A Twin-Screw Vise Revolution

[Will Blick]

George, it has threads, they are just not "exposed"...look further down on the same link provided in OP...

[Will Blick]

I am curious how well this performs vs. the LV twin screw vise.... any thoughts? Anyone ever see it work in person?

My biggest concern also would be the QR.... seems to perform well in the video.... but often these are problematic over time....

[george wilson]

I guess I'm being dense.I still don't see any threads,or understand how the vise works.

[Tim Put]

There are no threads.

It is tricky to tell, but I think I see how it works.
There's a one way clutch (like a ratchet but cooler and slicker), the vise "screws" spin freely in one direction, in the other direction they turn that wobbly collar to pull the "screw" inwards, and simultaneously they spin that pinion gear which drives a wedge shaped rack locking it in place.

[George Neill]

As far as I can make out, there are no threads. I assume the two pinions (connected by the rack) have integral cams that force the clutches to tension the pair of long guide bars and lock them. I suspect the actual movement necessary is slight and therefore, anyone used to tightening a normal vice to extremes would soon damage this new type of vice.

Longevity would be my main concern. I can't see how the clutches and guide bars will resist rapid wear and if you're used to working with regular sized stock (1in, 2in, etc.) then the wear will predominate at these openings.

It is clever, but wheels are not readily reinvented.

[Derby Matthews]

That I couldn't keep a clutch in. Sold it to a guy who owned a full service station / repair station and a fully stocked parts store next door. In Hinesburg, VT. A year or two later he had it out front with a for sale sign on it. My girlfriend (unknown to him) stopped in and asked him why he was selling the cool-looking Jeep Sedan. "Can't keep a clutch in it" was the reply.

Question 1):

How many lb. of pressure / #'s of hard tightenings before these tandem clutches fail?

2): how difficult / expensive is it to replace them?

3): (Assuming #'s 1 and 2 answered) Do you take Paypal?

[harry strasil]

Personally, I think the cogged bar is tapered and the friction clutch just moves it to act like a wedge, I don't think its got much actual tightening travel because of the limited amount of wedge action.
Why are we trying to second guess the man, if you buy one you know your gonna take it apart to see how it works. The Curiousity killed the cat routine. Especially if you can't get it to work after you reassemble it.
Just give the man his DUE, he is smart or like most inventors had a lucky accident.

[George Neill]

The clutches would, by necessity, be very hard, so it is the guide bars that would be the service items and I'm tipping they wouldn't be cheap. Depending on the design of the vice and the length of the guide bars, it may be possible to switch the bars end to end to extend their life.

[george wilson]

I had wondered if the angled washers would produce a "screw effect" and sort of bite into the smooth steel bar enough to make it cut a shallow spiral.

I was doubtful,though,because I didn't see how much tightening force the bars would accept before letting go. I'm assuming that those washers are sharp edged,and hardened to be able to work.

Harry,I'm not ever going to buy one of these vises since my last workbench has already been made. At 69,I'm not wanting to make any more,nor do I have room on my bench for a wide vise,or room in my over crowded shop for another bench. Besides,I could make one if I wanted it,provided I understood how it worked.

I got lucky years ago,and found a huge slab of beechwood in a country lumberyard. It was 6" thick,over 30" wide,and about 9' long. I let it dry in my shop at work for several years until it settled down. My bench top is 4" thick all the way across. The legs are fully 4" x6",double mortised to the cross bars at top and bottom. I had to plane the cup out of the 6" thick slab. It had a piece of barbed wire in it,which is why it was never made into smaller lumber. I drilled the wire out,and plugged the hole tightly with a boat shaped plug.

The rectangular dog holes were made with a Monarch mortiser through the solid wood top. They are 3/4" x 1 1/2". I added large beech wood drawers underneath,and "out rigger" shelves at each end underneath the top beyond where the legs ended,to hold sandpaper or other small things.

I made all the hardware for my tail vise,including the steel screw,nut,and decorative handle. It slides on a vertical steel track that is about 1/4" x 3" x 18". ALL MEASUREMENTS HERE are approximate as I don't feel like going to measure the bench. I'm sick with a bad cold and some fever.

