Proper Tool Angle

B

BarnyardEngineering

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My Logan 815 lathe has a standard rocker tool post and one 1/4" tool holder that fits it.

I put a 1/4" carbide roughing tool in the tool holder, put it in the rocker tool post, and set the tip of the tool even with the point of a center drill in the tailstock. Trying to make some chips on a chunk of 1-1/2" mild steel round bar just to say I made some progress with the %$#@ thing...

The problem I have is the tools point upward and the entire relief face of the tool is rubbing on the material. Suffice it to say there is a lot of noise and not much cutting going on.

Lowering the tool puts it below the center of the work, which I've been told is bad bad bad.
 
Your Armstrong type tool holder was made for HHS tools, the angle is wrong for carbide. Use carbide for hardened steel, It's like using the Lexus to take out the garbage while the Jeep sits at home.

If you must use carbide, ignore the tool holder and make a stack of (something) so that the carbide holder is clamped in the "lantern post" horizontally.
 
Unfortunately I don't have any HSS tools or blanks to make them from. That opens the whole can of worms of getting a decent bench grinder and learning to grind tools.

I've got an Aloris clone tool post coming in the mail now. Hopefully that will work better.

I bought this shoebox of tooling from the guy who sold me the lathe. He couldn't have been using this lathe because nothing was compatible with anything else.
 
Even though you have a 10" lathe, will it turn fast enough to really take advantage of carbide? I agree with Tom - your tool post is causing you to run out of clearance with that bit. I think the QCTP will solve many problems for you but a really good HSS tool will solve even more of them and you might want to learn to grind a tool.
 
You can get by with lowering the tool just enough to stop the nose from rubbing with little risk. Having the tool low gives the work a tendency to climb up on top of the tool, but it's not a real big concern unless you turned diameter is small enough to be flexible. I'd also look at the leading edge side clearance of the tool. Most out of the box brazed bits really need a little work to get an optimum cut.
 
What about just putting a thick washer under the dished base of the lantern post? This might allow you to then lower the tip enough (using the rocker) and get back a bit of the relief. Until your other toolpost arrives, anyway.

-frank
 
A thick washer is one way but it has its own drawback. It may not be consistent in thickness. This will cause any number of problems, one is the tool height itself. At any time in loosening it can change. Any time you add something to the tool post like this vibration is the chief concern. I am not saying it won't work, just giving you an idea what to expect.

"Billy G"
 
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