Hey there,

This past weekend I picked up a Peter Wright solid box 65 Lbs vise that has the screw missing/broken off. (They welded the thing together and planted it in the yard as garden art. I got it for $30 bucks).

I cut it apart and am trying to figure out what the thread size is so I can repair it. I thought it was an Acme 1"-4 and ordered a threaded rod from McmasterCarr. But it's to small and the thread pitch is wrong.

Anyone know what the thread size/type is for this vise? I'd love to get it working again.

Thanks for any info you may be willing to share.

Bill.

I can't help with the thread size, but I was just cruising a popular auction site and saw just the screw and handle for a post vice for sale. I Wouldn't think there would be a lot of different thread sizes for post vices so it might be worth checking out. Someone please correct me if I am wrong.

I'd assume every manufacturer would have a different screw size for every size vise they made.  Correct me if I'm wrong!

It's a square thread not an Acme. It's difficult to know the pitch, since you're guessing at something made in England, maybe 1850 to 1930. It's the kind of thread put on old house jacks and old office chair bottoms.

Makes sense that it's square thread as I can't find anything that matches in the Machinery's handbook.

I also read on Anvilfire that old house jacks had the same thread shafts as many vices, But how can one know what size to purchase??,

Not sure what to do.  On one hand I'd like to make it as close to stock as I can, but on the other I want to use it, (and I will be using it) but I want it to be strong as it can be also.

 

 

The original users didn't care much about them being "stock"; they shifted parts around with "reckless abandon".   As I recall "Practical Blacksmithing" includes a discussion of methods of repairing screws/screwboxes from 120+ years ago.

When I get some time at the shop I must run around and try the house jacks screws on the postvise screwboxes to see if that holds true.  I remember people using house jacks as donor material for both the screw and screwbox; but not just using 1 part.   I have about a dozen postvises and 8 or so house jacks for a decent sample size.

14 hours ago, Bill M said:

 

Not sure what to do. 

Why not just measure the female thread ?

A simple inside caliper should be all that's required to ascertain the OD of the thread, and a "pitch" of that size should be equally simple to determine.

Keep in mind that the female thread will be slightly larger than the male screw.

And by measuring the distance from any given point on a thread to the same point on the next thread, ( in inches ) you can arrive at the pitch, by dividing that distance into 1 inch.

Yes, this assumes the thread is an SAE rather than a metric size, but the conversion from one to the other is no problem either.

Quite possibly, the thread used on the pivot bolt ( and the actual diameter of that bolt ) will be a good indication of whether metric or SAE threads were used in its manufacture.

On a square thread of that size, minor errors and ambiguities in your measurements will not significantly affect the outcome, as the differences from one size to the next will be substantial.

 

.

 

SmoothBore-I did measure the female thread and thought it was a 1"-4 Acme, but was wrong. I believe its a 1-3/8" 4 square thread.

I just can't seem to find any square thread stock or house jacks of that size, but I'm still looking.

 

Thomas Powers, Looking forward to hearing what you find.

 

Thanks for the input, much appreciated.

 

Bill 

Going to be a week or so before I get a chance to go to the shop

All good.

There's a huge street antique fair Sunday in the town next door (Pleasanton, CA) Hopefully I'll find something there.

In the mean time I've built a large electrolysis tank from an old gas cylinder and am cleaning off the rust from the vise parts. 

 

Are you going to straighten up the moving jaw stem? The reason the screw sheared could be as a result of, or at least linked to the evident over-tightening.

Does the screw from your installed vice fit? 

The levelling jacks on the scaffolding system I have are square threads of a similar size. They are rolled into tube I believe, if you could fit them and use the threaded tube as a sleeve over a solid core, maybe sweated with silver solder, or just welded either end?

Do you know an engineer with a screw cutting lathe?

Buy a large threaded rod and a nut to suit, does the place you bought your 1" acme thread do nuts to suit? and either fabricate the nut into a housing to fit the vice or weld it into the existing female piece. Any thread form with a 1/4" pitch would work.

Alan

Yes, I plan to straighten the stem.

The screw on my installed vise is too small.

All good ideas you've listed Alan, thank you.

One way or the other I'll get it working again, I'd just like to get it as close to original as I can. 

Bill