More turret work, starting hatches

I began making the hatches on top of the turret.  Being a scaled down tank, the hatches would obviously need to be scaled down also.  However, then a person could not fit through them.  To solve this, I am doing a large hatch big enough to get in and out of,  that will be flush and hard to see.  This hatch will then have on it, 2 smaller hatches which are true to scale and will look good. One of these (the round one) will be used to stick your head out of to see when driving.


I am also doing some filler work on the outside of the turret, to smooth it out so it will evetually appear to have been cast like the real ones.  For body filler, I’m using a filler (powder form) that you add to epoxy resin to thicken it into a paste that you can spread smooth, then sand (like bondo).

Lower hull almost done

I finally finished fiberglassing all of the outside surfaces of the lower hull. Stopped and sanded a few times, before adding more cloth/resin, to keep everything fairly smooth. Definitely not a perfect job, but most of this won’t be visible, I just wanted it nice and waterproof. Then I primed it with self-etching primer, then sprayed a coat of green. Still need to do a little more on the first coat (ran out of paint), and then spray another coat. Then I will be ready to flip it over and paint the inside, and get it all ready to mate it back up with the frame.


It’s always nice to see stuff in it’s final color!

Hull and frame about to become one

Although it doesn’t look like I’ve done much, I did a few things I was previously putting off, and finished up the bogey mounts.   I finished up some welds I never quite did on all 4 sides of the joints, and ground down all the welds that were sticking out off the frame, which would have kept the hull from fitting right.   So, without further ado, today’s pictures…

Here’s the outside of the bogey mounts where I ground the welds flat, flush with the frame:

Here, you can see I finished fiberglassing the inner seams:

Here is the frame inside of the now really-close-to-being-finished hull:

All the hull needs now is some more sanding, maybe some more fiberglass resin in places, and of course, my favorite part… paint.  But for now, I have the frame sitting in there so I can drill all those holes through the hull, so I can then mount the bogies, and the rear idler arms.  I will also drill holes in a few other places where the frame and hull will be bolted together.

Making bogey mounts

Before I can have a rolling chassis, I  need to make the frame mounts for the 3 bolts that attach the bogies to the frame.

Here are the mount  pieces:

They will be welded to the frame like this:

Bolting the bogies on, to hold the mount pieces in place while I weld them on:

Here they are, all of one side bolted on, ready to be welded… they really make this chassis start to look like something.

Once the mounts are all welded in place, I will remove the bogies, add the spacers, bogey arms, springs, upper rollers (which support the track), and finally the wheels.  I am currently using 1/4″ bolts.. I’m a little worried they will be weak, so I might drill them out and replace them with 3/8″ or even 1/2″ bolts.  I could also just replace the bottom center bolt making it the load bearing bolt.  We shall see.

One other note… the wood hull will also need to have these same holes drilled, so the bogies can mount on the outside of the hull.

The Incredible Hull

I finished cutting the pieces of the main hull, and began gluing and brad-nailing them together.  Only being 3/8″ plywood, and using normal butt-joints, doesn’t create the strongest joints.  But it turned out to be a really nice fit around the frame… like a glove.

I then did a little research on the best way to strengthen those joints/seams, and it quickly became very obvious what I should do.  It’s a hull. Water tightness or water resistance would be a cool feature.   Sounds a lot like a boat.  So I decided to use fiberglass.  I already had the supplies (2 part fiberglass epoxy) from some past boat repairs, so I just bought some fiberglass cloth, and cut it into strips.  You can buy it already on a roll, but cutting it worked fine for me other than all the extra strings all over the place.  I flipped the hull over, and placed it on the upside down frame.. this way, I know everything will be square and still fit after the fiberglass dries and gives the hull the rigidity I am looking for.

There is apparently a method in boat building called “stitch and glue”.  Where you literally just take adjoining pieces of plywood, and drill little holes and stitch them together with wire (or zip ties).  Then you “glue” the seams with an epoxy, or fiberglass tape and epoxy.  Then you cut the stitches and do another layer to fill your holes.   For the seams that were not easily wood glued and nailed, I decided to try my hand at this stitch and glue method.  Turned out to be really cool and was easy to do.  It’s a little ugly now, but fiberglass appearance shouldn’t be judged until after some sanding, and more coats of epoxy and sometimes more cloth.   Also note that in these pictures, where you can see white colored cloth, the epoxy has not yet soaked the cloth completely.

So far I am so pleased with the fiberglass method, I am pretty sure now that the main tank body later on will be made of thin plywood, with fiberglassed seams.  It’s light, strong, waterproof, and easily fixable if it has issues.  You can still easily cut it, drill it, or add more fiberglass to it.  And of course, it can be painted.   Stay tuned for the completion of the hull!

Back to building… finally.

Sorry for the HUGE time off since my last post.  I’ve just been super busy with about a million other projects, including even having to go through and clean and organize my shop work space.

Also, I scrapped the whole sheet metal hull idea.  I started to do it, but the metal was just SO thin my welder wasn’t working great, and it was just really hard to work with.  I decided using pretty thin plywood would be much easier to work with, easier to attach stuff to, and easier to modify later if I need to.  It may add a little weight, but I think the trade-off is well worth it.  I mean, it is a tank after all, not an ultralight plane.

I started by cutting the bottom pieces, using 3/8″ plywood:

Then I cut the sides:

So I guess my next steps are to just cut a couple more pieces for the front and back, and start joining them all together to make a solid hull that will be bolted to the frame.   And of course, once that is complete, I will finally be able to finish the bogies, and begin attaching them to make a rolling chassis.

Back to work…

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.

Rear Idler Assembly

The rear idler wheels are, much like the drive wheels, the ones “in the air”, except in the rear of the tank.   They need to be able to move or pivot to take up any slack in the track.  I have thought about different ways to do this, each with different benefits, and pitfalls.    The easiest would probably be a a sliding axle type of setup, but your hull needs an elongated hole in it, in which water and dirt can enter.

So, I am using the design that Dave Manson uses in his famous 2/5 scale Sherman (his many videos are a youtube sensation, the ultimate tank builder’s HowTo).

His design uses an eccentric shaft, which basically has 2 arms at 90 degrees, with a connecting rod going through the hull.

Looks like this:

I have begun building the idler assemblies, because I need to know where to have a hole in the hull, which effects my frame design, etc etc.

I am just using 8″ long 5/8 bolts for the idler axles.  Some 5/8″ steel rod as the “peg” that goes through the hull and connects to a lever.   The lever, then, when pulled down, pushes the idler wheels back, which tightens the track.   Very elegant solution, thanks again to Dave Mason.

Frame again

Frame coming along nicely, and drivewheels are done…

Clamping second side to completed first side:

Both sides done set out to decide width:

Notice the (soon to be) supports across the bottom of the frame.  The drive sprocket teeth are shaved to a point, and drive wheels are fully assembled (except bearings):