Can I turn a part from hard clear plastic?

[Just for fun]

Sounds good on the plastic. You won't have a problem, slow and easy.

 

[twhite]

As said above slow and easy. Drilling and tapping plastic is easy once you have done it a few times.

Looking forward to seeing your finished parts.


Cutting oil is my blood.

 

[SLK001]

I'm willing to try to turn plastic, but drilling & tapping? The thought makes me shudder...

Put a bottoming tap in a drill chuck loosely inserted into your tailstock and, while holding the chuck firm, ram it into the plastic with your spindle turning at its lowest speed. When the tap is deep enough, let the chuck go and check for proper depth.

 

[feral_cat]

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Plastic is easy to machine. Slower will help surface finish to prevent heat build up

 

[ChazzC]

A few days ago I ordered some of the red acrylic rod from eBay, and it came in the mail yesterday! It looks great. I haven't tried turning it yet, but the color looks very close to the other red Permaloid knobs on the lathe. The good thing is the rod you suggested is 12" long, so there's enough material there to practice cutting a few times before getting it right.

By the way, a guy on another forum has a Rivett 1R watchmakers lathe, and he was kind enough to send me closeup pics of the plastic knob on his tailstock runner. The dimensions noted in the first picture are his measurements, not mine.


Notice that the female threads in the Rivett knob are cut directly into the plastic! I was going to use a threaded insert, but now that I see a real Rivett knob, I'd like to do the same with my (attempted) replica. I'm willing to try to turn plastic, but drilling & tapping? The thought makes me shudder...

I’ve drilled and tapped Acrylic and had good success going slow as others have said; however, I recommend tapping by hand, not under power (even in back gear). I also suggest using diluted dish detergent as a cutting fluid to get smooth threads.

 

[Firstram]

D&T the threads first, wipe or fill the interior with Acetone to chemically polish the inside. Don't get any on a finished part or it will ruin the finish. Weld-On acrylic adhesive works the best but acetone should work well too.

 

[cazclocker]

I’ve drilled and tapped Acrylic and had good success going slow as others have said; however, I recommend tapping by hand, not under power (even in back gear). I also suggest using diluted dish detergent as a cutting fluid to get smooth threads.

I plan to tap by hand. Tap held in tailstock, plastic acrylic piece in the headstock.

As said above slow and easy. Drilling and tapping plastic is easy once you have done it a few times.

Looking forward to seeing your finished parts.

I'm looking forward to seeing them too!

I’ve drilled and tapped Acrylic and had good success going slow as others have said; however, I recommend tapping by hand, not under power (even in back gear). I also suggest using diluted dish detergent as a cutting fluid to get smooth threads.

Thanks for that - I was planning to tap by hand.
Question: I saw someone else here warn me AGAINST drilling a pilot hole, because of increased likelihood of cracking/shattering the plastic. But if I need to tap, I'll have to drill the initial pilot hole, won't I? Seems kind of obvious I'll have to. What say you?

 

[Chewy]

All I can add to this is that I did about 50 through holes 8-24 in 1/4" plexiglass. I drilled the correct tap size and started the tap in the drill chuck by hand and then hand turned it. Came out great. Since you are doing blind holes, you will need to remove the chips every turn or so to be on the safe side. Other option is to get a reverse spiral tap that removes the chips as you go. Don't sweat it, it's not that hard. Do get a new tap that is sharp.

 

[SLK001]

I'll have to drill the initial pilot hole, won't I? Seems kind of obvious I'll have to. What say you?

Not a pilot hole, but a tap drill hole.

Since your hole is shallow, a taper tap probably isn't going to have enough hole to even start threading. A plug tap might give you one or two turns. A bottoming tap will give you the most threads (and it looks like that was used on the original part), but a bottoming tap isn't used to start a hole, without very careful alignment. As long as the tap is in line with the part, it should work just fine. Starting the tap will require a lot of force, so if you are going to do it by hand, turn the spindle by hand while you are pushing the tap in with the tail stock ram. Practice, practice, practice getting the threads correct before you finish your part.

 

[cazclocker]

Not a pilot hole, but a tap drill hole.

Since your hole is shallow, a taper tap probably isn't going to have enough hole to even start threading. A plug tap might give you one or two turns. A bottoming tap will give you the most threads (and it looks like that was used on the original part), but a bottoming tap isn't used to start a hole, without very careful alignment. As long as the tap is in line with the part, it should work just fine. Starting the tap will require a lot of force, so if you are going to do it by hand, turn the spindle by hand while you are pushing the tap in with the tail stock ram. Practice, practice, practice getting the threads correct before you finish your part.

SLK001, very interesting point. Actually, last night I decided to do just what you say - start the hole with a plug tap, and finish with a bottoming tap. Thanks for the reminder of required force to start the tap.