Spring Cut off Tool Follow Up

**winkys workshop** · Feb 11, 2022, 11:18 AM

**Toolmaker51** · Feb 12, 2022, 02:13 PM

re Winky's cart, beginning of vid to about 1:20 in. Kids learn quick; turning is turning but no turn is like getting sideways!

Part of noise is due to insufficient feed rate, another is material not perfect round - so the chip load isn't consistent. Advocates of angling the leading [cutting] edge point out ~1°-3° will have the part release while some nub remains on stock. A handy setup reference for next time, if nothing else.
Offering the successful tool is more than commendable.

**winkys workshop** · Feb 13, 2022, 08:41 AM

The blade angle may not be needed but it seems to work well. There is a lot of stuff going on here and it's hard to predict. A feed rate of .001" to .002" per revolution works very well but outside this rate is not so good. It has to do with the amount of spring in tool. Some seem to think the screw is an adjustment but it is a stop. However, I suspect strengthen the spring would allow for an increased feed rate. With that being said, tool post and compound flex (which the tool holder is currently addressing) may start to be an issue. The feed rate is probably about right anyway so I'll stick with the design.

**Toolmaker51** · Feb 13, 2022, 11:29 AM

Cutting angle referred to, is form of front, not top rake. There's justifications to leave nub on either side.

Back Rake & Top Rake; figuratively are synonymous. 'Form' indicates a cutting edge creating a predetermined contour without particular movements of either axis, beside attaining depth. Single-point threading, fillets and radii, multiple steps, O-ring grooves, chamfering can all be labeled thus, part features being accomplished by 'forming tools'.

Spring Cut off Tool Follow Up-tee_parting_tool.jpg

**winkys workshop** · Feb 13, 2022, 07:45 PM

Originally Posted by Toolmaker51

Cutting angle referred to, is form of front, not top rake. There's justifications to leave nub on either side.

I might be using the wrong terminology. Back rake is ground into the top of the tool so the angle of the tool is creating (in effect) a back rake. I have heard this called top rake also but I have no idea if this is correct. Never heard of "form of front".