Page 1 of 5 123 ... LastLast
Results 1 to 10 of 43

Thread: How much jaw lift is too much?

  1. #1
    Join Date
    Jul 2017
    Location
    Springfield Mo
    Posts
    193

    Question How much jaw lift is too much?

    My question tonight is just like the title says, when tightening a milling vise, how much lift in the movable jaw is considered too much? The vise i picked up for my mini mill is on the, err, 'frugal' side, and ive noticed that when placing a piece on parallels the side contacting the movable jaw lifts about 5 thou as measured by my iffy dial indicator. Personally i think its a little higher of a number. Doesnt seem like much, but it does bugger things up when im trying to mill down bar stock to a consistent dimension

    So, is this normal to see in a mill vise? Are the Kurt style vises subject to the same problem, or would i see better results if i were to make the switch. Shars sells a decent looking 3 inch kurt style im eyeing, but it would be rather pointless if i were to drop the money and find out that the new vise would have the same problem.

    For reference, my present vise is the 3 inch mill vise that Little Machine Shop sells:
    http://littlemachineshop.com/product...ory=1963256912

    And this is the one im thinking about getting:
    http://www.shars.com/3-x-2-95-lock-d...g-machine-vise

  2. #2
    Join Date
    Sep 2012
    Location
    Australia
    Posts
    344

    Default

    Those vises always have jaw lift, because there has to be clearance for the jaws to slide, and they're manufactured to a price point (that's very low compared to their mechanical complexity). You should still be able to get reasonable results in most cases where you're doing things like milling down stock square, using a soft face or deadblow hammer to seat the stock back down onto the parallels as you tighten the vise. It's a necessary part of using such a vise.

    Kurt clones take up a lot of table real estate for their size, but don't open very far either. You'll quickly grow frustrated that such a large vise only opens 3 inches. Yes, you can swap the jaws around to the outer faces for larger plate work, but that's extra setup, and 3 inches isn't a very large vise - that mini Kurt only opens half an inch wider than the vise you already have - meaning you'll be doing it often. They're also not a 'standard' item, so the quality will be variable and largely unknown until you've got it in your hands.

    On a mini-mill type machine, I would look at a screwless toolmakers vise before one of those mini-Kurt clones. This vise opens 60% more than the mini-Kurt, although it doesn't have replaceable jaws, or external jaw mounts - neither of which are features you might need on a mini-mill. By and large, they're also manufactured to very good parallelism and squareness tolerances, regardless of where they're bought from, and the jaw hold-down feature is very effective if you understand how to use it (the closer you can get the screw to parallel, the better). And if you ever decide to move up to a big boy mill, the vise will have a second life as an insert vise.

    http://www.shars.com/products/toolho...oolmakers-vise

  3. #3
    Join Date
    Nov 2015
    Location
    Sydney
    Posts
    1,109

    Default

    I'm getting 0.0025 to 0.005 mm on a Kurt.

  4. #4
    Join Date
    Oct 2002
    Location
    Bremerton Washington
    Posts
    5,754

    Default

    Got jaw lift? Locate a U-clamp, stud, and heel block over the jaw to force it back down. PITA as in more set-up hassle but it works.

    The relics we apprentices had to contend with popped up a visible amount on tightening. Those vises were 20 years old, veterans of WW II and many round the clock war emergencies. They were in their last stages of wear, suited only for us apprentices and other low forms of life. If you didn't clamp the jaw down, work you were trying to square up took on the look of a polygon.

  5. #5
    Join Date
    Jun 2004
    Location
    N.J.
    Posts
    682

    Default

    Put a length of steel round rod maybe 0.25 dia. horizontally between the workpiece and the movable jaw. As the jaw lifts the rod will roll downward and push the work against the vice base

  6. #6
    Join Date
    Mar 2015
    Posts
    1,703

    Default

    Parallels, and a dead blow hammer?

  7. #7
    Join Date
    Jan 2014
    Location
    Long Island
    Posts
    2,067

    Default

    Get yourself a dead blow hammer. They look like a mallet but the head is filled lead shot or sand so they impart their energy to what you are
    striking instead of bouncing back at you. I picked this one up at Lowes a couple of years ago for $25:

    Snug the vise up a little. You will need to learn how hard to strike the part to get it to seat back down onto the parallel. Use just enough force
    to get it to seat, this is a case where more is not better. Try to ensure that the face of the hammer strikes flat against your part. I usually
    strike the part slightly off center closer to the movable jaw. Once seated make sure you didn't lift it off the other parallel. Then continue
    to snug and seat the part until you feel the vise is tight enough.

  8. #8
    Join Date
    Jan 2008
    Posts
    451

    Default

    Dead blow hammer for the win!

  9. #9
    Join Date
    Jan 2010
    Location
    Kansas City area
    Posts
    5,115

    Default

    With the Kurt style and copies you can limit the amount of lift by tightening the setscrew in the middle of the movable jaw. You can remove the jaw by backing out the same screw. Many people know this, but many don't.

  10. #10
    Join Date
    Dec 2015
    Location
    Chilliwack, BC, Canada
    Posts
    2,785

    Default

    MOST vises lift a little and you can see this by the fact that typically the parallels shift easily. But after tapping the work piece down with a dead blow or lead hammer the parallels are pinched in place. That assures you that the work is down correctly.

    I suspect that the proper Kurt style does a good job of holding the work down well. But the cheaper (as in affordable for home shop use) Kurt "style" vise I bought needed some tuning and smoothing in that angled face clamp down area to give it a more Kurt like operation. But it still lifts with thinner items held high on the jaws. So out comes the dead blow to deal with that.

    For a mini mill I really like the suggestion from the other guys to use a screwless vise. These style vises naturally lock downwards and while you might still need to rap the work down they do provide a smaller size vise to use on the smaller machine. And in fact LMS has THIS MODEL ON CLEAROUT just now. At the $65 price I might even suggest buying two so you can set up the pair of them to use for longer work pieces similar to what Joe Pieczynski shows in some of his You Tube videos. The nice thing is that these use up FAR less table area than the Kurt style you are considering. And not only is it around 3 inches shorter but it also does not have the lead screw stub sticking out to snag on you or get in the way of the hand wheel for the table.

    Another advantage of the screwless LMS vise is that if needed it can be set up on it's side and clamped to the table to better hold items vertically that need something done on the ends. Try THAT with a Kurt style with anything other than a rather large and bulky angle plate in addition to the vise.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •