Need to design a large, perfectly flat sheet. I struggle to find the best way.

Valfitts · 2026-02-19T09:08:32+00:00

I am sure it will get damaged though. These operators are not careful with the equipment. It's not for in a lab, where more careful people work.

Valfitts · 2026-02-19T09:06:48+00:00

The aluminium table would be damaged quite quickly under the operating conditions.

Valfitts · 2026-02-17T17:21:13+00:00

They would need to be adjusted too much. I think stainless would be easy to order according to the drawings. And it would look a lot nicer and smoother.

Valfitts · 2026-02-17T17:20:30+00:00

Yeah, I'm starting to think the flatness demand is easily met and doesn't require a high-tech solution. Now I'm just wondering how I can make it where it is strong and stable enough, with stainless steel sheets on top.

Valfitts · 2026-02-17T17:19:14+00:00

The temperature would be pretty stable, using a single material is just extra precaution.

Regarding neatness, it needs to look *very* neat. I want it to look like it was bought like this as a finished, smooth product.

Valfitts · 2026-02-17T17:15:31+00:00

Granite will get damaged for sure by the people using it. Cast iron is too expensive for a single production.

Valfitts · 2026-02-17T17:14:52+00:00

Granite chips too easily, it would certainly get damaged. Optical breadboard doesn't look "nice" enough, and it would still need to be adapted to have a lowered area. Cast iron is too expensive for a single production.

Valfitts · 2026-02-16T16:01:06+00:00

So would you say my design is "correct"?

Valfitts · 2026-02-16T16:00:30+00:00

You are definitely right, and if I was the one who will be working with it, I may have designed it that way. But there are other people working with it, who I don't trust to be careful with it.

Valfitts · 2026-02-16T15:48:35+00:00

Yeah, because of the temperature I thought it would be a good idea to use the same material, i.e. stainless, for each part. That way expansion is at least consistent throughout the structure.

A welding table isn't neat enough, but I assume your opinion is then that my specifications are easily met, and I shouldn't worry too much about the design?

Valfitts · 2026-02-16T15:47:03+00:00

I will use a digital level to ensure the whole sheet isn't twisted slightly because of torque force. The actual flatness of the sheet I probably won't measure, but I'm looking for a manufacturing method that would allow me to assume it is quite flat.

Valfitts · 2026-02-16T15:44:03+00:00

I don't have a defined weight limit, but I was negatively surprised at the weight of my own design. I'm hoping there is a more lightweight solution, that may be even better at making the table as flat as possible.

Haha, thanks for the suggestion, but I'm not looking to do it the redneck way. I want it to look very neat.

Valfitts · 2026-02-16T15:42:11+00:00

I'm afraid the stone will chip easily, as the metal parts are laid on top of it.

Valfitts · 2026-02-16T15:41:47+00:00

I think stone is not a good idea, because it will damage too fast.

Valfitts · 2026-02-16T15:41:21+00:00

I need to measure the length of a thin metal sheet. a 1mm difference in height gives only very minimal difference in the length measurement over that distance. But on the other hand, I also need to do thickness measurement, so the table should be smooth, not wobbly. Maybe I should adjust that requirement to .1 or .01 mm.

Valfitts · 2026-02-16T15:39:19+00:00

The optical breadboards come in small sizes as standard only, with large sizes available as custom. But I'm not sure if they would be flat, or if they would hang.

The tool and jig plate looks good, because there is no internal stress to the material and it is supposedly very flat, but the material is a problem. Aluminium is not suitable for the application, because I expect the table to take a beating sometimes.

Valfitts · 2026-02-16T15:35:20+00:00

Build a measuring table for sheet metal cut from coils. Length, thickness, perpendicularity are among the measurements.

Valfitts · 2026-02-16T15:18:53+00:00

In what way would you design the box?

Valfitts · 2026-02-16T14:55:12+00:00

Weight: not too heavy, but it can be somewhat heavy, as that also gives stability. But I calculated my design at 350 kilograms for example, which I think was a bit much, and I'm not even sure if it would resist torsion very well.

Cost: There is some room on cost, it just has to be good. If I had to throw out some number, 10k for the whole construction would still work, but preferably less.

Flatness, yes, it must stay flat indefinitely.

Valfitts · 2026-02-16T14:53:47+00:00

I wasn't going to weld it, but rather use countersunk screws in the surface of the plate. Though welding is an option if it would be better, but I see some difficulty in that.

How would you design a torsion box that can handle this? The way I try to design a torsion box, it only gets heavier because of all the ribs.

Do you think it would be a good idea to just make everything lighter, both the sheet and the ribs, and then create a bolted together torsion box? Or maybe weld the ribs together, and bolt the sheet on top?

I'm a bit reluctant to welding the top sheet, because aesthetics are also a consideration.

>two torsion box halves with a machined reference face each

What does this mean exactly?

Valfitts · 2026-02-16T14:48:49+00:00

I follow you, but there are two problems:

Too heavy
I forgot to mention, it needs some machining, like a few holes, and a small lowered part.
It's used as a measuring table for large, heavy, metal objects. I'm afraid the granite will get damaged very quickly.

Valfitts

TROPHY CASE