# Tool bit angles for machining PVC?



## dawgnabbit (Jan 2, 2008)

Hello, All

I'm experimenting with a new (to me) modeling material - PVC plastic. I have two questions about machining it that I'd like to submit to the collective expertise of this group.

1. What tool bit angles work well for turning PVC. My first thought was "lots of back rake" to get a clean cut, but that peels off long continuous chips that wrap around the workpiece, marring the finish and rounding over sharp shoulders. Scrapers don't seem to work much better. What actually works best? Recommendations on angles, speeds, feeds would be most welcome.


2. I tried turning a long (~12") cylinder of 3/4-inch PVC pipe. Diameter was spot on and finish flawless near headstock and tailstock (with live center), but the center 3 inches or so was rough and stringy. I think this is due to shaft whipping. My question is: What works better to tame this behavior, a steady-rest (which must be repositioned to make the whole cut) or a follower rest on the carriage? I'd like to know what works for you folks.


Thanks for any help you can offer.

Dawg


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## xo18thfa (Jan 2, 2008)

Steve: I found that PVC machines cleaning with the same set up as brass. A little higher speed and a smidge more radius on the tool nose. Slightly steeper rake. All the setting for brass.

The flexing sound like you should try a follower rest.


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## Gary Armitstead (Jan 2, 2008)

Steve, 

Follow Bob's suggestion and use a follower rest. Your cut will be stable the entire length.


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## dawgnabbit (Jan 2, 2008)

Okay, thanks, guys. That's what I needed.

I don't have a follower rest for my Atalas 6" lathe and haven't seen one that will fit it, so I'll have to come up with a shop-made version. Should be an interesting project in itself.


Dawg.


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## Gary Armitstead (Jan 2, 2008)

Steve,

There is an Atlas follower rest on E-Bay right now for $56. 3 days to go.

http://cgi.ebay.com/Atlas-Craftsman...1c0fbd1e28

Also another on this auction site.

http://for-sale.yakaz.com/atlas-craftsman-6-lathe

Just do a Google. They are everywhere. I have a 12 inch X 36 inch Atlas I have had for 30+ plus years. Bought it brand new-came with all the goodies including a steady rest. Good luck in your hunt. You could probably make one pretty easy.


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## xo18thfa (Jan 2, 2008)

Posted By dawgnabbit on 30 Jan 2010 06:37 PM 
Okay, thanks, guys. That's what I needed.

I don't have a follower rest for my Atalas 6" lathe and haven't seen one that will fit it, so I'll have to come up with a shop-made version. Should be an interesting project in itself.


Dawg.





Shop-make one from wood. That shouldl be stout enough for PVC, I would think. Incorporate roller bearings too rather than the usual rubbing surface.

Atlas 6" are the best home shop lathe ever. What version do you have. Mine is the newer kind with the square headstock.

These guy have lots of stuff for the Atlas.

http://www.littlemachineshop.com/default.php


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## R.W. Marty (Jan 2, 2008)

Hi Steve,
I found that very light cuts and a slow feed rate really helped my work. But then I really don't know much about it.









So, what'cha building??
Later
Rick Marty


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## dawgnabbit (Jan 2, 2008)

Hi, All

Gary, Bob - Thank you for the links. Clearly I need to make better use of my internet resources!

I didn't know about "Little Machine Shop," thanks. Looks like I'm gonna have to spend some more money. Aw, Shucks!









Bob - I don't know what version my lathe is, but it looks like this, if that helps. I bought it new from Clausing in 1978, for the princely sum of $295!










Rick - Just making underframe compressed air tanks for a diesel. Being lazy, I tried to turn stock for both at once, hence the too-long piece of PVC stock.


Dawg


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## Treeline (Sep 7, 2009)

You might try a wooden dowel sanded for a slip fit inside the PVC pipe to steady and stiffen it.


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## xo18thfa (Jan 2, 2008)

Posted By dawgnabbit on 31 Jan 2010 07:17 AM 
Hi, All

Gary, Bob - Thank you for the links. Clearly I need to make better use of my internet resources!

I didn't know about "Little Machine Shop," thanks. Looks like I'm gonna have to spend some more money. Aw, Shucks!









Bob - I don't know what version my lathe is, but it looks like this, if that helps. I bought it new from Clausing in 1978, for the princely sum of $295!










Rick - Just making underframe compressed air tanks for a diesel. Being lazy, I tried to turn stock for both at once, hence the too-long piece of PVC stock.


Dawg 
That's the same one I have. Got it in 1978 also. Live Steam had adverts for them. Mine is grey in color now. What a great machine.

Bob


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## RimfireJim (Mar 25, 2009)

Posted By dawgnabbit on 31 Jan 2010 07:17 AM 
Hi, All

Gary, Bob - Thank you for the links. Clearly I need to make better use of my internet resources!

I didn't know about "Little Machine Shop," thanks. Looks like I'm gonna have to spend some more money. Aw, Shucks!









Bob - I don't know what version my lathe is, but it looks like this, if that helps. I bought it new from Clausing in 1978, for the princely sum of $295!










Rick - Just making underframe compressed air tanks for a diesel. Being lazy, I tried to turn stock for both at once, hence the too-long piece of PVC stock.


Dawg 

That is entirely too clean. You obviously don't do any work with it!








I have the same lathe, same color. I bought it used over 20 years ago because I knew I couldn't live without one, then ever since then I've worked where I've had access to a full machine shop with a better lathe! One of these days, when I retire . . .

A steady rest will work probably just as well on your 12" PVC as a follower rest and may be easier to kludge up out of wood and three bearings. Easier as in easier to mount to the ways rather than to the carriage. As the stock gets more flexible (either longer or thinner or both) a follower becomes more important, but even then you can have whipping in the center while you're making a cut near an end and your cut can be affected.


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