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Derek Cohen
07-09-2012, 11:38 AM
For the past few months I have been discussing a parallel guide adjuster designed by Jim Ritter. My input has largely been devil's advocate while Jim sharpened up the design for production. I have no interest in this venture other than wanting to see a good product made available for others to use.


The leg vise parallel guide adjuster is an alternative to the St Peter's Cross, both of which enable a leg vise to function without the pin adjuster. No more stooping and setting the parallel guide for a specific width. Instead there is a single setting for all work pieces. In theory there should also be more pressure as the chop is more upright.


Yesterday I completed assembling the pre-production kit, and here are a few pics with my impressions.


From the front you will not notice any change to my leg vise ..


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/1.jpg


Close up you may note that I have replaced the steel screws with brass .. :)


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/2.jpg


From the side you will see a solid parallel guide and, above it, a chain ..


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/3.jpg


Solid paralel guide?!


Yeah .. in for a penny, in for a pound ... off came the parallel guide of my 6-month old leg vise ..


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/4.jpg


.. and replaced with this new, hole-less version ..


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/5.jpg


Inside the bench the chain mechanism can be seen ...


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/6.jpg


Outside ..


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/7A.jpg


In all, including building a new parallel guide (which I do not expect others to do), the installation took a day.


So how does it work?


It grips ...


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/7.jpg


... and grips ...


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/8.jpg


.. and continues to grip ..


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/9.jpg


.. no matter how little there is to grip ..


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/10.jpg


Downside? The mechanism requires that the internal wheel guide is removed .. this one ..


http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/11.jpg


As a result, there is a little more resistance in the parallel guide moving back-and-forth compared to before. The chop still moves smoothly, and the effort is similar to that of the Record #52 1/2 I had on my old bench. Of course, this may just reflect the need for a little fine tuning since the parallel guide is new. As it stands, this is a rejuvenated vise, one that promises to work with a much greater range and considerably less effort.


Once Jim gives the OK I will post a pictorial of how I installed the kit.


Regards from Perth


Derek

Jim Koepke
07-09-2012, 12:19 PM
Once Jim gives the OK I will post a pictorial of how I installed the kit.


Regards from Perth


Derek

Looking forward to that and maybe even a little explanation of the inner workings. It looks like it could work with a cable and pulley set up as well as a chain.

jtk

Derek Cohen
07-09-2012, 12:28 PM
Hi Jim

We discussed the use of a chain and pulley, since that was my idea as well. Jim had solid reasons why it would not work well - keep in mind that he spends his life dealing with the stuff. Hopefully, Jim will be along to explain.

Regards from Perth

Derek

Jessica Pierce-LaRose
07-09-2012, 12:38 PM
Not knowing how everything is put together exactly, I may be wrong, but it looks like if you still wanted the wheel on the back, you might be able to mortise something in place behind the plate mounting the lower gear?

The photos make Jim's design make a lot more sense - it definitely "clicks" for me now - I was having a hard time wrapping my head around was going on before. I can see what was said about needing to make new gears - I haven't seen anything off-the-shelf that small before.

Jim Ritter
07-09-2012, 1:43 PM
Thanks Derek great job as always. As to the cable... I thought about that but the ends would have to be swaged, that is expensive, it also creates a fixed length with a long turnbuckle that is harder to accommodate. After talking to many people about their vise arraignment, screw length, distance between screw and beam every one was different. Custom adjustability was important. The chain can be cut or added to if you make a mistake and cut it too short. Chain also has less stretch than cable.
I actually placed my lower wheel on the inside of the leg and the action is very smooth, until it is extended past about 9" but it still isn't bad. I also considered a slot down the middle of the beam with a smaller wheel inserted. But for me the wheel behind the leg works just fine.

Sam Takeuchi
07-09-2012, 1:50 PM
That looks like a very promising system, yet very simple. Chain in tension keeps the vise upright? Does it stretch a bit when you are closing the vise? Does the vise face tilt at all? Any slack/slop at all?

