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| taper problem. |
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| wheeltapper:
Hi here's a weird one. I'm turning a No2 morse taper, so its a fair chunk of metal, not a flimsy thing. I have the saddle locked, I'm turning the topslide feed with a socket on the centre nut driven by a cranked handle so no side to side wobble. I get near size and take three cuts without changing the cut so no spring, lovely finish, and the damn thing is fatter in the middle than the ends!! have I got a special topslide that goes round corners or am I just going round the bend? any ideas. Roy |
| lordedmond:
your tool is not at precisely centre hight hence the barrel shape |
| DMIOM:
or maybe the top-slide gib(s) aren't evenly worn - certainly on a mill you can find they're slacker in the middle... Dave |
| Mike Cole:
Geo H Thomas gives the figures in his book 'The model engineers workshop manual' . But the old story of tool height not being on center gives a barrel shape is a bit of red herring. The error with a tool 30 thou out is something like 0.000012 in or one 12 millionths of an inch. Look to your tailstock fitting and the gibs. Mike |
| wheeltapper:
the results so far, tools dead on centre height checked with a facing cut, no pip. tailstock not used. no discernable sideways movement of the topslide throughout its travel. Roy |
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