View Full Version : Now why would they do that?

12-27-2006, 10:28 AM
Sheesh...my cutter grinder project is on hold. I lost/misplaced the nuts for the sliding "T" bolts for my swivel table (from my broken vise). Thought it was no big deal I have hundreds of 1/2"X13 tpi nuts. Only thing...it turns out these are 1/2"X12 tpi. I looked in every store that may have them yesterday and everything was 13tpi. Nobody had a 1/2"X12 tap. I don't feel like making new "T" bolts. What a pain. WHY 12tpi???
Hoping the bolt place will have some. Nice! Get to drive through a snow storm for two stinking nuts! Oh well...they could be 11 1/2 tpi I suppose :D
Now WHO dreamed THAT one up?

12-27-2006, 10:34 AM
1/2"x12 tpi was Whitworth thread used all over the world for over 100 years still used on British made machines until metric system was introduced into Britain in the early 1970s

12-27-2006, 10:39 AM
Just use some regular nuts and stretch them a bit until they thread on.

Your Old Dog
12-27-2006, 10:47 AM
Just use some regular nuts and stretch them a bit until they thread on.
Mine usually do that on their own when they warm up.

12-27-2006, 10:52 AM
I wonder why it's called screwing? Broaching is more like it.

12-27-2006, 10:55 AM
1/2-12 was also used in the 19th century in the US. It hasn't been used here since the very early 1900s. Unless they're Whitworth, you don't have a snowball's chance of finding any more...and finding Whitworth nuts would be quite a challenge.

Your Old Dog
12-27-2006, 11:14 AM
When I was a teenager I was building a ham radio transmitter. I had misplaced a little flat bladed screwdriver that I needed. I thought it dropped into some cardboard boxes under the workbench. I dumped everything into the middle of the floor but nothing. I looked for another hour before coming into the house all po'd and threw myself down on the couch. My dad said "what's wrong bud?" I told him I lost the only screwdriver that would work for what I had to do on my transmitter. He got up out of his chair and walked over to me and reached in my shirt pocket and said, "you mean this one?"

Have you checked your pockets? LOL

Or, since no one else has mentioned it, have you looked in the last place you had it? I'm sure that's where you'll find it unless it has legs of it's own. LOL

12-27-2006, 11:15 AM
Make a tap.

12-27-2006, 11:26 AM
Make a tap.
LOL!...If they don't have any nuts...I'm going to hack the weird ones off and tig new bolts into the square flanges.

12-27-2006, 11:27 AM
Just think of it as an anti-rotation nut ;)

How about turning down the end a short distance and threading them for a 3/8" or 7/16" thread? Drop a spacer or washers on it and you can save the rest of the 12 pitch thread ... but I'm not sure why ;)

12-27-2006, 11:45 AM
Saw off the existing stud. Drill and tap the tee nut for 1/2-13. Buy a stud the correct length. Locktite the stud in the tee nut. Reassemble the vise and use it. On the other hand, you can buy a 1/2-12 tap from MSC and make a nut.

12-27-2006, 02:18 PM
Got it! I looked closer at the "T" bolts. They welded studs into them anyway. I ground off their lil' bit of weld..punched the studs out and welded in new ones with 1/2"X13 threads. I still don't see why the Chinese would do this. All the other fasteners on the vise are standard everyday course thread bolts.
They must have got a good deal on some dies on Ebay :D

12-27-2006, 02:21 PM
Chinese, you say...are they metric?

Spin Doctor
12-27-2006, 03:56 PM
One reason the thread may be an odd ball is companies loved to do this stuff. Special screws for their machines so if you lost or broke them you had to go to them to buy one (or two/three/whatever). When was the last time you saw a 1/4-24 or 3/8-18/20? Plus when there were no standards machine designers just used what ever they darn well felt like.

daryl bane
12-27-2006, 11:42 PM
If this is a Chinese unit we're talking about, those threads are not by design. I've run into this quite a few times in different sizes. Its just really bad, super shoddy manufacture. I recently got one of those Deckel copy SO grinders, and there were threaded holes and bolts so sloppy, who know what configuration they were. I went back and heli-coiled all of them to a standard size. We just got some barstools(chinese) and the bolts used metric allen keys, but threaded 1/4-20.

Paul Alciatore
12-31-2006, 11:30 PM
I think the Chinese are doing a lot of "Zerox" designs. They take an existing machine and copy all the parts. If the original had 1/2-12 threads then their copy will have the exact same. The changes they do make produce some strange combinations of English and metric.

Perhaps in a few years or so, they may start to actually design things.

12-31-2006, 11:57 PM
LOL!...If they don't have any nuts...I'm going to hack the weird ones off and .

Russ,were buds and all but no way are you hacking my nuts off:eek::D

02-25-2007, 06:22 PM
You can get them here in Norway.

02-25-2007, 08:29 PM

"All the other fasteners on the vise are standard everyday course thread bolts."

Bet you that the other fasteners are Whitworth also. UNC and Whitworth have the same TPI counts in most of the smaller sizes, and ordinary hardware store nuts from one system will quite happily screw onto bolts of the other system, though the threads are often a sloppy fit. The exception is 1/2 in, which is 12 TPI in Whitworth and 13 TPI in UNC. Even the Chinese usually stick to one thread system, often Whitworth, on this sort of gear.


12 TPI was used in at least one application in the USA until the end of the 1920s to my knowledge. I have several twenties Chevrolet engines - all the head bolts are 12 TPI.