A question about lock (jam) nuts

I'm involved in doing some metalwork for a DIY twin screw chain drive woodworking vice. The design shares features with this Lie Nielsen product:

The locknuts on the driven screw (there is a sprocket/chain arrangement linking the screws, which is hidden in the jaw) hold the screw between a pair of thrust bearings, I'm sure that works, but to my eye it is ugly - so I wondered about other ways of doing it.

So far I have thought about making a round 'nut' drilled so it could be tightened with a pin spanner and held with threadlock (it could then be recessed into the jaw) or using a Nylock or Stover nut which again could be recessed. What I don't know is how secure these fasteners are comparison with lock nuts.

Any advice?

Robin

Edited By Robin Graham on 11/12/2018 23:08:33

Normal nuts and a strong locktite

.

Unless there might be a future need to remove the 'nut' your first idea seems excellent, and you could use a high strength retainer [such as Loctite 601 or 638].

Question: Are the double nuts [as illustrated] used so that they can be easily undone if necessary ?

MichaelG.

Some kind of plastic cover as used for pipe ends or RF connectors before use would go a long way to improving appearance. The picture above is a disgrace from a high end product. At least make a dome nut for the outer one. The trouble with a special needing a pin spanner etc is availability of said spanner twenty years from now. Best might be to recess the inner nut slightly while still allowing enough to protrude for a sheet metal spanner, dome nut on outside.

I looked up some pics of chain vices and noted one brand used dual socket fittings for the option of having the handle either end and also that the handle socket end has a boss screwed to the jaw and the socket retained by a simple screw. If that screw is strong enough for the handle then why not make a matching boss and domehead nut with similar screw retaining it (or plaigerise dual sockets)?

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Oops !

I thought it was some DIY project

... Having just looked at the website

https://www.lie-nielsen.com/nodes/4068/workbenches

MichaelG.

Edited By Michael Gilligan on 12/12/2018 00:19:35

Turn the left hand screw down to form a flange to retain the sprocket. Cut a keyseat in the screw and a keyway in the sprocket. Then there only needs to be a single nut to retain the sprocket.The nut can be drilled to be  tightened with a pin spanner, so it can be made flush or recessed.

Edited By Mark Rand on 12/12/2018 00:59:04

I used one of these on my woodwork bench.

**LINK**

You could add the extra handle which gives you the option of tidying things up. My version has a resettable locking pin to allow one screw to be disconnected from the drive so they then act independently. This allows the vise to be skewd to accomodate tapered work pieces.

regards Martin

No need to complicate stuff... recess the vice jaws sufficiently to allow a socket to fit & fit Nylock nuts, jobs a good 'un

George.

It’s American. Obviously function over form! Or plain economics, and using the cheapest fixings.

If it a commercial product, I would have hoped for a better Handle fitting than a Tee piece for iron pipe.

Instead of using locknuts, a self locking nut, such as a nyloc would look better, in my view.

Or maybe a single nut, locked by a small grubscrew?

Things may get a little interesting when the chain develops a bit of slack and the screws no longer rotate exactly in phase! The road to hell, as ever, is paved with good intentions.

Nice concept, though.

How about making a proper Engineer's job of it and using a shaft and bevel gears to drive the second screw? (Obviously with Phosphor Bronze bushes, or Ball Races, to carry it? With a sealed cover over everything, to exclude sawdust)

As long as money is no object!

Howard

Thanks for replies - the pic in my opening post is indeed of a high-end commercial product. The hardware kit for the vice retails at $285 in the USA. I glad that I'm not the only one thinking a bit more finesse might be expected for that sort of money, especially as Lie-Nielsen's target market seems to be those who want (and are willing to pay for) tools that are both functional and works of art.

I should perhaps have made it clearer that I'm doing some metalwork here as a favour for a woodworker who has already chosen the design and sourced the raw components - my part is just to do some machining. I do this kind of thing from time to time if a project interests me and I think I may learn something.

I'll try some things bearing in mind your comments.

Howard - I like the bevel gear idea! Probably doable for less than the cost of the LN product. Maybe a central handle connected to both screws through a differential gearbox of some kind would be even better

Thanks again, Robin

If you wanted to make something that looked a bit nicer then I would do as you are thinking and have an inner round "nut" and also make the outer nut round but with a blind thread and dome of fully round over the end. You could even add a bead detail to the inner nut so it looks a bit like the cast Tee handle boss. Just use two pin spanners to lock them up as you would do with the locknuts so just as easy to undo if needed.

I don't really agree with the suggestion that loosening the nut will allow the vice to hold tapered work, as there is no provision in the bearings that the ends of the screws run in as soon as the jaw is canted to one side it will all lock solid. There is also the fact that the tool tarts that like LN etc spend all their time tweaking their planes and sharpening the blades that few actually get round to making anything, sounds familiar

If you really want a vice that can angle the jaw then a pattern makers one would be the better option. Though that means you lose the main advantage of the twin screw vice which is to be able to drop a board down between the two screws and clamp it up evenly, ideal for things like cutting dovetails on wide draws etc. The main selling point of the twin screw/chain setup is that it eliminated racking, nuts really only get touched to set it parallel when first fitted.

Edited By JasonB on 13/12/2018 08:40:21

LN of course claim Heirloom Quality is their status, when you only had a horse and cart, those double nuts would look OK

In an ideal world this would be a dome nut, but your chances of finding a dome nut with what looks like about a 1" square thread are probably close to not a lot.

Buying a suitable plug (bottoming) tap would not be easy either.

Pity as it would look very nice.

The ends of the two screws are reduced diameter with probably a UNC thread on the nutted one, the Sq thread does not extend out much into the jaw.

Pics of the parts for those that are curious, you can see that the bearings would not allow the jaw to be angled and besides you don't have a way to do up the nutted side.

Edited By JasonB on 13/12/2018 15:11:53

As the MAN said "What,s in a name" ?

I always thought that stuff was way overpriced,while being no better than many other makes,but then,I could never afford it anyway,so maybe it was a case of sour grapes?

As the basic principal was patented in 1892, I suspect that American woodworkers prefer a 'traditional' appearance - it's probably been made that way for decades.

There are folks who feel the same about machine tools believe it or not

Neil

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Except for those nasty double nuts ... which is where we came in

MichaelG.