Classic mistake

[moerman]

Today I felt sufficiëntly confident to do some turning on my new lathe. I had to make two identical stepped washers. The exact outer dimensions were not critical, so I eyeballed the first one. Then I had to make an identical washer. I measured the stem of the first one and it was 0.75 mm smaller in diameter then the second one. So that is 3 times 0.25 mm which equals 3/4 turn of the dial, right? So I cut exactly that amount from the steel stem. Checking the diameter with my caliper showed the actual size .... It was exactly 0.75 mm to small in diameter . But at least now I know that the dial is accurate 

luckily the stem of the stepped washer is out of sight so it was perfectly usable, but I learned a valuable lesson.

[Johnb]

Done that too!

[Jo]

  Yes radius versus diameter so easy a mistake to make.

To confuse matters some lathes have their cross slides marked in diameter  I have over come this by using either dial gauges on the cross slides, which of course reads radi and DROs on the other two which reads in which ever I want = diameter

Jo

[steamer]

Had a similar issue when I commissioned my newly restored SouthBend 9 lathe.   It had the big dial option which according to the manual meant it was "direct reading"...but the leadscrews are actually for the radius....so although the dials are easy to read, it reads radius.......but the first part I tried was scrap.....


Dave

[philjoe5]

Making the simple parts you were after is a good place to make mistakes.  It hurts more when you've got a few weeks invested in making a complicated piece, and then mess (bugger, stuff etc.) it up.  DAMHIKT

Cheers,
Phil

[fcheslop]

Did the same mistake when boring a pulley out on an unfamiliar lathe :facepalm2:still repeat some of the remarks the gaffer made