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  1. #1
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    Dec 2006
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    926

    Kurt Vice Setup Help

    I need help setting up my vice square on my mill more accuately. Normally I put a dial test indicator in the chuck and use a bungee cord to lock the rotation of the spindle by way of the Bridgeport Spindle Brake, here's the type of indicator I use http://www.wttool.com/category-exec/category_id/17411. For setup I find a point on one end of the fixed jaw of my Kurt vice, zero out my dial test indicator and zero out Y on my CNC DRO, move back from the face, go to the other end of the vice jaw and go in to my CNC DRO Y Zero and adjust the vice until the dial test indicator reads zero. I lock the vice in with about 110 Foot pounds on a Toqure wrench and check again, I keep doing this until it's perfect.

    The problem is even though I've recently run a diamond stone over the jaws and they feel flat if I move the indicator over 1/4" it will read that it's off. So I don't know what I should be doing and what points on the jaws I should be testing to get the vice square to the mill. Any help would be apprecaited getting it setup more accurately.

    P.S. What tool can I use to drill and tap into the top of Kurt Jaw, I think they are hardened, I want to make a permanent work stop.

  2. #2
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    Well the jaws are case hardened to 60 Rockwell as far as I know, so I'd give up on the idea of a tapped hole unless you care to thread mill after drilling. I guess if you wanted to mill .125" off with a coated carbide endmill where you wanted the hole, then you could drill and tap it. The keyed block the back jaw bolts to is soft, so you can machine that and make a stop from there. I have also made a bunch of M6 holes in the side casting to mount a universal stop I bought from US Shop Tools. (I gave up being worried about the vise's resale value).

    Sweeping the indicator over the 6" long jaw will tell the tale. If the jaw is damaged and is no longer flat (unlikely), the indicator will show it. If the vise just isn't square, the indicator will trend consistently in one direction in a very linear fashion. This method takes out sources of error like the indicator holder moving slightly this way or that. You would see that on a reversal of travel, but not in the middle of a sweep. Also, putting the Bridgeport in low gear takes care of most spindle movement. A magnetic base on the quill would take the spindle out of it altogether.

    Dave

  3. #3
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    From what I can tell, your experiencing a vise jaw that is not flat.
    Vise jaws can deform with use.

    Case hardened jaws are only hard on the outside.
    So imagine if you were to clamp a fully hardened ball bearing in your vise and clamp on it with lots of force. It would dimple the jaws a bit.


    2 things you can do...

    1) If you have access to a surface grinder you can re grind the jaws nice and flat and parallel. Then put them back on, and that little bit of indicator error your seeing will be gone. (For the time being) Till it wears again with use.

    2) OR The other thing, is clamp your part in the vise exactly how you will be machining it, and indicate the part surface true. If you are doing a production run of parts this will repeat nice for that run of parts.
    But then you will need to re indicate all over again if you move to another location on your vise.


    Vise jaws will move.
    If you indicate a vise jaw with nothing clamped in it and get it nice and true.
    Then clamp a small part in it, say on the right side of the vise.
    If you check the remaining portion of the vise with an indicator it will be out of square again. By a small amount, but it will give you an idea of what is happening with your vise as you clamp in different areas or clamping with different forces.

    I hope this helps.
    By the way, How much error were you seeing?
    And what tolerance are you holding on this part?
    -Jon

  4. #4
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    Jun 2003
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    70

    Squaring Kurt vise

    110 Ft-Lbs seems pretty high. Folks typically only tighten vise enough to resist the cutting forces. You would like the vise to move in the event of a crash.

    Procedure to square vise:

    Eyeball vise jaw square with slots in table.
    Lightly tighten one side of vise to act as a pivot leaving other side free.
    Zero indicator against jaw on tight side.
    Move indicator along the jaw toward the loose side of vise while tapping it about the pivot point to keep the indicator near zero.
    Re-zero indicator on the tight side and repeat till indicator holds true.

    Kurt jaws often have .0005 to .001 wave in them.
    Jim Short
    www.tahlinc.com

  5. #5
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    Thanks for the info. This is all stuff I know or have tried. The error I'm seeing is about .0002", so not very much. And it's not linear. I don't think the jaws are warped I just think they have a very small wave as Jim said, nothing noticeable to the human eye or even my diamond stone. When I ran the jaw over the stone I saw even scratching. I've had problems in the past where I didn't tighten the vice enough and it moved, not noticeable during machining, afterward when the part was off and I recheckd the vice. I posted years ago and even called KURT and no one could tell me the torque so now I just torque it pretty tight. This shouldn't hurt anything right?

    Anyway, I might be trying to over do things maybe I should just leave it. If I can cut a part square today then I'll leave it. I just reset it because I thought the parts were a little off.

  6. #6
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    Feb 2009
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    kurt vise setup

    another way you could set your vise if you think the jaws may have some damage is to put a parrallel in the vise, leave it sticking up above the jaws about 1/2 inch. Then use your indicator to zero as explaned above.

  7. #7
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    Mike Good idea. Although I know for a fact that my parallels are warped, that's what you get for buying cheap parallels. Although the clamping force might straighten them out.

  8. #8
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    It may not be the vise or set-up. If there is any looseness in the gib adjustment(s) aka sloppiness, the table can move slightly (cock) on direction reversal. If you reverse direction again, the table will "cock" again.

    This is fairly common on machines with a few "miles" on them.

    My $0.02 worth, Dick Z
    DZASTR

  9. #9
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    Lets think about this....

    You are using a $ 23.00 indicator with .0005 graduations and telling us the jaws are off by .0002 ?!?

    I would doubt you can trust those results.

    Case hardening is only a couple of thou thick. Use a dremel and grind through at the spot where you want to drill.

  10. #10
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    That was just an example of the indicator I have, I wanted to make sure you people knew what I was talking about. I'm sure I paid at least $30 for my dial indicator :-). When I go to X0Y0 with the indicator, it's CNC, and go back and forth 10 times it's always dead on, on deviation. Then when I pull back from the jaws and move to X5.5 Y0, after the vice is adjusted it's DEAD on, then if I move to X5 Y0 the dial test indicator will be be a few hairs off of zero, so I'm guessing it's about .0002 off.

    As for the drilling I realized I don't want a permanent work stop on top of the jaws anyway so I'm drilling into the body of the vice where it's soft.

  11. #11
    A trick for putting a Kurt vise on is to line up the back face of the bolt slot with the back face of the T slot. You can eye ball them almost flush with each other and then feel with your thumbs to get the last little bit.

    This technique will get within .010" or closer if you're good. A lot of times I can get to about .001 or so. Regardless of the number, it only takes a tap or two to get it perfect.

    You could also pull up against pins that are the width of the T slot but thats for hacks. By the time you get your pins in, I'll be done.

    A good machinist should be able to get the vise on and dialed in, in less than 3 minutes. When I was an apprentice I'd get yelled at for taking more than a few minutes. I was timed with a stop watch behind my back.

    Should be able to dial in two vises parallel to a gnats ass in less then seven minutes, with no cheater bar.

    The key to getting something dialed in quickly is to get close before you start. Goes for anything in the shop. Take a second to get it lined up by eye and or feel and it will save a lot time later. There are all sorts of things like this that add up into time savings. Seconds add up to minutes and then to hours.

  12. #12
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    Mar 2007
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    4

    WOW !!! GO WELDEN !!!

    with a stop watch...... Now that is HARD TRAINING !!!!!

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