Jim Ritter
07-09-2012, 1:57 PM
That looks like a very promising system, yet very simple. Chain in tension keeps the vise upright? Does it stretch a bit when you are closing the vise? Does the vise face tilt at all? Any slack/slop at all?
The chain length is adjusted so that it always closes toe in so to speak. As full clamping pressure is applied the jaw comes parallel. Not much of what I would call slop.

Sam Takeuchi
07-09-2012, 2:16 PM
The chain length is adjusted so that it always closes toe in so to speak. As full clamping pressure is applied the jaw comes parallel. Not much of what I would call slop.

This is really, really, really nice. Self aligning and all. Are there any issues and kinks to work out still?

I think it's the first time I felt excited about a vise of any kind.

Todd Burch
07-09-2012, 2:27 PM
I may have to finally build a bench and put one of these puppies on it.

Jim, what cute name are you going to call this "Leg vise Parallel Guide Adjuster"? I think PGA is taken... ;)

Jim Ritter
07-09-2012, 2:47 PM
This is really, really, really nice. Self aligning and all. Are there any issues and kinks to work out still?

I think it's the first time I felt excited about a vise of any kind.

Thanks for all the excitement,that is exactly how I felt and my wife was wondering what was wrong. The last thing I did was standardize the sprockets for production,to try and rein in the cost of manufacture. What Derek installed is what I would call the easy install kit. I will offer it without the metal brackets to lower the cost. The upper sprocket would then be mortised into the leg as I did on my bench. Derek has the first with mounting brackets for the sprockets.

Haven't thought up a good name yet. Just been calling it the chain leg vise. Maybe a naming contest is in order. What do you think?

Chris Vandiver
07-09-2012, 2:59 PM
Thanks for all the excitement,that is exactly how I felt and my wife was wondering what was wrong. The last thing I did was standardize the sprockets for production,to try and rein in the cost of manufacture. What Derek installed is what I would call the easy install kit. I will offer it without the metal brackets to lower the cost. The upper sprocket would then be mortised into the leg as I did on my bench. Derek has the first with mounting brackets for the sprockets.


Haven't thought up a good name yet. Just been calling it the chain leg vise. Maybe a naming contest is in order. What do you think?

"Missing Link"?
"Chain of Command"?

Rob Fisher
07-09-2012, 4:45 PM
Any idea when we could see this on the market and at what cost?

And how about "Chain Stayed Leg Vise"?

Jessica Pierce-LaRose
07-09-2012, 8:15 PM
I suppose another option to move the wheel further out would be to form some sort of U-shaped bracket after the lower sprocket holder, attached to the stretcher, and going over the parallel guide, sort of "pulling" down on that end of it rather than "pushing" from above.

Bryan Schwerer
07-10-2012, 8:15 AM
Let me just beg you to give us a chance to order this before Schwartz writes an article about it and everybody goes crazy. Please, Please, Please!!!!

Jim Ritter
07-10-2012, 10:20 AM
Let me just beg you to give us a chance to order this before Schwartz writes an article about it and everybody goes crazy. Please, Please, Please!!!!

Thank you for everyone's enthusiasm. It is very encouraging since I've never tried to produce anything like this before. Once I get the bids back from the machinists I can set a price and start taking orders to be delivered when the parts come in.

Tom Millington
07-10-2012, 10:24 AM
The obvious name is Ancora Chain Vise. Play up the nautical pun!

Carl Beckett
07-10-2012, 10:54 AM
You know Jim, I would have advised that you consider up front (before posting in a public forum) what type of business you might want to make out of this and whether you would want to seek patent protection (it doesnt 'have' to be expensive to get a patent). There 'are' cases here where successful businesses are launched and IP has come into play. (and besides, its neat to have a patent in your name!)

Having said that, Im looking forward to hearing more!

