[4]

Machine Bolt Thread Size?

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

Scruffy

Active User
H-M Supporter - Gold Member ($25)
Joined
Jun 5, 2013
Messages
482
Likes
277
#1
A year or so ago I brought home a brown&sharp model 0 horizontal mill, I have finally got around to tinkering with it.
The power shaft that feeds the table power feeds has a u-joint design I've never seen. It's missing a fillister head machine bolt and I can't figure out what thread size it is.
Looks like 1/4 by 28 but it isn't. None of my thread gauges seem to fit it. The outside diameter of the threads is .235.
It's got me scratching my head more than usual. Any ideas out there?

Thanks ron
 

Billh50

Active User
H-M Supporter - Gold Member ($25)
Joined
Jan 26, 2015
Messages
1,924
Likes
1,427
#2
It is one of brown & sharp's special bolts. There should be a thread pitch gage that will fit the thread pitch. But the O.D. will be small. If you can't make a screw I would consider tapping it out to a standard thread. Your 28 pitch gage does not fit? Does it look like something closer or farther apsrt for the pitch?
 

JimDawson

Global Moderator
Staff member
H-M Platinum Supporter ($50)
Joined
Feb 8, 2014
Messages
6,888
Likes
5,047
#3
M6 x 1 maybe? (.239 x 25.4 TPI) Not something I would expect to find in an old B&S, but sounds close.
 

Scruffy

Active User
H-M Supporter - Gold Member ($25)
Joined
Jun 5, 2013
Messages
482
Likes
277
#4
Thanks for the response bill. It may be 1/4 by 28. I didn't have my glasses on and didn't realize my thread guage only went to 20. Thought it said 28 ??
Their's too many horse flys in my shop rite now to fool with it. More later.

Thanks ron
 

Billh50

Active User
H-M Supporter - Gold Member ($25)
Joined
Jan 26, 2015
Messages
1,924
Likes
1,427
#5
Brown and sharpe used their own thread sizes. I had to retap many on an old brown & sharpe universal miller. They wanted $5 each for screws at the time so I just retapped them to standard sizes. It may have a 28 pitch but be major diameter is undersize so that a standard bolt will not fit.
We just went through this on another thread for a tap handle.
 

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
2,138
Likes
1,587
#6
Brown & Sharpe made their own standard threads before there were existing standards; I had a B&S #2 universal mill that dated about 1906, I used it in my shop for about 35 years, it was a fine accurate machine, but yes, most of the fastener sizes were "different". I remember those little screws mentioned, they had a little teat on the end to help guide them back into the oil holes, and they had a radiused face.
The smaller screws are made in machine screw sizes, not fractional sizes, hence the odd size diameters.
 

Tony Wells

Registered
Registered
Joined
Jan 22, 2011
Messages
7,053
Likes
8,120
#7
It's possible that it is not a nominal 1/4 screw. a #14 machine screw (now largely obsolete) has a nominal major diameter of 0.242. In the past, in addition to the lack of standardization, certain industries used fasteners that are now difficult to obtain. Sewing machines, some locks, typewriters, etc, and even doorknobs had what we now consider "special" screws. Some diligent search might turn up the proper screw, but often it isn't practical, so unless you are a real purist in your restoration or repair, do what you must to bring it compliant with current standards.
 

Ulma Doctor

Infinitely Curious
H-M Supporter - Gold Member ($25)
Joined
Feb 2, 2013
Messages
0
Likes
2
#8
i happened across some antique/old vintage taps and dies a couple years ago.
there were many size and thread pitches i have never seen before namely
1/2-12 tpi
#14-20 tpi
#8-36 tpi
3/16-24 tpi
 

BGHansen

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Nov 23, 2014
Messages
880
Likes
2,198
#9
i happened across some antique/old vintage taps and dies a couple years ago.
there were many size and thread pitches i have never seen before namely
1/2-12 tpi
#14-20 tpi
#8-36 tpi
3/16-24 tpi
Hi Mike,

Don't throw away the 1/2 - 12 tpi tap. I read in a recent thread that the thread is used on a PM lathe. OP posted that he'd measured the thread at that pitch (as I recall) but questioned his measuring. Matt chimed in that the lathe in question does use that pitch. As a side note, my Jet JVM-830 mill has a 1/2 - 12 tpi thread on the quill handle. I broke the plastic handle and ended up making an aluminum replacement (somewhere on the POTD thread).

Bruce
 

Ulma Doctor

Infinitely Curious
H-M Supporter - Gold Member ($25)
Joined
Feb 2, 2013
Messages
0
Likes
2
#10
Hi Bruce,
i should have specified, it was a 1/2-12 die in the lot :oops:the other sizes were taps and dies
but a 1/2-12 tap is easy enough to make if you have some O1 and an hour (double that in my case ;))
 
Joined
May 4, 2015
Messages
3,389
Likes
1,628
#11
I have a bunch of odd ball taps , 1/4- 32 -36 , 14- 24 - 40 even smaller taps much finer then the norm 4- 5- 6- 8- 10- 12 , some are for gunsmithing others I think clock building . I watch for them when looking on eBay. But some came from brownells and mittermires.
There's an old brown & sharpe in north Jersey for $225.00 or so. If I had help I'd buy it good looking mill
 

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
2,138
Likes
1,587
#12
One of B&S thread standards was 1/2-14, they used it in machine construction and in the ends of taper adaptors for the spindle; it can still be found as standard in some later catalogs. Thread standards such as we use today did not come about until the world war one era, before that it was up to individual manufacturers to set standards for their products; realize that B&S is one of the earliest machine tool manufacturers in the USA; they needed standards, so they created their own ---
 

Scruffy

Active User
H-M Supporter - Gold Member ($25)
Joined
Jun 5, 2013
Messages
482
Likes
277
#13
I’m sorry .i started this thread with a question 2 months ago. Billh50 got it right. 28 pitch, major diam. Less than a 1/4.
I made one on a 16 by 54 lathe. Took 3 tries kept breaking it off. That was my first single point threading. On me you figure out the basics it can be done!
Thanks ron
 
[6]
[5] [7]
Top