Is there a good way to prevent a vice from shifting when tightening the second bolt - Page 2
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  1. #21
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    Quote Originally Posted by Larry Dickman View Post
    Bolts? Who the fuck uses a bolt to hold down a vise? Stud and a flange nut.

    Another vote to shitcan #4.
    Agree, assuming you mean a spherical flange nut and washer.

  2. #22
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    Ok, I'll say it, scrape the two surfaces flat and match each other. It won't move when tightened. I did it to mine years ago as experiment /practice, and doesn't require gorilla strength to hold even under heavy cuts. I bet this was common practice in ye olden days.

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    Never liked the excessive slop in the Kurt vise mount holes. So I made a couple of bushings that align the bolt to vertical. Tightening operations on the vise to
    get it lined up are reduced and at the end I'm just lightly tapping the vise into position.

    dsc_1045.jpg

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    The old vise that came on my mill got scraped flat on a surface plate and seems to hold just fine on the table with 3/8 studs. I indicate the vise within 20 thou or so, snug down both of them lightly, tap with a copper hammer to within a few thou, then moderately tighten one bolt and tap in to about .0005. That is as close as I can get it. Then snug the bolts down evenly , and then tighten. An standard box end wrench does fine.
    Number four is weird- in all my reading, in virtually every trade and field of endeavor, I have never come across a recommendation to heavily torque one bolt of a series and leave the other(s) loose - it does not matter if it is a head bolt on a gasket, or a solid cast surface, that surface IS going to cock some.

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    All of my machines have 3 or 4 double locks on them, I space them 2 inches apart and clamp 2 precision ground hardened 1/2 x 3 x 24 bars in them about .1 above the vises. I tighten the vises on the ground bars and lightly finger tighten the old down flange nuts with my finger, indicate, snug, indicate, lightly tighten.

    "A post pubecient girl's worth is usually sufficient...........Bob"

    Keep an eye on her the first few times, sometimes girls get in the shop and want to proove how strong they are.

  7. #26
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    Remind me to keep you guys away from my mill.



    Quote Originally Posted by metlcutr55 View Post
    45 years ago as an apprentice @ Newport News Shipbuilding, one of my fellow apprentices was a very powerful young fellow likely the strongest man ive ever met. as a gag he took joy in doing this to his mates....a few of the manual machines we ran, a huge vertical slotter and a big taper cincinnati horizontal mill both used cast one pc tslot bolts in the 7/8 to 1" range. Don would wait until you were gone, and tighten your bolts until they wouldn't move. you'd have to go find a longer wrench or a cheater, and you could hear them "creak" when releasing. I watched one fellow Fred work for at least 5 minutes unable to loosen, before someone else helped him with the cheater bar method. im sure it wasn't good for the bolts or machines. then there was the other extreme, that same fellow Fred who worked to loosen for 5 minutes set up that hor mill once, put a 4" sq pc of alloy steel in the vise, and buried a 4" multi flute endmill side cutting 2" deep, and tried to climb mill. even with the climb mill dial engaged, it made a horrible noise when the vice was yanked off the tbolts and the mill exploded into shards. I guess he should have had Don tighten them bolts for him first.

  8. #27
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    If you want to at least double the resistance to your vise moving at whatever torque you apply to your nuts, place a piece of ordinary printer paper between the vise and the table. Paper doubles the coefficient of friction between two smooth steel/iron surfaces. It is very easy to test this out by simply giving the unbolted and unpapered vise a push while it is sitting on the table. Then put a piece of paper between. You’ll see feel the difference immediately. Secondly, and this is less intuitive but true, use a film of oil between the vise and table to better lock the vise/paper/ table. When you suck the vise down the oil fills all gaps prevents easy air movement in the tiny passages between the vise and table. In 2012 this idea was discussed Here and the following study supporting “viscous damping” was cited.
    Introductory Course on Theory and Practice of Mechanical Vibrations - J. S. Rao - Google Books

    The 2012 thread is here A way to reduce chatter and vibrations.

    I've been using paper and way oil ever since. You will find that after you’ve clnched down your vise this way you have to “break it loose” to move it after you release your holding bolts.

    Incidentally, one of the first things I taught my son when he started showing interest in machining was to absolutely NOT over tighten stuff. It did not take him long to get the idea of the sequence of dead loose/ snug/ bolt starting to stretch(stop)/ bolt too tight (might squeak)/ bolt or part failure.

    Denis

    Added: No one has mentioned wiping down the table, running your bare hand over it to feel for tiny burrs, swarf, or debris and then very lightly stoning and looking for shiners and hand wiping one more time. Basic? Yes, but skipping basic steps can cause problems whose source might not be recognized easily.

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    Lap your nuts.

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    Use the key slots on the bottom of the vice. Saves having to tram the vice every time it goes on the table.

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    Quote Originally Posted by Larry Dickman View Post
    Bolts? Who the fuck uses a bolt to hold down a vise? Stud and a flange nut.
    .
    Have to admit that I do a this a lot.
    Does the fact that I use ground washers give me some slack?
    Keys, bushings,,all that nice but my tee slots are real not high precision and while I'll stone vise and top have never stoned the keyways.

    One question is how square is square enough when mounting a vise?
    Another is has the vise ever moved in normal use if just nice and easy on the fasteners.

    "No torque wrench needed,just common sense".
    Problem here is that some have no idea of torque to force applied, humans come in differing sizes and tight to one is cheater bar to another.
    For sure I think that one should have that "feel" be it a insert holdown pin or a vise base.
    Yet I get a lot toolholders to fix that the screw or pin would not come out and the head now rounded. Why do people do this?
    Seems it would be common sense to me but these bolts. clamps, screws are small guys and "I did not want the insert to move".
    Mini version of mounting a vise.

    Bob

  13. #31
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    Quote Originally Posted by EPAIII View Post
    Remind me to keep you guys away from my mill.
    we were late teens early twenties, all mechanical maintenance millwright apprentices, and did not get enough machining instruction to understand radial cuts, full width cuts, differences in materials, etc, etc. so we worked best we could. these were old non cncs with massive box ways, and big motors and mechanical feed gearboxes. we got our machining info from the older guys who got theirs from the older guys, ad infinium. if we had a screwup it likely showed up on the part and tooling and fixturing, and the machines were tough enuf to withstand the blow. we could have been better supervised, and yes it is a good thing we never got to run your likely very nice cnc. many of the old machines had no dro's, you made long moves by tape or scale measure and counting dial rotations, and precision moves using an indicator. not that anyone there understood the importance of tangency to an indicator reading beyond guesswork.

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    One way I found to prevent a vise from shifting is to have my fingers in a nearby t-slot.

    It only happened once and it was a long time ago.

    More seriously, the flatter everything is the better it all works.

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