SU-100 Build Thread
 

Hello all. I have decided to build a Soviet SU-100. I will chronical my progress on this thread. I chose this tank for a couple of reasons. First, wherever I go, I'll probably have the only one, there are conversion kits for it, no rotating turret, and a huge gun.
I will use a WSN T-34 and a conversion kit I got from BYA. I will use HL electronics and convert it to HL metal gearboxes for reliability.
I plan to up-gun this one substantially. I'll start with my standard tank CO2 setup and modify it from .177 caliber to .236 or .25 cal.

So let's get started;

Here is some info on the SU-100 in case your not familiar.

RE: SU-100 Build Thread
 

Ordered my conversion kit and T-34 from Back Yard Armor. $85 each. They arrived in about a week. Good experience with BYA. The conversion kit comes with a resin body and parts as well as the metal items shown below. The quality of the resin casting was very poor but can serve as a starting point. THe metal parts were of pretty good quality. The resin parts are thick and solid. Too thick, I had to use an air sander to remove enough material so it would fit up.

RE: SU-100 Build Thread
 

THe donor T-34 was stripped down to bare minimums and all the interior plastic removed. There will be a lot of room to work with. Mocking up the gearboxes proves I will have to do some cutting on the rear to make them fit. I still have to add an additional stiffening plate.
A little trimming on the conv kit and things are starting to fit up.

RE: SU-100 Build Thread
 

Looks a nice kit.Going to good when done.
Looking forward to more on this thread.Thanks for sharing this with us.

Do the HL gearboxes obstruct the top of the hull as they look quite high?

RE: SU-100 Build Thread
 

Looks like the gearboxes will fit easily. There is a lot of room in the hull.

RE: SU-100 Build Thread
 

Nice project, I am installing HL metal gearboxes in my t34 also, nice to see they fit !

RE: SU-100 Build Thread
 

Lookin good so far can't wait to see more as you progress..........Do the spockets fit the Hen Long gearboxes without any modification?

Cheers Ian

RE: SU-100 Build Thread
 

The gearboxes do not fit without modifications. I cast an entirely new rear sprocket and turned it on a lathe to get it in the correct position. I am curious how others have done it.
This is a shot from my build. Need to get back on this project soon.







DH

RE: SU-100 Build Thread
 

Yes sir, you do have to get back to this build. In fact if you don't within 7 business days you are obligated to send me those wheels. :D:D:D

RE: SU-100 Build Thread
 

OK, my worst fears have been realized. The gearbox change will call for major modifications. Time to retreat to an easier plan. Right[sm=drowning.gif]. Experience has taught me that when confronted with a tough problem, come up with an overly complex plan then get a government grant to pay for it. Sooooo.
Had to do some trimming on the lower hull. When complete, it will call for a slight non-scale feature but it will be minimum and should be barely noticable to most. Plus it will be on the lower hull.
Once the battery box and all the internals were out the chassis was completely flexible so I cut to shape a length of .060 (that's 1.5 mm for the civilized world) 6061 T-6 aluminum. Cured that in short order. I actually now have perfect axle placement as can be seen in the pic's.
I still have to fit the drive sprocket which will be tricky but doable.
By the way, the gearboxes are for a Walker, which has a 1/4" longer output shaft than the Tiger, et al, gearboxes.

RE: SU-100 Build Thread
 

I am watching this with great interest as I am about to start my SU100.

I am just going with the metal gear replacement that is available.

I have the same resin conversion kit you are using. I used to cast 1/24 slot car bodies, and this casting is very poor in my opinion, so I concur with pscartozzi's assessment. Some time in some really hot water to reshape will be necessary as well as lots of hole filling and sanding. Still it is quicker then building one from scratch. I have a feeling the mold being used might be getting old. I just wanted to point this out so somebody doesn't run out and buy one expecting to have a perfect resin casting to work with. This one will take some time to make right.

I usually work quite fast in the winter, but with summer here, I have all those husband things to do, cut grass, wash cars, house maintenance, Bar-b-Q etc. Maybe it will rain lots!!!!

