Eccentric Turning Production Run

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Ken I

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Oct 31, 2010
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Cape Town, South Africa
I had to turn out 24 eccentric pins :-

Tedious to clock each one in a 4 jaw, so I mounted my ER32 collet chuck in my 4-jaw for a "production Run :-

Top Left - my ER32 on a home made adaptor flange - fits my lathe - extra holes adapt to my mill and dividing head.
Mid-Left - the castellations are for the hook spanner (the smaller flange also fits my smaller lathe).
Bottom-Left - ER32 / Adaptor Flange mounted off center in 4-jaw.

Right - Initially clock ± true, then set one pair of jaws horizontal - move the toolholder in to touch - back off by the eccentric required - open the nearside jaw and jack out the offside jaw to the tool holder - this is your "rough" setting. Follow up by clocking up your "throw" (3.0mm in this case) using the cross slide handwheel for the 3.0mm and the micron clock as a fiduciary gauge (alternately long throw dial gauge).

The bottom right also shows the MT3 ER32 holder which isn't any use for eccentric work and I find it sticks out too far when used in the lathe spindle - hence my own adaptor flange.

The pointed ends were obviously 2nd op .

I have another eccentric part that I make fairly frequently - for that I have an eccentric bush with a grub screw to secure the part and I simply put it in the 3 jaw - fine where spot on accuracy is not required.

FYI - Ken I
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