Higher trolley for surface plate?

Hi all

In order to free up some workbench space I am thinking of making a trolley to hold my surface plate which is about 20" X 16" and always seems to be in the way.

I was thinking I might make the trolley rather higher than the workbench to reduce the amount of bending down involved when trying to read the height gauge and similar tasks.

Has anyone done this and is the increased height helpful?

Rod

Given the weight of a useful size surface plate like yours a tall trolley may prove somewhat unstable and possibly unsafe unless made rather larger than the plate itself.

If your bench legs and under bench storage arrangements permit a rather safer scheme would be to make a sort of pull out drawer for the plate with sturdy legs on wheels or rollers to support the front. When pulled out to use the plate the rear end of the drawer would be supported by the bench and the front by the wheeled legs. There would seem to be no great problem in making top of the drawer housing strong enough to act as bench surface.

Given some re-engineering of the bench it might be possible to make the surface plate slide beneath the top of the bench. But that will make it even lower which isn't desirable.

I've considered doing the pull out drawer mount system with my surface plate, which is larger than yours for at least a decade but the issue has never been quite pressing enough to do the necessary under-bench re-work.

Clive

Edited By Clive Foster on 27/07/2020 19:29:33

I have my surface plate mounted on a movable trolley made from
square steel tube,the height above the floor is about 36 inches
which suits me.No problems with stability .
A couple of loose pieces of square tube allows the cover to sit
alongside the plate as a temporary storage for parts etc.

The space underneath has 5 plywood draws for storage,when
not in use the top is fitted back on and the tubes are stored
inside the long top top tube of the stand.
The plate is 12 x 18 inch.

John

Further to what Frances said about heavy duty drawer slides I scavenged a few from old filing cabinets for that sort of job but never got round to engineering the sliding bit. Personally I'd want a bit of poistive support at the front for stability even if not explictly necessary to carry the load.

Clive

I use an IKEA Butcher's block for my big surface plate. It is tall enough for me and has two wheels so it is both easy and safe to manoeuvre around.

Andrew.

How about just standing it against the wall at the back of your bench (assuming there is one) with a substantial catch to stop it falling down. Something like a bar counter. With a bit of thought you could make it so that after you've lowered it down you can slide it forward to the front of the bench

This is what I do. It uses very little space and is easy to deploy into use. Mine just sits there on it's long edge face against the wall.

The important thing with any surface plate is that it unstressed. If it is stressed it is unlikely to be flat, and therefore pretty useless as a reference surface. Consequently, I would advise most strongly against storing vertically and pulling down for use.

Trolleys or drawer slides also worry me, in case the plate becomes stressed by the trolley surface not having the surface plate / table level in both planes.. Cast iron surface plates and tables are scraped and blued to render the surface absolutely flat, when in situ.

I made, if that is the right word, a granite surface plate for The WaterWorks Museum. It was "floated" on a bed of wet plaster, on a sturdy (2" angle iron) frame, fitted with levelling screws. In place on its bespoke stand, the table was levelled in both planes before use. The stand is not moved around, but kept in one place. It is also kept covered when not in use.

My surface plate is never moved.

For anyone who doubts the ability of a surface plate to deflect, remember this cautionary tale..

My employers bought a 6' x 4' x 6" granite surface table.(It probably cost well over £3K ) Someone left it leaning against a wall. When put into service, it was found to be bowed, and therefore useless!

Howard

I'd like to hear the reasoning as to why a symmetrical shaped piece of granite stood on one flat edge should be any more prone to warping that one stored flat.

Howard said that was left leaning against a wall i.e. at angle, not stood on it's edge.

Edited By Robert Atkinson 2 on 28/07/2020 21:52:32

Posted by Howard Lewis 28/07/2020 21:15:43
I made, if that is the right word, a granite surface plate for The WaterWorks Museum.
It was "floated" on a bed of wet plaster, on a sturdy (2" angle iron) frame, fitted with
levelling screws. In place on its bespoke stand, the table was levelled in both planes
before use. The stand is not moved around, but kept in one place. It is also kept
covered when not in use.
My surface plate is never moved.

Refering to the FAQ , question 12 on the site below
Mounting surface plates in the way described above is not recommended
The also point out that levelling is not necessary ,i suppose they would know .
Probably the reason the plate should not be stored in any other way
than on these three points.

https://www.starrett.com/precision-granite/precision-granite-faq

My own stand seen here in an earlier photo is mounted on the
three indicated marks on the underside,the mounting points
are on the two cross bars the four uprights at the corners
are a safety to prevent the plate from moving out of position
but do not touch the plate.

John

Actually Robert, I was referring to this

and I would contend that a portable surface plate sitting on edge is less likely to be affected by gravity than one sat flat on it's feet. I also don't believe that bringing one from upright to flat or that any other normal handling could possibly affect it's geometry (unless you dropped it). I carried mine to a scraping and alignment class on the seat of my van where it was checked with an autocollimator and found to be in good fettle.

