How to Mount Parting Tool

[oskar]

I bought this parting tool but not sure how to use it. Some sites show the tool located behind the stock and some in front of the stock. Which is the right way to mount the tool?

 

[P. Waller]

Are you asking which side of the tool is Z 0.000 ?
If so use whatever works for you, there is no "correct" way.

 

[benmychree]

Generally, the tool is mounted in front of the stock; on heavier lathes it can be mounted upside down in the back, especially on turret lathes; I'd think, especially on light lathes, backside mounting would not work very well due to the tendency for the tool's cutting forces to lift the carriage.

 

[Bill Gruby]

On a heavy lathe either front or back. As Benny said, the small lathes have aprons that will lift slightly with the pressure of the rear nounted inverted blade. IMHO on light lathes only front mounts will do.

"Billy G"

 

[oskar]

Thank you all, I will mount it at the front.

 

[mikey]

Sorry guys but I respectfully disagree that a light lathe should only mount parting tools from the front. Parting from the front on a Sherline lathe is problematic at best but I use a rear mounted parting tool post on my Sherline lathe and it will part almost anything from that position. It is mounted directly on the cross slide and I suspect this makes a difference but I can part most materials at 2-3 times normal turning speeds without issues. I haven't had a dig in or chatter in probably 15 years or more and I have parted stuff that is as large as my chuck will hold with a P1-N blade (0.040" thick). Everything from 4140 to plastics have been parted without issues this way.

Not an argument; just an experienced opinion that a light lathe is better off with a rear mounted parting tool if it can be solidly mounted there and the lathe run in the normal direction. If it cannot be mounted in the rear then it will do better with the tool mounted in front with the blade upside down and the lathe run in reverse. For a bigger, more rigid lathe, then do what works.

 

[TTD]

If it cannot be mounted in the rear then it will do better with the tool mounted in front with the blade upside down and the lathe run in reverse.

^^^ That’s exactly how I have to part off with my little 7x12.

The first few times that I parted in the conventional manner (blade out front, chuck spinning forward) was dismal to say the least…not to mention nerve-racking. Wasn’t a matter of “if” the blade digs in, but more “when” is it going do dig. Broke one blade, messed up a couple pieces…I absolutely cringed every time I had to part off. Pucker factor = 11/10

Then I read about the upside down/reverse method. I’ll admit that at first I didn’t understand why this would work any better, but thought I would try it anyways as it surely couldn’t be any worse than my current method. Wow!…the difference was night & day. No more chatter, no more digging in, no more stalling the wee ½ hp motor out & no broken blades since. Now parting off is just another step to do & I don’t give it a second thought. Pucker factor literally dropped to 0/10.

Now, I’m still just a newbie with only a few years under my belt so take it for what it is, but I truly believe that anyone with a small, light lathe who hasn’t tried either the upside down/reverse method or rear mounted method should really give it a try…I think you just might be (pleasantly) surprised with the results.

 

[4ssss]

A lot of the problems in cutting off on a lathe have to do with the speed of the spindle. As you get closer to the center, the speed of the cut increases, so slowing it down helps quite a bit. That's where a VFD is helpful. I normally keep my motor pulley on the faster side, so my slowest spindle RPM I have is around 550 without the back gears. I'll start at that speed, and around 1/2 way thru I'll re-sharpen the tool, and drop the speed down maybe 30 % with the VFD. Adding an angle to the tool (longer at which side of the cut you need to save) allows the cut off part to be held a little longer so you end up with a reasonably burr free part that you cut off.

 

[Ken from ontario]

Then I read about the upside down/reverse method. I’ll admit that at first I didn’t understand why this would work any better, but thought I would try it anyways as it surely couldn’t be any worse than my current method. Wow!…the difference was night & day. No more chatter, no more digging in, no more stalling the wee ½ hp motor out & no broken blades since. Now parting off is just another step to do & I don’t give it a second thought. Pucker factor literally dropped to 0/10.

That's how I mount the parting tool also (on a small mini lathe) and I first learned about it from Mikey, parting with an inverted blade and the lathe run in reverse is just one way of doing the job but to me as a newbie hobbyist it is an easy (and safe) method .

 

[T Bredehoft]

After I replaced the [plastic] gibs with steel ones on my Atlas/Clausing MK2, I was able to part with the tool behind. With the plastic gibs I was unable to tighten them enough to keep the compound from lifting.