While I used to love to make work benches,the ones I like to make are too much for my back trouble these days.

However,the vise in discussion is an interesting mechanism,and I am curious as to how it would work. Until I know better,I'd be afraid that the steel bars would get spiral scratches on them,and might wear out,but that is just conjecture on my part. The inventor is very clever to come up with the idea.

[George Neill]

George, If you imagine two Irwin type bar clamps (with round bars instead of oval bars) mounted in tandem. The Irwin clutches are tightened by squeezing the triggers. No spiral threads are cut in the bars.

With this new vice, as I understand it, the clutches are tightened by rotating the vice handles/guide bars/pinions which put pressure on the clutches.

[george wilson]

I'm not sure how squeezing the triggers intermittently equates to a constant rotary motion.I'm being really dumb over this!!! I mean,you release the pressure of the "clutch" when you release the trigger,then take another bite by squeezing the trigger again.

[harry strasil]

It would be easy to work if there were full length keyways in the guide rod/operating rods. Not clear enough to see if there are and the actual mechanism is never shown working, just the outside portion.

[Will Blick]

> I still don't see any threads,or understand how the vise works.


I was referring to the threads on the rack n pinion.... was not sure if you saw that picture below the video....

I think the clamping methodology is mix of R & P with 2 cams... here is the procedure, as I see it....


1) The shaft floats freely through its bearings with no pressure, hence the QR action after clamp handle is loosened....


2) when you tighten handle clockwise the long shaft turns the cammed pinion gear.... due to its cammed shape, it engages into the rack. The threads in the gear and rack are angled, so when the gear turns the rack, it forces two key actions:


a) the cammed gear exerts pressure on the shaft, nearly siezing it in its bearings (quite easy to sieze a shaft).


b) the angled gear / rack threads force the gear/shaft towards the rear shaft bearing. The rack force overcomes the siezed shaft in the bearing. The entire assembly moves back just an inch, which is all that is required to create several hundred pounds of of clamping pressure. You can see in the pix below, the visible shaft between the shaft bearings represents the QR state, or floating position, .... when the clamp is fully tightened, the cammed pinion with shaft will move back and cover that area. The shaft will now be exposed behind the front bearing... this would represent the "clamped state"...






3) So the clamp will only tighten maybe an inch max, thats what's so clever...you only engage the inch worth of clamping pressure where you need it along the entire shaft. Very similar to a 24" parallel clamp, where the threads are only a few inches long, but we all know how that gets positioned, well that is the same conceptual premise the inventor worked from here..



This is quite clever.... the main benefit, as I see it.... its not a pure clutch... its not really a conventional quick release system either which has gears that will grind out.... instead, when the you loosen the handle, its a full free floating system...when you tighten, you simply engage gears that were not previously engaged....at most, the shaft bearings might wear over time, which hopefully will be a quick change out.... if so, it's the best of all worlds....

assuming I got it right

:-)

[george wilson]

I am sick right now,and can't follow all the abbreviations,Will. I see that the machined washer is held in a tilted position by a little,long bolt that keeps it tilted. I can't see that the pinion gear is cammed,either.

P.S.,I figured out your abbreviations. I've got a fever,and not doing too well. Do you mean that the TEETH and rack are angled? The teeth in the gear look straight to me.

Harry,I am wondering if there IS a key way which the inventor doesn't want us to see. THAT would make the 2 pinion gears rotate together and power them to make the rack slide sideways,to keep the jaws parallel.

[George Neill]

2) when you tighten handle clockwise the long shaft turns the cammed pinion gear.... due to its cammed shape, it engages into the rack. The threads in the gear and rack are angled, so when the gear turns the rack, it forces two key actions:


a) the cammed gear exerts pressure on the shaft, nearly siezing it in its bearings (quite easy to sieze a shaft).


b) the angled gear / rack threads force the gear/shaft towards the rear shaft bearing.

Would a single cam profile inside the pinion be sufficient to grab the guide bar or would that not be a bit of a hit and miss situation? I envisaged the pinions containing one or two sprag clutches.

I don't see any angular (helical) cut to the pinion or rack teeth, but I don't believe it would be necessary anyway.