Shop made chain drive twin screw vise

Dave Black

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638
Location
Central PA
Several years ago I made a twin screw chain drive vise for my old work bench and now I have a new bench so I decided to make a new one. This vise is different than any other ones I have seen before. It operates like a mechanics vise. The screws are towards the bottom of the jaws and there are slides that keep the jaws from wracking. I will try to go through the steps to make one.

First you need some steel tube to make the slides, you need 2 different sizes and the smaller one needs to slide inside the larger one without much play. I happened to have some laying around. The larger piece was 1.25" outside and the small piece was 1.125" outside.
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I made the jaws out of beech and drilled holes for the slides to go in. To get the holes accurately spaced I clamped both jaws together then clamped them the the drill press. I drilled the 1.25" in the stationary jaw then changed the bit and drilled the 1.125" hole in the moving jaw, I did that without moving the the jaws on the drill press. This way the slides will line up.
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For the screws I used 5/8" all thread. You could use whatever you want but for me the 5/8 was cheap and easy to get. At the end of the large slides you need to weld on some nuts. Then put the slides in the jaws. You can press them in with a clamp or gently hammer them in using a wood block to protect the slides.
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At this time you should be able to slide the jaws together
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The next step is to cut all thread. To measure it just pull out the movable jaw to what you want the max opening to be and measure from the outside of the jaw to the nut at the end of the slide and maybe add and inch or so.

To allow the movable jaw to follow when opening the vise I double nutted inside small slide. A washer goes on the outside and is screwed on the jaw. Then the sprocket goes on. I welded a nut on the sprocket so I could screw the sprocket on then tighten the set screws on the sprocket.
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Then screw on the handle which I tapped to screw right on the all thread and tighten against the nut. and put on the chain. It may be a good idea to plan the distance between screws so the length of the chain works out well. Somehow I got lucky both times I built the vises and the chain is snug but not tight.
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Right now its getting late and some of this may not make sense so if you have questions let me know.
 

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The benefit is that you operate both screws with one handle instead of 2 handles on the old fashioned kind

I agree and you can really crank down very very hard...at least with mine, which is a commercial version of what Dave so nicely made. Another benefit, no racking, so no spacers needed!



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I made the wooden chop using the parts provided, including the chain which is not shown in the box. Probably cost a little more than what Dave spent. ;)
 
Do the commercial ones have wracking problems if you clamp at just the top of the jaws?

Are you describing racking where the bottom of the chop toes in? I would have thought that your chop had to be very large (top to bottom) to have that to be a problem. Are you experiencing that with your vise? I sure have not with mine.
 
Are you describing racking where the bottom of the chop toes in? I would have thought that your chop had to be very large (top to bottom) to have that to be a problem. Are you experiencing that with your vise? I sure have not with mine.

Yes, bottom toes in. I dont have that problem with mine, when I designed it a few years ago I thought that it would be a problem so I came up with the idea for the slides. My chop is 7" tall and the screws are at the bottom rather than in the middle.
 
Impressive build Dave!

What are the gears and chains from?

Did you think of polishing the slides to get them to slide better, or were things just right?

The hand wheel, are you going to put a handle on it, maybe that sounds funny, but you know how a tablesaw hand crank has a short handle sticking out of it, so you can crank it faster...? I would imagine if I put a little handle on that wheel, I'd be smashing my hip with it every time I walked by it, so maybe not a great idea....

Great build!
 
The chain and sprockets are standard #35 chain size. You can get at tractor supply company or a bunch of other places. I have a handle for the hand wheel but it wasn't in when I took the pics, I have hand wheels on my other vises and I don't have much problem running into them. If it becomes a peoblem I can change them to a lower profile style. The slides are not that tight that they bind so no need to polish these.
 
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