Building a TIG cart

[frieed]

My current cart is a flimsy three shelf cart from Harbor Freight modded by removing the middle shelf and cutting a hole in the top shelf for the argon cylinder. The TIG welder sits on the top shelf, the water cooler on the bottom, and a cheapo plastic hose reel on back to hold cables and a built-on extension cord.
This setup works fine but is pretty cheesy.



I have decided that the next time I swap my argon tank I'm going to trade in my 125cf tank and get a 275cf tank. The new tank weighs north of 175lbs so lifting it up and dropping it through the hole in the top shelf is no longer an option (I'm old and feeble). I'd also like to have a couple drawers for parts, hoses, etc. (especially after today when I knocked my parts kit off the workbench and broke 2 pyrex gas lens cups. grrrr)
Here is the plan I came up with, thank you free Sketchup.
The Sketchup file has been attached. (tig cart.skp)




I enlisted Carl (Ilean) to plasma cut the sheet metal and he delivered, thanks Carl



Time to cut some tube for the frame


and the results laid out with the plates..


Let's get the tube jigged up on the fixture table
Top level first:


Then the lower level


All tacked up and ready for some real welding

 

[frieed]

Next, let's weld it all up. I've been doing all this with TIG and I'm happy with the results so far, or at least this particular weld



But then reality kicks in. There is a 10" unsupported leg at the back of the lower frame and welding in the back separator caused the tube to bend.
That's about a 1/8 movement at 10" with 0.120 wall tube.




Okay, I guess I should have put a spacer in before I welded, maybe next time...
How to fix. 20T hydraulic jack moves it enough but not evenly on both sides. For the second side I had to pre-load with the jack and then run a few passes with the TIG torch to get the metal to relax, quench, and life is closer to good. (note to self, I need an oxy-fuel torch for heating).

Cool, I'm good, or so I thought. In reality, the bending was the easy life lesson.

On to the real pain....
The model I drew was done with square edges on the tube and it made it simple to inset the plates between the frame members. Looks spiffy and is easy to do, on the computer that is.


Remind me to consult the Design for Manufacturability folks for the next cart. On this one, all of the plates that Carl cut for me are sized to fit between the frame members and during the tacking together phase everything was just fine. After the full up welding and the kinds of movement shown above, much, much grinding, fitting, grinding,.... etc. the end result is here, after primer.



gaps, gaps, gaps....
and lots of time I did not need to spend.
proper solution would have been a single sheet that sat on top of the frame and got tacked in place.
oh well....

I welded this (the upper shelf) with TIG, but then accepted reality and changed to MIG which bridges gaps easier for the bottom (with it's larger gap, but less grinding so I guess that's a plus)

 

[frieed]

After jacking with the sheet metal for so long, I have a new favorite tool, an 8" bench shear.
I bought it to clean up the edges on plasma cut aluminum coupons so I could start practicing TIG welding different joints on aluminum but it works just fine trimming this 16ga and 10ga mild steel. You can see the end caps that I cut for the tube.




I got the legs installed and the upper and lower platforms married together.
This thing is pretty heavy. Tube for the lower frame is 0.120 wall 1x2, the uprights are .108 wall 1x1, the cylinder platform is 10 ga (~0.120), the upper frame is lighter 0.080 wall, and all the shelf plates are 16 ga.

Time to get the wheels on this buggy, starting with 1/2" bolts welded to the frame for the rear wheel axles.
They are positioned just behind the center line of the cylinder putting most of the weight on the back wheels, but with a little weight towards the front for stability.


Followed by the front swivel caster


Well, what do you know, it looks like a cart


Time to get the horizontal bars that the drawer slides mount on and then some paint.

Which gives us this, weighing in at 65lbs :

 

[frieed]

Now it's time to start with the drawers...
This is going to be interesting.
I don't have a metal brake so I had Carl cut the sides and bottoms as individual pieces, to be assembled with a ridiculous amount of outside corner welding. The parts are sized to be assembled inside corner to inside corner and the plan is to use lay-wire technique with the TIG torch and fuse them together. They'll probably come out looking like pretzels.

