Making Reproduction Erector Box Latches - A Tutorial by Bruce Hansen

One part that is missing from a lot of eBay "treasures" is a part that was never assigned a part number - the box latches. These were made out of steel and washed in brass until 1957 when the lithographed sets had latches which appear to be Cadmium plated. This tutorial will show you how to make reproduction latches.

I measured the thickness of a number of latches anywhere from 0.028" - 0.040"; I used 0.040" sheet stock. First, here's a sketch of the latch blank. The first step is to lay out and scribe the blank. I coat the steel stock with layout blue and mark the dimensions with a carbide scribe:

Next, center punch and drill (2) 3/32" holes at the outside edges of the bottom slots. The outside edge of the hole should be at the edge of the scribed line. You don't see it in the picture, but the sheet metal is clamped to the table. Drilling unclamped sheet metal is a good way to make an unintensional saw blade.

Drill a 7/16" hole in the blank next:

I used a sheet metal shear to cut blanks. A tin snips or aviator snips would work also.

There is a handy sheet metal shear/punch called a "nibbler" which I used to trim the inside hole of the blank. One source for a "nibbler" is Radio Shack for about $10.

Here's a picture of the rough trimmed latch blank:

I ganged (3) blanks together and filed the top radius:

The inside features and outside radii are filed with needle files. One tip here; position the blank up/down so the bottom scribe line is flush with the vise jaws. Then file down right to the jaw top. Now is a good time to file any burrs from drilling, shearing, etc.

I cleaned up the surface with a wire brush. Two tips here; grip the blank only at the bottom as shown with a vise grip or pliers. If you use a vise grip on the "show surface", make sure you tape or protect the surface from the vise grip jaws; they'll leave marks. Second tip; with wire brushes it's a good idea to wear a full face shield. The wheel can/does throw wire pieces which are essentially needles.

I did the 1st latch bend with a press break. This is one of those Taiwanese all-in-one sheet metal machines with shear/break/slip roll in one machine. The bend could be done in a vise also.

There is a 2nd bend which I did in a vise with a large screwdriver. If you have an existing latch, you'll see what being done here:

The bend position of the latch over the box is done by scribing a line 1/8" above the box top. Install the blank on a box, lay a 1/8" thick scale on top of the box and scribe the line on the blank:

Now, bend the blank; use a break or vise/block. I ran the blank over the wire brush one last time at this point:

The blank is electroplated with the setup shown here. I use a brass plating kit from Caswell Plating ( called "Plug 'n Plate". The brass kit costs $35 and includes a transformer, plating wand and 4 oz. of plating solution. Plating is simple, clip the black negative lead on the blank, dip the wand in solution and wipe the wand on the part. The solution is cyanide free and plates about 1 square inch per minute. There are kits/solution available for nickel, cadmium and other metals also. I wasn't able to get a bright brass finish; more of an antiqued brass finish which looks pretty close to original latches.

Here's a look at the final product. An original latch is in the upper right: