NO 26TPI THREAD CUT SETTING

[JasonBModerator @jasonb]

Now if you really want to be clever Neil you could tell us what temperature we need to get the workshop and workpiece upto when we cut the thread so that as it returns to normal use temperature it will shrink to the exact pitch required

[Neil WyattModerator @neilwyatt]

Hi Jason,

The answer appears to be one degree C/K! Did you know that already?

Neil

[george BROCKISParticipant @georgebrockis29399]

The handbags are out .

"use temperature it will shrink to the exact pitch required" lol

[JasonBModerator @jasonb]

Posted by Neil Wyatt on 11/11/2014 17:29:37:

Hi Jason,

The answer appears to be one degree C/K! Did you know that already?

Neil

No

But does that apply to all materials? I would have thought you would not need to get a copper rod as warm as a steel one

[Neil WyattModerator @neilwyatt]

AArgh Jason! My brain is already starting to dribble out of my ears!

Neil

[JasonBModerator @jasonb]

Back to the subject, I just worked out if my 280 can cut 26tpi.

40 spindle driving 65T = 0.6153846

50 driving 80 = 0.625

60 driving 75 on the leadscrew = 0.8

0.6153846 x 0.625 x 0.8 = 0.3076923

0.3076923 x 26 = 7.9999998 which is good enough for me and my 8tpi leadscrew provided I do it when Good Friday falls on a Thursday

 

EDIT if I use the Windows calculator that gives the 40/65 to far more decimal places it comes out bang on 8

Edited By JasonB on 11/11/2014 20:56:30

[Anonymous]

No need for decimals, or calculators:

40/65 x 50/80 x 60/75 = 8/26

Purely integer arithmetic.

Andrew

[Author]

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