Parting Question: Seems Feed Is Really Fast.....

I agree with epanzella, you can't have too rigid of a set up for parting. I had problems on an Atlas 12 x 36 and a Rockwell 10 x 36 using latern style tool holders. I made a tool holder block for a piece of 5/8" x 1/8" HSS cut off blade. Mounted the steel block to the compound with a bolt/T-nut. Marked the center line of the lathe on the block with a chucked up scribe. Milled the slot for the blade, drilled/tapped a couple of holes to lock the blade. Went from pecking away to getting through 1 1/2" rounds of steel with no issues. Tom's Techniques has some good info at his web site. He always sharpens the HSS blade before cutting.

Bruce
 
So I'm going to cautiously say I've got it figured out.

Operator error would be the world.

I went out yesterday and bought a machinist square, good to .0025

I chucked up a piece of 6061, set it up my usual way and chatter chatter chatter.

I backed off the tool and dropped the square against the work piece, rolled up the tooling to the square and there it was: not square to the piece as indicated by the square.

A quick little adjustment to the compound and try again.

Touch of chatter as I entered, then nothing but a nice smooth curl as I plunged into the work. Still need some pressure, but nothing like before.

So, it seems somehow that all this time I have been messing up getting the tooling square to the work.

Hopefully, that was the problem but I will be looking at the other items mentioned in this thread. To optimize the setup if nothing else....
 
We don't call it "operator error", or "human error" any more. We call it human factors. :).

Sure hope you found the problem. Keep us posted.

David
 
great white said:
So I'm going to cautiously say I've got it figured out.

Operator error would be the world.

I went out yesterday and bought a machinist square, good to .0025

I chucked up a piece of 6061, set it up my usual way and chatter chatter chatter.

I backed off the tool and dropped the square against the work piece, rolled up the tooling to the square and there it was: not square to the piece as indicated by the square.

A quick little adjustment to the compound and try again.

Touch of chatter as I entered, then nothing but a nice smooth curl as I plunged into the work. Still need some pressure, but nothing like before.

So, it seems somehow that all this time I have been messing up getting the tooling square to the work.

Hopefully, that was the problem but I will be looking at the other items mentioned in this thread. To optimize the setup if nothing else....
Click to expand...

Good to hear you got it figured out. I line up my parting tool to the face of the chuck. With it not turning of course.

Tom S.
 
Well, worked for a while.

Chatter is back, although not as bad as it was.

I think maybe it's lack of ridity in the compound assembly. I can make chatter appear and disappear be leaning on the end of the compound.

I guess I'm going to have to play with the gibs and see what I get....
 
Glad you are making progress. Any chance of us seeing a picture of your set up?
 
Quick update.

I changed out all the gibs screws for slighly longer Allen heads and that allowed me to get the slides a bit tighter and a bit more precise. Basically, took out some slop. It's stiff to turn the hand wheels, but acceptable for parting operations and then easily backed off a bit for turning operations.

I also made sure the front of the compound did not extend past the carriage support.

I cut off some 1" steel rod and was able to do it with minimal/no chatter. I did have to feed (what seemed like) heavily. If I backed off the feed it would start to chatter/squeal, but a heavier plunge back into the material would get under the chattered surface and start cutting well again.

I was also able to play with speeds as i was cutting, which also seemed to help. There was a pretty fine line between chatter and none for speeds. The variable speed DC motor conversion was worth its weight in gold there. Even at low rpm, it just leaned into it and got it done. Lots of torque and the cycletrol kept the speed constant, unless i was compensating as the tool plunged in to the center.

Still seems like heavy feed is needed, but now I'm guessing I'm just getting used to parting operations on this particular lathe.

The aluminum chatter might be the spring in the material as much as the machine. I'll have to try a really heavy feed next time i cut Al and see how it goes.
 
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