Work bench questions

[R6 Racer]

Can anyone tell me how thick of steel should I get?

I have built workbench & was hoping to put a steel top on it.
I would like to use it to weld on (amongst other things) & I am worried about lighting the wood on fire underneath the steel. What thickness of steel do you think I can get away with safely? 3/8", 1/4" thicker thinner ??? What?

Steve

 

[Jack Olsen]

Well, the problem with that bench is that it's all wood. If you're grinding on it, especially, you're going to potentially be setting some part of it on fire -- no matter what surface you've got on the top. Is there room nearby for an all-metal bench?

Whether you're going to heat up the wood underneath a metal top with welding itself depends on what you're welding and how you're holding it in position, I guess. Some guys weld on wood benches without any problem. (You just can't attach the ground clamp to the work surface when you're doing it that way.) So 1/8" or thicker would probably be fine, so long as you remember not to concentrate heat right on one part of the top for too long. You could also use thicker steel (like 1/4") and put some spacers in between the metal and wood so it's harder for heat to radiate.

But if I were in your shoes, I'd use that bench (it looks nice!) for wood projects, and maybe put in a fold-down or free standing metal bench somewhere else in the garage for welding. That way you won't have to worry that slag or grinding sparks are going to light anything on fire.

 

[moose knuckle]

I have a 3/4 in wood top on my bench, covered w/ 1/8" steel for welding. I do not have any crazy heat concentrated in one area to start the wood under on fire, so I see no problem w/ doing it like this.

 

[ahaidet]

I use an 1/8" top on mine and weld on it regularly. I really do not concentrate any heat on the top at all. Sometimes guys will like to tack weld things to the bench to get everything setup/jigged in place. I don't tack anything to the top. When I have a situation where I might need to do that I use my t-slots to clamp things. I have sort of a "poor man's T-slot top".

Here is my workbench thread for more details.

If you have the room Jack's fold down work surfaces are a pretty good use of space and is another option.

 

[R6 Racer]

I was watching Mike Homes when an idea came to me. They were talking about a drywall fire break between 2 row houses. Could I use that?
Let me explain my thinking...
My bench is inch & a half plywood on sistered 2x4's so its plenty strong enough! If I was to put a bench sized sheet of drywall on top of the plywood then put a the 1/4" plate on top of that. Trim the top out with angle iron making a contained area that the drywall is in so as to not allow any space for it to expand into when pounding on something on the 1/4" steel plate top. Having fire proof drywall under the 1/4" plate should stop any burning issues.

Wadayathink bout the drywall thing?

Steve

 

[csp]

Unless you're applying a constant flame and getting the steel red-hot, you're not going to burn the wood underneath.

You also need oxygen for fire to start and probably not going to have anything close to enough for combustion. The worst you could do is scorch the underlying wood.

 

[R6 Racer]

Jack thanks for the complement on that bench. That is a fixed position bench in my garage & I am hoping that it will serve as a welding bench & a rebuild bench for auto repairs. Even with my car parked in the garage I have 6 feet of space from the car to the bench.
I have a wood shop in my basement. That is where my woodworking bench is! I am also in the process of building an assembly table for the wood shop.
csp I was kinda wondering about the oxygen thing too. What do you think about adding the drywall?

Steve

 

[Spareparts]

The only thing I would worry about is getting it hot enough to cause the wood to smolder, it could do that for a couple od days till it got enough air to flame up, that could be when you are away from home or in the middle of the night God Forbid. Think about building a metal frame with the metal top, some heavy wheels on one end and a lifting device for the other end to makt it portable.

 

[R6 Racer]

Anyone have any thoughts on the drywall idea?

Steve

 

[Jack Olsen]

Drywall is good from a fire perspective, but lousy to pound on. I'll bet there are other fireproof/insulating materials you could use -- I just don't know what they are. Even a thin sheet of aluminum would probably substantially reduce the heat transfer. But that's the hunch of a guy who is not a fire safety engineer.

All that said, unless you're putting an O-A torch on one spot for an extended period of time, I don't think you'd have any problems with 1/4" steel on top of the plywood. My concern would still be grinding slag/sparks on the vertical wood surfaces -- that backsplash and wraparound. Here's a picture that shows how much stuff I covered with cheap aluminum flashing to keep my plywood walls from catching fire around my fold-down welding table. It's all been painted since then.

