Grinding fingers or "dancers"

I have been given the job of grinding a .0625 dia drill blank ( M2 steel ) end down to .020 dia .25 long with a .010 rad at the shoulder. This part will see plastic in a mold and has to be good both in diameter ( +0.0 -.0005) and surfasve finish the entire length. I was thinking of using a dancer to support it but am afraid of bending the work into the wheel. I am also thinking of plunge grinding .030 steps back to the finished length ( also setting the work behind center to prevent sucking up into the wheel... anyone with some good ideas ?

Reply to
Dave
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Hey Dave,

If it is the end result, rather than anything else, I think I would get a piece of 0.020 of the same material, put a hole in the 1/16" to accept this 0.020", radius the shoulder into the 1/16", and then fasten the 0.020" into the hole by what ever means is necessary.

Do you not have ejector pins in the proper dimensions to do this? Pretty commonly around here, there would be a pin-in-a-pin, so that if the 0.020 "breaks", it is a simple matter to drop in a new one. If the 0.020 piece has a "shape", then they would both be "dutchmanned" to keep alignment.

Take care.

Have a good day.

Brian Lawson, Bothwell, Ontario.

Reply to
Brian Lawson

When I get into that situation, I take a surface guage & make a setup with a rubberband so as to just touch the very end of the diameter (180 degrees opposite the grinding wheel contact point) with the end of the surface guage rod. Loosen the surface guage locking nut so it moves freely. Pressure is not as important as is just having a mass constantly bucking up against the part is.

Reply to
Wwj2110

My technique when faced with such stuff in molds is to grind to size+ on the tool grinder and then put the part through a hole to ream to size. The reaming does two things - sizes the part so that the end is slightly smaller than the base (very small but it should be there) and forces all of the scratches to the direction that will allow easy removal from the plastic part. I'll note that the pin will be kind of difficult to pull from the plastic if it doesn't have any taper to it so be aware of that.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

Reply to
Bob May

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