Jim Ritter
07-10-2012, 12:41 PM
Good one Tom, I like it.

Curt Putnam
07-10-2012, 1:49 PM
Jim,

Whatever the name, I hope you will be ready to sell (at least) a parts kit by this fall. I've got a bench build coming up and have determined that I want a leg vise for the face. Was pretty much set to go with Jameel's unit but the price keeps deferring the decision. In part the lumber species question will be determined by the vises' cost. If you have a retail price point in mind could you share that? Privately and confidentially if need be.

Michael Gaynes
07-10-2012, 9:08 PM
How about extending the bracket and tucking the wheel in behind the sprocket as rendered here:

Jim Ritter
07-10-2012, 9:54 PM
That might actually work. But the sprocket would have to be lower than you've illustrated( however you did it) the angle of the chain to the beam would tend to want to lift the beam. I measured 600# of force where Derek has his beam located. Working forces are less but it still is higher than you might expect. That lifting would tend to wreak havoc on the jaw mortice.

Derek Cohen
07-11-2012, 5:52 AM
What I will try out this weekend, when I am next free, is adding spacers to the bracket to move it out from the leg, and then return the wheel to its position on the leg (behind the bracket). What do you think of that?

Regards from Perth

Derek

Jim Ritter
07-11-2012, 9:04 AM
Hi Derek, I don't think you need to rush into this. I'll make up some brackets here and give it a try. On yours if you add spacers to move the sprocket out it will impinge on the working space of the vise. Unless your new beam is longer than I think. A spacer and longer screws might introduce a source of flex in that area that might be of some concern. Is there room to put a roller under the beam on the inside, like I fitted to mine? I would try that first.

Carl Beckett
07-11-2012, 9:16 AM
Hi Jim,

It sounds like you can measure the forces at various points in this mechanism. Im curious, is the force carried through the chain much higher than the force that goes through the pin (or beam) during the traditional operation?

Im trying to get my head around the counteracting moments (I think that the chain is creating a moment on the lower section, which counteracts the moment applied when part is clamped). But this means 2x or higher forces involved (because of the shorter moment arm the chain creates) than the traditional design. No doubt I could benefit from sketching out a free body.

But if so, anything that can be done to increase the distance between the upper chain and lower chain sections would decrease the forces needed.

(now one way to eliminate this effect would be to transfer the forces through the lower gear itself - then drive this gear via a pickup off the lead screw. Too complicated in practical terms, but would be nice to get the forces transferred to the leg and not the vice front.... youve likely been down a number of these paths)

But spacers shouldnt impact the angle the force puts on the beam as long as the gear is still close to the beam. Any vertical forces just get transferred between the two gears and through the leg, no problems there.

Jim Ritter
07-11-2012, 10:10 AM
Hi Jim,

It sounds like you can measure the forces at various points in this mechanism. Im curious, is the force carried through the chain much higher than the force that goes through the pin (or beam) during the traditional operation?

Im trying to get my head around the counteracting moments (I think that the chain is creating a moment on the lower section, which counteracts the moment applied when part is clamped). But this means 2x or higher forces involved (because of the shorter moment arm the chain creates) than the traditional design. No doubt I could benefit from sketching out a free body.

But if so, anything that can be done to increase the distance between the upper chain and lower chain sections would decrease the forces needed.

(now one way to eliminate this effect would be to transfer the forces through the lower gear itself - then drive this gear via a pickup off the lead screw. Too complicated in practical terms, but would be nice to get the forces transferred to the leg and not the vice front.... youve likely been down a number of these paths)

But spacers shouldnt impact the angle the force puts on the beam as long as the gear is still close to the beam. Any vertical forces just get transferred between the two gears and through the leg, no problems there.


Thanks for your input Carl, a member in another forum kindly lent me his gauge. Without breaking anything me Lie-Nielsen screw developed 1200 PSI 6" above the screw. The handle torque to create that was more than I need to clamp a piece of wood but I was curious and some people are heavy handed. I needed to know I was witin a safe load on the chain. I knew it worked (I had one in use for a year) I just didn't know what the safety margin was. My beam is lower, it is 18" below the screw and the force was 400 PSI, Derek's beam is 12" below so I measured at that distance and got 600 PSI. With the pin or the chain the forces are the same.
The chain moment is only shorter than the beam moment by the distance between the chain and the pin, say an inch or two. The beam on my bench was put low to lower those forces and to incorporate the side stretcher as one half of the sprocket holder. I do not have the metel brackets at all on my bench. I made those just for Derek to test out.
You are right, moving the lower sprocket further away from the beam does not change it's moment arm but in the photoshopped image that was posted above the chain is at an angle to the beam. It must be parallel in order to transfer the force directly out to the jaw.
The force on the chain want to rip the lower sprocket off at a 45 deg angle between the two chain directions.mthat is why the brackets extend down further instead of centering the sprockets.

http://i1135.photobucket.com/albums/m628/boatman53/4a44e212.jpg

http://i1135.photobucket.com/albums/m628/boatman53/33462096.jpg

http://i1135.photobucket.com/albums/m628/boatman53/08084edf.jpg

Hope this helps. Jim

Jessica Pierce-LaRose
07-11-2012, 10:37 AM
I suppose another option to move the wheel further out would be to form some sort of U-shaped bracket after the lower sprocket holder, attached to the stretcher, and going over the parallel guide, sort of "pulling" down on that end of it rather than "pushing" from above.

Too late to go back and edit my post, but just realized that was stupid suggestion on my part - the chain is obviously in the way!

I suppose maybe you could fit a spacer of UHMW or something else slippery in a similar fashion to how I pictured adding the wheel in my silly post, but with it fitting under the chain to help support/guide the parallel guide further away than mortising the wheel allows.

Derek Cohen
07-11-2012, 11:18 AM
I spent about 10 minutes playing with the leg vise this evening and think that I may have licked the "problem". I do not believe that there was one in the first place. It's all in the tuning of the chain. It is all new, so I am learning as I go along.

First, I noticed that the parallel guide moved more smoothly when the tension on the chain was relaxed. So I relaxed the chain progressively until it was floppy. Then very floppy.

Then it became apparent that the chain tensions itself when the chop is holding a board. This is the important part because the chain must position and lock the chop in the same way as the cross bar in a hole. And it appears to do so , regardless of how floppy the chain is set.

I will keep experimenting, but the leg vise is working really nicely at this stage. It will open easily, and then grip a wide range of widths very securely.

Regards from Perth

Derek

David Bird
07-11-2012, 12:00 PM
I'm no patent attorney, but I do a lot of patent work. The last time I had this issue, the rules allow an inventor to apply for a patent up to one year AFTER an initial publice disclosure of an invention. So there's still time, but the clock is ticking.

Jim Ritter
07-11-2012, 12:31 PM
Derek the floppier the chain is more out of parallel the jaw will be when tension is applied. There should be just enough tension on the chain so the jaw is parallel at the optimum clamping strength. You might try lightly clamping a piece of wood, measure the parallelism of the jaw then adjust the nuts to correct. I think you might be able to turn the nuts without unclamping but give it a go.

Carl Beckett
07-11-2012, 3:44 PM
I'm no patent attorney, but I do a lot of patent work. The last time I had this issue, the rules allow an inventor to apply for a patent up to one year AFTER an initial publice disclosure of an invention. So there's still time, but the clock is ticking.

This is my understanding as well David - for US based patents.

I encourage a completely separate thread to discuss commercialization and invention feedback ideas........ (I know there might be a culture of shareware here, but at the same time I like to see individuals rewarded for efforts/ingenuity, since ALL technical problems have an economic component)

Jack Curtis
07-11-2012, 8:07 PM
Doing a search for prior "art" is very time consuming, and a huge job for an individual. Made somewhat easier by the internet, but still a lot of work.

