M4A1 Sherman

[Herr Dr. Professor]

Keep us informed! I think it's interesting to see if you can make a 3D printed gearbox hold up. It may be enough to show off on the living room carpet or the basement floor, which is about all my tanks do anyway.

[RiskyR]

Keep us informed! I think it's interesting to see if you can make a 3D printed gearbox hold up. It may be enough to show off on the living room carpet or the basement floor, which is about all my tanks do anyway.

We'll see, I'm not done experimenting yet

So what to do while waiting for the top hull to be printed..?

After getting inspired by Spinetti (with his 1/12th scale Hetzer Build) and some motivational words on facebook, I started on designing my own differential with differential steering. Buying a complete differential would probably be stronger but I really enjoy brainstorming and figuring out things like this myself.

So far I've got this, a complete differential from scratch with reduction built in. The drums are for differential braking (idea from Spinetti), but I haven't gotten to the point of creating a working mechanism yet.

That said, I'm very happy with what I've got so far, especially as I'm no engineer! Once the design is finished I'm going to print everything and test it out. If it doesn't work I'll probably buy a differential anyway...

Fits perfectly

[RiskyR]

Also some progress on the other drivetrain, as I want this option to be a possibility as well, because most R/C tank electronics are based on the 2 motors/gearboxes principle.

So the design of my first gearbox has been revised on lots of points. Everything is mounted in ball bearings and the housings have been modified to make optimal use of the space which I needed to insert the bearings.

Everything looks good. I've ordered motors, bearings, 4mm steel rod and small screws to build this version of the gearbox.

Fits good in the bottom hull. I've added an extra support bracket just aft of the drivetrain to stiffen it up a bit.

[RiskyR]

Sneak peak of the first part of the cast hull
Some minor cleaning up needed, but very happy indeed!

[Tiger6]

Looking good so far. You might want to think about investing in a cheap resin printer like the Elegoo Mars for doing things like lifting eyes and periscope guards.

[RiskyR]

Looking good so far. You might want to think about investing in a cheap resin printer like the Elegoo Mars for doing things like lifting eyes and periscope guards.

Thanks! A resin printer may be a good option for the future, but first I want to finish the prototype and improve it where needed

[RiskyR]

The top hull is printed, but I can't pick it up due to my dad being in quarantine!

I've been busy redesiging a lot of parts. Most of the suspension has been remade from scratch and improved where needed. Also more detail added.

I've also been thinking about the bottom hull. Even though it's decent, I wasn't happy with the construction/design anymore.
After some thinking I've completely remade the bottom hull in Fusion. It should be much stiffer now and easier to assemble, now with screws or bolts instead of only glueing everything together.

Another reason to redesign the hull is for better fitment, as designs in Fusion are way more accurate and actually nicer to build. The Cast hull is something I haven't been able to do in Fusion (yet) so that's still made in Blender. From now on I want to design the new parts in Fusion.

Once this model is finished I want to continue with other Sherman variants, including the M4A4 with the stretched hull. With my new design it should be easy to lengthen the hull.

[RiskyR]

I finally got the Hull! Glued it together, looks very nice. Does need some work to give it a cast look, but I'm very happy with the shape.
Unfortunately there was a small error in the STL file, which resulted in a minor defect on the right hand side of the centre section. I'll have to fix that.

I'm very very happy so far! I've already got some improvements in mind for the hull, so that it can be assembled easier. I think a project like this is never really finished

So, what do you guys think?

Most details aren't added yet, because they didn't come out of the printer as planned...

[HERMAN BIX]

Thats coming together wonderfully Mr Risky
Must be rewarding to see your efforts taking actual shape over time.

[RiskyR]

While the M4A1 with its cast hull and complex turret shape is giving me lots of headaches, I had to do something else..
So I started on the second variant I want to make, the Firefly with the long M4A4 hull. You can see how much longer it is.

Making steady progress as I built this sherman from scratch in Fusion, really like how the program works. The complex shapes of the M4A1 is a very different story though.

If there's enough interest I'll open a new topic for the Firefly.