Chatter problem

Hi

I`m making a duplicating carver for roughing out wood carvings. I have a four pulley carriage that runs on .5 dia drill rod. It seems the angle of the pulley pushing down against the drill rod cause the carriage to move with too much resistance. I would like to make new pulleys similar in design to shouldered timing pulleys. The problem is I`m using a straight faced carbide tipped lathe cutter and was hoping to cut the full width of the cutter in the aluminum. It seems that I`m getting too much chatter. I`m looking for advice on the correct technique and or the right tooling for the job. I did try a 3/8 wide cutter and moved the cutter laterally to get the .501 groove width but even a smaller cutter produces chatter.

Thanks for the help

Wide grooving tools are always a problem. There are several things you can try, one is using a negative rake tool, another try using the tailstock and live center, even if the piece is chucked. Make sure the carriage is locked, and there is no play in the cross slide. Slower speed would help, but most home lathes don't go slow enough. Lots of cutting oil, friction on the sides of the groove will add to the problems. My guess is that for that wide of a tool, anything less than a 7A J&L isn't going to be rigid enough. Good luck.

The possibility of chatter goes up rapidly with the amount of edge doing the cutting. Thus, you want to work the cutter back and forth as you do the cut and let the fianal cut happen only at the end of the process when the whole cutter is finally engaged. Thread cutting for a typical 60deg. thread is usually done at 29 deg. or so so that one side is doing the cut while the other side is just dusting the surface. This basically reduces the cutting action to 1/2 of what a straight drive in causes. Even then, the cutting action can be quite shakey if the cutter isn't done right and positioned correctly on the work.

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