jlpservicesinc Posted November 1, 2016 Share Posted November 1, 2016 3 hours ago, gote said: y conclusion is: Yes the taper will transfer force to the plates but that does not put less strain on the bolt. It only changes from shear to a much higher tension AND it is mostly by friction. The friction will only develop if the jaw sinks a little so it wedges. Thus there must be sufficient radial play in the bolt. Otherwise it is a question of shear anyway. If the bolt is pulling the plates so tight that the wedge-support situation develops without this radial play in the bolt, the spring will be unable to open the vise. The shear situation causes a stress concentration. How important this is, depends upon how soft the pieces are and how close the contact areas are. Is shimming a bad idea? No. In my vise, the plates are much higher than vide. The distance from the bolt to the leg is much less than the distance from the bolt to the upper and lower edge of the plates. The bolt pinches in the wrong place. The edges of the plate will move less than the centre. This differs very much from the pics you show of rusty vises. In those cases you may be right. Okay, so the stress is the same if you want to get into equations. The force applied is the force applied and can be exponetially equated to difference loads, thicknesses.. etc, etc.. . What is not the same is the area in contact.. a tapered bolt offers more contact than a straight bolt.. Also for it to bind there would have to be no lubricant and forced in dramatically.. LOL.. fun right.. If you have to shim your vise.. The question becomes why? And how much of a shim in area are you actually putting in contact with the vise arm that is helping to eliminate the play you are associating with torquing when threading a bolt? is it a big shim in area so offering more area to the vise jaw arm? The arm only has so much width or thickness.. Or is it a shim 13mm wide at each side of the bolt? Is there that much play because the vises bolt, or cheeks are worn or because it's rusted and the material is gone.. Each one of these pays into the next.. on any of the vises I have shown you. You wouldn't be able to fit even a 0.0001 shim into the joint unless there was something drastically wrong..Like a bent bolt or a completely egged out pivot hole, or a front jaw being bent downwards from abuse and then you would still need a egged out pivot hole.. Post some pictures of the vises worn surfaces and lets see exactly what the problem is. Quote Link to comment Share on other sites More sharing options...
gote Posted November 1, 2016 Share Posted November 1, 2016 If the bolt can pull the taper towards the plate so much that the lateral movement of the jaw is decreased appreciately by gripping in the taper, it will jam. The forces axially in the bolt are increased by the longer lever up to the jaw. Even a morse taper will jam sufficiently to work in spite of the oil on the machine. The shim that seems to be correct is 0.7mm. That decreases lateral movement from around 5mm to less than a half without binding the jaw. Yes the shim will be the same size as the free part of the plate. A ring around the bolt would not help at all since it is the play at upper and lower edge of the plates that limit lateral movement of the jaw. A tapered bolt can be used to adjust the play in a pivot. Choosing right diameters on hole and bolt will also do the trick. I find it questionable if it is more difficult to make cylindrical surfaces to the right tolerances than to make taper that is correct in the plates, jaw and bolt. Anyway, I would think that the bolt is subject to shear and some tension rather than to linear load in the contact surfaces. Besides you are claiming that the load is taken by the wedging and not by the bolt are you not? I have two somewhat related problems with the vise. A: There is too much play at upper and lower edge of the plate so there is uncomfortably much lateral play between the jaws.If this is due to sloppy manufacture, wear, bending or other abuse or what I do not know B: The moving jaw sits a little bit to high. The cirular surfaces that are intended to transfer vertical load from the jaw to the plates do not have real contact. (This is German style) Conclusion is of course that the present bolt is not worn. A worn bolt would let the jaw down to the contact surfaces. The quick and dirty is probably to use a slightly undersize bolt or one that is turned to be a crank with a small excentricity - say 1mm in which case the jaw could be adjusted by turning the bolt. Since I do have a lath but not a set of reamers that is probably the best way to go. Oops sorry I only saw the bottom part of your message. I have to break off now but the moving jaw does not twist it moves laterally. Quote Link to comment Share on other sites More sharing options...
