PDA

View Full Version : urning on the back side of a lathe?



dilligaf
04-11-2008, 03:48 PM
i have been watching Professional Machine Shop Course from smart flix. In the video he says to turn on the back side of the lathe when cutting a taper using the compound rest. How do you do this on a SB 9" with a screw on chuck? Do you turn your cutting tool upside down.

thanks
Jason

JCHannum
04-11-2008, 04:13 PM
I have no idea why anyone would recommend that procedure. Anyone with a lathe and video camera seems to feel qualified to produce a movie of machine tool instructions.

If you want to learn lathe work, get a copy of How to Run a Lathe by South Bend and the Atlas Manual, and follow the instructions in them.

micrometer50
04-11-2008, 05:02 PM
On old lathes ,with loose headstock bearings, cutting from the rear MAY cut down on chatter. With the tool upside down and the lath running in the usual direction the cutting force is pushing down.

dilligaf
04-11-2008, 05:23 PM
actually the video is very nice and very informative I do have the books that you talk about but i like to see better then read. these videos have been out for some time.

thanks
Jason

dp
04-11-2008, 05:37 PM
Do the vids suggest reversing the spindle direction and to cut from the rear or to do the cut from the rear with the spindle turning in the forward direction? I don't see any advantage to doing both.

smiller6912
04-11-2008, 05:40 PM
I like the videos, Darrell does a great job, have you seen the custom riffles that he builds, WOW. He also builds a line of special gunsmithing tools, if you ever need to get the receiver off of a Remington 700, he is the guy to call. What he is doing with the taper is showing you that with this setup the toolpost is coming too close to the chuck and that you can cut the taper on the back side running in reverse to get a better position. You don't have to cut on the back he is just trying to get you to think about how you can solve problems.

NickH
04-11-2008, 08:22 PM
If you really wanted to do it correctly you'd use a taper turning attachment, try it conventional, if that don't work try it as suggested, not sure how easy it would be (fairly bl**dy impossible with most lathes I suspect) when you generally need to support the work with tailstock & center,
Nick

b2u44
04-11-2008, 08:54 PM
I like to cut tapers from the back-side of the lathe because the compound can be in a more convenient position than if cut on the front-side... That being said, I have a cam-lock spindle which can be run in reverse without unthreading. The only way you can do this is to run inverted tooling (upside-down). Otherwise, you'll end up unscrewing the chuck when the lathe is running. If you have a quick-change toolpost I don't think you should try this as it might pull the tool off the post.

tattoomike68
04-11-2008, 09:33 PM
I FAKE TAPERS, no taper attachment, no compound.

This is an old job shop method that sounds ghetto....


You set the feed to go away from the chuck and plunge the cross slide as you cut, the faster it happens the better. use a file and some emory cloth and you did the job some folks would have taken all year to do.

on large tapered pipe threads I do it this way..


I fake taper pipe threads by turning the tool upside down and threading away from the chuck and running backwards while slowly plunging the crossfeed in. :P I know that sounds crazy.

On big tapered pipe threads I would cut a little taper to start with.

It takes a little practice but work very well.