Alignment Pin

I am thinking ahead here. I have 4 screwless vises I plan to key to the table of the Hurco mill I am working on. The plan is to have a key on the
bottom that will allow my to set the vise on the table, pull it forward and clamp it down for a modestly decent repeatable square to the table. For multiple vises I'll cut a "straight bar" I can clamp into all of them at the same to to get a good average square the length of the setup. (Same straight bar I'll use for aligning and keying the vises to begin with.)
I know this method isn't "perfect", but for the most part it should be pretty good.
Here is my other thought. Put a pin in the bottom of each vise, and drill an array of holes in the table so I can move a vise a fixed amount on the table. Maybe spacing holes at one inch. Based on my experience with slip fit alignment pins on molds I probably can't get repeatability better than a couple thousandths this way and still be able to set and remove the vise easily, but I am thinking it might still substantially speed up setups for odd jobs.
What obvious and stupid thing am I over looking?
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Bob, don't drill into your table.
If you want a jig like that, key a tool plate to fit the slots on the table, then drill the plate.
Lloyd
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On Tue, 28 Aug 2012 14:26:37 -0500, "Lloyd E. Sponenburgh"

YES!!! No drilling into the table!!! Ever! Not even by accident!!
Gunner
-- The essential differences between liberals and conservtives is that liberals could not exist without conservtives to defend their freedom and support them economicaly.
Conservatives on the other hand, can exist and live quite well without liberals."
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Lloyd, Gunner,
Why?
I can spend over a grand on a piece of metal to bolt to a piece of metal. To use it I would have to do a lot of machining basically duplicating a lot of the work already done to the table of the machine. Then it would increase the overall weight on the table to nearly the recommended capacity of the machine. A couple hundred pounds for the tooling plate and 160 pound of vises and I would then only be able to have a couple pounds of work piece on the machine before exceeding the 500lb weight limit on the table.
I know there is a strong aversion to cutting the table, but is there a really strong reason?
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Yes. The table is cast. Holes where holes do not belong may induce stress fractures. Holes will collect debris. Holes will induce corrosion which may induce fractures.
Why, exactly, do you suppose you would spend $1000 on a slab of metal you can machine from raw stock? You don't have to buy pre-ground "tooling plate"... not if you're going to drill a bunch of holes in it, and certainly not if all the accuracy you care to get is two thousandths!
G'head... I don't care if you drill holes in your table. Don't ever come near my shop with any tools in your hand, though.
Let me see... 500-360=?? Yep... that comes out to "a couple of pounds", all right.
Bob, my ONE vise weighs 160lb.
LLoyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message

Excellent. Thank you. I know the table is cast. But isn't it cast, ground, and then machined.

Ok, fair enough. I wasn't think of drilling the equivalent of a matrix plate though. Just a single row down the table between two T-slots in the web that resulted from previous machining to make the table. A slot to go with a second perpendicular key on the vise would be better as it could be machined to a closer tolerance and still allow for pulling the vise forward against its reference surface of the existing T-slot. I have seen tables machined with slots in two directions.

I have seen matrix plates setup with a recessed screw in each hole that is not used. If the hole is not under one of the four vises it would be plugged. Even if it was it could be, if you slightly recess the plug.

Ok... certainly a possibility as even with a plug they could hold coolant.

LLoyd I wish I had your resources, but I have looked for things as simple as a slab of cast iron with just that sort of thought process in mind and even when I find a piece at a fair price by the time I get it to Yuma it costs a lot more than you might think. Gas and diesel aren't cheap anymore. Neither is time.
I did a quick check of on-line new just to check really quick and I found oversized tool steel (not ground) for little less. A piece that is a little under spec for what I would want to do that job (couldn't find what I wanted in a quick search) is almost $800. There may be something infinitely better and infinitely cheaper that you with your vast knowledge and experience know about, but I don't. I can only work with the tools that I have.

Well, I would like a lot better accuracy than that, but I don't know how I would be able to get it with a setup that allows the vises to be removed and reinstalled easily except possibley my double key method discussed above. I am sure I could get them straight to less than that over the length of the table with just the single keying, but the pin idea was in regards to accuracy of position left to right. The distance between them can also be set with a parallel plate, but the absolute position would not be the same every time. Since I am not retired, and I am not a full time machinist, and I don't have your experience I am looking for ways that *I* can reduce setup time.
> G'head... I don't care if you drill holes in your table. Don't ever

No need to be snippy. I have already kissed your butt in the past and let you know I respect your experience and expertise. I still do, but I am not going to do any more butt kissing. I asked because I wanted to know. Your answer has some rationality to it. I'm not 100% satisfied, but I am going to mull it over some more.

Uh-huh. And I am sure its really efficient to start every job with several hundred pounds extra weight on the table.

I guess I can't use that one then. 4*160d0. Wouldn't do me much good.
Its one reason I decided to go with several screwless vises on the table for now. The working envelope to weight ratio is exponentially different. The difference in the price is too.
I would sure hate to feel your wrath when you find out my intention to machine the vises on the top side to create step jaws to hold wider pieces of plate then they were designed for. LOL.

