Home built welded sheet metal drawers - beginner learning the hard way

This post is to document the good, bad and ugly aspects of my construction of 3 drawers for my welding cart/table.

I had done a little research early on but didn't find lots of info at the time regarding building welded metal drawers from scratch.  What I did know upfront is that thin sheet metal is challenging to work with.  I also gathered from various sources that high heat input would likely lead to warping.  I had experienced this already when stitching some small rectangular pieces of sheet together or the bottom of the cart.

Anyways, knowing the the following setup was not optimum, I decided to go ahead anyways.  I just wanted a useable result but it need not be overly pretty.  The knowledge gained far outweighed the unattractive welds in this case.

1. .035 gas-less Flux core setup
2. 20 or 22 gauge sheet metal (forgetting which off top of head right now)
3. 1 drawer was made from a single continuous piece of sheet metal which was just cut in places to allow forming.  Forming involved hand bending (as in clamp and push like mad) and hammering over a wood mockup of the final drawer.  The end result is sort of a Christmas package type of look - solid sides and bottom with diagonal welded seams on the ends.  This drawer is the most rigid of the 3 due to the amount of overlapping sheet metal from what I can tell.  The resulting dimensions and tolerances of the drawer were not very close due to the hand bending and hammering required. 
4. The other 2 drawers were made of individual rectangular pieces of sheet which were then welded together.  
1. One drawer was mostly corner welded.  This drawer had the most issues.  I had huge trouble trying to avoid blowing holes in the edges.
2. The other drawer used over-sized pieces which I bent 1-2 inches around corners.  The bending was done by clamping a scrap piece of angle iron to my welding table which the sheet metal between them.  Bending was done by hand and some light hammering.  This drawer was done last and utilized knowledge gained from the previous 2 drawers.  This drawer was the easiest to produce plus it had decent rigidity and dimensions/tolerances that were reasonably close considering the methods I used.

Early lessons

• Doing tack type welds was the most viable way to prevent major warping
• Attempts at continuous welds resulted in just unbearable ugly welds.  Burn through was prevalent - alternating holes and blobs.  The blobs seemed to be a bit cold - more like they adhered to the surface than fused properly to surrounding metal.
• Flux core wire is just plain messy and a real pain to cleanup afterwards. 
• Prepping the areas where welds occur with a wire brush drill attachment helped with weld consistency since some light to medium levels of rust had been forming.  This is much easier to do BEFORE clamping things together.
• A good solid clamping of the pieces helped significantly.  It seems like the overlapping sheet metal had a sort of heat sink effect when well clamped.  When not well clamped, the top level of sheet metal tended to vaporize more or less - leaving holes with fused edges at best.
•  Clamping some scrap bar or angle stock improved things further.  I think this was a combination of the heat sink effect and tighter overlap.
• When welding inside the box, the lower level of light seemed to cause extra problems with the self-darkening helmet. I'm not sure if some extra lighting directed into the box would have helped reduce shadows and allow me to see a little farther along the direction of travel. 
• Sheet metal snips usually resulted in ugly cuts, tired and extremely cramped hands and plenty of sore spots from sharp pointed edges through fairly thick gloves.  
• A cheap Chicago Electric sheet metal shear from Harbor Freight was a huge improvement over the manual snips I have.
• Inside corner welds are especially challenging.  Extra lighting would help even though I was working outside.
• My recent addition of a Hobart magnifying lens in my Harbor Freight helmet did help weld visibility (I think I got a 2 diopter lens). 

What would have provided a more professional result (some low cost ideas while others are $$$).

• A sheet metal & pan brake - I think this would make the biggest difference for several reasons.
• Using bends instead of welds results in less heat distortion; bend as much as possible.
• Proper tooling has a better chance of maintaining correct dimensions.
• An improved design which prevented or reduced inside corner welds would help.  A design where welds occur outside of corners and probably only on the external sides would make for quicker and easier welding. It would be easier to cleanup outside welds as well.
• A reasonable amount of overlapping metal combined with proper joint design and attachment method should increase rigidity a bit.  This is based somewhat on the methods I used and the skills/equipment I had available - it may be wasteful under other circumstances.
• Avoid welds on the the front if at all possible. These just resulted in poor looks and more cleanup.
• Use of TIG and lower amperage or gas MIG + smaller wire ( .023 seems recommended per a few blogs).  These seem like valid suggestions I ran across for reducing heat distortion.
• Use of a good backing plate as heat sink.  I just picked up some aluminum to use in the future.
• Possibly the use of some rivets in place of some welds.  Sometimes simple is better..
• Some yet to be determined way to minimize the hazard of some sharp edges.  Rolling the top edges seems like it would do the job but I would have need to plan that in the beginning.  Not sure what other options might be viable. I'm not very impressed by the results of a light sanding of edges or a light grinding with a Dremel.
• A proper set of jigs to hold things in place would prevent a few problems.

 In the end, I have 3 workable drawers.  One has been mounted and very functional for 6 months or so.  The other 2 I am gathering what I need to mount them to the welding cart/table.  A couple coats of enamel paint goes a long way to improving the overall look of things.

Just want to give a hats off to the professional welders and hobbyist that have gained the skills and patience to work with sheet metal and produce many of the awesome examples out there for viewing over the internet.  It is certainly more than one skill; welding is part of it but component and jig design are a big part of it from what I just went through.

[2014/05/07 Update] Some pics of the before final assembly.

The slides and brackets are upside down for picture taking convenience. I will be welding the angle iron "feet" to the underside of my welding table/cart top. It is a very hefty assembly - I could surly have gone lighter weight with the angle iron which is 1/4" think.  The flat pieces welded to the angle are 1/8" think. I may take some smaller flat bar and weld it between the 2 sides - that should make it easier to keep the spacing close as I try to weld this onto the cart.

Here I am test fitting things.  Remember that the whole thing is upside down from how it will get mounted.  I will rivet the drawers to the slides once I work out the exact spacing.  I mainly need a little space at what will be the top so that I can still clamp the table in the general area of the top drawer.  I also tend to clamp the ground cable to the table top in that area.

I am still debating whether to empty the whole cart and flip it over so I can weld this on or simply try to raise/clamp it in place and weld from below.  Welding from below is *really* not a strong point for me but at the same time the cart weighs much more than I originally intended and some aspects will make flipping it more difficult.  Guess I will figure it out when the time comes.

[update 05/8/2014] I ended up tacking the drawers in place while upright.  A few clamps and a little help got it in place reasonably well.

Here is end result.

 Not perfect but very usable.

Thanks for looking!
Scott