Posted by Ron V on April 24, 2006 at 06:01:52:
In Reply to: Re: Problem with Fellows 36-6 posted by Robert E. Almstrom on April 23, 2006 at 21:05:22:
Thanks for the offer of help.
With the cam which came on the machine I'm getting around 0.022" back-off.
As I mentioned in the original post, it doesn't seem to matter which cutter I use or if the job is internal or external. For example: 4Dp, 25deg PA, 62 internal teeth using a standard 15 teeth cutter or 7module, 20deg PA, 68 external teeth using a standard 15 teeth cutter. It doesn't matter which set up I'm using the marks or scoring are still there.
The color of the marks doesn't seem to vary that much from the job's color. Both these jobs are K1045 high carbon steels so leave a dull almost grey color anyway. There is no evidence of cutter rub on the teeth of the cutters. All of the cutter’s tooth faces are shiny with no observable changes in color due to cutter rub.
Changes in back-off angle from one extreme to the other appeared to make no difference. At present we are running at around 6deg towards the rail.
One thing I was wondering though. Our Fellows 6A uses a spring loaded drive to the lower worm set. I guess it has as a sort of cushioning/dampening effect so as to isolate the “intermittent driving” of the indexing mechanism, due to the table relieving, from the rest of the machine. The 36-6 doesn’t seem to utilize this it seems to be a solid, positive drive with no dampening. Why would both machines be so different in their indexing drive trains and yet are so similar in the way they operate? Should the 36-6 have a dampening mechanism as the 6A?
Many thanks, Ron.
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