Sub-plate strategies....

There was a long-running thread on this topic over on Practicalmachinist.com with much good information. Turns out one of the big gotchas is coolant seeping under, corroding the mill table and bonding it to the tooling plate.

Mounting the plate on spacers will save a lot of time during tool changes, if you can spare the Z clearance. I have several fixtures like that, on risers for production runs. Makes for a nice speedup.

If you are going to add T-Slots, why not just make the plate removable? Something doesn't make sense at that point.

No adding dowel pins to your vices ~may~ help in some cases, but sometimes you need to mount the vise differently. It all boils down to WHAT is your job mix? Production for the Holo- Barre? Prototypes?

The production scenario would have multiple fixture that pug into the base plate, and have specific purpose.

Prototype parts, and the sub-plate might not always be the correct solution.

I have a plate mounted on risers, that has a grid of reamed holes on

1" grid centers, and a grid of 1/4-20 holes also on a 1" center. That is the Handiest thing for making flat parts! Picture frame or odd shaped flat parts, it is the clear winner in terms of ease of use. Throw the dowels in to locate the part, use the bolt holes for a box of custom clamps.

Does the Fadal already have T-slots?

Why not make your switchable fixtures with features that index fore-and-aft on the slots, and side to side on -- um, well, uh -- something convenient?

Then switching the thing from "production" to "prototype" isn't any harder than from "one production thingie" to "another production thingie".

Generally I keep a pair of vises on the machine at all times, clamping "fixtures" into soft step jaws which are bolted to the outermost holes...for production, you can often double your throughput by making two fixtures where for instance there is a lot of hold down screws to deal with but your cycle time is short....

Here's a similar setup showing the jaw position--just envision using a thicker plate ( your fixture, IOW ) and having two vises lined up instead of just one:

In most cases, the jaws can be left in tact even when the vises are being used in the more conventional manner.

I see that Jonnie Bonkers must have once again gnawed through the restraints, and is dishing out the DEADLY google stars again. LMAO! He got called out once again posting where he did not have a clue, and now he is lurking here, with the ever deadly single google star. What a putz!

In addition to warpage from thermal stresses.

How bout a sheet of nylon sandwiched in there? On the order of 1/4" thick or so? For both corrosion and thermal stresses?

Or nylon standoff blocks, about 1" thick, 4x4", under each bolt?

I realize this doesn't help rigidity any, but my machining is generally lite stuff, and my accuracy requirements rarely tighter than a few thou.

Mounting the plate on spacers will save a lot of time during tool changes, if you can spare the Z clearance. I have several fixtures like that, on risers for production runs. Makes for a nice speedup.

If you are going to add T-Slots, why not just make the plate removable? Something doesn't make sense at that point.

No adding dowel pins to your vices ~may~ help in some cases, but sometimes you need to mount the vise differently. It all boils down to WHAT is your job mix? Production for the Holo- Barre? Prototypes? ===================================================

Both, ackshooly.

So mebbe I can have my cake and eat it too:

A sufficiently thick plate, to cover the whole fadal table (and mebbe then some, if I want to more efficiently mount the 4th axis!), both drilled/tapped AND t-slotted? Mounted on a "nylon insulator", or spacers?

If I made this plate extend 8" or so past the table in X, it would give me extra room to mount the 4th axis, so that only the nose cone would infringe on the work area. I would proly have to shim this overhang to the way covers, as there might be a little bit of sag, depending on how thick the alum plate is -- just for a little extra support.

Are all these realistic? Some? What thickness plate?

Place a sheet of oil-soaked brown paper between plate and mill table.

EA, I'd go 1 1/2" or 2"

EA, Nylon is hydroscopic, I'd choose something else.

goodgawd....

But, with all those t-slots, 1/2 holes, AND and overhang, it seems reasonable. If I dispensed with the overhang, could I go thinner?

Hey, what else besides nylon? Clear acrylic or sumpn? Any kind of "window plastic"?

