I had a friend looking for the above nut. I told him to try McMaster Carr. He stopped by yesterday and gave me two 1 1/4-7 nuts that thread just fine on my lathe. How can this be? There is no play in it and it threads on all the way to the plastic washer. Any thoughts on if this could damage the threads or?
-
December 2025 Turning Challenge: Single Tree! (click here for details) -
Congratulations to Bob Henrickson, People's Choice in the November 2025 Turning Challenge (click here for details) -
Congratulations to Guillaume Fontaine for "Old Tea Pot" being selected as Turning of the Week for December 15, 2025 (click here for details) -
Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.
1 1/4-8 nut
- Thread starter Sam Force
- Start date
john lucas
AAW Forum Expert
If you don't have to force it you should be ok. Are you sure the nuts are 7 tpi. That is a standard size. 1 1/4x 8 nuts are for special applications and not common. Of course for whatever reason lathes picked 1" 8 abd 1 1/4 x8 as a standard.
It came from a local bolt supplier and was IDed as 1 1/4-7
This brings up the question of "if 1 1/4 by 7 tpi is industry standard, why are lathes 1 1/4 by 8 tpi?
robo hippy
robo hippy
7 tpi thread is a no go.
FWIW, I ran into the other side of this supply problem – looking for 1-1/4x8tpi rod for a storage solution. It's super hard to come by... until I had the "oh I have a 3D printer now" facepalm moment and had a threaded flange printing up not long after. (This was for wall storage of a sanding disc, fwiw.) My first guess at a "nut" with true threading for this size, depending on the precise need, would be to buy an inexpensive small faceplate.
As to why the 1-1/4x7 nut seems to fit... close threadings have an annoying tendency to almost fit, if not too many turns are required. I have to suspect that's what's going on here?
related to close threadings, imagine my vague cursing in the shop from a few weeks back on a project that had both 10-24 x 2-1/2" bolts AND (the extra cursed size) 12-24 x 2-1/2" bolts. close enough that threading the #10 into the #12 by hand for a test fit feels right, but under load just slips out like the threads have been stripped. but then the threads are fine on inspection. ? ?? ?!??? both with the same head style, despite completely different vendors, in very similar clear bags upside down on the bench. I'm still slightly miffed at the nameless engineer who spec'ed a hole size intended to be tapped at 12-24.
McMaster Carr does in fact have 1 1/4 x 8 nuts. If yours fit, they fit, but I suspect they were mislabeled at the local supplier. Easy enough to count the tpi yourself or use a thread gauge. Very hard to believe a 7 tpi nut would thread all the way onto an 8 tpi spindle unless it was a super sloppy fit.