Harbor Freight 7x, Follower rest. Turning Plastic to .200?

I would try to source some .2 rod myself. That follow rest is gonna chew up the finish as the brass is harder then the plastic.. Maybe one with bearings in the fingers would work. I see alot of spring cuts in your future ahahaah
 
Maybe you could round the ends of the fingers and polish them up on that steady? eep it nice and slick
 
chuckorlando said:
I would try to source some .2 rod myself. That follow rest is gonna chew up the finish as the brass is harder then the plastic.. Maybe one with bearings in the fingers would work. I see alot of spring cuts in your future ahahaah
Click to expand...

The finish isn't a big deal. Actually, the diameter is more like .227 or something ridiculous.
Would the follow rest help in getting consistent diameters?
 
I had to turn some Teflon parts, these were about 12 inches long and about 5/8 dia. I couldn't use a follower rest because it would damage the surface. Here is what I did:

The tab on the side is held by the tool holder
The hole is the starting diameter of the plastic
Feed the plastic through the hole and the tool bit cuts to size in one pass
IMG_0287.jpg
Its made from a chunk of cold rolled shaft with a key slot and the key welded in for the tab.
IMG_0286.jpg

Worked great after I got it set up, it took a couple of test cuts to get the tool bit set to the right depth. I've had this kicking around for about 25 years, never had a use for it since.

IMG_0287.jpg IMG_0286.jpg
 
Need more info please. Tolerance on the 0.227” OD, what kind of plastic, what lathe do you have, 3 jaw, collet, any shoulder, how many parts? I do a lot of micro machining and have many ideas for you. But please narrow my typing down to just one idea. I hate to type! Thank You and maybe a picture or two.
 
JimDawson said:
I had to turn some Teflon parts, these were about 12 inches long and about 5/8 dia. I couldn't use a follower rest because it would damage the surface. Here is what I did:

The tab on the side is held by the tool holder
The hole is the starting diameter of the plastic
Feed the plastic through the hole and the tool bit cuts to size in one pass
View attachment 84031
Its made from a chunk of cold rolled shaft with a key slot and the key welded in for the tab.
View attachment 84032

Worked great after I got it set up, it took a couple of test cuts to get the tool bit set to the right depth. I've had this kicking around for about 25 years, never had a use for it since.
Click to expand...

I have a similar tool but for the life of me can’t find it right now for a pic, sorry. As said, it’s a dedicated tool, once set-up it is real only good for that billet diameter. Finished OD can be tweaked a bit. The one I have has a brass bushing up front that can be changed to suit the billet stock diameter. It works very well, a little extra set-up time is all.
 
You can make a follower rest which bolts to the tool holder, e.g.: http://www.frets.com/HomeShopTech/Tooling/MiniFollower/minifollower.html

This is approaching a lathe box tool, as commonly used on turret lathes but also used on engine lathes for volume work and especially when turning items to a small diameter. Again, you can make one similar to the one shown earlier in this thread or make one to be held in the tailstock chuck since your part is modest diameter and reasonably short. Google Images has lots of pictures of box tools - most for turret lathes - but shop built tools need not be as fancy as those shown. A fringe benefit of the tailstock mounted box tool is a parting tool (or whatever) can be ready to go in the toolpost.

John
 
Trying to turn about a 15/1 length/diameter ratio in small diameter plastic. (~.200)

Damn, so I rigged up a piece of 1" Al stock to attach vertically to the carriage in front (closer to the spindle) of the tool holder. I drilled an "exact" sized hole with bit in the spindle for the stock to feed through, and I can adjust the cutting tool to vary the diameter. The only problem now is that the final pieces come out OVAL!! About .010" difference between the small and major diameter. Adjusting the RPM and feed rate make NO difference. Any ideas?
 
If it's oval I would assume it is either not on center side to side or for some reason it is pushing the tool or part at the same point in rotation.
 
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