Thread: parting tool for small lathes

Originally Posted by JST

It is a very good way to make the holder, cuts the chatter down by a lot. Same thing is used on planers and shapers for wide surfacing cutters.

Spring type toolholder. Very old-school device, bit they were not so dumb back them.... lots of old-school things like this work well.

You set it up so the springiness lets the tool swing away from the work if it tries to dig-in. That cuts the energy input that drives chatter, so the tool will cut smoothly with no troubles.

I have the same, came with my lathe. The thing is spring loaded so it can flex some under heavy loads. But I don't use it. Get better results with a cheap chinese carbide tool than I do with HSS. And the HSS parting blades are more expensive than the chinese carbide, which I can sharpen myself, or even regrind.

Parted a bunch of parts this weekend, solid stock 20mm, making barrel nuts from them later. 600rpm and an acid brush with some greasy cutting fat and it went fine and fast. It's only 2mm wide to boot.

It does feel like a waste to not use this tool though, it's a nice piece of equipment, but why waste money on expensive HSS (by comparison to carbide).

Originally Posted by Rickyb

Sorry. I do realize this is a production forum. However this thread had the appearance of a non production discussion. Aside from 9100 bill there seemed to be a lack of understanding of some of the physics behind cut offs. The premise of solving a rigidity problem by adding more compliance and using machines lacking rigidity didn’t sound like high production with worries about tool life.

It also has allot to doo with how sharp you can make a HSS cutter versus how sharp of an INSERT you can BUY.….

Originally Posted by DennisCA

I have the same, came with my lathe. The thing is spring loaded so it can flex some under heavy loads. But I don't use it. Get better results with a cheap Chinese carbide tool than I do with HSS. And the HSS parting blades are more expensive than the Chinese carbide, which I can sharpen myself, or even regrind.

Is this Chinese partoff tool a steel blade holding a somewhat wider carbide nugget that does the cutting? These work well because they are less critical about getting the steel blade exactly perpendicular to the spindle axis.

I use such a blade (but mage by ISCAR) held upside down, with the lathe in reverse, so I get both the modern cutoff blade and the spring action that prevents digging and jamming.

As for the old holder for HSS cutoff blades, I've never seen one like that. The blade is Sandvik Corona C45, but what is the make and model of the blade holder? Hmm. Wonder if it will accept a modern carbide-nugget cutoff blade assembly?

Yeah that's what it is, they aren't very peculiar about that as you say.

The holder was made by Bergström, a swedish QCTP system, which I got on my lathe:
Bergstrom Quick-set Toolpost

Originally Posted by DennisCA

Yeah that's what it is, they aren't very peculiar about that as you say.

I assume that the modern blade is to too wide for the old holder to fit.

The holder was made by Bergström, a swedish QCTP system, which I got on my lathe:
Bergstrom Quick-set Toolpost

I looked Bergstrom up, and found the following US patent: US2616326A, issued in 1952. Also US2148852A (1939) and the cutoff blade spring holder, US2150959A (1939). Bingo!

(To get copies, enter the string "US2150959A" (sans quotes) into Google Patents.)