Bob
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P.S. I do want to thank you for taking the time to reply. As always it was educational.
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That's what machinable, replaceable jaws are for.
I wasn't being "snippy", Bob. You sounded bound and determined to drill the table. I didn't see any particular likelihood of stopping you.
On my machines, wherever there's a hole, there's a beefed-up part of the casting.
Do you know that the table is solid beneath where you want to drill?
I still don't see (without measuring your table slots, etc.) why you couldn't do this with some sort of welded-up frame keyed to the slots, rather than fudging up the table.
LLoyd
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wrote:

As a point of reference, I just ordered two pieces of 1" A36 plate cut to size and Blanchard ground that came to $1.35/pound.
From this outfit: http://www.americangrinding.com/divisions/grinding /
I've been buying from them for many years. I'm in New England, but even considering freight I haven't found anyone closer that beats their prices.
As far as drilling the table goes, I'd be reluctant to do it myself, mostly for irrational esthetic reasons, but it's unlikely to cause any harm as long as you put some thought into the locations.
--
Ned Simmons

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And have some fore-knowlege of the nature of the casting beneath the holes.
LLoyd
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On Tue, 28 Aug 2012 17:52:22 -0700, Bob La Londe wrote:

Make a strip that fits a T-slot and drill your holes in it.
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On Wednesday, August 29, 2012 3:40:05 AM UTC-7, xpzzzz wrote:

Makes perfect sense. My goal wasn't to permanently mount all the vises and leave them forever. If I wanted to do that I would take my time. indicate them once and be done. My goal is to be able to quickly drop them on and off in different positions, but "know" pretty close where they are when I do.
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Set the vises in place by measurement and then notch a long piece of bar stock to fit snugly between all the jaws. You could make a spacing rod to align the first vise off the end of the table, then use the notched bar to position the others relative to it.
Or mill the notches with CNC, whatever gives you the best accuracy.
What do you use as a work stop to locate the stock X-wise in the vises? It's the only thing that has to be accurately positioned.
jsw
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On Wednesday, August 29, 2012 5:59:58 AM UTC-7, Jim Wilkins wrote:

Currently on my little stepper based table top mills I indicate roughly off the end of the work piece and then cut it to size. Then I know the machine edge and the physical edge are the same. My table top machines really are geared towards shooting from the hip like that though. I'm trying to get a little more reasonable out of the big mill so I can more time making parts, and less time setting up the jobs.
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news:9af14e7a-60b8-4bd4-8639- -Currently on my little stepper based table top mills -I indicate roughly off the end of the work piece and -then cut it to size. Then I know the machine edge -and the physical edge are the same. My table top -machines really are geared towards shooting from -the hip like that though. I'm trying to get a little -more reasonable out of the big mill so I can more -time making parts, and less time setting up the jobs.
Here is an example of how to set up a stop so you can remove and replace the work piece.
http://www.micro-machine-shop.com/vise_accessory_stop_2.jpg
In this case the collet block has to come out to unscrew the retaining ring to swap parts. I would have set the rod end against the lower edge of the tube end rather than the collet block.
The home-made work stop at the left rear corner my 4" Wilton vise is a flat rectangular plate that pivots in or out of the way on a screw, something like this but minus the adjusting screw, and spaced out a little ways to make brushing off the chips easier:
http://www.micro-machine-shop.com/solid-jaw_adjustable_work_stop_1.jpg
Set the zeros by clamping a 1-2-3 block against the stop and edge-find it.
I think you could align the vise by running the table to a known position with a ground rod in the collet and sliding the vise until the attached work stop contacts the rod. I'd use an edge finder or feeler gages rather than banging a heavy vise into the rod.
Just checked; I can position my 42 Lb vise to within about a quarter of a thousandth by tapping it with a soft plastic hammer.
jsw
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wrote:

And if you do bolt this expensive slab of metal to the table how do you align it to the table? With keys into the tee slots?
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Yeah, John. But I think you missed his purpose. If I read him right, he wants more "resolution" to his keying system than the slots will give him.
Me... I'd work with the spacing given, and move the work origin as necessary.
It _is_ a CNC, after all.
LLoyd
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On Tue, 28 Aug 2012 21:28:16 -0500, "Lloyd E. Sponenburgh"

Well, he could rig a grinding head and grind, or just machine, one tee-slot so it has a nice even width and then grind some square stock to match and use that for key stock. I'd guess that you could get somewhere about 0.001" accuracy without trying too hard.
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wrote:

Because you if you are never able to work the entire table and ways. .... you will ultimately wear loose spots in the gibs and ways if you are unable to move the work around, balancing the wear. Never put your vise on a mill and keep it in the same spot year after year. Particularly on a CNC machine. You wear out the screws, the ballscrews the nuts and cages and so on and so forth in one small section, when you work only one spot.
Ive tested literally hundreds of mills of all different sorts..and I was able to match wear up with the clean spots on the tables with the areas of most wear....IE..where the vises were locked down and never moved.
On EVERY mill Ive ever owned..Ive put the table on , on the sides, the left quarter, right quarter...alll over the place, to minimize wear in one spot on the ways.
If you are a big company and are cranking out a gazillion parts and the mill is simply a tool...go ahead and replace that mill every 3 yrs..or replace the ways..which cost damned near as much. Its part of the cost of doing business. But when you are a small shop or hobby guy...those bastards cost like the devil....
Gunner
-- The essential differences between liberals and conservtives is that liberals could not exist without conservtives to defend their freedom and support them economicaly.
Conservatives on the other hand, can exist and live quite well without liberals."
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Bob La Londe wrote:

Well you could possibly use a slightly different method. Pick a T slot and true it up on both edges, then cut a dovetail on each side. Now make a saddle that would clamp to the dovetail and locate the vice. Bridge two if possible. For the lateral location you could mill a small notch on the dovetail to align with a matching pin on the base.
--
Steve W.

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