The drawers are 18.5" deep and will be hung on 22" full extension slides. This gives me 3.5" of over travel to let the back of the drawer clear the cart handle. Nuisance, since 3/4 extension slides were $7 a pair and these were $19....

so I used magnetic squares to hold the pieces together while I tacked them together


As it turns out, with a fair amount of finessing, this worked out quite well



I experimented quite a bit with the welding process and settled on running pulse with 33 pps, 50% duty cycle, 110A on current and 50A low current with a simple lay wire technique.


as you can see, the drawer lays flat on the table so no twist was induced, although the panels do oil-can a bit.

after cleanup, not perfect, but I'm really happy with my first attempt at outside corners on thin sheet.

 

[frieed]

Here is a step I wish I had photographed because it's really important to fab. work. ( I may go back and mock it up for pictures)
I welded the legs, 32" pieces of 1x1, to the bottom of the top frame. To do this, I used Harbor Freight welding magnets to free my hands up.
The magnets are by no means accurately square, but that doesn't matter.
With the magnets in place, use a decent square ( I used an aluminum speed square to avoid annoyances from the magnets) to find the corner that the tube is leaning away from. Weld a HEAVY tack on that corner and remove the magnets as the tack will support the leg in place. Bump the leg to adjust while you do the remaining tacks. Each tack will pull the leg toward the weld. Once tacked, weld the sides that the leg is leaning away from the most. I was using a small carpenters square to check (flat 6"x12" or so thing) and was amazed to watch what was a 1/8" gap 12" up the leg stayed the same after I welded, only to watch it pull into alignment as the weld cooled.

 

[I Lean]

In for more updates.

 

[mesha]

That cart is gonna be sweet!

 

[ricsrx]

i had some rear wheels like that and they did not roll well under the weight of my cylinder. but they were HF wheels

 

[mesha]

That fixture table is amazing.

 

[frieed]

It's a certiflat 2'x4' kit
https://weldtables.com/collections/...ng-table-top-kit-certiflat-by-tab-slot-u-weld

 

[zmotorsports]

Cart is looking nice.

Great job.

Mike

 

[Greg]

It's a certiflat 2'x4' kit
https://weldtables.com/collections/...ng-table-top-kit-certiflat-by-tab-slot-u-weld

Great.... something else I didn't know I needed!

 

[Hickey]

I've been trying not to look at those fixture tables. I know I will obsess about it if I do.

 

[DAA]

Heck, I don't even weld and I think it's sexy.

- DAA

 

[frieed]

A question for anyone that has welded up thin sheet metal to form a box:

I had the drawer parts done on a cnc plasma setup but since I don't have a brake I had sides and bottoms cut as separate pieces with the intent to weld them up into drawers. I had the parts cut to align inside corner to inside corner and my question is about tacking them up. I can go the magnet route, but I was wondering, what if I were to lay all the pieces flat, tack weld the sides to the bottom and then bend the sides up and tack them. Would the tacks hold up to a 90* bend (16ga mild steel) to make the sides meet at the corners ?

 

[bryson]

A question for anyone that has welded up thin sheet metal to form a box:

I had the drawer parts done on a cnc plasma setup but since I don't have a brake I had sides and bottoms cut as separate pieces with the intent to weld them up into drawers. I had the parts cut to align inside corner to inside corner and my question is about tacking them up. I can go the magnet route, but I was wondering, what if I were to lay all the pieces flat, tack weld the sides to the bottom and then bend the sides up and tack them. Would the tacks hold up to a 90* bend (16ga mild steel) to make the sides meet at the corners ?

Try it! It can't hurt (much) to try it. I don't TIG much, but I know a MIG tack would not hold up like that. If anything, it'd just bend the metal around the tack and that's no good. Luckily, you can straighten sheet metal pretty easily.

 

[frieed]

I could also add heat to the tacks but I only have a MAPP torch (at the moment).

 

[Hickey]

I think the tacks would break or bend the base metal too much. I would clamp the two pieces on your fixture table. One on the top, and the other clamped to the side. The table will provide some heat sink.

 

[frieed]

unfortunately my table doesn't have sides ...

 

[I Lean]

https://weldtables.com/collections/fabsquares