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Brains not tools… Making an Enclosure for Electronics.

Step 1 Create the Plans.

Step 1 Create the Plans.

Sometimes you just gotta do it yourself. Even if it probably makes no sense to do it. I spent a big part of the weekend building an enclosure box for the power-supply I have been using with the thermistor board. However,I consider it a success and I learned a thing or two. Besides, it is kind of fun to take a big rubber mallet and beat the heck out of something. The wife and dog are safe for awhile!  (No, I don’t do that! It was just a dumb joke… don’t get me sent to counselling.)

One piece of the cardboard mock-up

One piece of the cardboard mock-up

I really had no idea what I was getting into and I even do a pretty lousy job wrapping Christmas presents so I knew this would be a challenge.   The first thing I did was take accurate measurements of the power supply I was going to enclose in this box.   I then drew a box around it, and then determined what the ideal dimensions would be once it was flattened out into two pieces.   I then used a piece of poster board and built the model.   This was very good for several reasons.  First, cardboard is much much easier to cut and bend than metal.  The second reason was I quickly determined the 1/4″ tabs were not going to be big enough.  And the final reason was I learned I better do the main bends first and do the tab bends later.    This was just the first of many lessons I learned.

Next, I went to the net to learn a little about bending.  I did not want to go out and buy a metal bending brake, so the first question to determine was “Is this even possible without a brake?”.   Yes it is.  It is not convenient, but it is possible.  Falling over a large piece of equipment in your garage that you have only used a couple of times is not convenient either. Besides, one of the goals of this site is to NOT push the tools. I found a site: How to bend sheet metal that gave me some answers.   However, I will change some of that as I continue with this description.

Cutting the sheet.

Cutting the sheet.

I have some sheet metal laying around. (Ask my wife, I have lots of stuff laying around.)  I have some trim metal my son had when we built his house, but I thought that would probably be too thin so I used a section of flat metal I bought several years ago when I thought I might do some body work on an old truck I bought from my parents.  The truck was not really repairable, the body was so bad rusted that the leaf spring eyelets had rusted through.  So I ended up selling it for junk and still had the new sheet metal.   The metal measured 0.034″ thick which is probably too heavy for this purpose.  Too heavy just means I had to work a little harder.

The bottom piece after cutting.  Note the scribe lines in the picture

The bottom piece after cutting. Note the scribe lines in the picture

I laid-out the metal using the plans except I made the tabs 3/8″ instead of 1/4″ as shown on the plans.   The only really effective way to mark something like this is to use a metal scribe.  Pencil lines will wipe away, and marker lines are too thick to be useful.  The picture to the right shows the bottom piece after cutting.  I used aviation shears to cut the metal.  Two things I learned are:  First do not completely stroke the shears.  If you do completely close the shears the end of the shear makes an indentation in the metal that will cause you problems later.  Second, if you are using relatively thick metal like this use the right angle shears I show in the picture.  This keeps your hand away from the metal and is more easy to slide down the cut line.   It was not a quick process, but quick enough.

Clamping the metal in preparation for bending.

Clamping the metal in preparation for bending.

Now I was ready to start bending.  The first step is to clamp the metal.  I went through several iterations of figuring out the best way to do this.  The picture shows close to the last iteration. The Irwin bar clamps were not powerful enough to actually clamp the metal so I used two C-clamps to tightly clamp the metal.  (Refer to Episode 29 -Clamps for more detail about clamps.)  The bar clamps were used to hold the backing piece of hard wood to the work bench.  If you look very closely you can see I rounded the edge of the backing block to make a bend radius.   Later I stopped using that side of the backing block and I think I got better results for this gauge of sheet metal.

Measure, adjust, Measure, adjust, and then measure again.

Measure, adjust, Measure, adjust, and then measure again.

Measure, measure, and measure again. It was fairly late in the process before I developed this way to measure.  I should have checked for squareness when I marked and cut the metal.  I should have compared and measured the differences in the top and bottom pieces.  The rule always is to check and check often and if necessary cut your losses before you put any more work into something that may be going wrong.   Actually, in many ways I lucked out.

After the bend is completed.

After the bend is completed.

Once the metal is securely clamped, use a rubber mallet or some other “soft” hammer to make the bend.   If you notice on the previous pictures as well as this picture the V cuts are deeper than I had planned.  This was done once I had already had bent the top piece.  Things were not going to fit correctly if I had continued to completely follow the plans as they were drawn.  I think my problem came about either because I did not figure the “take-up” correctly, or just some lousy measurements.  In any case I coped and the final product came out ok and will work with the power-supply.

Soft hammers need to be used to keep from “dimpling” the metal.   A rubber mallet works well for the large bends.  However when it came to bending the tabs a rubber mallet was not as effective.  In a few cases I even had chucks of rubber flying off the mallet because the tabs were so small.   I did try a hard faced claw hammer a couple of times.   This did get the metal to bend, but I did have some dimples.   I was able to remove those, but I basically got lucky again.  Often hitting a piece of metal with a hard object will stretch the metal creating major headaches later.

The completed Enclosure.

The completed Enclosure.

The last picture shows the completed enclosure.  The circuit behind it is the one that will be put in the box.   While this is not as perfect as the factory made ones, I did not have to buy an oversized box jut to be able to place the circuit inside.  I really don’t think it looks all that bad.   It does look better than some of the Christmas presents I have wrapped.

Gary

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