Can you use a magnet? Iv'e been using one for a few months and I'm hooked like a crackhead. (no, im not stealing from my grandma! lol) I drop a kurt vice on it and only GOD can move it. Some say it magnetizes the part sucking in chips, and thats true...and false. Seems if you place it correctly relative to the poles its not magnetized. It's really strange, but true.

What ya gonna be cutting? If soft, prolly go with t slots. If hard cutting go with a hardened plate with threads. What kind of range of operations do you think might end up in that machine?

Your only going to make it once and at some point you may want to face the whole plate. Delrin might might be a better choice, but I'd lean towards alum. or

303 for the risers.

I took a large plate and screwed and doweled a piece of 1" x 6" alum bar to the underside of the plate. I can hold the plate in the 2 vises that are semi-permanent on my mill. I loose some Z height but so far this hasn't been a problem.

Best, Steve

All real good Ideas -

definalty 1.5 -2 " WHT If there's deal on 3" snag it ever consider Freemax 15 or 45 for material selection? =3D cheap - a dream to machine- does not corrode or oxidize like AL. One complete plate to cover the bed only would be very inexpensive- so my feelings would be in the 5" range so you can continually re surface it down. cut all your weird shaped nests directly into it - what ever your little heart desires. on the side of this sub plate is where you mount - bolt the shit out of another thick ass plate- for the outrigger holding the 4axis rotary.

Yes definitely FM 3-5 in material & lots o eye bolts

All real good Ideas -

definalty 1.5 -2 " WHT If there's deal on 3" snag it ever consider Freemax 15 or 45 for material selection? = cheap - a dream to machine- does not corrode or oxidize like AL. One complete plate to cover the bed only would be very inexpensive- so my feelings would be in the 5" range so you can continually re surface it down. cut all your weird shaped nests directly into it - what ever your little heart desires. on the side of this sub plate is where you mount - bolt the shit out of another thick ass plate- for the outrigger holding the 4axis rotary.

Yes definitely FM 3-5 in material & lots o eye bolts

==================================================

I will definitely need my cabinet-installed wench for THAT one!!

Holy shit, a 5" 18 x 36" plate??? I think the XY table motors would burn out!!! My rapids would be, like, 10 ipm!!

The magnet is good, but of course not for alum... and I can't imagine a table-sized magnet would be cheap....

Or a plastic film but in any case you will still get electrolysis at the hold-down bolts etc--especially if the feed water for your coolant mix has low ph and you've a tendency to simply walk away leaving your machinery and tools sloppy wet for extended time periods after use.

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D

Actually you could use 2 plates or more. Naturally now thinner. Mounted on tapered hyd. lock posts.- wired into the control. custom made height roller track cart for quick change overs Its a custom made pallet system. One in the machine being worked on, the other outside being set up. Like a horizontal.

900 lbs WTF? Fadels use tonka toy moters?

Lots-0-mold shops are using magnets. Because the brunt of there work is now hard cutting of nice magnetic H-13 @ 50Rc or NAK- butter steel. Vinny's right - easy to set up- unobstructed cutting on 5 sides of a block- Its just a bitch to get your block off when done. Funkin magnet wont release till you beat it silly with dead blow mallet. Aluminum your sol can't holdzit except when you drill & press in a zillion 1/4" pins - you have magnetic parallels that will hold in any direction.

-- ~g~

"cncmillgil"

You just need to run a demag sequence at the coil and you for your work piece to stay in intimate contact with the pole pieces until residual magnetism is at zero.

Place your magnetometer....

( Mine was made by Annis ):

in the immediate vicinity and then repeatedly reverse the coil polarity--the actual reversal frequency will vary depending on core saturation density and workpiece coupling impedence but generally speaking it will be significantly lower than 60hz--more likely it will be closer to ~2hz or so and it will probably require 50 or less reversal iterations--VERY important that at each reversal you also to gradually reduce your field voltage--eventually ending at nothing...and when your magnetometer needle no longer swings back and fro but instead just sits at zero even if you lift it away or probe different areas surrounding the business end of the whole mess well then bob's your uncle.