Tiny lathes will humble you.

[erikmannie]

Yes, if the particular lathe is up to it, carbide can speed metal removal, but I see all to many folk using negative rake tools on low power/rigidity machines because they esteem how many cutting edges that they may offer rather than how well they preform under the conditions that the machine may provide; forget about how many edges are offered, concentrate on how freely they cut.

The carbide is appealing because (1) you know the cutting geometry is spot on (this shows my level of confidence in my HSS grinding skills), (2) faster work via higher RPMs, (3) faster work via deeper cuts, and (4) faster work via switching out a dulled cutter.

Of course, the smaller the lathe, the less likely we are able to capitalize on the benefits above.

To HSS’s credit, it can offer better economy, the ability to grind a custom cutter, improved performance on smaller machines, and nostalgia.

Both HSS and carbide can achieve the same level of quality work.

Maybe a particular machinist’s choice of carbide vs. HSS is a reflection of (1) how large their lathe is, (2) how much of a hurry they are in, and (3) which type of cutting material they are used to working with.

 

[erikmannie]

I gravitate toward positive rake cutters, and, yes, this dulls the tips more quickly.

Advantages and Disadvantages of Negative Rake Angle in Cutting Tool

Advantages and disadvantages of negative rake angle in cutting tool on machining or metal cutting. Pros are stronger tool tip, longer tool life, suitable for old machines, increased feed and depth of cut can be utilized. Cons are more cutting energy and power consumption, induced vibration...

www.minaprem.com

 

[addertooth]

Well it was a simple problem, with a simple fix.

My vertical reference for center height had got "bumped" and was about 1/64th high. I had aligned the top surface of my cutter to the reference.. resulting in a tool that was set too high. I am surprised it didn't do far worse than "chatter".

When things go weird, always go back to your basic setup and confirm things all over again. Fixtures and jigs can always get bumped.
Last night I thought about it, and remembered the pressure to start the cut seemed just a bit high (but, because the Gibs are a bit tight still, I didn't know if some of the resistance felt was the too-tight gibs), at the time I chalked it up to "new tool and new lathe which may feel different". I now know to use previous experience as the guide, and don't simply chalk up oddities to a different lathe and tools. After reading all the other posts from people who had problems cutting cold rolled steel on mini-lathes (without chattering), I had initially assumed it was a challenge for these little lathes. Properly set up, it isn't, cuts like butter at the right RPMs.

 

[dbstoo]

Well it was a simple problem, with a simple fix.
[ snip ]
After reading all the other posts from people who had problems cutting cold rolled steel on mini-lathes (without chattering), I had initially assumed it was a challenge for these little lathes. Properly set up, it isn't, cuts like butter at the right RPMs.

Glad that you found the problem.

I've used several of this class of lathe for 20 years. If adjusted properly and used properly they really do work just like any other lathe and you should expect similar results if used the same way. The biggest difference is that it does not have extra mass in the saddle to act as a damper. For example, the 7x10 apron and saddle together weighs a skooch over 5 lbs. A 1/4 inch turning tool exerts more than enough force to lift the saddle if it's not properly adjusted. A large lathe like the 14x40 Southbend (by grizzly) has a saddle+apron assembly that are much more massive so they are less likely to be moved by cutting forces.

 

[addertooth]

dbstoo,
Yes, I have considered the merit of adding weight to the saddle.