Thread: Welding table design

I am frustrated with not having a large, perfectly level work surface to make up gate frames and other welded items. The concrete slab in my shed is too rough, and the workbench is too small.
I have a large number of benches to fabricate - about 80! measuring 2400 x 1200. I will need to be able make frames quickly on a large bench that I can set up a jig on.

My welding advisor / expert thought an 8mm sheet of plate(3m x 1.5m) would be the best bet as a table top, reinforcing the bottom with 100 x 5 mm flat on edge, to give a rigid, twist free surface.

My initial idea was just to make up a 50 x 50 RHS frame and sheet it with 18mm ply, with a 1mm sheet of gal on top, but the expert thought that would be too hard to make perfectly flat, and not easy to weld jigs or clamping tools to, whereas the 8mm would be much more durable (bloody heavy too, but I can move it with a forklift.)

Ideally, I could also tilt it, so that lots of repetitive welding wouldn't be too hard on my back.

What do other people or professionals use? Any hints or tips would be most gratefully accepted.

Sheet on top of ply is hard to get flat and really hard to weld tabs to for jigs and what not. For a metal fab bench imo always go the heaviest you can afford. 8mm should be a good minumum with a nice heavy support like 100x100 angle.

I'd avoid mixing ply and sheetmetal, as the metal may well transmit any heat to the wood! I had a setup like that but ended up topping it with kiln bricks, for a brazing bench.
If these benches are identical, make a large jig out of 25mm square RHS with flat bar lugs, and place it at a suitable height, even on metal trestle legs. The open nature of the jig won't affect the job, may even help as sparks, grindings etc won't build up, and will allow clamping from many different places (ie. inside the "bench" area, not limited to the outside edge.
I worked in wrought iron workshop for a while, making security screens and doors. That is the sort setup we used all the time.... very rarely used a flat benchtop in the way a woodworker does.
Of course you might need a flat place to weld up your jig!!

Cheers

Originally Posted by Andy Mac

I'd avoid mixing ply and sheetmetal, as the metal may well transmit any heat to the wood! I had a setup like that but ended up topping it with kiln bricks, for a brazing bench.
If these benches are identical, make a large jig out of 25mm square RHS with flat bar lugs, and place it at a suitable height, even on metal trestle legs. The open nature of the jig won't affect the job, may even help as sparks, grindings etc won't build up, and will allow clamping from many different places (ie. inside the "bench" area, not limited to the outside edge.
I worked in wrought iron workshop for a while, making security screens and doors. That is the sort setup we used all the time.... very rarely used a flat benchtop in the way a woodworker does.
Of course you might need a flat place to weld up your jig!!

Cheers

That's exactly right! - I need to start out somewhere dead flat, just to make the jig, otherwise my errors will just multiply.
I like the idea of the open jig though. I would ideally like to build in some cam clamps to hold everything nice and tight.

Hi
I did product development for a metal furniture company for a number of years and had to build all of the jigs for production. I too longed for a perfectly flat bench to work off and I eventually built a 4”x 4” square tube framed bench 4’X 8’ I ordered a sheet of 1/2 “ plate for the top thinking it would be nice and flat, when it arrived I found it was not very flat and dished up to the center of the sheet around ¾ inch. I managed to pull it down to the frame of the table but just ended up with two dished sides to the table. I think your best bet is to weld up a tube frame make sure it doesn’t have any twist in it the best way to do this is to make up some welding corners out of plywood or tubing they are very handy to have there are a couple of pictures I posted on the recent thread on clamping. Start with the perimeter of the frame clamp the corners with the corner jigs don’t worry about weather your floor or bench is flat or level. Once you have it clamped together take an ordinary carpenter level and level up one side by shimming up the appropriate side, now go to the opposite side and do the same it doesn’t matter if remaining two sides are level as they will still be parallel to each other. Once you have added some internal framing the frame should remain flat. You have to also be careful where you weld on the frame as the heat can warp the tube. I will try to find time to mock something up tomorrow and take some pictures to better explain. I would use this technique to build one of your benches and then use that frame as the basis for a jig.
Darrell

We also use large industrial trestles at work (I work in a fab shop specializing in heavy construction)

We only use flat style tables for marking out cleats n setting up fixtures..............

