Here is my RC semi-replica of a Soviet self-propelled gun. Metal only. This is an almost completely kitchen-table product, as I used a minimal amount of equipment and tools as I built it. I didn’t face any difficulties casting the aluminum mantlet, and I wrote articles on that earlier:
Casting aluminum parts at home is easy! A muffle furnace and equipment.+0
Dec 18, 2015, 5:22:32 PM | Konstantin Morozov Ufa
Article http://www.rcfair.com/blogs/view_entry/12989/

Casting aluminum parts is easier than you think!+2
Dec 28, 2015, 1:04:51 PM | Oleg Trapeznikov Polyarnye Zori
Article http://www.rcfair.com/blogs/view_entry/13050/
Only one or two such tanks were built at Uralwagonzavod after WWII – the intrafactory Uralmash-1. The one and only specimen is now exhibited at the Kubinka Tank Museum near Moscow, and the second one – the ten times smaller replica – is, happily, at my home)))

Materials include stainless steel of various brands and DT and AMG aluminum alloys; all fittings are made of stainless steel too, tracks – of galvanized steel; all parts are argon-welded, no soldering was done. The traction part includes two 550/12V brushed motors, a dual-clutch two-gear reduction transmission and independent coil-spring suspension. Total weight – 17kg. Dimensions – 700/200/400mm. In this article, I’m going to demonstrate the process via photos and vids instead of describing it.

What motivated me to choose this particular model was the World of Tanks (WoT) game, which I’ve been a fan of since the time when it was beta-tested before getting out into the open. Everybody likes the SU-101, and the most important thing about it, I think, is its velocity and crazy appearance (let’s disregard flaws, because my tank's only enemies are road ditches)))).

The first work was done a year ago, and that was nothing more than vague sketchwork. I’d found drafts, which I then saved in Excel, printed out and pieced together into a single A1 draft. At that moment, I had a welder and a batch of 3mm heat-proof stainless steel sheets.

I used the draft when putting together the two halves of the body, each made of stainless steel sheets.






Then the work stopped for more than six months. That happened for the simple reason that I needed a turning lathe or use help of people who had the skill of turning and lathing. At that time, I could afford neither. However, I finally got some money and bought a lathe, which I’d dreamed of for quite a while. I bought Corvet 400 and installed it on my recessed balcony, which I now use as a miniature workshop. Also, it took a little while for me to learn the skill, buy appropriate equipment and materials, so in the fall I continued my work.


First, I turned lever pins, road wheels, pins with bushings and rollers with ball bearings.







I also bought dual gearboxes from a Hitachi screw gun and Hobbyking X-Car 45A Brushed Car ESCs. The HK-310 transmitter was all mine. After a lengthy debate with myself over how I had to operate two ESCs at the same time, I chose a channel mixer, which is used on ‘flying wings’ (one would say that I could have chosen Arduino, but I decided not to). I wouldn't even consider buying an airplane transmitter with a built-in mixer, because it was extortionate for me.

Later, I’d spend all post-work evenings turning metal sundries and went to my dacha on weekends to weld and polish the stuff. Also, I ordered all sorts of M2 and M3 stainless-steel fittings at AliExpress and silicon O-rings for balance beams’ axels, and bought lock rings and springs at a local car accessories store.











Initially, I planned to make roller bands out of black sealer. I decided not to use raw rubber, because it was too hard and I didn't know much about it. However, the sealer did not work either. Merlin sealers solved the problem, although I had to do a bit of grinding.
I also had to hire a guy to laser-cut track shoe guides and drive sprockets.



Next I was to put it all together – assemble the transmission and weld the tracks. The tracks consist of door hinges, the track shoe guide is argon-welded, and the treads are studded together. The output drive bar features two ball bearings and is connected to the screw gun gearbox with a pair of discs from an angle grinder.







Later, the whole thing was disassembled and reassembled many times, and there were tons of sundries, which took tons of my time.










Now, my first test drive.




Now, my first test drive. The power unit included 6V brushed motors and a two-cell LiPo pack, but that was far from enough. I wanted 12V motors and hence I took out two automobile compressors. I also bought a lead accumulator, but it wouldn’t work because of poor capacity.



Then I had to spend a few weeks jazzing it up, as I had to craft small tanks, the gun and other strap-on stuff. I had to cut a lot of old Soviet-style pots and kettles, skewers, cups, etc., as I needed the right kind of stainless steel and aluminum. It also took extremely precise impulse welding.










Now that all parts are collected, here are some general pics.











This time I used a three-cell LiPo pack, which pretty much sped up my little tank. However, it gained 17 kg of weight. At low gear it behaved like a crazy trophy collector – not fast, yet with excellent traction and moderately warm motors with ESCs. At top gear the motors heated up pretty bad and stopped when moving uphill.





Now I’m intent on replacing 550 motors with 775s, although I’m not yet sure about their current consumption level or whether or not the ESCs will make it. Although my passion had ebbed a little by the time, building it was an excitement for me, so I don’t think I’ll continue to improve it. I do have some ideas and tools though – I can replace the motors, add a gearshift guided by Servo via Channel 3, connect the halves of the body, so that they would unfold by aid of a shock absorber, seal the seam to make it waterproof (now the power unit is sealed with O-rings and oil-seals), place the on/off switch on top and camouflage it. Although it was freezing cold, I did arrange a little shoot for my little fighter in the city’s Victory Park right in front of its full-size ‘siblings’.













Sorry for not posting all 170 pics, a dozen of vids and tons of written text right here. If you need details, please, welcome to rcdisign forum. Thanks for reading, viewing and watching!

Well, one more thing: the whole thing also involved foam-casting of the gun mantlet. There is a brief description of the process in one of my old posts:
Casting aluminum parts at home is very easy! Lost-foam casting. +1
Dec 17, 2015, 4:42:08 AM | Konstantin Morozov Ufa
Article http://www.rcfair.com/blogs/view_entry/12980/

To do that, I made a styrofoam template and attached a gate later



That took quite a bit of effort. I had to match my tank with models used in the game, as well as with my draft and scale parameters. As you can see, the mantlet is empty. I cast it from scrap duraluminum. I used a makeshift muffle furnace, about building which I wrote in one of my previous posts.
Casting aluminum parts at home is easy! A muffle furnace and equipment.+0
Dec 18, 2015, 5:22:32 PM | Konstantin Morozov Ufa
Article http://www.rcfair.com/blogs/view_entry/12989/
<br class="block_preview_blog mceAtomic" /> Now it is twice bigger and mightier, although it uses the same principle. I poured plaster into the mold and left it to dry for about a week; before pouring in the plaster, I heated it up to 250-300°C using my gas oven (until the foamplex template began to smoke). The last thing I had to do was to polish it with a metal brush and even it out.



This is the translated version. You can read the original Russian article here.