I couldn't comment on how the one left leaning against a wall ended up bent, but I'd expect that a 4' x 6' x 6" plate would require good support and adjustment when mounted horizontally in order that it wouldn't bend under it's own weight. My 18" x 24" surface plate is 4" thick giving a 1:6 thickness to length ratio. The plate mentioned would have a 1:12 thickness to length ratio so much more bendy - twice as likely to bend as one which is small enough to man-handle onto it's edge.

I picked up a 24" square cast iron one a little while ago to help me with refurbishing a Herbert Junior surface grinder.
I was struggling for bench space and have located it on top of a sturdy 3 drawer filing cabinet (well it's actually 2 drawers + cupboard).
The cabinet is topped with a quartzite slab obtained from a kitchen fitters supplier, and provides a nice flat stable base.
The plate has 3 feet, rather than the 4 of my 12" square one, so I positioned the third foot at the back and shimmed the other two at the front to get it as level as I can.
The height is just right for me at 5'11" ; I don't have to bend over but can still lift things like the grinder table up onto it OK, so a reasonable compromise.
Fortunately I have a hydraulic table, so with that and some wooden blocks as well, I was able to slide it into position along a couple of lengths of angle iron.

Bill

Edited By peak4 on 28/07/2020 22:26:34

The granite was not standing on a flat surface, but on an edge, my post said that it was leaning! THAT was the problem.

ANY material subjected to a load will deflect. How much depends up, on the stiffness, and the applied load.

Watch a TV aerial mast in a strong wind.

If you LEAN a sheet of any material on one edge, the weight, acting through the centre of gravity will bend it. Think of a sheet of thin steel, or aluminium.

A sheet of paper laid flat has almost no stiffness, Stand it on edge and then try to bend it.

If you are stopped en route to the Dartford crossing, on the bridge near Junction 13, on the M25 you will feel it deflect appreciably when a heavy lorry goes past on the other carriageway.

Remember the film of the Tacoma Narrows bridge failure! And more recently the bridge collapse in Italy!

In the case of the surface plate, a 6' x 4' lump of granite, 6 inches thick is HEAVY, and so will bend in the same way as a thin sheet, but not so obviously..

Since we are talking surface tables which are required to be absolutely flat, deflections of a tenth of a thou become very significant and unacceptable. You can't measure to a "tenth" if the datum surface is a tenth different in level from point to point.

Howard

In industry, surface table are supported on massive steel supports, (some 4 or 6 inch angle, channel or square with more than four legs) which probably weigh more than the table that is being supported.

And the ones that i have seen have levelling screws, to ensure that the actual surface is level in both planes and unstressed.

That is necessary for use in a Standards or Calibration Room.

The "bent" surface table was condemned by the Toolroom staff, who know much more about such things than i would claim..

But we are probably each talking different levels of acceptable accuracy.

Howard

Hello Rod,

In your original post you say a higher surface plate would reduce the amount of bending to read surface gauges and the like.

Just pick the instrument up in your hands to reach a convenient height.

Regards, John

Well I keep my granite plates standing on their edge, and I have the means and ability to check them when sat on their 3 feet. So far none have taken a set from being handled or leaned.

I think we need to get some perspective here. The portable plates we tend to use are shipped in a timber crate by regular courier. They aren't going to take a set from vertical storage.

Thank you to all who contributed ideas and photos on this topic.

I had been concerned about a trolley being top heavy but the plate weighs about 120 pounds and if I put it on a trolley the combination will weigh perhaps 180 pounds, plus weight of items stored beneath the plate, which is quite a lot more than me, so if I bump into it I think I will just bounce off rather than knock the trolley over! Still best to be safe so perhaps a stand, ie with feet rather than castors, would be best. Having said that, John Pace reports no stability problems with his trolley and ingenius side table, and I am not sure mine would be much different, just a little bigger in all dimensions.

I like the idea of drawer slides but was trying to get the plate higher rather than lower.

I like the idea of standing the plate up at the back of the bench but it's more than I can lift!

The different ideas and solutions have given me a lot to think about.

I will mull it over but at present I am thinking of trying to make space for a "high bench" somehow, and standing the surface plate on one end and using the rest of the surface for marking out/ tiny work /desk work. I have a high stool left over from a kitchen refit and it would be good to be able to sit down for fiddly things.

Thanks to all who contributed.

Rod

Nice tall stand will be great, feet as far apart as you can tolerate. Maybe a safety strap to a wall or workbench. A couple of diagonals should deal with earthquakes.

To get the height right stack some shoe boxes on your bench and play with the metrology kit on top, that should tell you what you need.

I am reasonably tall but have a bad back, getting a workplace right for me is a constant problem. The ability to make adjustment is sometimes more important than being right in the first place.

Good luck with the project.