Tiny Tank Update: TRACKS!

There comes a few times in the course of my silly projects where something tiny and insignificant looks like a much bigger deal than it actually is.  Yesterday my friend Matt came over and we spent some time tinkering with the tank.  We pulled the rotten muffler off of the engine, tinkered with the transmission a bit, and spent a lot of time discussing changes to the drive train. 

At the end of the day, we'd re-designed the axle for the idler wheels at the rear of the tank, built it, and installed the first track:

The problem with progress like this is that you end up taking a step back to see how it looks and get stuck staring at it for a while.

We didn't get much else done after this picture was taken.

Now I need to draw up the CAD drawings for the drive sprockets at the front end so I can replace my MDF stand-in with a proper sprocket and then see about making it go.  I've just finished drawing up the finalized design for the drive sprockets, so now I need someone to cut these out for me:

Hopefully I'll have this baby up and running this month.  Fingers crossed...

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Tank Progress Continues...

It's been a busy week, but I've still managed to make a lot of progress on my little Sherman tank.  First off, I had to rip down an ipe plank and make the last sixteen track shoes I needed.  Here I am turning the ends on the lathe:



Once I had all the parts I needed, I lined them up on the table saw and pulled out the jig:


Then it was time to pre-drill, glue, and screw all of the parts together.  There were 58 outer track plates and 58 inners, so I had to turn down 116 ends, fit them with 116 stainless bushings, then drill 232 holes and drive 232 screws, all while sandwiching a strip of conveyor belting and a thich coat of epoxy in between.  It was a long afternoon:


In the end, this was the resulting track:


I also made a lot of progress on the transmission.  I learned a lot along the way.  Among the lessons: I can't weld worth a damn.  Also, the grinder absolves the welder of many sins:


After I'd cleaned up the welds (most of which looked like some kind of moon rocks) I mounted the shafts, gears, and belts:


Now I just need to attach the idler levers, mount the whole assembly under the driver's seat, connect a drive belt to the engine, and run chain to the drive shafts at the forward end of the tank.  Then I'll just need to cut out my drive sprockets, hang the tracks, and start tearing up the back field.

Here's the finalized design for the drive sprockets:


It turns out that a nine-tooth sprocket is the largest I can reasonably fit under the sponsons on either side of the tank.

Stay tuned for further updates on this goofy project...

Cranking Away on the Tank Again

To spurn myself into making progress on the little Sherman, I pushed it back into the workshop and solemnly swore that the next time it left the room would be when I drove it out. 

It turns out I know me pretty well and having this beast in my way was just the motivation I needed to get it done and moved.  So far this week I've finished assembly on thirty-two of the fifty-eight track plates I need in order to build my second track.


Then I hoisted the turret up and out of the way so I could get to work on the drive train:



Sometime in the past two or three years, a shipmate in the naval reserve turned me on to Dave Manson's Youtube channel where he's been detailing all of his scaled tank projects down in Australia. He's made some amazing finished tanks, but the main thing he figured out that I was stuck on was the transmission:

The man is a genius!  With a few minor adjustments, his transmission idea would be an exact fit for my own Sherman.

Not long after seeing the video, I ended up ordering almost all of the bits and pieces to make the transmission.  On several occasions I've gone ahead and mocked up a housing to help me decide how it will all come together.  Each time I ended up just jumbling all of the parts back into a box, setting it back inside the hull and letting it rust just a bit more.  On Monday I caught my father in a welding mood and we spent a few minutes sticking the steel frame together:



Here's how it looks right now:


This whole assembly will fit under the driver's seat.  Now all I need is to get all of the belts to connect the split shafts in front to the counter-rotating shafts in back, and an input pulley to attach one of the counter-rotating shafts to the engine.  I'll be adding one more vertical post so I can put in one more pillow block bearing to steady the shaft that the engine input will be attached to.

I'm working out the exact shape of the engine mounting plate.  When I've got it cut, I'll be bolting the 7hp Honda engine into the engine compartment.  Then I can start plumbing in the exhaust and fuel systems.

Stay tuned for more progress.  I'm hoping to have pictures of my niece driving this beast around during her Christmas visit.  That, and I really want this thing out of the way so I can walk around in the workshop again.  The list of new projects is getting longer again.

More Pictures of Matt's Tank

I really don't have much to say about these photos. Mostly, this is just what Matt's tank looks like now. He made quite a bit of progress while I was away:

The main focus of that progress was the construction of the turret:

Here's a shot of the back side:

And a pic of Matt inside:

And me:


He still has to find an engine, then build his suspension and one track before he'll be caught up to where I am on my tank project. That gives me a little bit of time before I'll have to pull mine out and start work on the transmission.

The plan is to have them both up and running about the same time so we can do battle.

Stay tuned...