Anachronist58 Posted November 1, 2016 Share Posted November 1, 2016 7 hours ago, gote said: 7 hours ago, gote said: Quote Link to comment Share on other sites More sharing options...
jlpservicesinc Posted November 1, 2016 Share Posted November 1, 2016 2 hours ago, gote said: If the bolt can pull the taper towards the plate so much that the lateral movement of the jaw is decreased appreciately by gripping in the taper, it will jam. The forces axially in the bolt are increased by the longer lever up to the jaw. Even a morse taper will jam sufficiently to work in spite of the oil on the machine. only if over tightened.. Only if it's jammed in very hard.. I have machines and lathes with Morse taperes.. I know how they work.. and only if badly fitted to begin with.. 2 hours ago, gote said: The shim that seems to be correct is 0.7mm. That decreases lateral movement from around 5mm to less than a half without binding the jaw. Yes the shim will be the same size as the free part of the plate. A ring around the bolt would not help at all since it is the play at upper and lower edge of the plates that limit lateral movement of the jaw. A tapered bolt can be used to adjust the play in a pivot. Choosing right diameters on hole and bolt will also do the trick. I find it questionable if it is more difficult to make cylindrical surfaces to the right tolerances than to make taper that is correct in the plates, jaw and bolt. Anyway, I would think that the bolt is subject to shear and some tension rather than to linear load in the contact surfaces. Besides you are claiming that the load is taken by the wedging and not by the bolt are you not? A taper has the adjustment all ready built in vs having to figure it out.. If you are an engineering type and it's all about the numbers than fitting by feel may not be your thing.. I know someone that unless you can read it to 0.00001 it's not accurate.. That great for him.. I am happy to 1/32nd of an inch.. Like I have all ready mentioned forging a bolt to shape is not a big deal even when working to tight tolerances.. I think you are overly concerned with what or what doesn't the bolt do.. It works together as a whole unit.. Even if you use a straight bolt like many of this vises did.. It's the taper in the bosses that distributes the pressure across many sq" vs just on the bolt.. 2 hours ago, gote said: I have two somewhat related problems with the vise. A: There is too much play at upper and lower edge of the plate so there is uncomfortably much lateral play between the jaws.If this is due to sloppy manufacture, wear, bending or other abuse or what I do not know B: The moving jaw sits a little bit to high. The cirular surfaces that are intended to transfer vertical load from the jaw to the plates do not have real contact. (This is German style) Conclusion is of course that the present bolt is not worn. A worn bolt would let the jaw down to the contact surfaces. The quick and dirty is probably to use a slightly undersize bolt or one that is turned to be a crank with a small excentricity - say 1mm in which case the jaw could be adjusted by turning the bolt. Since I do have a lath but not a set of reamers that is probably the best way to go. Oops sorry I only saw the bottom part of your message. I have to break off now but the moving jaw does not twist it moves laterally. Not a problem.. Have you had the vise apart yet? Check all parts for known wear.. Don't make assumptions as to what is worn or not.. If the front jaw is higher the back jaw might be bent.. This can be corrected by first filing or burring the high side till it just about sits where it belongs then ream it then put a morse taper ream through it or pick a ream with the degree you want.. Or just drill it straight if it has a straight bolt all ready.. If the cheeks are not making contact with the reciever grooves, check the distance and then measure the difference in jaw height.. someone might of drilled the hole all ready and did a terrible job making the jaws out of plane as well as the contact surface of the cheeks.. Quote Link to comment Share on other sites More sharing options...
Anachronist58 Posted November 1, 2016 Share Posted November 1, 2016 (edited) 8 hours ago, gote said: On 10/29/2016 at 1:27 PM, Anachronist58 said: I rilly like the RiffRaff this site attracts!:rolleyes: RiffRaff = People regarded as disreputable or worthless. (Check your dictionary) Now Mr Gote, I have indeed a very fine 20th century dictionary, whose definition of aforementioned term, succinctly concurs with your own source. However, I have stated this as Hyperbole, as members here "occasionally" do, and in my usage, it is meant as a high compliment, an honor to be in such esteemed company. As, perhaps, akin to "Les Miserables"' if you will? Robert Taylor 8 hours ago, gote said: On 10/29/2016 at 1:27 PM, Anachronist58 said: I rilly like the RiffRaff this site attracts! Unstable Text Editor Edited November 1, 2016 by Anachronist58 Unstable Text Editor Quote Link to comment Share on other sites More sharing options...
gote Posted November 2, 2016 Share Posted November 2, 2016 Dear Mr Taylor I am not offended but please forgive me I meet so many people who do not understand the words they use. Quote Link to comment Share on other sites More sharing options...
Anachronist58 Posted November 2, 2016 Share Posted November 2, 2016 Dear Mr. Gote, all is well and amicable. I tend to view the people of this community as being, on average, outside of the average, outside of the norm, if you will. More specifically, those of us who shape glowing steel, et al., into a manifestation of our vision, our imagination: We tend to stand apart from those who believe that oranges and bananas grow on store shelves (I know of these people), and in that sense, I attribute to "us" a rogue spirit - indeed, we are non-conformal, at our best. I often accuse my spouse of being a hoodlum, but only to imply something quite honorable about her character. Consequently, I am honored to in conversation with you, as well. Robert Taylor Quote Link to comment Share on other sites More sharing options...
jlpservicesinc Posted November 2, 2016 Share Posted November 2, 2016 36 minutes ago, Anachronist58 said: Dear Mr. Gote, all is well and amicable. I tend to view the people of this community as being, on average, outside of the average, outside of the norm, if you will. More specifically, those of us who shape glowing steel, et al., into a manifestation of our vision, our imagination: We tend to stand apart from those who believe that oranges and bananas grow on store shelves (I know of these people), and in that sense, I attribute to "us" a rogue spirit - indeed, we are non-conformal, at our best. I often accuse my spouse of being a hoodlum, but only to imply something quite honorable about her character. Consequently, I am honored to in conversation with you, as well. Robert Taylor Well Said Robert.. Quote Link to comment Share on other sites More sharing options...
gote Posted November 6, 2016 Share Posted November 6, 2016 No I have not disassembled the vise. I simply do not have the time. When I do, I want to do a thorough job and restore all the intended functionality. That will take me several days. Biggest problem: This vise is designed to pivot around a vertical axis. The mount is cylindrical and there is a locking screw at the back and two screws that tighten the mount. Unfortunately the leg is broken(cut?) a little above floor level and someone has welded an L-bar to it. Presently I have the bar stuck into my dirt floor. I can neither use the rotating facility nor do I have a good support for the leg. My intention is to remove the L-bar. To take a piece of pipe and, using the leg as mandrel, shape it to fit the (tapered) leg. To heat the pipe and force it onto the (cold) leg. To cast a piece of concrete into the floor with an integral piece of heavy plate on top. To turn a stud that fits in a hole in the plate and also fits the pipe. To put in a couple of washers so I can adjust heights if something moves. The too high jaw does not make a problem at "jaw level" The error is far too small to make a problem. You are probably right that someone has messed with the bolt and holes. Since it is a German style vise, the intention is that the vertical force be transmitted to the plates by the plate top surface. As it is, there is a (slight) play there so the force is taken up by shear in the bolt instead. The play is less than half a millimeter. It is bad engineering practice to try to take the load simultaneously on the bolt and on the bearing surfaces and I prefer to have the load transmitted by the bearing surfaces. I think that is a superior design. Thus a quick fix would be an undersize bolt. I could imagine that the original design used holes slightly elongated vertically and that someone has reamed them to circular and put in an oversize bolt. (Or that the original play has been filled by rust) I will know better when I have taken it apart but presently I guess that I will elongate the hole in the jaw stem slightly upwards and fit a new bolt. The horizontal shear on the bolt is far less than the vertical caused by pounding. In a a German style vice I do not want the bolt to be a tight fit vertically since I do not want it to take the load. Quote Link to comment Share on other sites More sharing options...
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