David Bird
07-12-2012, 12:38 AM
(To the best of my layman's knowledge) under current US patent rules, the inventor must disclose prior art of which he is aware. But he is under no obligation to search for prior art that he doesn't know about. The USPTO will do their own search.

The risk to the inventor of not searching is that the Patent Office will find prior art, so the inventor loses his investment in preparing the application. Or worse, a challenger turns up valid prior art after the patent has issued, so the inventor loses his investment in the whole process.

A thorough search for prior art in the US patent record can be expensive. But a cursory search is easy. I do it all the time.

Carl Beckett
07-12-2012, 8:40 AM
A provisional US patent can be filed for $110. The gives you a year to advance the art.

The USPTO is piloting a program for small business via the SBIR program. They wont write the patent for you but will assist with expedited review. (they recognize there is a problem with small/big business collaboration and first to file issues, so are wanting to help even the playing field some for the little guys).

I dont think an exhaustive search on prior art is a requirement. Of course its in your own best interest to do some, so that your claims arent completely redundant (read - worthless) over whats out there. At the end of it all it will come down to the few unique claims of your invention. (and remember, a patent doesnt give you the right to do anything - only prevents others from profiting from your idea - so to some extent if you are going to make a commercial product you should be doing a prior art search anyway because if you use any feature of someone elses claims then they can block you or lay claim to profits). This is part of the problem with the patent system - kinda a 'veto' system which doesnt always motivate someone to GO DO and advance a technology (way too much just buried in the corporate coffers)

So start a patent by listing the 'claims'. Meaning, what are the key elements that are unique to this invention. List these out. Then you can write background and body of the invention, and reference prior art on the non-unique aspects.

My experience is you can patent about anything if you want (it can come down to the shape of the bracket being unique). Which might not be all that useful from a commercial standpoint, but then again most patents arent (and sometimes a patent on a very minor detail is useful just to prevent an offshore manufacturer from using the VERY SAME MOLDS/CASTINGS to produce a knockoff, after the original company has PAID for these molds!

Derek Cohen
07-12-2012, 8:47 AM
I wrote:

First, I noticed that the parallel guide moved more smoothly when the tension on the chain was relaxed. So I relaxed the chain progressively until it was floppy. Then very floppy.

Then it became apparent that the chain tensions itself when the chop is holding a board. This is the important part because the chain must position and lock the chop in the same way as the cross bar in a hole. And it appears to do so , regardless of how floppy the chain is set.


And Jim replied ..


Derek the floppier the chain is more out of parallel the jaw will be when tension is applied. There should be just enough tension on the chain so the jaw is parallel at the optimum clamping strength. You might try lightly clamping a piece of wood, measure the parallelism of the jaw then adjust the nuts to correct. I think you might be able to turn the nuts without unclamping but give it a go.

Hi Jim

The best way to examine what I described is to do so visually. So here I a bunch of pictures.

This is what I meant by a floppy chain ..

http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/13.jpg

Here is the position of the chop - just slightly open. The chop looks fairly parallel, but admittedly it is not doing any work. Still, it opens parallel.

http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/14.jpg

Now if I insert a thin board ...

http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/15.jpg

... the chain tightens up ..

http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/16.jpg

Here is a wider board. I am attempting to assess for parallel. The easiest way is to see if both the sides of the board are held evenly ..

http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/17.jpg

This board is easier to see. I would say it is perfectly parallel (where it counts - at the chop) ..

http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/18.jpg

Here is another example. With the chop closed down but not tightly, it is apparent that the top is toed in slightly. The chain is loose, indicating that there is no tension ..

http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/19.jpg

Now I add a quarter turn on the screw. The chain tensions, and the chop pulls square ...

http://i13.photobucket.com/albums/a262/Derek50/Workbench%20and%20Workshop/Leg%20Glide%20Adjuster/20.jpg

Throughout this process, the leg vise is working very sweetly.

What do you think?

Regards from Perth

Derek

Paul Incognito
07-12-2012, 8:41 PM
What do you think?

Regards from Perth

Derek
I think I want one of these!
Please let us know when they'll be available for purchase.
Paul

Carl Beckett
07-13-2012, 8:39 AM
I think I want one of these!
Please let us know when they'll be available for purchase.
Paul

Yes, what Paul says...... +1

Jim Ritter
07-15-2012, 2:14 PM
Thanks again Derek you do have a knack for conveying information. That is definitely looser than my chain but the difference could be I have 18" between the screw and the chop and yours is 12". I most likely have a bit more flex in the chop. As long as it grips when you ask it to and tensions up parallel I think you found your sweet spot for your combination of chop, beam spacing, screw etc.

Paul Erickson
08-17-2012, 12:43 PM
Derek, What size chain is that? It looks to be larger than a bicycle chain. I'm also wondering if there isn't a way of incorporating the internal wheel guide with the chain pulley? Perhaps with a grooved wheel?

cheers, Paul

Jim Ritter
08-18-2012, 12:06 AM
Hi Paul, the chain is a #35 roller chain. It is much stronger than a bicycle chain,and has a little more room between the side plates. I tried to combine a sprocket and roller, just couldn't figure a good way to do it. The two different diameters would turn at different rates. I only have one roller on mine, it is on the inside of the leg on the underside. Placed on the inside the bulk of the weight of the chop etc wants to tip the works into the bench but the chain resist that force. Mine works very smooth, one finger operation. A friend on another forum is installing it in conjunction with BenchCrafted glide screw. Depending on the spacing between the screw and the top of the beam the forces on the chain can get pretty high. I measured 600# where Derek has his placed. Mine are further apart and the potential is 400#. I would discourage the use of a bicycle chain.
Jim

Derek Cohen
08-18-2012, 12:53 AM
Hi Paul

I was hoping that Jim would answer first since he did all the work designing the mechanism.

What can I add? Well, I was initially a little concerned that a roller would not spin as smoothly as a sprocket. Jim has a sprocket on his leg vise which he hand made as there was nothing small enough on the market. When the production prototype came along, the solution was to use a roller since this would be significantly cheaper to make. I remained concerned that it would not work as well, but trusted Jim's judgement. I do not have a sprocket to compare, but the roller works very well, and I doubt that anyone would remain concerned after using it.

With regard the force on the chain, what I can offer is the experience of snapping the wooden dowel I was using when the parallel guide was tightened a touch more than I should have (and not nearly as much as it could have been). This dowel was 1/2" in diameter and made from Wandoo (http://www.fpc.wa.gov.au/content_migration/plantations/species/arid/wandoo.aspx), a West Australian timber that rivals steel! It snapped as if it was made from Pine. Clearly there is a lot more power in a leg vise than one realises. Go with a thicker chain.

Regards from Perth

Derek

Paul Erickson
08-18-2012, 6:07 AM
Thanks Jim and Derek,

Now I'll just have to find a local source for #35 roller chain.

cheers, Paul

Paul Erickson
08-18-2012, 6:35 AM
Hi Derek,

I notice that you have what looks like leather in the inside faces of your vise. I am assuming that you install it with the rough side out for better holding, is that correct?

cheers, Paul

Paul Erickson
08-18-2012, 7:28 AM
Hi Derek, I don't think you need to rush into this. I'll make up some brackets here and give it a try. On yours if you add spacers to move the sprocket out it will impinge on the working space of the vise. Unless your new beam is longer than I think. A spacer and longer screws might introduce a source of flex in that area that might be of some concern. Is there room to put a roller under the beam on the inside, like I fitted to mine? I would try that first.

Hi Jim,

Any chance of seeing a picture of how you have your roller setup? I am having trouble seeing how it doesn't want to cause the vise to tilt away from the bench.

cheers, Paul

Jeff Wittrock
08-18-2012, 8:32 AM
Jim,

I would just like to say again that I think this is a very clever idea. I hope that you are able to successfully produce and market this as a product. I love having a leg vice on my bench. At least for the type of work I do, there are very few times when I find myself needing (wanting) a vice other than leg vice and wagon vice I have. I think anything that removes some of the inconvenience of using a manual pin in the parallel guide while not being overly complicated is going to be a winner.

Good luck

Jim Ritter
08-18-2012, 9:26 AM
Paul check your PM. Here is a photo of the sprockets I'm having produced.

http://i1135.photobucket.com/albums/m628/boatman53/4C8A5514-1D45-4454-BD7E-B309DD44CA2D-2748-00000895DE0496F8.jpg

Derek.. I'll send you the production sprockets when they come in. I like them much better. They will be a straight replacement for what you have.

Chris Griggs
08-18-2012, 9:41 AM
Jim, this is incredibly brilliant! I want one. Do you have any rough idea yet about how much you'll charge? Or would you rather not say yet?

Seriously, this is one of the coolest developments in vises I've seen... I love that it can be fitted to any old leg vise! Derek, nice write up as always - thanks for sharing you experience with it.

P.S. Jim, I just checked out your website. Beautiful work!

Jim Ritter
08-18-2012, 9:57 AM
Hi Paul, I can try and get a photo when I'm at the shop later today. But you won't see much. Because I knew the forces involved and I planed to use the stretcher to support the lower sprocket the beam is very near the floor. At the moment my lower roller is a 1" high density plastic disc that I turned on the lathe and mounted in a block of wood. I'll document it as best I can for you. It was meant to be a temporary let me try this plan set up but it works so well I didn't want to remove it to build a permanent roller carriage. I still have some final details to do on the bench and finishing which will take place this winter, that's when I'll redo the current set up.
Let me try a different way to explain, the screw keeps the upper end of the vise jaw from tipping awry from the bench, so if you put a roller right on the chop itself it would support the chop very well, but centered under the weight the bottom of the vise could tip in or out at will there would be no preference. But move the roller to the leg and off center from the weight the forces want to push the bottom of the chop into the bench. The chain prevent that inward motion just as the upper roller would. The chain being a fixed length keeps the jaw parallel.
Jim

Jim Ritter
08-18-2012, 10:06 AM
Thanks everyone for all the kind words. This has been a fun and exciting project for me. Not what I usually do for a living so there have been some bumps along the way. I want to thank Derek again taking a chance to putting one on his bench and taking the time to post and field questions. Thank you, Derek.
Jim

Jonathan McCullough
08-18-2012, 11:28 AM
Two rollers coaxial with the sprocket, with radii slightly larger than the sprocket/chain combination?

Derek Cohen
08-18-2012, 1:15 PM
Hi Derek,

I notice that you have what looks like leather in the inside faces of your vise. I am assuming that you install it with the rough side out for better holding, is that correct?

cheers, Paul

Hi Paul

I used a suede leather. This was slightly more textured on one side than the other. I have the smoother side on the outside.

To all: at some stage - probably once the kits are in production - I will post a step-by-step pictorial of my installation. The reason for holding back on these pictures is obvious.

Regards from Perth

Derek

Paul Erickson
08-18-2012, 3:17 PM
Hi Paul

I used a suede leather. This was slightly more textured on one side than the other. I have the smoother side on the outside.

To all: at some stage - probably once the kits are in production - I will post a step-by-step pictorial of my installation. The reason for holding back on these pictures is obvious.

