Plastic for lathe milling?

[Scott Mc Laughlin]

Hi,

 

Two questions here. I need to make some experimental clarinet parts (the barrel). I need to drill a bunch of tubes about 50mm long with a bore about 12–20mm (I’ll make several with different bore sizes).

 

• Do we have a lathe that can mill plastic at this size?
• Any suggestions for a suitable hard plastic for milling and where I might get it?
• Cheap clarinets are made from ebonite but that’s hard to come by.

 

Best,

Scott

[J C]

Hi Scott,

We do indeed have a suitable lathe, I've just been testing it out with pleasing results. 

You Are looking for delrin for your plastic 

Hackspace not properly open yet though. I'll let a director comment on that part

Joe

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[Dylan Schink]

Delrin machines very well, but it's not immune to melting and ruining your surface finish. Keep your tools and work cool, break chips often, and use a light lubricant, and keep tools wicked sharp (this is far more important for good results on plastic than metal).

Dylan Schink - Chat @ Spike

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[Dylan Schink]

It's also probably worth mentioning that boring out delrin (or any plastic) with a twist drill needs some special considerations. Plastics can't carry heat away from the cut surface well, and expands less metal when it gets hot, so deep bores have a really bad tendency to bind up around the drill bit, giving a terrible, melted surface internally (or simply destroying the part). 

Again, the solution is to cut a little bit at a time, take slightly aggressive cuts (half a millimetre cut depth is reasonable), and let the drill bit cool fully before going in for the next plunge. I've heard soapy water as a lubricant is great for delrin boring, but I've not personally used this method myself.

Dylan Schink - Chat @ Spike

[Dylan Schink]

Most of these problems can be avoided with a boring bar, but of course you need to create a pilot hole for clearance before you can use one.

Dylan Schink - Chat @ Spike

[Scott Mc Laughlin]

Great, thanks everyone! I’ll order some Delrin and wait for the hackspace to re-open.

 

Best,

Scott

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