similarly.    Not hard to do, particularly if you have some really cheap drill bits - just whack them in a drill and spin merrily away against a grinder until you get the taper you need.

Just gently ream by hand no need for a handle on them, just spin gently.  There's a knack to it of course but it is surprisingly accurate - I had a more or less matching  set of tapered dowels with fine grit paper glued on them to finish off- would be very simple to print something to suit each note.  

Before final tuning I had a series of dowels that I used to sand across the holes to make a nice curved finger transition- a bit of overkill for a pennywhistle but OK for a bagpipe I would think - It would be better to have that shape printed in but something like 240grit wet paper would work reasonably well.

Sadly the reamers are long gone but here's a pic of a Violin Peg reamer I made using the same technique.

I'd love to see more of your printed instruments - you are rekindling some very fond memories!

RE:

PLA machining has to be done at very low speeds or the friction causes it to melt and either grab or blob up; this can be used for a form of friction welding but I digress.

I usually do similar finishing with needle files or wet and dry paper used wet...

Reamers for plastic exist, sometimes called socket savers, but I've never seen them in tonehole diameters.  Take a trip to a plumbing supplier and look at their tools, if something looks suitable ask them for your sizes or if unavailable contact the manufacturer.

Cheerio,

RE: Cutting PLA Cleanly - Finishing toneholes on instruments

I agree entirely - if I wasn't clear in the above post - my "machining" is all done by hand with bits held between fingers - no machines at all - and wet sand only.
cheers,

P

Posted by: @diem

PLA machining has to be done at very low speeds or the friction causes it to melt and either grab or blob up

RE: Cutting PLA Cleanly - Finishing toneholes on instruments

Thanks, that's a clever tool - I'll try that. I think any blade cutting a tight radius on PLA has to be curved; my scalpel will do edges just find but not radii.

RE: Cutting PLA Cleanly - Finishing toneholes on instruments

Also, if you're interested in my work, I play and discuss a lot of my instruments - printed or otherwise - on my twitch stream, Saturdays at 4 Pacific: twitch.tv/camstlouis

RE: Cutting PLA Cleanly - Finishing toneholes on instruments

The other day I had to use a fine grinding wheel on a slow-speed dremel to get rid of some residual elephant's foot on a small PLA spacer that I had printed on my 'other' printer.

RE: Cutting PLA Cleanly - Finishing toneholes on instruments

Thanks for that - that's about 10 am Sunday for me - will be difficult to do but I've been enjoying your clips!

Posted by: @camstlouis

Also, if you're interested in my work, I play and discuss a lot of my instruments - printed or otherwise - on my twitch stream, Saturdays at 4 Pacific: twitch.tv/camstlouis

RE: Cutting PLA Cleanly - Finishing toneholes on instruments

I also use a "Rot-a-burr" (not sure that's its official name) de-burring tool to "break" sharp edges on prints. Works very well. Two suggestions apropos your problem: Print at 100% infill so that the tool does not break into the infill space, which will cause it to "catch" and dig in. If that is too wasteful of filament, then at least increase your perimeter count (at least 4, but 6 or 8 would be even better), which will have the same effect, i.e., put more solid material in the areas where you will be doing the contouring.