 

[RobSmith]

Use that stuff they put over wood floors to lay tiles on. Years ago it was asbestos (banned) now its called 'Hardiplank" or 'Villaboard' in Australia. I think it's called compressed fibre board too. It's very solid and there's nothing in it to burn Plus it doesn't hold or carry heat at all.

 

[R6 Racer]

Jack I am putting a sheet metal cover on the back splash & the side 6" high. I am also planing on using a welding blanket (hung from the ceiling a la curtain) to protect everything else around the area. I was worried about pounding on the drywall too. My thought was that since the drywall was compressed between the 1/4" plate (which would dissipate the impact over a much larger surface area) & the bench, that it would have no where to expand into, which I think it would need in order to break up. What do u think?

Rob I think that's the kind of thing I'm looking for, anyone else heard of this or know what is called?

Steve

 

[NUTTSGT]

You could build a portable welding table and leave your workbench alone the way it is. Use the table in the middle of the floor and reduce your risks.


sorry for the crappy pic.

 

[ahaidet]

I think using the drywall is not such a good idea. I think over time it would get smashed under the bench and eventually you would have a real mess under the 1/4" steel. I understand the steel would help to distribute the load through-out the drywall but I would think that over time the drywall would fatigue and begin to break down. The fiber board I would think would be a better choice.

It depends on the power/type of your welder as well. With my 110V Mig in order to get the other side of 1/4" steel hot enough to smolder wood I would have to deliberately direct enough heat into the top to run a bead. Gas welding may be different as you are using an open flame.

In my experience it’s the sparks from the MIG welder or from Oxy/Acet cutting that are more of a concern than the heat from the actual welding to starting fires. Those little sparks run off and try and hide in places and get in to all kinds of trouble. That’s why Jack's backsplashes are good for the areas that are plywood. Even then the sparks/spatter rarely stay hot enough for long enough to catch a large piece of wood on fire. Its things like saw dust, oil residue, dry grass, rags, paper towels, strings from the hole in your jeans that you have to watch out for... (don't ask how I know about the strings on my jeans... lets just say I was not hurt but it scared the **** out of me enough that I am very careful now with welding and possible points of ignition) Keeping a clean shop, containing the sparks, having water and a fire extinguisher nearby will go a long way to fire safety with regards to welding.

That’s just my 2 cents.

 

[csp]

Durock cement board or Hardieboard are readily avaialble in any big box home improvement store. They are used behind tile installations in wet applications like showers or bathrooms. These would last longer than drywall, but any pounding would eventually break them down as well.

Personally I think the risk of even smoldering is minimal, very minimal. You'd have to concentrate heat in one spot for a very, very long time to get enough heat transfer to promote any kind of ignition. Even smoldering requires oxygen.

 

[R6 Racer]

I was at H.D. yesterday & the guy there suggested cement board (it's a lot harder & apparently more fire resistant than drywall). I also just found (free) most of an old 1/2" thick rubber pick up bed liner (the flat kind), with a large chunk of one corner missing. I'm going to cut a bench sized piece & throw it on the bench under whatever, whenever I have to seriously wail on anything.
I think am going to use the cement board, weld 6 bolts onto the bottom of the 1/4" plate & bolt threw the cement board & the plywood top to secure everything in place. That way I can go back & change out the cement board if it starts to loose structure, or I find something better.
I think the welding "curtain" that I'm planing will get used for all grinding as well as welding, hopefully solving all errant spark problems.
All my wood working is done in my basement so there will be no sawdust to ignite & YES I do have a fire extinguisher right there!
I think that should cover all the bases.

Thoughts?
Steve

Thanks everyone for your input!

 

[R6 Racer]

Nutsgt I think I might steel that idea as well, modified a bit (I can't leave anything alone) for any projects that i have to get a 360 viev of.
Thanks

Steve

 

[Deltarat]

I have a 4x8- 3/4 plywood top table on casters for wood working and I just bought a 4x8x 1/2 to make a welding table that will be on casters too.

 

[R6 Racer]

I wish I had that kind of room!