Pictures -Moxon Vise Workshop

[Tim Sherwood]

The original posting is getting pretty long. So I thought I would put the pictures in a new one. There were five of us in the shop Sunday to start to make a Moxon style vise for each of us. Attending were : Mark Goetsman, Richard (Graywolf), Jerremy (RonJ103), Michael (VTXMANMike), and me. We discussed the options of using steel screws, acme screws , cams, and wood screws. I was sure we would end up with five different versions. But, thanks to Richard, we all decided to make a wood screw version. Richard has made a couple of these vises , which are a permanent part of his workbench. He brought along a very nice wood screw and handle from that bench. With that inspiration , and the fact that he offered his thread box and tap, we all jumped in. We started with a rough 2" slab of Maple , and a couple hours later we had produced one sample pair of screws.

We used the typical 1 1/2 " import screw box.

The discussion and decision phase took about an hour.

We cut a billet from the slab I had. That had been "donated" from a member's dumpster.

We turned the billet into an octagon with the table saw.

Can you believe FIVE NCWW members, and no lathe ? So the octagon was rounded into a dowel with a plane.
It had some highs and lows , but was plenty good enough. It varied in diameter only from 1.45 to 1.48.

We used the thread box to thread the dowel. It cut easily, thanks to Richard's sharpening of the cutter.
It also helped that the dowel was a little undersized. But the threads were full depth with no flat tops.
We used liberal amounts of BLO for a lube.

We felt pretty good about our trial sample;from slab to screw in one workshop.
We even tapped one hole just to prove it would fit. For the next workshop, on 6-29,
We'll each try to have a pair of dowels to thread and slabs cut for the jaws.

 

[Hmerkle]

Fun to watch!
- PAINFUL that between five of you noone had access to a lathe!

(Can't somebody (lathe guy) be cajoled into making 10 blanks before the next workshop?)

Oh! it's a WORK - shop its meant to be labor intensive?! :widea:

 

[tarheelz]

Cutting an octagon on a table saw with no jig of any sort. Impressive (and scary to this clumsy oaf).

 

[pviser]

+1 on the jigless octogon cut. Is there something not apparent in that single view?

 

[Mike Davis]

I don't see the problem, that's how I cut all my lathe blanks.

If any of you guys want to come use my lathe we can make arrangements.

 

[Tim Sherwood]

We had no problem cutting an octagon with the table saw. In the picture, Jeremy is just setting the bar onto the right face. He will push it through using the grippers sitting on the table. Since these are 1 1/2" bars, there is still a decent flat surface to register against the fence and the table.

Mike , thanks for the offer of your lathe. I'm going to see how many blanks I can cut from my wood pile. Then I'll talk to you about a good time to get together.

 

[pviser]

Thanks, Tim. I figured that there was more to it than what was readily seen in the photo.

 

[Hmerkle]

Tim,
Will the handle be integral to the screw or attached later?

will it be more like a front leg vise where the diameter is larger and the screw thread smaller?

 

[Jeremy Scuteri]

It is possible that the first cut *may* have been made using my hand before Tim strongly urged me to use a push stick. The piece seemed plenty stable, but I can't argue that using a push stick is a smarter approach.

 

[Jeremy Scuteri]

Wait a minute, it's a SawStop. I don't need no stinkin' pushstick. Kidding, kidding, kidding. (before anyone gets there panties in a bunch, I know safety isn't a laughing matter).

 

[Tim Sherwood]

Paul , your reaction to the picture of Jeremy ripping the dowel was dead on. Those fingers would be spooky close to the blade. But I don't mind an occasional nick on my gripper.

Hank I think we'll have several versions of the handles. I plan to leave mine as the original octagon. I don't feel that this type of vise needs a ton of force in order to grip. If I'm wrong, I can add something more.

 

[Jeremy Scuteri]

I also plan to have integrated octagonal handles.

 

[Hmerkle]

So now my curiosity is aroused,
I wonder with an 1 1/2 screw and a handle ~2" dia. what kind of clamp load the vice achieves...

I used to think it was funny when the Bessey clamps came out that there were round handles, I thought hm... cant get as much clamp load with those as you can with a pony (larger diameter turning a similar diameter screw... and maybe you can't,

But, I see now that you can acheive 600 to 900 lbs. or more - that is a lot of clamp load!

So I am going to go out on a limb here (picture a big fat guy on an itty-bitty limb) and say that the Moxon should be capable of generating 1500 to 2000 pounds... what do you think?