Any framework like the one you described we do on a fixture made of RHS we have done this for production runs in the many hundreds on numerous occasions its quick simple cheap and works well....................Reading back is pretty much identical to what Andy described..............

If your interested I can do something for you in sketchup to show you the procedure

REgards Lou

That would be really great, but I will post a piccy in sketchup of what I want to make. Just have to spend some time in the Sketchup forum first, figuring out how to do it!

Here we go, I have spent some informative and infuriating hours learning some sketchup basics.
Here is a picture of the table

I was thinking of makign the two long sides first, then putting the cross braces in. Making a bench and jigs to make multiple sides is relatively easy, I am not sure the best way to then make a jig to put all the cross pieces (10) in, while keeping everything nice and square

Any suggestions? I have quite a few of these to do.

Nice drawing, but are you sure you want to make it out of galvanised? You would have to grind every joint before welding only to spray galvanised paint back on the welds afterwards. I like the idea of a bare or painted steel frame, which you weld (good idea to still grind the paint if necessary), then lightly sand and anti-rust prime the whole thing before painting it with a final colour (or leaving it with the uniformly primed colour).

A 6mm or 8mm bare steel top should be fine - you definitely wouldn't want this galvanised, unless you want to get metal fume fever every time you weld something on top of it.

Sorry Edd, I have probably not explained myself clearly. I want to make a heavy duty workbench with an ultra flat top, so that I can then make multiples of the bench I have drawn the picture of. these will be used in a nursery once they have a mesh top on.

Other members then suggested simply making some jigs to make them up with, and I was posting the picture to show how the end tables will look.

The duragal is specified by the client, and the manufacturer say you can weld straight over it without grinding, as was discussed in a previous thread, see
http://www.woodworkforums.ubeaut.com...ad.php?t=75513

There are 40 plus of these to make, so I really want to avoid grinding every joint. Hot dipping after making them was prohibitively expensive.

Ah I see now. Sorry, I thought the diagram was for your workbench for some reason - ie. the one off job.

There are many ways of doing it. One would be to make a jig and make 80 of the 2400 x 900 sides, then join them together with 90 degree clamps to end up with 40 units. I've used the strategy of 1" plywood and nailing wooden guides in to clamp the material against, but there's two problems in your case:
• The jig will get burns and marks from clamping and welding. I don't think it would last 80 members (for 40 benches) or 160 (for 80 benches).
• This is way bigger than anything I've done on plywood, so any variations in straightness will be magnified, and it will be bloody heavy.

Make one bench then use that as the jig frame..i.e fabricate all the others on it upside down
Use lots of anti-spatter..

Hi quercus
You ll have no problems welding through dura gal. However the fumes are very dangerous. I have just purchased a new speedglas adflow system which has gal filters. These are expensive $2000+ but well worth the money if you fabricate gal regularly. I used to be very hesitant when i got jobs in gal, but thats not an issue now. I also wire brush the welds straight away after welding each run, this is much easier than when cold.

On bench design, i have 2 sheets of 16mm laminated particle board. The top plastic layer burns easily and the sheets warps, probably not recommened. However as I only fabricate sheep and cattle yards, gates and ramps etc, this slight warp doesn't worry me. I fabricate panels directly on the bench with out a jig, I find it quicker without using a jig. I mark the upright pieces, then clamp them to the angle I have welded along the edge of the bench. About 1500mm each way at 90 deg. I then lay the rails along and just put them in place and weld them up. I can do upto 20 cattleyard panels a day by myself this way, however I am not doing precision fabrication.

Hope this helps
Mitch

Thanks for that guys. I will probably make up a jig on a bench to make the sides, then clamp the sides to a box type jig made out of ply as Edd mentioned. I will cover the areas that may get welding burns with some gal or copper sheet.

At work we have been spoiled a bit. Our welding bench is 50mm plate 2.5M X 2.5M on top of 100 X 100 X 10 RHS legs. Great for welding jigs straight on to etc.