Vice keyway locator, how accurate.

[Bill D]

Some milling vices have a slot with a piece of key stock screwed onto the bottom. this is used to locate the vice on a milling table so it is parallel to the table. my question is how accurate is this method on it's own with out a little checking and tweaking with each relocation.
Is this accuracy good enough for most small workpieces or is just intended as a guide and it has to indicated in each time it is moved.
Bill D.

 

[hickstick_10]

thou or two if its a good vice, with a decent table with a properly fitted alignment key. They really are time savers. Alignment keys are specially made for this purpose, there usually hardened and ground also.

If your using a peice of keystock on the other hand you may have some hard times ahead of you, and crooked parts,

 

[dfw5914]

Depends on the specific vise, as well as the condition of the slots in the table. I guess you could also include how meticulous the person making and installing the keys was. I've never had one that was much less than .001 over six inches (or much over for that matter, but I've only ever used Kurt vises and they have always been on fairly beat up machines)
I always indicate/clock in the vise, even for stuff that does not matter, just habit I guess. It only takes two or three minutes and the keys do save a little time.
The keys do make nice little stand offs to help keep the bottom of the vice from getting scratched up when on the bench.

 

[adammil1]

I also get 1-2thou with mine when indicated. Usually all it takes is a bump and then it is good. Years back when I first discovered this feature I posted about it here, and the great now deceased JimK I remember told me that the key was really more there as an actual holdown device to give you more hold than just friction alone, and not so much for ease of location. None the less I sure like this feature, and often I just place the vice on the machine and it is good with out much adjustment.

 

[Clive603]

Bill

Biggest problem with fixed key is the "tight enough to be accurate but loose enough to slide and remove vice" conundrum. Especially if your slots are less than perfect. Its arguable that a single key isn't the best way of going about things due to potential problems with a single piece of swarf or other gremlin toy part way along so two shorter keys or even dowels are sometimes said to be preferable.

I feel that sufficiently effective substitute for a proper key is to machine out the slots a touch and make a pair of stepped T washers with rectangular stems as part of the hold down kit. Top end of stem under the washer head is wider to fit the new slots and bottom end narrower to be a nice sliding fit in the table slots. When you mount up the swivel pull it straight back or push straight forward so that the T washers contact nicely with the table slots and the base slots along one side. With my 4" vices I find this repeatable to a conservative thou in 2 or 3 inches. Good enuf for rough work. One day I shall make a pair with a built in eccentrics to help set fine angles.

Do the slot milling in situ with the vice inverted and gripping a suitable bar previously indicated parallel to the table movement. Probably sensible to make a set of Tee nuts and "just the right length" clamp bolts as well to keep with the base. Standard set parts always seem to long or too short for vices and, in my experience, the "just right" pair of bolts you eventually found turn out to be just right for something else and vitally occupied elsewhere when you need them for the base! Assuming the little man who hides under the bench and steals my tools hasn't grabbed 'em with the help of his tame(?) hunter-hider gremlins.

Not a bad idea to use light alloy for tee nuts et al if you plan to make them. Swarf and debris, carefully positioned by the resident gremlin colony, grinds into the nut rather than the bottom of the table slot. Still a pain to dig out but the level of verbal encouragement involved is significantly less than that required when doing the same operation in the table slots.

Clive

 

[LoveMachine]

I usually remove the keys from vices that I have to use because they prevent me from dialing in the vise as close as I'd like for precision work. As mentioned earlier, it takes just a few minutes after a bit of practice.

 

[wlbrown]

vise keyway

HELLO TO ALL,
i have found them a few thousands off, but
if this is the case, you can put a shim behind
the fixed jaw, and correct this. then the
repeatability will be good.
good luck to all.
wlbrown

 

[CalG]

If the key's are reduced a bit to slide comforably in the slot, I think they are great. Just pull, or push them against the table slots. (always the same way once you get to know which way)

For some reason, I always indicate a fresh vice placement. (lessons learned perhaps)

ASS- U - ME

CalG

 

[machine1medic]

If the key's are reduced a bit to slide comforably in the slot, I think they are great. Just pull, or push them against the table slots. (always the same way once you get to know which way)

For some reason, I always indicate a fresh vice placement. (lessons learned perhaps)

ASS- U - ME

CalG

In job-shops that consentrate on tooling, more than manufacturing,
a good pracice is keys deduced a few thou, and shrap-edges and corners removed.
This gets you close and practice get's you home by indicting.
Takes less than half a minute.
Reduces table gouging from loading and unloading vises.
Not every-one is strong enough to get a vise all the way into position.
Go to an 8" or 10" even more-so.
m1m

 

[ErnieD]

I once had a brand name vise that was off .003 to the key way in the bottom of the vice. I ground a piece of stock and longer than the vise was wide to a good fit to the T slot. I then clamped the stock to the table, turned the vise over and clamped the jaws on the ground stock then trued the key slot to the jaws. I then made a set of step keys to suit and everything went smoothly from there. Alignment is always around .0005.

Ernie

 

[67Cuda]

I just saved a minute and half indicating a vise in, but wasted 5 minutes bull shitting with the guy next to me.

They are a waste of time.

Tom

 

[Winfield]

I just checked my keyed Kurt D688 vise on my Tormach PCNC and saw no movement of the BesTest TDI over six inches. I regularly change the Kurt keyed D688 vise for other keyed fixtures and RT. I have been using the keyed Kurt vise for the past 3 years on the Tormach. Saves me alot of time not needing to dial in the vise or fixtures. Works well for me. YMMV. BTW I use Kurt D30-33A stepped keys on both the D688 vise and angle fixture I built. Saves me time so I don't wind up like Fredder here http://i72.photobucket.com/albums/i163/miltons_stuff/frederClock.jpg Now that's a waste of time! It seems that some think vise keys are a bad vice but not me.

 

[Troup]

Here's another approach - I made this after being inspired by a suggestion from a member of this forum: "smallplanes" Leics, UK ...

http://www.practicalmachinist.com/vb/general/spindle-tram-indicators-197809/index2.html#post1294272