Regards from Perth

Derek

Any particular glue you use to attach the leather?

cheers, Paul

Jim Ritter
08-18-2012, 5:07 PM
Here are a couple of shot of the beam roller on the leg vise. The dark wood is the beam, the vertical wood on the right is the leg. The side strecher is at the top of the photo. The wood with the roller is as I said just to try it out, it is wedged to the back leg and shimmed with old credit cards to find the right height.
http://i1135.photobucket.com/albums/m628/boatman53/D94E7F25-63A0-4EC3-A189-C75CB56C8FB7-2748-000008B08AC4EC58.jpg

This shot is with the jaw extended and the end of the beam visible. I don't know why I cut a decerative end on the beam because it is never visible.
http://i1135.photobucket.com/albums/m628/boatman53/BB0D2FC1-B00D-415E-8D85-5FE9D060DCB8-2748-000008B0A9C28C7F.jpg

Jim Ritter
08-18-2012, 5:12 PM
I thought of that but the beam would have to be wider than most people are using and I wanted an easy installation. After using mine with just the lower roller I decided it wasn't worth pursing.

Derek Cohen
08-18-2012, 9:11 PM
Any particular glue you use to attach the leather?

cheers, Paul

Hide glue, Paul ... to attach a hide .. :)

Regards from Perth

Derek

Derek Cohen
08-18-2012, 10:47 PM
Interesting placement of wheel, Jim. I'm not sure how much "work" it is actually doing on that side of the leg. The idea of a wheel, as I understand, it to take the weight off the chop, which would naturally sag. The sag causes the parallel guide to bind in the mortice. The inner wheel (behind the leg) would not do much in the position you have since the down force is on the other side. Consequently, what is needed is a wheel with down force on the inside to balance what is on the outside ...

Outside:

http://i13.photobucket.com/albums/a262/Derek50/Bench%20build/Final9.jpg

Inside:

http://i13.photobucket.com/albums/a262/Derek50/Bench%20build/Final10.jpg

When the inside wheel is removed the chain maintains balance by equalising the tensions inside and out. Then the inner wheel is unnecessary. The outer wheel continues to lift the chop and reduce down force, so it stays.

Thoughts?

Regards from Perth

Derek

Edward Clarke
08-19-2012, 11:18 AM
To heck with the other questions and on to the important stuff. Are you taking pre-orders and how much? I want to get this done before I finish the legs on my bench.

Mike Olson
08-19-2012, 3:32 PM
Is this chain the same type of chain used on garage door openers? just wondering as it appears if you can get your hands on an old chain drive garage door opener it would give you all the parts you would need for this.

Jim Ritter
08-19-2012, 6:15 PM
I don't know if it is the same size, I never inspected the workings of one of those. I don't even know anyone who has one. Do they have sprockets other than on the motor?

Edit: I just did a search and it appears that the garage door chain is anywhere from #40 to #65. Not that it wouldn't work it is just bigger. I also saw no other really useable parts other than the chain, and the chain is pretty cheap to start with.

Jim Ritter
08-20-2012, 9:22 AM
Hi Derek... Not sure why you are confused. Your lower wheel and my lower wheel work the same way, they just are placed 3" different in relation to the beam. The beam is glued and pinned at a 90 degree angle to the chop, so that relationship doesn't change. When you open your vise say 4" and I open mine 1" both rollers are now at the same spot on there respective beams, and function identically. The glide vise style needs the upper roller to keep the beam parallel to the screw for that smooth action. The upper roller prevents the beam from it's natural inclination to have the lower part of the chop swing into the bench. If that inclination to swing into the bench didn't happen you would need 4 rollers to keep that beam aligned. As said before the chain prevents the chop from swinging in. With the wheel on the inside it just enhances the desire of the beam the swing into the bench because it is further from the weight of the chop. But it is a mute point really because they work identically. Hope this makes sense.
Jim

Clark Harbaugh
10-16-2012, 6:19 PM
Jim,
Have you made progress on production on this yet? Just started the construction of a bench, and I would love to incorporate this.

Edit: Disregard. I found more info on the web site. Thanks!