Sub-Plate strategies....

Awl,
If I make a fixture on a subplate, and the subplate bolts to the table via t slots, I will have to indicate the plate each time I put it on.
And, if I have a "palletized procedure", where I'm just swapping fixture plates with loaded parts, I certainly wouldn't want to have to re-indicate each swap.
So ahm thinkin, put a sub-subplate on the table, indicate accurately, and on that subplate have it accurately pinned so that the fixture plate drops accurately onto that, so each swap of a pallet is now accurate, no indication required.
Is this half-right? Pitfalls?
The next Q is: Does it make sense to drill/tap *the vmc table itself*, so that the sub-subplate itself can be put on accurately? Or is drilling/tapping the table itself just sacrilege?
I guess this could make sense if you were swapping the sub-subplate with vises etc very often.
Do people bolt on a thick subplate permanently, and swap out fixture plates AND vises on one subplate? We've had threads on alum subplates warping tables, as well.
--

Mr. PV'd

Mae West (yer fav Congressman) to the Gangster (yer fav Lobbyist):
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Proctologically Violated wrote:

PV:
    Rather than answering your questions, I suggest you peruse the recent Subplate thread from a month or two ago in here. And then do the same on the recent subplate thread in Practical Machinist.
    And YES, drilling and tapping into the table IS SACRILEGE!
--
BottleBob
http://home.earthlink.net/~bottlbob
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Put three M12 holes in the table for holding a chuck. Should have done it years ago.
--

-JN-

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Go buy a renishaw probe. Not the expensive 3d one, just a 2 dimensional one for pickups.
Procedure for putting a 10 X 10 X 2" plate on the table of a mill with no probe. 1. clamp halfass to table, load indicator and indicate parrallel and getting tight at same time. 2. Using indicator or edge finder pick up plate x-y location. 3. Touch off tools on top of plate.
with probe... 1. Clamp part to table. Don't even pretend to care if its strait. Just clamp. 2. get probe from tool changer and probe 2 spots on front, creating correct coordinate rotation. perfect alignment in seconds. 3. Probe block in for x and y. Seconds again. 4. Probe top of plate for z offset, since all tools are set from the table or any spot on the table, this will tell the machine the difference in height from the table. All tools previously loaded from last jobs will still be set now.
total setup...2 minutes literally. No mirrors, no edgefinders, no backache. You can easily add the pickups into the begining of the program with a click of a button. Then drop a plate on and walk away.
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Chick Grid Plate, set up once, indicate 2 holes farthest apart from each other, make sure indicator reads zero at each one, indicate 1st hole closest to rear left corner, set grid up in cad system from that hole, "build" all tooling on grid plate.
I have tooling I made years ago, still drops onto grid within .0002, for +/- .005 work, it works great, for anything closer, pre-machined tooling hole in fixture is indicated every time said fixture is put on grid plate.
Have VF-5 and VF-2 set up the same way. I also made 2 "keys" that align my 4th axis tables to the grid plates, also within .0002, so that I can run the tailstocks on the same setup.
I love my chicks!!! :)
I have a "sub" plate on one of the 4th's, has dowel pin holes for bolt on tooling that gets designed into jobs, makes it "easy" to run rotary work. I have it saved as its own file, every time I add a "new" set of holes, the file gets overwritten, keeps me from having overlapping holes, and allows me to design tooling around or on holes already in the plate. Also has a set of holes for a Chick 6" double, makes changeover fairly quick. Have run several different part configurations on the same set of holes, just worked out that way!!
"D"
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Proctologically Violated wrote:

To sub-plate, or not to sub-plate. That is the question. Whether 'tis nobler in the shop to suffer the nicks and gouges of soft aluminum, or to take arms against a sea of pallets by indicating them.
To think, perchance to dream. Ay, there's the rub: For in that muddled thought what dreams may come.
Perhaps a dream of something wondrous, and wondrously simple, to wit:
Thou thinkst naught of locating a part in a vice. The simplicity of it sparkles with promise. A back jaw, straight and true. A stop of our own device, trusted and sure. But what boots it to limit this wonder to vise jaws alone? Dream Hamlet. Dream! Bigger, better, faster! 'Tis within your grasp. I know it!
A rail across the table's breadth, fitted just so into the depth of the most distant tee-slot. Plumb grooves fashioned into the rail, and each with a tapped hole, horizontal in aspect, whereby a small key might be affixed, to serve as stop and safety.
And pallets! Endless varieties of pallets! Each a mere plate, and each with a vise or fixture pinned eternally to it's face. And each, no doubt, with edges square and true on it's back and nether sides, the better to locate perfecly against yon rail, and to find unerringly the stop that marks its place. And thru-holes to match the lattitude of brethren tee-slots, and to clamp quickly, deftly, effortlessly! 'Tis a consummation devoutly to be wish'd.
This is the power of something more than plates, the undiscovere'd country, from whose joy no machinist returns.
KG (with a bit of help from a dead English guy)
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On Aug 7, 12:30am, "PrecisionmachinisT"

glegroups.com...
I hate it when plates aren't de maged any recommendations on stand alone demagnetizers Thats one piece of ancillary equip't not found too commonly in shops nowdays, because we cut AL TI SS AL/BRONZE ect. Tool steel? WTF is that. Unless of course your a die or mold shop.
--
~g~

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