BIGGUNDOCTOR Posted September 13, 2015 Share Posted September 13, 2015 That screw came out of some sort of drill, the end has a Morse taper, with another adapter in it.I have been mulling over cam vises lately. Many ways to do this. Quote Link to comment Share on other sites More sharing options...
Dave51B Posted September 15, 2015 Share Posted September 15, 2015 I got the vise cut apart where it had been welded at the wedge. The spring was bottoming out ,so the jaws wouldn't close. Hence the add-on piece to one jaw. It's been wire wheeled and the weld goobers ground smooth. I think I'm going to drift one of those slots out to accept a pin to pivot the cam. I hadn't noticed the threads were left handed, but doesn't matter in this case. It will only be used rarely. I guess I will make the cam out of wood to test the fit, leverage and travel. then make the steel one to match. Unless some math guru comes along...... Oh, and I found the #50 stamped on the moveable jaw just above the screw, and a bunch of 5s stamped into the side. Dave Quote Link to comment Share on other sites More sharing options...
VaughnT Posted September 16, 2015 Author Share Posted September 16, 2015 Looking forward to seeing what you come up with, Dave. Quote Link to comment Share on other sites More sharing options...
Dave51B Posted September 17, 2015 Share Posted September 17, 2015 (edited) Just trying to figure out the geometry of this. As I see it, I will not need the adjustable screw. Maybe add a turnbuckle to adjust the foot peddle height. Anybody have a good way to measure jaw pressure (squeeze)? Other than putting my finger in to see if it hurts....Right now I have a 2" radius for the cam..... Hopefully more to follow Dave Edited September 17, 2015 by Dave51B dup pic Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted September 17, 2015 Share Posted September 17, 2015 (edited) The main advantage of having adjustment on the length of the pin through the jaws is that you can have a narrower range of opening/closing movement but exert more pressure per inch of foot pedal movement.If you have a fixed pin length you can only adjust the height of your pedal for comfort by adjusting the length of the connecting rod between cam and pedal.My suggestion of drop in u shaped spacers to shorten the pin length (dropped in between the head of the pin and the fixed jaw) would give you a series of jaw travel arcs and a near instant adjustment and enable you to have a slower acting cam exerting greater pressure per pedal movement.I think you will have to just make up a cam and see what happens. Plywood rather than cardboard would enable you to actually operate the vice...Alan Edited September 17, 2015 by Alan Evans Quote Link to comment Share on other sites More sharing options...
MarkDobson Posted September 17, 2015 Share Posted September 17, 2015 i like where this is going, cant wait to see what you come up with! Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted September 17, 2015 Share Posted September 17, 2015 (edited) Oops sorry! On closer inspection I see you are using plywood.If the cam operates on the point of contact you are using, the jaws will move more. If you cranked the pin yoke up you could have the cam push on the jaw above the pin hole and exert more pressure but with less jaw movement.If you want to be able to push down on the pedal and then lock it where it grips so you can be both hand and foot free...a slight sideways wobble on the pedal and a ratchet bar fixed beside it would work. Alternatively a spring link in the con rod and a single hook to hold the pedal down would maintain pressure.hmmm getting complex. Have you figured out what you will be using this for? That would determine the final action you require.I know! The obvious answer is to buy a "SuperJaw" foot operated vice, and rebuild this one by using a pin with a screw thread and tommy bar and a nut behind the fixed jaw… Alan Edited September 17, 2015 by Alan Evans Quote Link to comment Share on other sites More sharing options...
Dave51B Posted September 17, 2015 Share Posted September 17, 2015 After sleeping on it, I am thinking maybe making 2 cams and sandwiching the pull rod. This would solve the problem of the cam hitting the pull rod when closed. Also raise the contact point for more leverage. Just need a flat washer for the cams to ride on at the screw hole in the moveable jaw. A few adjustment holes in the cams would change length of pull. Thanks a bunch for the input. I'm really not sure exactly what I'll use this for, I guess it depends on how it turns out. I'm hoping though it will be handy for twisting and bending to save heat. This is my 4th post vice, so any heavy work will be done elsewhere. Perhaps squeeze some solder to compare holding strength. should do that anyway DavePs : any one else wonder why the spring is upside down in VTs original pics ? Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted September 17, 2015 Share Posted September 17, 2015 (edited) The Superjaw makers claim one tonne pressure on their jaws.The spring of a given strength would be better able to hold the jaw open against the weight of the pedal, con-rod and cam, with it up the other way. It has more travel but also more leverage against the weight.Alan Edited September 17, 2015 by Alan Evans Quote Link to comment Share on other sites More sharing options...
Dave51B Posted September 17, 2015 Share Posted September 17, 2015 Allen, that's what I was thinking. Trying not to get ahead of myself, but will probably just add a lift spring on the foot peddle. Dave Quote Link to comment Share on other sites More sharing options...
VaughnT Posted September 17, 2015 Author Share Posted September 17, 2015 If you use a threaded portion and nut on the back of the fixed jaw, you can adjust the opening of the jaws to fit specific sizes of stock. Right?The way you have it set up now, the vise opens all the way and then has to be closed all the way. With a threaded end, the cam and moving jaw stay in the same position relative to each other, but the amount of travel is reduced to just what is needed to clear the metal you're trying to hold.Does that make sense? Seems like it does to my mind. Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted September 17, 2015 Share Posted September 17, 2015 (edited) If you use a threaded portion and nut on the back of the fixed jaw, you can adjust the opening of the jaws to fit specific sizes of stock. Right?The way you have it set up now, the vise opens all the way and then has to be closed all the way. With a threaded end, the cam and moving jaw stay in the same position relative to each other, but the amount of travel is reduced to just what is needed to clear the metal you're trying to hold.Does that make sense? Seems like it does to my mind.It is very close to being a standard leg vice then ain't it? there must be reason they ended up like that.If you took a standard working vice, and mounted a lever like a giant claw hammer to operate between the thrust washer and the moving jaw. You could use the the standard thread to give you your base adjustment. And by means of a con rod and pedal effect your hands free closure...Do look up the Superjaw vices, originally from Australia but De Walt and Elu market them branded.I use mine a lot, especially on site when installing. Excellent shooting bench too.Alan Edited September 17, 2015 by Alan Evans Quote Link to comment Share on other sites More sharing options...
VaughnT Posted September 17, 2015 Author Share Posted September 17, 2015 It is very close to being a standard leg vice then ain't it? there must be reason they ended up like that. Truly. But, the key feature is the speed of closure and the ability to keep your hands free to work the metal and tools. Quote Link to comment Share on other sites More sharing options...
Dave51B Posted September 17, 2015 Share Posted September 17, 2015 Yes I did look up the superjaw vice. Kinda looks like the jawhorse brand. Looks handy....VT, I agree on the threads on the back, but got to thinking about the exposure to damage, without the regular screw box for protection. I know how I work... Right now after some more fitting and twisting, looks like a French curve is needed on the cam. Got to go....Gotta fire in the forge. Just came in for breakfast, Dave Quote Link to comment Share on other sites More sharing options...
VaughnT Posted September 17, 2015 Author Share Posted September 17, 2015 It'd be small potatoes to create a shield for the threads that still allowed access to the nut. Of course, everything would depend on what you plan on doing with the vise. Were it I, there'd be a stop block and rack of teeth attached to the fixed leg so it could be used to upset and form rivets. Quote Link to comment Share on other sites More sharing options...
Dave51B Posted September 24, 2015 Share Posted September 24, 2015 Got a little done today...I went back to the screw to gain some leverage. I added a bearing to cut back on friction against the jaw face. Any thoughts ? Still pondering the lever angle and length... Dave Quote Link to comment Share on other sites More sharing options...
Dave51B Posted September 27, 2015 Share Posted September 27, 2015 Small issue : screw grinding and binding on bottom of moveable jaw. Fix : hopefully in progress.... Dave Quote Link to comment Share on other sites More sharing options...
Dave51B Posted October 5, 2015 Share Posted October 5, 2015 This thing may just work out. If the vid shows up, I'm kinda tickled........... Dave PA050001.AVI Quote Link to comment Share on other sites More sharing options...
VaughnT Posted October 6, 2015 Author Share Posted October 6, 2015 (edited) Looks like you've got some solid engineering there, Dave! My thinking is that the cam, when closed, should just barely pass TDC and kind of lock in place so you don't have to stand on the pedal while you're working at the vise. In the OP it looked like there was a short length of rod that would have propped against the stump and prevented the jaws from opening. If you have to stay standing on the pedal to keep the vise closed, you're rather limited in your ability to move around, grab another tool, etc.Sounds right, right?In your video, you've got the bearing hitting the screw by the time the jaws are fully closed, but how does it act when you try to grip some bar? Can you get enough weight/leverage on the jaws to securely hold some half-inch square for twisting? Can you adjust from 1/2" to 3/4" without throwing off the cam? Edited October 6, 2015 by VaughnT Quote Link to comment Share on other sites More sharing options...
Dave51B Posted October 6, 2015 Share Posted October 6, 2015 VT, Your way out in front of me so far. I haven't gotten the foot linkage put on yet. The way I have it ,I will not be able to lock in place with out a system on the pedal linkage someway. No way with this design to get past center. The screw can still be adjusted on the back for different size stock. I just have added spacers in there now, till I figure out how long to leave the threads out the back. I do reserve the right to change any and all features at any time......... Dave Quote Link to comment Share on other sites More sharing options...
Frosty Posted October 6, 2015 Share Posted October 6, 2015 Pretty slick Dave. I'm thinking if you put the treadle on another lever linkage you'll have a compound lever for severe grippage.Welcome aboard Martin, glad to have you. If you'll put your general location in the header you might be surprised how many IFI folk live within visiting distance.Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Dave51B Posted October 6, 2015 Share Posted October 6, 2015 Thanks for the encouragement guys. I still have to plan out the mount and final height of this thing before I really get into the pedal linkage setup. I may have to take a step back and make a few bottle openers......A few 12oz. liquid decision makers could help. Dave Quote Link to comment Share on other sites More sharing options...
VaughnT Posted October 6, 2015 Author Share Posted October 6, 2015 I'm trying to think of a simple way you could build a ratchet and cog into the foot pedal so you simply step on the pedal and lock the vise closed. Seems like it should be relatively easy, but....If you're only going to be working a small range of stock sizes, it might be that you can build in some automatic stops at given thicknesses. Maybe something like a toothed cooking trammel. Of course, it's late and I need to get some sleep, so I might not be thinking too clearly! I am thoroughly enjoying watching it all come together, though. Makes me kind of proud to have played even a small part in this adventure. Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted October 6, 2015 Share Posted October 6, 2015 Truly. But, the key feature is the speed of closure and the ability to keep your hands free to work the metal and tools.I think you misunderstood my comment. I was in agreement/supporting your screw thread adjustment proposal…but just trying to be funny/clever (and evidently failing) in the way I said it! This thing may just work out. If the vid shows up, I'm kinda tickled........... DavePA050001.AVINice as it is in the video, in use you probably do not need to generate that amount of travel...that range of jaw opening. The amount of movement of the lever and therefore foot pedal will be hugely reduced when you are just set up for a regular process with one size of work piece. The last part of the arc when you have maximum pressure applied by the cam and minimum movement of the jaw will be the bit to concentrate on with regard to your pedal leverage and con rod connection points.All depending on the actual jobs you are going to use it for of course.Alan Quote Link to comment Share on other sites More sharing options...
Dave51B Posted October 6, 2015 Share Posted October 6, 2015 Thanks guys, VT, I'm going to see how it works with constant foot pressure, with the option to add a locking system on the pedal if desired. Alan, I do have another hole in the cam, forward of the one in use on the vid. It causes the jaw to only travel about 1" It maybe the one I use. Not sure yet. I'm trying to have as many adjustments as possible, at each pivot and linkage length. I have already scrounged the piece to weld to the leg. It has holes evenly spaced for leverage adjustment. More to follow....... Dave Quote Link to comment Share on other sites More sharing options...
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