I'm a woodworker making a vise for a workbench. A metalworking friend made most of the metal parts for me but he doesn't have a lathe capable of making the nut for the benchscrew. The nut needs to have an internal 1.125-6 dual-lead ACME thread (class 2G thread-fit most surely). My friend can't do it because the coarsest thread his lathe will cut is 4tpi and to do a dual-lead 6tpi thread you need a lathe that will cut 3tpi. The nut needs to be 2" by 2" by 1.5" thick with the hole for the bench screw exactly in the center. It also needs to have four holes drilled and tapped to accept screws for mounting. It should be made out of
12L14 cold-rolled steel.
Please let me know if anyone would interested in helping me out with this project and how much it would cost.
Mitch, I would think something like this would be available from a woodworkers supply house - like where you would get the parts for the rest of the vise. If you custom made the vise, then it may take a bit of "hunting" for the part - or someone may be able to make it for you. HTH Ken.
You're probably better off, from a cost point of view, to look around for a more simple solution.
Here are some possibilities you might want to check out.
Record makes a number of wood working vises that are designed to be secured to a bench.
A company here in Canada called Lee Valley sells a variety of screws and nuts for the business end of various clamps and vises. They even have a twin screw job.
There's a similar company in the US called Garrett Wade Tool, but the catalog that I have is a few years out of date and they don't show any of this type of hardware. Might be worth asking though.
If you are determined to get the thing done yourself, then how about a different screw/nut set up. Something with a more common pitch would be easier to make or buy. Check industrial supply places like MSC and McMaster Carr. Even if you have to have it made it will be easier and naturally cheaper.
Sigh! If you must do it the way you described... :-) Ask your machinist friend to get himself any two gears for his lathe that are 2:1 and pin, glue or keystock them together. Then do a set up for 6 tpi, with the "fudge" gear and an extra idler anywhere in the drive train and run the lathe BACKWARDS. This will get your 3 tpi.
Don't be surprised if he doesn't want to do it! I figure this job will take the better part of a day and he will still need to "work in" the fit.
And I don't know what shop rates are in your area, but you should probably figure $25 to $50 an hour.
Just wondering why you would want a leaded steel for this. Although it might machine more easily, I would think that just about any cast iron would be longer wearing.
Ummm, where did the screw come from? Evidently not from your friendly metal worker. Does wherever you got the screw have nuts to fit? Even if the nut is of a shape that doesn't fit, you could turn it cylindrical and silver solder/braze/weld it into a
2x2 block. Cutting a double lead internal acme is going to take a while.
If he's going to do the nut, why not have him also do the screw? The screw is probably got a simple step down for the attachment to the handle with a crosswise hole and that should be easy for him to do. In addition, he may be able to give you some better material than what the present screw is for material. It also gives the guy the ability to make the fit that you need without problems.
-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!
Remembering a great story from an older copy of Fine Woodworking about the joys of trying to get a Patternmaker's vise, have you considered casting it from babbet metal or lead? All you would need is a two-part collar, the screw, and some molten metal. The nut would be more than strong enough, I suspect, and this would eliminate the necessity of machining a somewhat challenging project. Regards Dave Mundt