 

[Mike Davis]

Easy enough to test once they are built, but I think it will be less due to several factors. There will be some flex in the faces so the pressure will not be transferred directly as the Bessey clamps, the clamping area is much larger so pressure is spread out more, the screw is wood so will have more resistance than the metal screws of the Bessey, fewer threads per inch also mean more resistance than the finer Bessey screws.

 

[Mark Gottesman]

I am going to make a couple of wood screws because I think they would be handy to have around the shop. Having said that I think I'm going to try this version of the vise.



I think clamping pressure with this setup will be adequate. If not, then I can crown the jaws a bit or add some suede. I like cam clamps and have used them on varius project and with a bit of cork they hold just fine.

 

[Hmerkle]

Easy enough to test once they are built, but I think it will be less due to several factors. There will be some flex in the faces so the pressure will not be transferred directly as the Bessey clamps, the clamping area is much larger so pressure is spread out more, the screw is wood so will have more resistance than the metal screws of the Bessey, fewer threads per inch also mean more resistance than the finer Bessey screws.

I am even more curious now - I had that arguement a long time ago about threads per inch and transfer of torque.

A finer thread "Allows" more torque becasue of tensile stress area, but the transfer of torque to clampload has more to do with thread friction than the pitch of the screw. (I.E. I use an acme thread in a vise rather than a fine pitched 60 degree screw thread...

Regardless, the outcome is what I am interested in... how much clamp load do two 1 1/2 wooden thread create in a moxon vise.

Answer: enough to hold the side of a vibrating blanket chest while I saw (what I call) dovetails!

 

[Hmerkle]

I am going to make a couple of wood screws because I think they would be handy to have around the shop. Having said that I think I'm going to try this version of the vise.

View attachment 12078

I think clamping pressure with this setup will be adequate. If not, then I can crown the jaws a bit or add some suede. I like cam clamps and have used them on varius project and with a bit of cork they hold just fine.

Someone posted the one using the bar clamps - I thought that was a unique variation too.
Certainly not traditional, but it does get the job done!

I REALLY liked Ken's design (Ken of Cary) since it is a double duty appliance!

 

[merrill77]

...There will be some flex in the faces so the pressure will not be transferred directly as the Bessey clamps, the clamping area is much larger so pressure is spread out more...

Flex and surface area are not factors if just concerned with the force applied, which I think is what he was asking. They are relevant when considering the clamping effectiveness, but then you must consider other factors as well (coefficients of friction, contact area, etc). Measuring the force applied is easy, by comparison.

 

[Hmerkle]

Flex and surface area are not factors if just concerned with the force applied, which I think is what he was asking. They are relevant when considering the clamping effectiveness, but then you must consider other factors as well (coefficients of friction, contact area, etc). Measuring the force applied is easy, by comparison.

Chris,
I am goign to side with Mike on this one. As you point out that are lots of factors that rob clamp load from the applied torque.

One of those things is the flex of the member or (face) of the vise, since torque is now being converted into bending of that member rather than clamping force.

Again, my curosity can over complicate things, the real questions is how much clamp load do two 1 1/2 wooden thread create in a moxon vise.

Answer: enough to hold the side of a vibrating blanket chest while I saw (what I call) dovetails!

 

[merrill77]

Chris,
I am goign to side with Mike on this one. As you point out that are lots of factors that rob clamp load from the applied torque.

One of those things is the flex of the member or (face) of the vise, since torque is now being converted into bending of that member rather than clamping force.

Actually, I pointed out out that there are lots of factors that change the effectiveness of a clamping setup.

The flex of a beam used to clamp does not cause a loss of force - it simply alters the vector of the force. Imagine that you have a curved caul. If you clamp, using two screws, and apply enough force (call it N) such that the caul is clamping only in the center of the workpiece, you are applying a force of N to the center of the piece. And you are applying a force of N to the entire piece, but note that the vector of the force has changed from the applied force at the 2 screws to the effective force at the center of the caul and workpiece.

If you then double the force (2N) and the caul bends so that it is flat against the workpiece, you are now applying a force of 2N to the entire piece. The force is distributed more evenly, but the total force applied is still 2N. There is no loss in bending the caul. There is work performed, since some of the energy expended in turning the screws was applied to bending the caul, which is now storing that energy as a spring. Force and work are different things (though related) and that difference can be hard to grasp.

Now lets assume the workpiece fits easily between the two screws. Increase the applied force further (call it 3N) such that the caul bends even further and is touching only on the edges. Again the vector of the force has changed - it is now directed in two places - each edge of the workpiece and directly slightly inward at each end, but the net applied force to the workpiece is still 3N. 1.5N at each edge.

I dunno if that is a clear description...it's been a long time since Physics 151. Where's Ethan? Want to drop in and give us a lesson?