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I Forge Iron

Easy Leg Vise screw and box replacement


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There is an relatively easy replacement for lost or broken screw/box for old leg vises. I Have done this on several vises that I found without the screw/box.

When leg vises were being made and sold there were probably only a few manufacturers of the screws. They also supplied similar screws for other purposes. 

During that same period a lot of screw type railroad and house jacks were made and sold. These types of jacks used high quality steel for the screw and cast iron for the female receiver. They were very heavily constructed and the screw pitch is similar to a leg vise pitch. If you cut the screw portion of the female receiver off you will have approximately the same amount of screw threads that are in a typical leg vise box. Being cast iron it can easily be shaped to fit the back of a leg vise, but you will need to leave an ample  amount of lip on the new ground receiver. House jacks are for sale on ebay usually fairly cheap. Make sure that when you purchase a house jack the thread is fairly close to what was probably the original size of your screw. That is for a small vise a 1 to 1.5in thread is good. On the one you see in the pictures that is a 200lb vise that I used a 2in X 18in thread on. The jaws on that one will open wide enough to use almost the  whole screw length. For a replacement washer I use an annealed piece of coil spring and a large washer. Let me know if you have any questions. Don't be concerned with the strength of the new screw, railroad jacks are rated in terms of tons and It's doubtful you will ever exceed its rated strength. 










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Thank you for the tip.

I have a question about another possible alternative. 

What about using scaffolding levelers?

Also what lead is needed for leg vises?

Good questions_

I'm not familiar enough about scaffolding levelers, I suppose they would work if the receiver/ box could be fashioned out of a scaffolding leg. They should be strong enough since they support a lot of weight.

By lead I'm assuming you mean the threads per inch? On my 100lb vise the threads are 2/in. on the 200lb vise with the replacement house jack screw the threads are 2.25/in.

Almost the same. The threads are flat sided on both and about equal in thickness.

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I have repaired my first post vice using Scaffolding levelers. I cut the origional screw off from the handle and re welded the leveler screw to the old handle. I laid a bead of nickle rod over the cast iron on the handlethen welded the screw with 7018. it has held for about 10 years now. I cut the female threads offwith a bandsaw ground the "nut" down to fit inside the cast iron "box" and re welded in the same manner. since my "box" was enclosed it limited the length of "male" screw I could use and had to cut the length a couple of times. Some of the levelers or scaffold jacks are aluminum so make sure you get the steel ones.

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  • 3 weeks later...

WELL... that explains a bunch. I just bought my first post vise on Friday (8/29) and it was covered in grease. After cleaning it, it looks like it may have experienced catistrofic failure at some time a long time ago. possible break/ reforgeweld on one main leg andmajor welding up under and around the screwbox area. BUT it has this long square threaded screw and a "box" of cast iron that sits on the back side. The top mount goes through the back leg and it was BADLY reforgewelded long ago.   And yes I paid toooo much for it.  The house jack screw setup is probably what it is. Oh well... I can make it work. And BETTER!

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  • 1 year later...

arftist - You are quite welcome. Since putting in this thread I have repaired a few more vises without screws/screwboxes. One thing that is very evident is the strength of the "new" house jack screw. I have actually stood on the arm of my 200 lb vise to tighten it on a piece that I'm working on. I think the original jack I cut up to make this screw/screw box was rated as being able to lift 18 tons. The metal piece being held in the vise doesn't move at all no matter what I hit it with. 

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  • 1 year later...
  • 1 year later...
  • 2 months later...

After 20 years or so,  I completely wore out the screw in my most used vise , a 5 1/2''  Indian Chief.

I bought a short length of 1 1/4'' B7 Acme threaded rod and a nut to fit it from Enco [ now MSC ]

I fabricated a new screw box from an appropriately sized piece  of heavy wall pipe with the nut pressed and welded in the front end.

I welded a cap on the back of the crew box and bored and tapped it for a grease fitting.

The screw box had a tab welded on so it doesn't turn in the back half of the vise.

The screw box should be  a somewhat  loose fit in back jaw of the vise so it can pivot a bit to stay aligned as the vise opens and closes.

The threaded rod was welded to the  cut off stub of the worn out  screw part of the handle.

 I ground everything smooth and gave it a black / rust patina with gun blueing  to match the rest of the vise 

Lubing the vise through the grease fitting pushes the dirt and scale   from the inside out.

I use a grease gun modified to pump heavy way  oil instead of grease which tends to hold dirt on the screw.

This repaired vise has held up  well in  hard daily use and should give me at least another 20 years of service.

As a side note,  I use the same modified grease /oil gun to lubricate the clutch and main drive pulley on my No. 7 Beaudry  / Champion motor driven hammer which has led to a dramatic improvement  in the speed and control of that hammer.  

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Vise and mount to bench.


Back end of vise and screw box


Replacement fabricated screw box and original spherical washers


Acme nut welded to end of pipe section and turned / ground  down to fit.


Grease gun modified to pump heavy oil.

Spring and push rod removed and hole plugged and bottom cap welded to body . Fill at the top at pipe plug  with  squeeze bottle with narrow spout.





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  • 4 months later...

I just bought my first vise not too long ago, it was missing the entire screw and box and replaced with what looked like a wood vise screw and nut. Problem is, the nut shattered and now I need to get it working again, preferably as cheap as possible. Scince I could buy a house Jack for less than $35 I found this post very interesting, but I don't quite understand how attaching the house Jack to the vise would work exactly. This is why I'd like to see the pictures from the original post. Please and thank you.


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  • 1 year later...

I undrestand that this thread is old, but, I just used this basic method to repair my post vice. My question is is there a purpous in the screw box being closed on the end. It looks like it would be easier to clean and lube if it were left open on the back side. Any thoughts on this. 

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The neatest method I have seen, the owner brazed a plate across the open back and then installed a zerk and so lubed his vise from the back pushing any old lube/crud out the front.

There is a lot of floating grit in my smithy so the fewer ways for it to get into the works the better in my opinion!

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