Author Topic: Stand for granite surface plate  (Read 1816 times)

Online PekkaNF

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Stand for granite surface plate
« on: January 25, 2017, 08:37:34 AM »
I was designing a surface plate stand around a tool cart (to have all dial gauges etc. convinietly at hand). When I got the tool box home, cleared the room and moved stuff around I found the place the tool cart, but it would make very bad place for the surface plate....too close to window and radiator.

Back to drawing board. I have been thinking of something very simple to make, easy to level and such. Much like this:
http://cdn.mscdirect.com/global/images/ProductImages/0015054-24.jpg

Any pointers?

I have been thinking of using  normal adjustable screw feet under the frame, and to level the frame close to level.

The part that makes my head spin is the three point support adjustment for the surface plate. I'll get the airy points, but:

1) How to make the fine adjustment? Normal screw is pretty hard to adjust accurately, just a little twich and bubble on level sifts from other end to other end.

2) The surface plate has no glued inserts for support. Do I just epoxy a piece of cast iron there?

Planning to see how much space is there and buy a small tool chest with drawers to fit inside of the frame, but that is not that critical.

Pekka

Offline Spurry

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Re: Stand for granite surface plate
« Reply #1 on: January 25, 2017, 08:52:47 AM »
Going by the design of my own frame, (bought with the plate) I would put the three main adjusting bolts on the two opposing ends.
That would make the adjustment less critical. But you could always use a finer screw pitch, say 1mm, with m12 diameter.
Insert other bolts round the frame too, which you just nip up without actually disturbing the level.
On mine, the bolt heads are covered by a disk about 50mm diameter about 13mm thick. There is a recess turned on one of the sides, which goes over the bolt head.
The plain side of the disk faces the plate.
My frame also has levelling bolts (head downwards) in the feet.
Hope that helps
Pete
Edit: Found an old photo of plate just before it was removed from my last shed.

Offline BillTodd

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Re: Stand for granite surface plate
« Reply #2 on: January 25, 2017, 01:45:11 PM »
The surface plates on all the cmms at work have five feet on which the plate rests. There are two extra either side of the single adjuster to ensure the plate cannot tip should some pillock sit on it (even though the smallest plate weighs 200kg and the big ones several tonnes) .

Bill
Bill

Offline sparky961

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Re: Stand for granite surface plate
« Reply #3 on: January 25, 2017, 05:30:39 PM »
The surface plates on all the cmms at work have five feet on which the plate rests. There are two extra either side of the single adjuster to ensure the plate cannot tip should some pillock sit on it (even though the smallest plate weighs 200kg and the big ones several tonnes) .

Bill

That sounds like a good idea. I've always thought the end with one support was a bit precarious, if not dangerous. Is it safe to assume these two extra ones are adjusted with a small gap and not normally touching?

Offline Spurry

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Re: Stand for granite surface plate
« Reply #4 on: January 25, 2017, 06:18:55 PM »
That sounds like a good idea. I've always thought the end with one support was a bit precarious, if not dangerous. Is it safe to assume these two extra ones are adjusted with a small gap and not normally touching?
IIRC the instructions for mine mentioned setting it level with the three triangulated bolts.
The other bolts are just wound up to touch, but not disturb the actual plate. Every bolt did have a lock-nut in addition to the threads in the frame.
Pete

Offline SwarfnStuff

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Re: Stand for granite surface plate
« Reply #5 on: January 25, 2017, 11:56:34 PM »
Hi Pekka,
I don't have room for such niceties but here is a link to Metal Tricks & Tips where he goes into the build of his "Rolls Royce" plate bench if you are interested.
https://www.youtube.com/watch?v=N9H_orEXKzI
Another of his videos I really like is hand shaping / graving a handle for a lathe, here.
https://www.youtube.com/watch?v=BDtrDv6uZTs&t=58s

John B
Converting good metal into swarf sometimes ending up with something useful. ;-)

Online PekkaNF

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Re: Stand for granite surface plate
« Reply #6 on: January 26, 2017, 01:59:46 PM »
Thank you very much.

Spurry, that looks really nice. Wish I had that much space and big plate. I'm planning to have about 630*400 mm plate and it's going to live in spare bedroom.

I am not conviced that three bolt mount on exact postion on light load will bend much 630*400 mm plate that is 100 mm thick. Those big plates and big loads are very different though.

I'm planning to use three point support on bessel points and put four points on extreme corners just to prevent the plate from tiltting.

I put some "sleeppers" under the tool cart and filled the drawers with measuremet istruments. The original castors and rubber mats stink big time. No way I will put antything that toxsic stench inside. But the tool box is perfect size, many drawers and trawers are veny nice size. Some cheap ones have very shallow drawers to limit weight you put there and then one or two way too big to cut the cost down.

I'm thinkking of putting a wood top on this tool chest and putting there one cast iron 400*400 mm surface plate and leave some space there.

Pekka

Offline Andrew Wildman

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Re: Stand for granite surface plate
« Reply #7 on: January 27, 2017, 08:04:59 AM »
If you are not wanting to get your plate level, just ensure it stays flat then you could just fix (with glue?) three coins to the top surface of your cabinet would work at the standard spacings for minimum deflection of a plate (google it!).  The Plate can just sit on these and the height is small enough to prevent tipping.

Online PekkaNF

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Re: Stand for granite surface plate
« Reply #8 on: January 28, 2017, 09:19:16 AM »
Got sidetracked with the tool chest, filled it with metrology stuff (except the ones that will be in garage).

Could not find near correct size table top material, bought some wiremesh plywood and cut it to size. I'm using it only as another table top.

Therefore I haven't started yet with the actual surface plate table. Bit stuc with three point adjustment. Fine thread would be very familiar, but I'm also considering 1:50 taper pin for fine adjustment.

Pekka

Offline Joules

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Re: Stand for granite surface plate
« Reply #9 on: March 07, 2017, 08:30:20 AM »
My small granite surface is on 3 felt pads used for furniture.  It doesn't seem to matter the pads are soft as they compress under the weight of the surface and still provide 3 points raised from the surface below and will only tip a few mm if you get too much weight on the edge.  I guess cork pads would work just as well.

Another option would be to hot glue ball bearings in place and shim them if you need level.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup: