New for 2025 - US M3 Half track

[tankfan0720]

New project for 2025! I've always wanted a US M3 half track. The issue with building one is the rear tracks.

I think I've got a working solution..

sprocket CAD model


Version 1 track. This would work if end connector blocks are metal?


Version 2 track. I like this version better - fewer parts.




So I printed a prototype in Army Green and Galaxy Black (Prusa)




Version 2 prototype track







Hopefully more fun in the new year!
B

 

[Sixth Vanguard]

That looks like a good solution.
I have loved US halftracks since I was a kid and built the Monogram 1/32 scale kits.
I have started more scratch build 1/6 scale attempts than I care to count.
When Randy's Killen made his US Halftrack

M3 Halftrack

I just saw the M3 halftrack this morning when Randy stopped by the house on his way to WOH. All I can say is it is one nice looking American vehicle. The tracks are very well done, has rubber front tires. All the undercarrage is there. Drivers compartment all the little details and more. If no...

www.sixtharmygroup.com

It was so good I never had to build one from scratch myself. I have quite a few of them. One is a built up prototype Randy sent me as well as a production kit. When FOA took it over I got another and one of the 'M16' kits witch used an 'FOA-ized' version of David Dibb's, of Armorpax fame, quad 50 mount. Unfortunately I got "FOA'd" and after many many attempts at getting the correct parts sent to me (for example I received 2 front fenders for the same side instead of one left and one right; 2 caliber 50 mounting rings for the same side of the quad mount instead of one left and one right; many warped resin parts... you know... classic FOA stuff) I gave up as I stopped getting responses for my requests for the correct parts to be sent.

I hope your kit is a great success. The US halftrack was so ubiquitous it really needs to be represented more in the hobby.

 

[tankfan0720]

Hi Sixth, yes I remember Randy's build - it was really neat. This will be RC, and won't be a kit. Its a "just for me" project. But I can help others get their stock rolling if need be.

Once upon a time, Armortek made an decent M3 kit, but the Achilles heal is/was the tracks, but also it only has one motor driving the tracks. This makes it hard to turn.. The rubber used in the track cracks and deteriorates with UV exposure. This design could be machined in Aluminum for a more permanent solution to the cracking problem. I will use an independent motor for each track, so should be better for torque and turning.

Yes I got "FOA'd too". Seems anyone who's been around 1/6 long enough has been burned by them. Damn shame. I bought their SDKFZ 251 kit for $500. The steel body is decent, but the resin parts are garbage. Warped egg shaped wheels, no provision for bearings and the two front rubber tire halves don't fit together -at all. I will have to make new running gear. Fortunately with 3D printing this is possible.

I've seen a pretty nice conversion of the FOA M3 and SDKFZ 251 into RC on Youtube. The steel body requires some work to put together without rivets. But with some creative tinkering for the drive train they make nice runners.

I like the scratch build projects. But I have a golden rule - start every project with the tracks and wheels. If you can make or get the tracks figured out then the rest is pretty easy.

Happy New Year! Hopefully more soon.

B

 

[Sixth Vanguard]

...
I like the scratch build projects. But I have a golden rule - start every project with the tracks and wheels. If you can make or get the tracks figured out then the rest is pretty easy.
...

That is a very good rule

 

[Rolling Thunder Tech]

Looks like you're on the way to another masterpiece. I also have two of the FOA halftracks, an M3 troop carrier and an M16 version, and one from Armortek, which I don't us much for RC as the tracks are like you stated above. If you do decide to produce replacement track assemblies, I would be interested in three sets.

 

[azazel526]

I always had a question about the M3 half-track armored vehicle, is its track a whole rubber strip? Or are its tracks regular piece by piece metal tracks and then they're covered in rubber? I've always had the idea of building the M3 half track, but I can't handle the full rubber strip track at the moment, so I'm afraid to do it, if the M3 half track exists with splice tracks, then I can try to start the project

 

[fusilier1944]

Please correct me if I’m wrong, but my understanding is that the tracks were metal cables with rubber over-molded into one giant loop.

I was joking recently with a colleague that we could 3d print 1/35 scale rubber tracks in a continuous loop with the Silicone 40a resin on our Formlabs printer. We basically were reinventing the old rubber band tracks that models used to come with. It could work for 1/6 too, but I think only on something small and static.

 

[tankfan0720]

Azazel526 the real tracks are one piece rubber over-molded over a large steel chain like assembly. Think industrial chain. The drive sprocket connects to the chain like pieces. As Fusilier mention the outer rubber is reinforced with steel cables (molded into the rubber). Interestingly you can still buy brand new tracks for your full size half tracks. They are made in same way as original. Photos below.

That said, I don't want to mess with rubber anything. At 1/6 scale its too difficult to duplicate, maintain, and get working correctly. Printed or machined links while not 100% accurate are easy to make, maintain, and should run great in RC application.

Another deviation I will make on the model will be the volute springs in rear suspension. These are difficult to make and hard to get working correctly. So I will use regular coil springs.

Real brand new manufacture track



New tracks installed



Rolling thunder PM me maybe we can work something out. Are your FOA M3's RC?

HNY all.

 

[azazel526]

Thank you for your answer, it seems that the rubber track is still a troublesome problem, and I need to wait and see for a while to consider some other solutions

Azazel526 the real tracks are one piece rubber over-molded over a large steel chain like assembly. Think industrial chain. The drive sprocket connects to the chain like pieces. As Fusilier mention the outer rubber is reinforced with steel cables (molded into the rubber). Interestingly you can still buy brand new tracks for your full size half tracks. They are made in same way as original. Photos below.

That said, I don't want to mess with rubber anything. At 1/6 scale its too difficult to duplicate, maintain, and get working correctly. Printed or machined links while not 100% accurate are easy to make, maintain, and should run great in RC application.

Another deviation I will make on the model will be the volute springs in rear suspension. These are difficult to make and hard to get working correctly. So I will use regular coil springs.

Real brand new manufacture track

View attachment 7753

New tracks installed

View attachment 7754

Rolling thunder PM me maybe we can work something out. Are your FOA M3's RC?

HNY all.

 

[Rolling Thunder Tech]

I feel that the track links are a viable alternative. I have a Hasbro half track that was converted to RC using Stuart track. Not very accurate but it works and is fun to drive. Tankfans' track links are very close coupled and is a great alternative to the one piece rubber track. For the full sized vehicle, it must have been difficult to obtain and replace the track loops in the field.

My dad was commander of Battery C, 50th AAA Army attached to the 1st Marines, with M16 halftracks in Korea and at the Chosin Reservoir.

 

[tankfan0720]

Wow Leonard, that's interesting about your dad - I bet he had some stories to tell.

I may make this into a M16. The quad mount would be an interesting model to make.

So far I'm happy with track design. There is very little visible gap between the links.

 

[Rolling Thunder Tech]

Which 3D printer and software do you use for designing and producing the parts? I've been wanting to purchase one and have been playing with the Fusion program.

 

[tankfan0720]

Hi Rolling Thunder - I use Inventor for design. Its similar to Solidworks. But Fusion 360 will do the same and has more features (CAM, FEA simulation) etc. I would use that. Fusion is made by Autodesk, same as Inventor.

For printing Bambu lab X1C and Bambu Studio slicer. Both great and easy to use.