Best parting toolholder and inserts for manual lathe

I have an old Tug40 lathe that I've been using for several years. It's not super accurate but I can make it do what I need to do and have made a lot of accurate parts on it.

Now, for years I have been using a manchester parting tool. I use this for EVERYTHING, including stepped profiling before hand blending. Well, I had a part come out of the jaws a few weeks ago and it destroyed my toolholder.

This is what I was using:


In order to run coolant I need to keep my RPMS below 400 (otherwise i get drenched) so my surface speeds are pretty low.

My inserts were this type (BOTTOM ROW)



Well apparently I cannot get those anymore so I got a sandvik toolholder and inserts and i can just not get them to work. They instantly start screaming, the inserts break, sometimes it pulls the tool into the part (there is about .020 backlash on the cross slide) but I've never really had any issues like that with the old inserts and tooling. I do a lot of stainless steel and these inserts might as well be made out of wood. They just don't cut for shit.

I've tried GF, TF and CM inserts and none of them cut worth a damn. It seems like the cutter angle is a little different? The insert height and toolholder angle is good (at least compared to how I used to run), but deviating doesn't help any.

Can anyone point me in a direction of a toolholder or insert for this tool that might be better?

Here are some pictures of what I have now:






Here are some things I've made in the pa

Well, first off; The Corocut 1-2 series is about as good as it gets, certainly on par with anything else out there, and is a long proven design. So with that in mind, whatever is wrong is you and not the tool.

That toolholder you've got is about the most expensive one in their range, dual high pressure through coolant ports, all completely unnecessary on a manual lathe. I don't know how much you paid for it, but they are comfortably double the price of a standard one.

Centreheight should be exactly on centre at the cutting edge, if that's difficult to get right because of the insert geometry, set it off the top face of the toolholder shank - that is level with the cutting edge by design.

Make sure that the toolholder is exactly square to the spindle - indicate, don't eyeball.

In soft materials they need speed and some kind of cutting fluid. In most stainless they will cut nicely at low speed, with coolant or cutting oil, provided you can set an appropriate feedrate.

xnewmanx said:

<snip>

Well apparently I cannot get those anymore so I got a sandvik toolholder and inserts and i can just not get them to work. They instantly start screaming, the inserts break, sometimes it pulls the tool into the part (there is about .020 backlash on the cross slide ) but I've never really had any issues like that with the old inserts and tooling. I do a lot of stainless steel and these inserts might as well be made out of wood. They just don't cut for shit.

I've tried GF, TF and CM inserts and none of them cut worth a damn. It seems like the cutter angle is a little different? The insert height and toolholder angle is good (at least compared to how I used to run), but deviating doesn't help any.

Can anyone point me in a direction of a toolholder or insert for this tool that might be better?

<snip>

Click to expand...

That ^^^ isn't doing you any favors. At all. (Yes, I know.....it worked okay before, but the slightest change to the setup could start it off again.)



Personally, I'll recommend Iscar's TangGrip over anything else.........YMMV



All that said, parting has a steep learning curve. Once you get over the hump you'll wonder why it used to be so hard. BTDT.

Just a few variables to watch:

-tool centerline. (very important!)
-rigidity (get it as close to the chuck as possible)
-the right chipbreaker for the material
-rigidity
-rigidity
-rigidity!

Fuck a parting tool. Spin it as fast as it'll go, and use a hacksaw or cut off wheel.......

If that's to hi tech for you, I have amazing luck with Iscar PentaIQgrip tool holder and IQgrip inserts.

But I still play with tonka trucks in my sandbox.

most of todays tooling is cnc based when it comes to feeds and speeds, it just does not work for me on a manual lathe.
i am still using old part off tools.

gregormarwick said:

Well, first off; The Corocut 1-2 series is about as good as it gets, certainly on par with anything else out there, and is a long proven design. So with that in mind, whatever is wrong is you and not the tool.

That toolholder you've got is about the most expensive one in their range, dual high pressure through coolant ports, all completely unnecessary on a manual lathe. I don't know how much you paid for it, but they are comfortably double the price of a standard one.

Centreheight should be exactly on centre at the cutting edge, if that's difficult to get right because of the insert geometry, set it off the top face of the toolholder shank - that is level with the cutting edge by design.

Make sure that the toolholder is exactly square to the spindle - indicate, don't eyeball.

In soft materials they need speed and some kind of cutting fluid. In most stainless they will cut nicely at low speed, with coolant or cutting oil, provided you can set an appropriate feedrate.

Click to expand...

That toolholder and the inserts were given to me by someone at work.

I was trying to part a 1/2 OD 304 SS tube at 280RPM. If I run any faster I get drenched with coolant, which is no fun. I did bring it up to 560 and it only made the problem worse. I know those surface speeds are low for a carbide insert but it's never failed me in the past. I have to make about 500 spacers and it's taking about 5 minutes per part. There has to be another way. In the past with my manchester tooling I could cut through it in a few seconds.

I have about 2500 hours standing in front of this machine. It may be "me" but it's not like I'm some total noob with this machine.

I will try to get the backlash out of the cross slide, I do think that could help prevent the tool from getting pulled in, but I'm just surprised I'm having so much trouble when up until this point parting was a non-issue, i was very adept at feeding correctly and rarely broke or wore an insert. I probably have gone through 6 inserts in the past 4 years. With these new tools I have already broken 6 inserts.

I'm parting right at the chuck. About 1/8" away.

I did see this post on another thread. Is there a high positive rake insert for that sandvik holder?

metlmunchr said:

High positive rake inserts will generally work pretty well on small lathes and can be run at far less than the published speeds with good results. I think some folks buy negative rake tooling because the insert cost per edge is definitely the lowest, but that's a mistake for a small lathe. Negative rake inserts cut by pure force and heat generation, so they require a rigid lathe and the capability to get the speed up to the heat generating range. For all around use on something like a Logan or a SB, toolholders for TPG inserts are probably the best balance of performance and cost. The performance of the higher positive rake inserts like a TCGT is probably better, but comes at a cost of about 3x as much per edge. Personally I prefer uncoated inserts if I'm running something like a TPG, as the edge seems sharper in the uncoated variety.

Click to expand...

Ok well I just figured I would jump back in here and say I’m all straightened out now.

The chuck was bad! I put a different chick on and now it cuts awesome. The only thing I can think is that the inner jaws were touching the part and the outer jaws were not. It was a huge 16” chuck that I rarely use. I’m guessing it was like trying to part a 1/2” rod with 3” of stickout and no tailstock support. I put an 8” on and all is well. I’ll investigate what’s wrong with the chuck at a later time. Thanks for the help everyone!

xnewmanx said:

Ok well I just figured I would jump back in here and say IÂ’m all straightened out now.

The chuck was bad! I put a different chick on and now it cuts awesome. The only thing I can think is that the inner jaws were touching the part and the outer jaws were not. It was a huge 16” chuck that I rarely use. I’m guessing it was like trying to part a 1/2” rod with 3” of stickout and no tailstock support. I put an 8” on and all is well. I’ll investigate what’s wrong with the chuck at a later time. Thanks for the help everyone!

Click to expand...

That's a very common problem and pretty much the inevitable final state of any type of sliding jaw lathe chuck. As the jaw guides and the clamping faces wear, the jaws increasingly spread out when tightened, pinching the workpiece on points at the back of the jaw and leaving it completely unsupported at the front. Good that you're aware of it now!

Can be mitigated by wrapping a sheet of paper around the workpiece, which will compress in the pinch spots and take up the gap elsewhere. If the chuck body is still good then replacing the jaws can get you back to good working order, but most often that's not the case, and you need to recut or grind the jaws in the clamped state to restore parallel clamping.