Keying the Vise - Maxing out The Work Envelope.

I've got several machines where I do use a vise. I don't use keys on
the bottom of any of them. I have in the past, but my experience was
unless I pulled the keys and machined them they didn't just position the
vise accurately enough I didn't have to indicate it in anyway.
People in this group encouraged me to learn to indicate a vise, and that
it wouldn't be that hard with some practice. "Don't be afraid to take
the vise off. Every time you put it back on it will be easier." They
were right. I still have some anxiety about placing a vise on the table
and indicating it in. I've got two machines where I use a pair of vises
dialed in together. That's a little more tedious but not horrible. A
couple minutes with a brass hammer and an indicator at worst. If I am
having a tough time it can take me five-ten minutes dial in two vises
together. Usually not. If using soft jaws I'll still skim cut them so
the average is consistent across the entire range.
Once in a while I slide a vise on the table, and indicate it so close I
actually find myself moving it off alignment, because I can't believe it
slid on so close the first try. Not all the time, but often enough that
I no longer need to go on a social media group to share my excitement
about it. Oh, I still get excited about it. I just don't need to share
it every time it happens now.
I do smile when somebody else posts about it for their first time. I
feel good for them. I don't make a big deal about it but I don't shit
on their parade either. I am happy for them. The first time it happens
it really is a big deal. Anytime anybody accomplishes something I try
to be happy that they have improved their skills. Not sneer down my
nose that I have been able to do that for years.
The one that really annoys me though is this guy. "Oh, I have keys on
my vise and every time I put it on the table its accurate within 5
thousandths." That last five thousandths is usually the most work to
dial in, and five thousandths over the length of the average vise is
just not that good. He isn't doing anybody any favors in my opinion and
his bragging about his short cut doesn't make sense to me. I think the
keys are costing him time really. If he just eyeballed it on the table,
put an indicator on it, and used the tap and travel method he could hit
better than 5 thou just as quick. That's not even why I don't use keys
though.
I feel like keys (on a vise) limit my ability to make maximum use of my
machine or my vise. Basically I can only place the vise in 3 positions.
Its going to vary by machine of course, but often I find if using the
t-slots to position the vise I either can't use part of the work
envelope of the machine or it clamps work pieces outside the work
envelope. I don't care for the average cast mill vise with bolt holes
either. Same limitations different cause. Yes I do have several, but
none of them have keys on the bottom. I like what is marketed as "CNC
vises" with a slot down each side and on the ends that you stick a clamp
of some kind into. Sure, you either have to buy or make vise hold down
clamps, but you can position your vise ideally for the work you want to
do and make the most use of your machine and your vise. You can even
clamp it down at almost any angle without the need of a rotary base and
without the loss/change of horizontal accuracy that might come with an
inexpensive vise and rotary base.
Now the guy who is proud of his keys. I try not to shit on his parade
either. Its entirely possible that whatever level of quick accuracy his
keys provide is good enough for the work he does, and ultimately that is
what matters. If you can produce parts within spec everything else is
wasted motion.
Now, I don't own any really expensive vises. Maybe the keys on the
bottom of a Kurt or Orange vise are dead nuts and maybe they only get
used on machines whose t-slots are dead nuts.
I do use keys. Just not on vises. I use a lot of shop made fixture
plates for cutting rectangular bar stock larger than I can easily hold
and position in a vise, and for holding more pieces of stock than I
could hold in the vises I could fit on the machine table. If I ever
perfect my own ideas for a universal fixture plate I may never put a
vise directly on the table of several of my machines again, but that is
a whole different topic.
Reply to
Bob La Londe
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I don't use keys either , and for the same reasons you don't . How close to dead on do you shoot for ? I try to get under a thousandth in 5 inches , and often get pretty close to dead on . Not that I do work that precise , I'm just anal - I'm the same with dialing in on the 4 jaw lathe chuck . I think my vise is a Kurt clone , not sure . But the swivel base that came with it came off right quick because it was clunky and a pain in the ass besides taking part of the vertical work envelope .
Reply to
Snag
I shoot for half thousandth over whatever range I am working. 6 inches or 18. Often that is beyond the flatness of my vise jaws unless I have surface ground them. I have surface ground vise jaws. I rarely hit that, but I usually don't stop until I have proven to my own satisfaction that I can't do it without grinding, or milling in place (soft jaws).
Reply to
Bob La Londe
I use a Gerardi 150mm modular vice on my manual BP and I'll be keeping the keys in place as it locates the vice so the deviation from one end of the fixed jaw to the other is 0.01mm as placed in the T slot. I could probably make that 0 if I wanted to try but haven't got the need. I can't think of a time when I've needed to angle the vice as I can angle the work piece by other means if required.
Reply to
David Billington
I've got several machines where I do use a vise. I don't use keys on the bottom of any of them. I have in the past, but my experience was unless I pulled the keys and machined them they didn't just position the vise accurately enough I didn't have to indicate it in anyway. ----------------------
I ordered an RF-31 to replace a worn-out drill press in a very small company shop, after finding that the spare Bridgeport in storage wouldn't fit (sob).
I found that the RF-31's table slots were slightly angled to the table travel, so to key the vise I made a close-fitted key and then milled steps in its top sides, parallel to the X axis. Clamping the vise inverted to the key located its jaws parallel to X to mill a key slot.
That was another pig with lipstick. The quill travel was slightly off square and the Z adjustment shifted when clamped, so I took the rare high precision job home to my Clausing.
It was a shop anyone could use, or misuse, so I tried to keep things simple. The vise was a Palmgren that weighed IIRC 17 Lbs, not a heavy Kurt clone that could crush someone's foot. It was adequate for the mainly aluminum and plastic machining of electronics, but not for heavy cuts in steel. I wanted it easily removeable so I could machine 19" control panels. jsw
Reply to
Jim Wilkins

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