Question: Parting Blade Thickness

[D_Harris]

Can someone tell me if parting blades that are 3/32" wide to big for a mini lathe?

I know that 1/16" is the norm, but was curious if there were circumstances in which a size 50% thicker would be warranted.

Thanks.

Darren Harris
Staten Island, New York.

[Harold_V]

As tool width increases, chatter becomes a problem. I expect you'd notice a change in performance by going to the wider tool, but a great deal depends on what you're trying to do, and how close to the chuck you intend to part. Material type, alone, makes a huge difference. Not having access to a similar machine, I hesitate to make blanket statements about the possibility of success. Might be worth a try if you can keep things close to the chuck and keep the blade short.

Harold

[websterz]

I would advise against the thicker parting tool on a 7x lathe. The wider the tool the more load you are placing on the motor causing the controller to fault out. If you turn the part fast enough to keep the motor from stalling you are going to start having chatter problems. A razor blade cuts through rope with much less effort than a chisel.

[D_Harris]

Thanks a lot.

I guess I'll stick with 1/16th". (Though a lot of what I'll be machining is plastic, like Delrin and Nylon).

Darren Harris
Staten Island, New York.

[Harold_V]

I guess I'll stick with 1/16th". (Though a lot of what I'll be machining is plastic, like Delrin and Nylon).

Darren Harris
Staten Island, New York.

That's to your advantage, as neither of them require much in the way of tool stability. You'll waste less material as a side benefit. On the positive side, if the cuts are quite deep and you need the greater width because of depth of cut, it won't be troublesome like it would be when parting metal.

Harold

[D_Harris]

Just came across this thread again and wanted to say thanks to everyone for the advice.

Darren Harris
Staten Island, New York.

[ptross]

perhaps I can change direction a little on this thread. what advise would you have for parting tool thickness when cutting mild steel, up to 1.5 inches dia, on a 12" lathe? I have rarely been able to part without fighting severe chatter.
Peter

[John Hasler]

Your problem is most likely rigidity.

[John Evans]

perhaps I can change direction a little on this thread. what advise would you have for parting tool thickness when cutting mild steel, up to 1.5 inches dia, on a 12" lathe? I have rarely been able to part without fighting severe chatter.
Peter

I usually use 3MM insert or 3/32nd HSS blades at 200 RPM with plenty of dark cutting oil. Many times I part with power feed at .002 per rev on either of my 12" lathes Chinese gear head or Clausing 5914 . Lock carriage when parting.

[Harold_V]

A couple things to consider.
Power feed, when parting, is usually superior to hand feed.
If chatter is a problem, increasing feed rate will usually help. Light feed encourages chatter.

H

[pete]

Depending on the exact design of that 12" lathes cross slide, then if a rear mounted parting tool holder can be mounted that can also help a lot. That greatly increases rigidity since your removing the usual poor support of the cantilevered tool holder sticking out in thin air and what is in reality a small and quite flexible top slide and the clearances and back lash within it's slide and feed screw. So if your lucky enough to have a tee slotted cross slide it's easy enough to add that. It's NOT a good idea to do a less than heavy duty job of getting that rear tool post bolted down though. A good solid jam up with the tool could if severe enough rip the tool post out of the tee slots. Myford lathe users have designed numerous rear mounted tool posts to solve this exact issue. Probably the most well known would be the George Thomas design http://www.hemingwaykits.com/acatalog/R ... _Post.html for a better idea of how it's meant to be mounted and used.

[Glenn Brooks]

I have a drawer full of various modern parting blades. They are all junk. Nothing but trouble with them all. Finally used an old NOS English made Elliot blade- that I acquired years ago.... very high quality steel. It cuts most everthing like butter. And, with the good quality blade Iam almost up to the point of plunge cutting when parting off.

So I am convinced now, parting on a lathe is all about the quality of the steel. Everything else is secondary. Don’t know what I’ll do if this one every wears out...

Glenn