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Pairing up two milling vices

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  • Pairing up two milling vices

    The drill mill at the museum came with a 100mm Bison vice and over the last few years, I have been keeping an eye on eBay for another one to pair up for long workpieces.
    One turned up last week with a swivel base, "good condition" and only one picture. I was feeling lucky and the price was 1/3 of new. When it arrived, very heavy, the base weighs as much as the vice, it was new, original grease and not a speck of swarf stuck to it.
    I had a spare alignment block for the original vice which fitted the new one exactly. I set up a 2-4-6 block in line with the X axis and clamped each vice in turn upside down and took a minimum skim of the rear of the alignment blocks.
    When I set the vices side by side and checked the alignment of the rear jaws, the older one had a run of 0.003" and the new one was straight, but 0.004" away from the first. I checked T slot for burrs and any damage, there was nothing to see or feel. Using the DTI revealed that the preferred slot, number 3 of 4 had a run of 0.004" run in the first 7" from the right hand end, then about another 0.0015" over the remainder.
    There's only one way to mill the edge of a slot on one of these machines and that is in two stages. First, swing the head 30 degrees right as low as it would go, using a 12mm WNT four flute solid carbide in an er25 collet, and slowly climb milled about 0.003" over the first 6", returned to the start and added another 0.003". I ran out of X axis about 6" short and lifted the cutter out of the slot.
    The head was swung 30 degrees left and I carefully took tiny cuts to match up the remainder. The join was just visible and could be felt. Checking with the DTI revealed that the join was actually a tiny dip caused by the dwell although it felt like a high spot. There is less than 0.0005" deviation now over the whole length and I think it is time to leave it well alone.
    The vices now match within 0.001", good enough for government work.
    I checked the height of the vices and they are within 0.0005". Quality control is good at Bison considering that one is ten years older than the other.

  • #2
    Hmm, I don't know exactly what to call it, but it makes me feel good that I was able to understand the process described.

    It did take a couple of reads to realize that an "alignment block" is what I would call a key?

    Do you not care if the alignment block is a snug fit in the slot? Just curious.



    • #3

      Glad it is to your satisfaction. But you did a lot of work for little gain.

      Having ganged as many as 5 vises at a time, soft jaws are your friend. And it kills two birds with one stone - no miss matched parallels either.

      If you simply must have hard jaws, then removing the tee slot key on one vice to allow one to 'float' for final alignment. A piece of straight steel gripped by both vises at the same time will provide a fast method of alignment.

      I would like to see some photos of your Bison vises. Never knew they made them.

      If you think you understand what is going on, you haven't been paying attention.


      • #4
        I wasn't sure what to call the "key which goes under the vice, as for it not being a tight fit in the T slots, it would be a lot of bother if you had to force the vice into the slots and lever it out afterwards. Just keep the vice pushed against the slot as you tighten the fixing bolts. I tighten in several stages from side to side. The key is a tight fit in the alignment slots underneath the vice and held in place by two 6mm socket head cap screws.
        These vices have alignment slots on both axes and the spare key was to have been cut in half to set the jaws in line with the Y axis, but I had never had a need for fitting the vice that way round.
        I did make a couple of sets of aluminium soft jaws but never used them.
        I had been lucky with only one vice as it had always been placed in the best part of the slot, in the middle, and did not know about the errors.
        There is also a Kurt type (cheap Chinese copy) 5" vice which uses a different slot and has no problems.
        The Bison vices are susceptible to jaw lift, but with a little work, this can be reduced to around 0.001".
        I would very much like a nice straight bar of about 2" square section and about 3 feet long, I keep an eye out for large parallels or straight edges, but they are like hens teeth and expensive.


        • #5
          I had a recurring job machining long front panels. I used three inexpensive vises and did an approximate alignment with a DTI on their fixed jaws. Then I put a blank panel in them and tightened the two end vises fairly snug. I loosened the hold-downs on the center one and tightened it on the blank panel. Then I tightened those hold-downs. I did the same for the two end vises, one at a time. The alignment was good enough (0.002" or better) for the work being done. And the alignment was fast and easy.
          Paul A.
          SE Texas

          And if you look REAL close at an analog signal,
          You will find that it has discrete steps.


          • #6
            Tom Lipton explains why he doesn't key his vice in the video below. I watched the video before I bought my mill, so I have never keyed it.


            • #7
              Good video, that's exactly how I line up other things which are not keyed. The big swivel/tip fixture which will take a vice without the key fitted, and the rotary table if the need arises.
              As I have already done the work and proved that it is possible to mill the entire slot edge of a humble drill mill, 3 feet 6 inches (just a guess as I will measure it tomorrow), I will keep using the vices with keys.
              I will probably have to wait years for a long job to come along.
              I bought a tiny Chinese Noga copy and it works quite well, an ideal size for one of the small 7X12 lathes.