track.html

Track

These are all the pieces needed to make one link of the track. The wood track pad is two pieces screwed and glued together with the edges cut to accept the metal links. Each link has 4 metal pieces with a total of 5 drilled holes and three welds. Two per pad are needed. The links are attached to the pad with 4 wood screws. Each pad has a piece of 3/16 x 4" aluminum bar with 4 countersunk holes. It is glued and screwed to the pad with 4 flat head screws.

By far the most time consuming part of this project is the track. I hope it lasts! The tank has a total of seventy pads, 35 to a side. The size of the track pad is 6 1/2 x 4 1/4 inches. The link center to center distance is 4 1/2 inches.

I started by cutting out the pads. The pad edges have notches cut in them to conform to the links.

Seventy pieces are required. I made a few over 72 to have spares. With all aspects of track building, working to have identical pieces is very important.

A small wood block is screwed and glued to the pad. This block is straddled by the tank's wheels and helps keep the track from falling off. Here I have a jig clamped to my drill press so I can quickly and consistently align the pieces for the pilot hole.

With the wood work done, its time to cut up some steel. I used 1" x 1/8" steel flat stock. Each link has a 2 1/4 and 4 1/4 inch piece. On the left you can see the two lengths, and on the right I'm starting to drill the holes.

The total amount of flat stock needed is about 80 feet. I built enough parts for 72 links, thinking I may need 36 on a side. It turns out the tank actually needs 35.

A track link forms a chain around the edge of the track. One end has a 1 1/4" length of 1/2" steel tube, the other has a 1 1/4" long 3/8" bolt. The long piece of flat stock has two holes drilled in it for the wood screws. The left hole is oversize so the distance between the tube and bolt can be set accurately. The short piece has a single screw hole.

I wanted to drill the holes before welding in case the metal hardened during the welds.

You end up spending some time drilling holes. The 1/2" and 3/8" holes tend to make racket and get the tools hot. You can see the discoloration of some of the metal cuttings. Eye protection is a must with most of this work.

I used a jig whenever possible. Here the same jig is used to drill both large holes.

I got tired of the noise and sharpening drill bits, so I decided to build an oiler. I cut up a $12 box fan and made an oil pump by making an impeller and welded up a cavity to contain it. It stands in 6 quarts of motor oil and pumps it through a length of 1/2" plastic tubing.

I used a length of 4 awg copper wire to hold the tubing. Under the drill press table I suspended a pan made from thin gauge metal, the kind used in HVAC duct work. The pan is tipped to direct the oil drippings to one corner, where a hole returns the oil to the bucket with the pump.

A nice side effect is the oil tends to wash the metal chips out of the jig.

After I was done drilling, I needed to cut the tubing. The oiler was fitted to my cut-off saw to help it cut true, and keep the blade sharp. I used some sheet rubber to wipe the blade as it travels past the stock. The whole saw stands on a metal drip pan to keep oil off the concrete floor.

After the cutting and drilling, its time to do a lot of welding. I bought a cheap flux-core wire welder from Harbor Freight. Here I've finished the 72 short pieces with the bolts welded in place. Next will be the tube and long pieces. Finally, the two halves are welded together after they are assembled in a jig to contol the tube-to-bolt spacing.

When I was welding it was winter time and quite cold. I welded inside the house by doing it next to the open basement door, in front of a box fan. The fan blew the welding gas out doors and I had a 'warm' place to work.

After the links are primed and painted, its time to assemble the track. Here a jig is used to align the pad and links. An electric drill was used to drive the wood screws. Before a new link is added, grease was applied to the bolts.

Pilot holes were first drilled into the pads on a separate jig clamped to the drill press.

The first track is complete! I started cutting up the wood during the summer, the welding was done in the winter, along with the painting, and now final assembly in the spring. It helps to be patient!

This was a happy day! At last the tracks were mounted on the tank, and it's starting to actually look like a tank! Woo Hoo!

I decided to add the aluminum shoes as a precaution against wear and tear. I always knew I had to do something to protect the wood pads, but I was never satisfied with a solution. I considered rubber but was concerned it would be to sticky, and the tank would have a hard time turning. Steel is heavy and rusts. Aluminum is expensive. The shoes are 3/16" thick 4" aluminum bar cut 5 3/4" long. At this point I promised myself that I wasn't going to do any more work on the track!