What tool shape for turning wood with HSS tool bits?

[randyrls]

I am trying to turn a few cylinders from wood on my metal lathe, but having difficulties with tare-out. How can i get better surface finish on wood?

Is there a particular shape for a tool steel bit for wood?

 

[raar25]

I would think a single point will have the least tear out.

 

[turncrazy43]

Skew chisel, very sharp and light bites should do the trick.
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Everyday I'm vertical is a great day

 

[Rich L]

Depends on the wood but I've had very good results turning African Blackwood and rosewood with an ordinary TNMG insert (carbide triangular with a positive rake chipbreaker) at about 700 RPM. The sharper the better and an HSS tool bit with a sharp edge and positive rake of about 10º would be easy to grind. Don't try to cut too much (feed) or too deep. Everything I do is on a metal lathe -- uh, except for milling. :biggrin:

Cheers,
Rich

 

[PenPal]

Look carefully at copy lathes tips that are used there where large and small detail is required there is no difference then between wood lathe or metal lathe also go find engraving tools look at the way they cut and are ground. There used to be a lathe (wood) made in Australia a mate of mine had one I will see him later in the week the tool was moved around by hand in a fixed holder so any grab would have been dreadful, even though it was a long time ago he may remember, most fitters and turners will know the grinds that work best not rocket science for them.

Have success Peter.

 

[Mike Young]

Tear out HSS cutters

I know this is an old thread, but I've just joined. I was a metal turner before becoming a woodturner. When I saw that the woodturners were starting to use carbide inserts in the end of their cutters I decided to give it a try. The tool holder on my lathe is set up to hold carbide insert cutters.
RichL suggested a triangular insert, & I've had some luck with those for hogging out wood, but I've had more success with a 1/8" wide parting tool insert, my favorite parting tool is shaped like a dog bone. It can be found in 1/8" & 1/4" wide cutters. When using a parting tool to turn on a metal lathe you can make cutting passes in both directions. Clearances are a little close on the triangular insert tool holders so you can't take as deep of a cut on the return pass. I also made a HSS parting tool that is only 1/16" wide. The things that pwhay & RichL were saying about draft and rake is important so you don't tear out, burn or burnish the wood. I also ground the top of my 1/16" HSS parting tool by holding it against the grinding wheel. This concaved surface creates a beautiful curly shaving. I use this little parting tool for the fine work when I'm cutting the pen blank down to final size.
The beauty of the carbide insert like the triangular cutter, is that the cutter is indexable. When you crash or it gets worn, just loosen the cutter and bring in a fresh surface. I have even used a tool holder that holds a round insert. That's about 180-360 fresh surfaces. Some you can even turn over and there are cutting surfaces on the other side.
Happy turning