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Help identifying and repairing this japanese vise

jerholz

Cast Iron
Joined
Sep 24, 2015
Location
Dallas, Tx
Not sure I got this in the correct section of the forum but here goes..

I picked this up (literally, with great effort) for $30 at an estate sale. The markings are "JAPAN" and 6, for 6 inch. My 6 inch calipers are there for scale. There is something stamped on the slide but I'm not sure what it says.

The threads are stripped out of the nut. The screw is in good shape. The OD of the acme threads is 1.060" and it's 4 TPI. Is that a standard acme thread and what's the best way to repair the nut?

Thanks,

Jerry


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Looks like a decent enough vise. I don't know what you have for tools, but I'd just make an entire new nut. If that couldn't work, I'd add threads to the outside end of the existing nut.

Counterbore the existing nut for a spigot. Make a new nut about the same od as the existing nut, with a short spigot to fit. Then braze the new nut in place. Forces put braze joint in compression, so mostly the braze just keeps the new portion from spinning and coming loose.
 
I've got a Bridgeport and a 12x30 gear head Hendey lathe.

I don't think there's enough meat to bore out the old nut and braze in a new one, but I like the idea of adding on to the end. I could just cut the whole threaded part off and weld on a new one.

Is that a standard 1x4tpi acme thread?


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I've got a Bridgeport and a 12x30 gear head Hendey lathe.

I don't think there's enough meat to bore out the old nut and braze in a new one, but I like the idea of adding on to the end. I could just cut the whole threaded part off and weld on a new one.

Is that a standard 1x4tpi acme thread?


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1" x 4tpi is a standard size, but in your first post you say its 1.060" which equals 26.924mm, so it is now up to you to do some double checking on size and tpi vs tpmm.
 
Having access to a lathe and enough meat on the screw to turn it down to 1" 4 Acme,

Then purchase a 1:4 nut and turning OD with leaving a shoulder on the push slide and Loctite it into a borehole in the old nut case. Tha (Loctite) should be enough for push and the Loctite enough for the opening. Could even set screw it to resist movement in the opening direction..
I would buy the nut and then feel fit the screw turning to fit the nut.


1"-4 ACME LEAD SCREW HEX NUT 1-2984-100N | eBay
 
That is a japanese copy of a Btitish made Record bench vice. Eron ( a Japanese maker of high end machine vises) used to make a similar Record copy. But that is not an Eron, the details are different.
 
Likely that is a decent vise but some vises that came out of China were made of cast steel and over-tightening them could break the moving jaw to drop it on one's foot.
Caution to keep that in mind when over-tightening any vise is due.
 
Make a new nut.

Chunk of steel that is shaped to hold in the lathe

Hand grind an acme internal threading tool[It is a vise, not a machine tool]

Fit the thread to the screw


Machine the chunk to fit in the vise
 
Thanks for all the replies. I'm going to cut the "barrel" off of the old nut and make a new one to weld on. I'll check first to make sure it's weldable. I'm thinking 4140 for the new barrel.

I'll measure the minor diameter of my screw and use the spec from a 1x4tpi acme internal thread to determine what size hole to bore to give the same clearance. Then I can just make threading passes until my 1.06" screw fits.

Comments and suggestions welcome. I'm not a pro machinist.



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Welding CI to steel could be a problem. Braze it instead.

Be sure to consider the strength of whatever you do.

The shouldered nut would equal full original strength.
The lead screw nut's entire part being made of steel would give full strength.
Welding steel to steel would give high strength.(if it is made of steel, not CI)

*Making the nut out of a rectangle so it notches in and shoulders to the lower part and having a couple of bolts pulling downward seems a good method. Guessing 1 3/8" wide 2 3/4" long and 1 1/4 " to 1 1/2" tall might do.

Plenty strong and no welding..and it could be fitted in with taking off the bottom until alignment (height) is correct.
 
Thanks for all the replies. I'm going to cut the "barrel" off of the old nut and make a new one to weld on. I'll check first to make sure it's weldable. I'm thinking 4140 for the new barrel.

I'll measure the minor diameter of my screw and use the spec from a 1x4tpi acme internal thread to determine what size hole to bore to give the same clearance. Then I can just make threading passes until my 1.06" screw fits.

Comments and suggestions welcome. I'm not a pro machinist.



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I am pretty sure the external machining on that part can be done with an angle grinder after the threads are cut. Use the bridgeport if you need to feel fancy about it but it is just a cast piece I think
 
I am pretty sure the external machining on that part can be done with an angle grinder after the threads are cut. Use the bridgeport if you need to feel fancy about it but it is just a cast piece I think
Understood. It just needs to be lined up well enough for the screw to not bind.

I was going to mill a tenon the full length of the nut where I cut off the old barrel and then mill a matching slot on the new barrel. Whether I weld or braze it, the joint will be in shear and should be plenty strong.




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If you are going to weld the nut, make it plenty sloppy when you fit it.
I'm going to weld (more likely braze) a new barrel to the nut. The nut itself fits like this...

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It moves up and down about 1/8 of an inch.


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Following this one and have a question. Does this vise have sentimental or some other hidden value unapparent to me to make it worth the effort to rebuild, since from the pics it does not look like anything special? :confused:
 








 
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