Need mill adVise

lesrhorer said:
Jaw lift is one of the most common issues in a vise. Kurt and Kurt clones use angled mating surfaces between the mobile jaw and the lead screw clamp. This produces a downward force on the jaw equal to the clamping force, which helps prevent the jaw from lifting. If the rear anvil can be detached from the vise, rather than the rear anvil and the vice bed being a single piece, then there can easily be all sorts of issues with the vise, including the rear jaw not being acceptably perpendicular to the bed, not parallel to the mobile jaw, not perfectly rigid, etc.

By the way, one can make up for some jaw lift (or a non-parallel work piece) by inserting a piece of round stock between the work piece and the mobile jaw.
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Been using aluminum TIG wire for that, or also trying some thin cardboard (cereal or cracker box) on that jaw. Both work pretty well.
 
akjeff said:
If you have the means to clean up a brand new sub par import, then you will have no trouble correcting what little could be wrong with a decent used Kurt. You can get a brand new "rebuild kit" from Kurt that will replace the spherical pivot, thrust washers/bearing, lock ring....... for around $20 direct from Kurt. If you're going to have to dick around with it anyway, might as well start with something that will last damn near forever. I got my D60 and swivel base for $250. Soaked it in Purple Power overnight, cleaned it up with a scrub brush and scotch brite, and then went over it it with precision flat stones. On the surface plate, there is not a single dimension that isn't under a half thou out. Sure, there are pits/dings here and there, but it has zero effect on the finished part. If you watch the auctions/sites, you should have no trouble finding a decent used D60 or D675 for the price of a new Chinesium vise. JMHO
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Well, I wasn't thinking of doing much cleaning up of the vise, either way. 'Just wanting one that isn't pure junk, and whose defects I can work around.

Your point is well taken, however. If the kit is that cheap, I might go with a used Kurt from HGR.
 
lesrhorer said:
That is certainly a great price. I am not familiar with the Enco. Do you have specs handy?
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No, not my ad. Enco was an old school import tool "manufacturer". Their stuff has a generally good rep.
 
Shotgun said:
Being both a hobby machinist and working from home is a dangerous combination. I spent my lunch hour checking a vice.

The fixed jaw and the bed rise .002" going across the 6" width. I'm pretty sure some of that is in my table. There is no movement of the tenths indicator going front to back across the bed, for as wide as the jaws will open. To check lift, I put the dial indicator on the movable jaw and clamped down on 2" diameter round. From just touching to "don't crank that hard", it rose .002"

This is a $120 vice from eBay, shipped from Perth Amboy, NJ.
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Found a good youtube video and had to run out and check my vice.

While it does have the angled pulldown feature, it wasn't working. The jaw was still lifting. A quick inspection of the "ram" reveals that it was never touched after casting. There's enough burrs there to grab the movable jaw, and not let the ram slide up on the angle.

As for the angle, it also had large burrs that could be catching. It also has what appears to be half of a ball bearing embedded in it that the ram bears down on. This bearing is full of pits, and has a coating that appears to be caked oil from heat treating. That's just a guess, but it flakes off like coked carbon. It also had a "ridge" around the flat part that would prevent it from rotating in the hole made for it. The hole that it sits in also appears to be as sand-casted. . . with very course sand.

I cleaned up the ram and angle with a file, and the ball with a file and a 2000 grit pad after removing the ridge with the grinder. Then I put it all back together. Now, it only lifts .0015"!!

I think there is still very little of the movement that should be between the ram and the ball.

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Shotgun said:
I've had the same question as @brino. So, would this be the answer? The figure of merit for a vice is that the part doesn't move one you tighten it down?

I just assumed that as long as the fixed jaw is flat, and the vice is stout enough, it could be shaped any old way. You stick a part in and clamp down on it, often sticking a piece of dimensionally unknown scrap in there to insure that it indicates against the fixed. Who care if the movable jaw is straight at that point? Once clamped down, and you've indicated the part if necessary, you don't take the part out until it is done. Again, as long as the part doesn't move in the vice while you're cutting, why would you care that the fixed jaw is not perfectly perpendicular to the sides, or perfectly parallel to the outside? Why would I care that the top of the vice is perfectly flat once I've bolted it to the table?

...
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Good observation, but only partially correct. I did a job on my mill for our bio lab. It was a perfusion cell that had to have a fairly precise fit to avoid leaks. The active window in the cell was something like 30 thousandths wide, and there might have been no gasket, so tolerances were in the range of a few thou. The vise I got with my mill was homemade with a stick welder. Jaw rise was adjusted with hold down bolts. But you are right about the sealing features. They all came in on target. But they were not perpendicular to the outer walls nor true to the bottom of the cell. The biologists didn't care. Only the internal structure mattered. The cover was similarly misshapen, but the mating surface and all internal features were correct. Such a deviation was not an issue in this case, but would be even for the lowly 1-2-3 block. If I made a 1-2-3 block whose top and bottom faces weren't parallel due to jaw lift, it would be a lot less functional. True, if you machine everything in one setting, all your features will be in correct relation to each other, but not necessarily to the unmachined surfaces. The bottom and at least two sides will be unmachined in a single setting, since they are inaccessible to the cutter.
 
FYI, a new Kurt DX4 has under 0.0004" lift under heavy clamp pressure, 0.0002" under moderate pressure. Quite a bit better than what I had.
 
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