[DavidhCNC]

I work for a tube forming company, and I make the wheels that the tubes get bent around. We got a TL-1 with a 3 jaw chuck a couple months ago, and I am still working out some issues. I started using a .315" carbide grooving insert to, for example, cut a .75" wide groove .25" deep. I have been having trouble getting the insert to cut smoothly without squealing or jamming up the lathe. I have had best results (still crappy results) with the SFM at 58 for 1.75" round stock at 0.0025" per rev. It still causes vibrations that don't sound or feel good to me, and leaves a rather poor finish. But the biggest problem is that it literally pulls the round stock out of the vise in the Z axis. To clarify, if I face of the round stock, skip the grooving process, and part of the piece, I get exactly the length I programmed. But if I run the grooving process, it lengthens the piece by up to .015"!

I suspect that my feeds and surface speed settings are all wrong. But with me being the only person in the company that knows anything about the lathe, and having just over 6 months CNC experience, I'm going by trial and error. So far lots of error. I also suspect that the TL-1 just doesnt have power/rigidity/etc. that it takes to properly cut with a grooving insert of that size. Can anyone help me before I strap a pack of C4 to the lathe?

Thanks,

David

[viking73]

58 sfm is really low. You need to talk to your supplier, they'll be able to recommend some good numbers for you.

[jeff3680]

Use a narrower cutter with a positive cutting geometry . Also using a different too for the finish operation helps .

[Billetgrip]

We had that problem on our ST10-Y while roughing diameters. We bought some serrated chuck jaws and haven't had any problems since.

[JimmyJazz]

58 sfm is really low.

Use a narrower cutter with a positive cutting geometry.

Seconded on both counts. 0.315" is a pretty huge grooving tool, with a lot of contact area, which is what causes the squealing. Maybe try a 1/8" grooving tool. I tend to lay off the coolant and use Rapid Tap when grooving, too. I'm still a fairly newb apprentice, so I let the CAM software choose my feeds for grooving -- the guys in my shop laugh at how conservatively slow they are, but they work for me for the time being. With your example of a 0.75" wide groove, 0.25" deep on the radius on a 1.75" shaft, and choosing 4140 steel for the material (400sfpm), my software is saying 0.005"/rev for roughing and 0.002"/rev for finishing.

I've read your post 3 times and I don't see any mention of what material you're cutting. With carbide cutting tools, most steels will be on the order of 250-400sfpm -- 300 is a safe starting point which shouldn't cause catastrophe no matter the alloy. I use 1200sfpm for 6061-T6 aluminium on my TL-1, but I see other guys here on the forums going faster than that (1500-1800sfpm).

Hope that helps.

-jj