Vise screw and screwbox repair - another option

[robodog]

A few weeks ago I asked about repairing the screwbox on a post vise. The threads of mine were totally mucked up - twisted and sticking out and unusable. Got some very good detailed answers on how to do it - based on removing the old ones that were brazed in and creating a new helix, which in turn gets brazed in place. Read that informative thread here.

I'm a newbie and this project is definitely beyond my ability. I went to see my friend, the wizard Chuck. Chuck is an inventor of new things but with a passion for old ways. Chuck has a fantastic shop with many old machine tools, some that are belt driven, but all of them hum magnificently. With his help and direction, we fixed it, but we decided on a non-orthodox method. Still worthy, sturdy, and cheap. (Apologies in advance if the formatting is sloppy.)


After inspecting the existing screw, we determined that there were effectively three options. It was so worn that the screw itself would need 1) some welding and turning work, 2) need to be turned down to a different thread count (meaning thinner and weaker thread), or 3) need to be replaced. The first option was way too time consuming. The second option would yield an inferior product. As to the third, we looked at Acme lead screws and nuts on McMaster Carr and figured it would cost almost $200 just for a nut and screw. The existing screw is (was) square thread - not Acme.

That's when I remembered that I had an old screw and nut from a woodworker's vise that I'd been hanging onto for about 30 years. ( Hey - you never know… some day…) Square thread, to boot; and similar thread pitch - about 2" vs 2 1/4" on the old screw.

So despite being a thinner stock 1 1/4" vs 1 1/2" we had the materials in hand and they seemed sturdy enough. The new nut is not as long - 2" - as the original screwbox and admittedly, this is more a pragmatic approach than a purist one.

After cleaning up the vise and parts, the first thing we did was to get the old brazed thread out. First we picked some of it out with an old screwdriver and needle-nosed visegrips. Then we heated the screwbox red and hammered and picked out the rest. After that we filed and scraped and ground the inside of the screwbox to clean it up.

Next came the existing cast iron nut. After cutting off the flange we threaded it onto the screw and chucked it in the lathe. Then we turned it down so that it would fit inside the screwbox. But the screwbox wasn't perfectly round so the the nut fit was a little irregular.

The plan to secure the nut into the screwbox was to braze it in place with welding access from four holes drilled through the sidewall. We also drilled and tapped four small holes for setscrews to hold the nut in the proper position for the brazing operation. First we used some silver solder between the new nut and the old screwbox - brazed in from the top. Then we did the same at each of our 3/4" holes and finally filled the holes with brass rod.

It ain't goin' nowhere.

We stuck the whole thing in a bucket of ashes for a slow cool down, figuring that'd prevent the cast iron nut from cracking.

Next comes the new screw. First thing we did was to cut the old worn out screw off from the turning knob. (We had previously removed the handle.) We used Chuck's old "Marvel No 1." electric hacksaw. Marvel did its magic on getting the new screw to the right length too, even though it was a harder steel. Then we ground the two parts to be welded back so that they were somewhat pointed or conical - giving room for the welding rod to get in and fill in. After that we took great care to ensure the two pieces were aligned and clamped securely on the table. The actual weld - done with five 7018 sticks - took several passes with cleaning and careful checking and a little bending to ensure alignment. Finally the grinding belt and the wire wheel to clean it up a bit.

By now the screwbox was down to room temperature. All but one of the setscrews were welded in place and just broke off. After cleaning the flux off, we took the grinder to it and ground off the stubs of the setscrews and cleaned it up. After a few turns back and forth the new screw was worked into the screwbox and then all the way in and all the way out.

A few other nicks near the vise jaws were filled with weld metal and ground/filed/brushed down to match the original tool. Here we reassembled it. She's ready to go back into use.

And gave it all we had to see if we could break the new assembly. Solid as a rock.

If you don't have a vise screw and nut laying around, a quick search on the web will yield several suppliers for this type of retrofit with a woodworking vise screw. Here are a few - I'm sure there are more available:

Woodcraft
Lie Nielsen
Lie Nielsen 2

Roger

[dablacksmith]

nice repair! looks like it will work well for you! more work than i would normally go thru tho unless i got the vice for free!

[CurlyGeorge]

That was definetely a lot of work. But looks ike you have a very good vice that should serve you well for a lot of years, and then some. Thanks for sharing the process and the pics. :D

[aametalmaster]

Great repair job. I love fixing parts like that...Bob

[arftist]

Good post. What was so expensive about the acme thread, was it the nuts? I have 12' of acme rod left over from a job, I don't remember it being very expensive.

[John McPherson]

Wholesale Tool carries acme rod and nuts in sizes up to 2", left and right hand thread available, and lengths as short as 3' up to 12'. Reasonably priced, easy to ship.

http://www.wttool.com/

So does ENCO. Not so cheap, but higher quality C1018, 4140 alloy, and 316 $tainle$$ $teel. You DO want this to last forever, don't you?

http://www.use-enco.com