Still just working on bogey parts, and adding supports on the bottom of the frame before I skin it with sheet metal.
The big spacer blocks are among the more tedious of items. They are what centers the bogey arms inside the track, by extending the bogey assembly about 3″ away from the hull.
Here I am adding the cross supports to the bottom of the frame, adding strength. The frame is still very light:
Two more of these on the bottom, and then I will go through and add gussets in places I think need a little extra strength. Then, it will finally be ready to be sheeted.
Sorry for the recent hiatus… been pretty busy. Some of which, was doing some work on my ATV trailer which will some day haul the tank around.
I have been working on the bogey pieces, and the frame.
And here I’m adding a support down the center of the bottom of the frame. I will still add more cross members from this support to the sides, but have to weld this one in place first:
So I’m still working on stuff, just lots of small steps to finish up the bogies and the frame. Stay tuned.
Here are the bogey parts:
From the side, notice the block that extends the bogey off the hull so it will be in the center of the track. Also, the back plate that sandwiches the bogey arms (need spacer where you can see the bolts going through):
What it’ll look like bolted to the frame (final version will have the road wheels and upper roller wheel of course):
So, I have one bogey (of six) completed, except for a spacer. I have most of the bogey arms done. And all the grey bogey assembly fronts, and backplates. Just need to finish drilling a bunch of holes, and cutting the big blocks.
Drumroll please… it fits.
One thing that is odd about this build, is that I actually am building the tank around the conveyor belt I got for the track. I got a piece from a rubber store that was 6″ wide, and about 20 feet long. I cut it in half, and each belt was 129″ long. From this, I determined the scale of the tank.
So, after making all this other stuff, I needed to test the belt length to make sure I was still on track. With the frame 5″ off the floor. Looking basically perfect:
Then, a quick test of the overall size of the bogies. The bogies are not done, there will still be a roller wheel on top, and they will be bolted to the frame, but, this is a decent test of their size:
I began cutting out the pieces for the bogies.
First, the main bogey assembly pieces (gray), and then the bogey arms (black). I need to make 4 more bogey arms… I ran out of that thickness of UHMW, so need to go get a small chunk. It’s the same thickness as the drive sprockets, 3/4″. I still need to drill holes, run the bolts, cut the springs, make the spacer blocks which go between the bogey assembly and the hull, etc. But they are starting to look like something, which is cool.
I also cut the road wheels (aka bogey wheels) out of a solid cylinder of UHMW, 5-1/8″ diameter. I’m cutting 7/8″ thick discs for the wheels:
Here I cut a spring, and set everything up to see what it would look like assembled… pretty darn awesome… and might even work, haha:
I finished the idler arms, with the bolt-on inner arm which will be used to adjust the tension:
Here it is, with idler wheels set on there, just for planning purposes at this point. Spacing etc will be determined later to line up with front drive wheels, and the bogey road wheels.:
Added square tubing to the front of the frame. Notice the 3″ wide gap on each side. This is where the pulleys and belts will run, so leaving it open give me a nice range of angles the belts can be at… which leaves me options for motor placement etc later on:
Added the tube in the front of the frame, which the fixed axles (5/8″ bolts) fit into. Still need to add more supports for it, and cut the center out, where nuts will go on the end of the axle bolts:
Drive wheel installed. This is very helpful for determining other measurements with the bogies, rear idler wheel spacing, etc.
Bogies are one of the more daunting and crucial tasks in a tank. First, there is the sheer numbers: 6 bogeys, 12 bogey arms, 24 road wheels, 6 small roller wheels.
They are also important, functionally, as they provide the tanks suspension, keep the track from coming off, and give the tank it’s ground clearance.
I did the math on the bogies placements, etc, to determine the desired length of the bogey arms and where to put vertical frame supports (the bogies will attach to the the frame supports rather than the thin wall of the hull):
Then, as you can see in the bottom of the picture, I determined if those numbers work on the actual frame I have made. I made a cardboard version of the bogies to help me do this:
I used the cardboard template on the 3/4″ thick UHMW (using gray should make them look cool), and will begin cutting those out soon. I got very lucky all 6 just happened to fit.. it took me a few tries to get them to all fit, and at least there won’t be a lot of wasted material:
Here are the little roller wheels, like 2.5″ diameter, that go ontop of the bogies, to hold up the track and keep it from hanging down and rubbing the bogies and stuff. These were actually given to me from a Plastics place, which is always nice: