Which parting blade thickness should I go with?

[Wonderclam]

I have a PM1127 lathe and I'm looking to buy a parting blade for my parting tool holder. I'm looking to get the "T" shaped parting blades, and the ones with cobalt mixed in.

I'm trying to decide which thickness I should go with. 1/8, 3/32 or some other thickness? I think I remember seeing a Tubalcain video where he recommended not to get the 1/8, and to get the 3/32 instead or was it the other way around?

Also, another unrelated question:

How much diameter should I be turning on my lathe at max? I've been weary of doing more than .050 as I'm not sure how thick of a cut my lathe can handle and I don't want to break anything.

 

[ddickey]

3/32" is a good width.
Never run an 1127 so can't comment.

 

[benmychree]

There is less chance of chatter on small lathes using narrow parting tools.

 

[T Bredehoft]

I use a 3/32 by 1/2 (concave grind on both sides) on my 1030, but I cannot feed it as heavy as I'd like, it stalls the drive. It could be I'm cutting 4140 half hard. I tried the one that came with the machine, it's aobut .140 wide, It either chatters or stalls.

 

[Chewy]

I use the Shars posted below on a 1228 Lathe. Works great. Don't buy cheaper straight parting tool. Mine is in junk drawer. I turn 1018 a lot. Charles

SHARS P2 "P" Type Type 3/32 x 1/2" x 4-1/2" M42 Cobalt Cut-off Blade NEW !{ | eBay

MATERIALCobalt M42. TOOL BIT CATEGORYCut-Off Blade. BLADE HEIGHT1/2. BLADE WIDTH3/32. BLADE LENGTH4-1/2. You may ask for freight cost before buying tools. Double end. Fit on tool holder202-9426 and AIORIS, DORIAN & KDK type quick-change toolholders.

www.ebay.com

 

[ttabbal]

On my 1127 I use a AR Warner HSS blade from littlemachineshop.com. I don't remember the thickness.

I found the biggest improvement by far was a rear mounted tool holder for it. The compound just lets it flop around too much.

 

[mikey]

I would try a P1 (1/16" wide) blade first and go to a P2 (3/32" wide) only if the P1 doesn't work. The narrower blade will cut with lower cutting forces and will work on pieces up to 1.5" OD or more. Your set up must be rigid, the tool must be on center and perpendicular to the work and the tool must be sharp.

As @ttabbal said, a rear mounted tool will work best.

 

[pontiac428]

My workhorse parting tool for my Atlas is P2. Small lathes don't like thick parting tools. I run P1 when I can get away with it. I really like way the 1mm (.040) blades from Shars cut, but they explode into a hundred tiny knives if they get bound up. So my go-to is P2.

 

[Pcmaker]

I would try a P1 (1/16" wide) blade first and go to a P2 (3/32" wide) only if the P1 doesn't work. The narrower blade will cut with lower cutting forces and will work on pieces up to 1.5" OD or more. Your set up must be rigid, the tool must be on center and perpendicular to the work and the tool must be sharp.

As @ttabbal said, a rear mounted tool will work best.

what's a rear mounted tool?

 

[ttabbal]

The tool is mounted on the back of the work, upside down. The forces and flex are different and seem less prone to chatter and catching. Gravity helps evacuate chips. The is less flex as it is generally a solid mount, no compound or QCTP flex.

Here's a photo of mine.