Thread: Surface Plate Stand Bracing

I've just recieved this surface plate stand which is steel angle and flat bar construction.
It has no bracing which in my head means the frame will be much less rigid
Clearly thought has gone into the frame, it has a shorter leg at the base with a leveling feature, multiple adjustable supports for the surface plate

So, should I try to add bracing, or do you guys think it will be fine without?

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In my opinion that stand will be fine for a surface plate. It's not like you are putting a heavy rotating machine on it. A surface plate by definition is dead, inert and motionless

The frame is braced in one direction because the tops are welded to the legs, and it's braced in the other direction due to the double bolt construction. I think it's adequate.

Graham.

It looks like the plate is only 18x18 or so? if so its not going to flex or bow anytime soon if its decently thick.

My understanding is that surface plates should be supported at 3 points only, and somewhat in from the edges. This information has been gained from YouTube videos of people having professionals mounting and calibrating surface plates for the customers (You Tube providers). I don't recall the actual percentage overhangs beyond the mounting points, but for quality plates the support points are often marked on the underside by the manufacturer. Here is a link for the Sandridge Granite stands to suit the plates that supports my recollection, I'm sure that some googling will turn up the method of determining the mount points.

I think the OP was asking about whether the frame should be braced, not whether the surface plate needs bracing. His frame appears to haver a nice three point mounting system for the surface plate, with two safety supports either side of the central one.

Graham.

Originally Posted by caskwarrior

It looks like the plate is only 18x18 or so? if so its not going to flex or bow anytime soon if its decently thick.

Plate is 600 x 600 (roughly 23 inch sides)
I agree, flex would likely be negligible as it is 100 thick (4 inches)

The frame just looks odd to me, and it's probably more of a concern that it may sway slightly if bumped

True, it has 5 mounting points, so may give 3 actual mount points and a pair of safeties, but if the safeties are also wound up to contact the plate, they become mounts, defying the 3 point mounting concept. And is the mount actually sized to put the 3 mounting points at the correct position under the plate, or is it a fairly generic mount that is supplied for a variety of plate sizes. Not a lot of info in the OP to determine things like that so I pointed the OP to the information and included a link to verify my recollections so they can make informed decisions.

Originally Posted by malb

...... but if the safeties are also wound up to contact the plate, they become mounts, defying the 3 point mounting concept. .......

The two extra mounts are safety mounts and should not be in contact with the plate, instead being set a mm or so clear. They are there to catch the plate should something heavy be placed in one corner. The safety mounts are more needed on these smaller plates.

Graham.

Originally Posted by Oldbikerider

The two extra mounts are safety mounts and should not be in contact with the plate, instead being set a mm or so clear. They are there to catch the plate should something heavy be placed in one corner. The safety mounts are more needed on these smaller plates.

Graham.

This is good to know
I suspected 3 points should be used and the other 2 barely in contact

That stand is fine, don't worry about adding extra bracing.

Put the plate on and see how it feels. Ultimately it depends on what you are happy with. It would be pretty easy to add some form of cross bracing at a later stage if you feel it's needed.

I recently built a stand for my 1000x630 plate. When I put the plate on the stand to test it, I wasn't happy with the amount of rigidity and so I made some further modifications which at the time were a PITA but I'm glad I did it because I'm very happy with the results now.

Simon

Well I went without the bracing, it's not too bad to be honest
Cheers guys for responses

I think the stand looks fine "as-is". I would not add additional bracing. My Starrett granite surface plate sits on top of a metal desk, and to tell you the truth - I don't remember what the bottom of the plate looks like anymore. As I recall - it rests on some small pads attached to the plate. I will need to check to see if there are only 3 pads (or 4).
David

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