Harrison mill levelling bolts

[Trevor HaywoodParticipant @trevorhaywood45643]

Hi, does anyone know what size bolts fit the threaded base lugs on the Harrison vertical milling machine

Thanks for any replies Trevor

Edited By Trevor Haywood on 23/04/2018 21:51:05

[Trevor HaywoodParticipant @trevorhaywood45643]

[not done it yetParticipant @notdoneityet]

Don’t know, but relatively easy to make a good guess, based on simple measurement.

Measure core size by insering a close fitting drill shank and measuring same. Check the pitch of other fixings on the mill. The base fixings are likely of a similar thread form, so consult thread tables in engineering books or websites.

Length of lugs is easy to estimate. They may, or may not,be all the same. The age of the mill might also be a clue as to whether metric or imperial thread form.

[Howard LewisParticipant @howardlewis46836]

If the threads elsewhere on the machine are Whit or BSF, the leveling screws are likely to be the same form.

Made some 3/4 BSW leveling screws for a lathe. Despite screwcutting the threads, as a roughing operation, the final finishing with a die was hard labour.

Howard

[Carl Wilson 4Participant @carlwilson4]

Hello,

I have a Harrison horizontal/vertical Mill which I’ve just bought and am setting about restoring. There is nothing Whitworth or BSF on it. It’s all Unc and Unf. I believe the levelling bolts are Unc.

I’m afraid I can’t give much more than that as I’m not in s position to access it currently.

Edited By Carl Wilson 4 on 28/04/2018 18:29:54

[not done it yetParticipant @notdoneityet]

Check a coarse threaded stud/setscrew/bolt 1/2” in diameter, if imperial. TPI will be different for whit and unc. Other diameters will be the same TPI.

[Carl Wilson 4Participant @carlwilson4]

Not wanting to be a pedant but…watch out for those thread angles. Whit is 55 degrees and Unc is 60 degrees.

[Trevor HaywoodParticipant @trevorhaywood45643]

Thread size is 7/8 UNC, I bought 4 x 3" set screws with lock nuts from a local fastener supplier, mill is now sitting level

Trevor

[Carl Wilson 4Participant @carlwilson4]

Nice one Trevor. You’ve helped me out with that answer too. Be a while before I need to worry about levelling mine though.

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