I am attempting to generate the code to modify a Collet chuck witha B&S #11 taper, to make it into a B&S #9 Taper. This is what the chuck looks like(in cyan) and the new profile I want to cut is shown in white:


When I clean up and import the dxf into LazyTurn, I get the correct profile:

Then I assign a roughing pass, and I get what I consider to be extraneouscuts in the X+, Y+ quadrant:


This will destroy the collet chuck, so it is obviously no good. I want to start each cut at a Z position greater tyhan zero, to take up the backlash in my lathe, and I then want it to follow the angle of the existing chuck body, to the proper depth, and then cut the taper.

Try grabbing the yellow arrow and draggin it to the left to indicate a different start location..

Art

>>and I get what I consider to be extraneouscuts in the X+, Y+ quadrant

   Just a note, those motions arent reallt extraneous, just what it woudl do if the bar was free hanging, as its as close to facing as it can get with that tool.

Art

Art:

I see that it is facing the bar, but I didn;t even have a line there(from outside to center at the "face" position. i think it would make more sense if lazyturn only did a machining operation on the profile that i have defined, no?

Andy

Try grabbing the yellow arrow and draggin it to the left to indicate a different start location..

Art

Trouble is, i want it to start further to teh right, so that in going way over there, and moving some distance back to the left befoore machining starts, it will take up the axis backlash.

Andy

Andy:
  Lazyturn requires all profiles to be closed, so if you didnt draw to zero, it did. I dont think it will do what your attempting.. there is no built in blocking zone or anything, the best you can do is draw the chuck and tell it to start at a safe point. I didnt allow any provision for backlash takup when an obstruction exists..

Art

OK, Art, i will play with it some more.

Thanks,

Andy

You may want to read Appendix "F" of the manual. You can start anywhere you want.
BTW, i would have set it up differently. Ground rod mounted in the collet and indicated in chuck, the tail held by a live center and also indicated in. After your done machining, check taper using light coating of die ( better than chalk) and see where there are high spots.
Frankly the shank should be ground to run really true.

RICH

Hi Rich:

I thought about setting it up the way you suggest, but that means that I would be advancing (negative) in X, then retracting as the cut progresses toward the chuck. I thought that wouold be a bad idea with the amount of backlash on my X axis.

The way I have it set up, I will be advancing(going negative) in X for the entire pass.

I just printed out the manual and will read it more thoroughly tonight-thanks for teh pointers!

Andy

I may just be thick, but I don't see anything in Appendix F that lets me change where the cut starts on the profile. All I see is a long explanation of coordinate ssytems and tool table.

Andy