Is Vise Jaw Lift a Problem?
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- เผยแพร่เมื่อ 29 ก.ย. 2024
- How bad is it when you get significant vise jaw lift? I was getting 0.0055 inches of lift when using my serrated MMM-USA Piranha jaws. I really like these jaws because the step is only 0.08 inches, allowing me to mill much deeper into a part. However, the large jaw lift had me concerned.
When thinking about workholding, it's worth thinking about how much holding power you actually need. A 1/4" 3 flute endmill will only develop about 35lbs of cutting force when taking an aggressive cut in 6061. A 1/8" endmill taking a more reasonable cut in the same material will produce a pound or two of cutting force.
A milling vise is a versatile workholding option, but it's overkill if you aren't taking heavy cuts in tough materials. With a high-speed, low-torque spindle, there's massive amounts of leeway in what constitutes a viable workholding solution - t-slot side clamps, miniature fixture clamps, vacuum or even glue. There are plenty of simple and inexpensive options that could potentially free up a lot of table space and allow for far more unattended running. I don't keep my vise on my mill table, because only a small minority of my setups actually need one.
Those are all good points. I think the important thing is the type of work. I can't remember a time when I couldn't use the vise. So for me the vise works very well. The back face is always parallel to X, and I have known Z heights for the jaws and parallels. That means for my jobs, setup is mostly picking up the X and Y zero and I'm ready to go.
It looks to me like the jaws are on the tall side. When you use the Piranha jaws, the lever moment is well above the vise jaw carrier (by what looks to be about .5"). When you are using the parallels, the part is deep enough in the vise that the moment load is at or below the carrier height.
That's the way they came from MMM-USA. The top of the Piranha jaws are about 0.4" above the top of the vise. I can live with a part lift 0f 0.003" for first ops. And by sticking up above the vise body a little, I can move the jaw to the front of the moving section when I need to (I've done that once or twice). In that case, the lift wasn't critical to the part.
Good work! I would use the serrated jaws as a first op only because I'm sure they distort the position of the part aside from the jaw lifting. Don't hammer down with serrated jaws, it can rise back up.
do you still have your morgan press?
I do. I'm starting work on a mold that will require the Morgan.
Good info John. First operation sturdy/solid is better than precise for a foundation to build from.
Holds true for most things.
yay.. its nice to see new stuff :)
Just to point out that you were measuring the part lift, not the jaw lift as the dial indicator wasn't on the jaw. The measurement is thus the compounded error of jaw lifting and part lifting in the jaws and reclsmping on the serrated jaws doesn't help it at all.
True. It’s really the part lift that I care about, which is why I measured it this way. The main point is that it’s not small when you’re using the serrated jaws.