Re: sb 13 compound angle markings.
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There are a couple of ways that the angle markings on a lathe can be set up, if I understand correctly. One is with zero on the axis of the lathe bed, and the other at 90 degrees to the lathe bed. I understand that US made lathes use the axis of the lathe bed, and import (i.e., Chinese lathes) use the 90 degrees... Quinn comments on it in one of her Blondihacks lathe videos, as her lathe is an import. One of the modifications I made to my HF 7x10 mini-lathe was to pull off the degree scale and throw it away. I use a protractor to set angles on it. The Clausing Colchester lathe I use at school, however, uses the lathe bed for the reference. Once I get all my lathes at home operational, I'm probably going to be even more confused than you are while switching from one lathe to another. I have Atlas and South Bend lathes, as well as Harbor Freight and Smithy. And I had a short night last night, and I'm severely caffeine deficient, so I may be confused already! ;)
Bill in OKC <----- Not a professional machinist. Have been taking a professional machinist's course that should last for 8 months or so for more than six years... You figure it out! ;)
William R. Meyers, MSgt, USAF(Ret.)
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On Thursday, September 30, 2021, 09:00:45 AM CDT, ken campbell <deltainc@...> wrote:
oh no !! .. i needed to grind a 1.5 degree angle on a form boring bar ... so i set my trusty compound angle to 1.5 degrees and dialed the compound past a dial indicator an inch ... great, 0.012 taper or so ... hmmm .. shoulda been 0.026 ... what the ?? ... so i set the compound to the 3 degree mark and now i get the 0.026 per 1 inch ... what the ?? ... yep, i indicated that i was cranking in 1.0 inch ... yep, i repeated the test against a perfectly straight piece in the chuck with the indicator stuck to the compound. yep, the index marks read 90 degrees at 1/4 turn ...
hey, after 40 years of this i just found out i am a beginner ...
or maybe the compound index is for included angles ?? .. i just threw that one in there ...
help ! ... can we not even trust south bend ? ... i feel my dog just died ... or maybe Regan was right ... trust but verify ...
ken the depressed