Instead of doing a thread myself, as I progress I may just throw in my comments and a couple of pics here if pscartozzi doesn't mind. However I may take awhile getting this one started. So it may be the pscartozzi will have his long finished before I even get rolling on mine

RE: SU-100 Build Thread
 

YHR, feel free to post here. I tried the metal gears. They are great and get rid of the slip-clutch. Mine worked great on flat ground but started slipping again when I hit resistance. The plastic gears in these things arn't bad. It's the cheap, thin wall plastic they use to support the shafts. It will quickly wear and the axles get real sloppy, causing slippage. There are no bushings in this thing. I wish you luck with them but the whole setup will be prone to problems unless you bush the shafts. That's why I'm going through all the gymnastics to put the HL's in.

RE: SU-100 Build Thread
 

Speaking of resin. Is it a resin or plastic molded kit ? From the pictures both here and on BYA, it looks to be some sort ot plastic. Which I was hoping for. Have not ordered mine yet, but was thinking about it. And I was looking at the SU-85 conversion kit. And if it is a resin, how srong is it ? I have seen other resin pieces that are so chalky like and brittle that they break or flake apart by just handling them or putting any kind of stress on them. Even if you reinforce the back with something. The outside get's ding up pretty bad in battle. And I do like to battle with my tanks. Thanks.

[sm=punching.gif]

RE: SU-100 Build Thread
 

I believe it is resin. It was made by a casting process, not injection molding. That's why there are bubbles and voids all over it. Still it is pretty tough.

RE: SU-100 Build Thread
 

OK, I've finished off my drivetrain, at least I think. I used a die sander to take about 1/4" off each drive shaft. This puts the WSN sprocket to the correct depth. I hollowed out the WSN gearbox cover and reattached it with the stock hardware. To attach the drive sprocket I drilled out and tapped the HL driveshaft with a 10-32 thread. I took the WSN drive pin and cut it down in length and threaded it with a corresponding 10-32 thread. A before and after pic of the pin is shown below. Now I can 'screw' on the drive sprocket. If needed I will treat with Loc-Tite but I'll do that later seems pretty robust right now.

RE: SU-100 Build Thread
 

I have given my HL board the standard treatment. Big heat sink, heavy guage wire and terminal block for the motors. I have never had a problem with HL boards.

RE: SU-100 Build Thread
 

WOW pscartozzi excellent work on the su 100 i think i will have to copy your arrangement on the motors for my T34 as it looks brilliant keep up the good work :D:D:D:D:D:D:D:D:D:D:D

RE: SU-100 Build Thread
 

I agree. Your board modifications look excellent. I highly recommend what you are doing. I think the Heng Long boards are actually quite good for the price. Spend a few bucks like you have and I bet they are trouble free.

Tank is looking excellent. I like the metal tray. Very inspiring to see these toy tanks turned into something much more.

RE: SU-100 Build Thread
 

Hi

Im just wondering wy you change the gearbox ?? - whats not good with the stock ones ???

Jonas

RE: SU-100 Build Thread
 

The stock gears drive the tank to fast and they aren't as robust as the HL metal and they are louder, you'll also wanna pull out the turret rotation gears, they are god awful loud.

RE: SU-100 Build Thread
 

Yeah the turret gear really is noisy , but does it not get better all that with 7,2 volts driving it ?? - I already ordered metal upgrade to the stock gears so I have to stick to thoose ..

RE: SU-100 Build Thread
 

Jonas, the primary reason I chose them is because both of my original gearboxes no longer work. They have a terrible design where there are no bushings or bearings and the gear axles rotate in thin plastic supports. Upgrading to these have bought me a 385 motor which is larger and more powerful than the WSN motors, metal gears, and a more realistic gear reduction.

RE: SU-100 Build Thread
 

Ok - now I get it ..... thanks for explaining it....

RE: SU-100 Build Thread
 

Quick update. I mocked up the HL electronics to try out the drivability of the chassis. I must say it drives like a dream. Excellent proportional control and smooth operation from the broke in gearboxes. Plenty of power if I decide to put on the metal tracks but I'm kind of a fan of the plastic. Here's a tip. NEVER drill your final elec mounting holes in an alum base plate until the tank is finished. The alum plate in my Tiger looks like it ran over a couple of mines there are so many holes in it:D
Since the lower hull is kinda done I have moved to fitting up the upper hull. Tons of sanding needed on the thick resin of the conv kit. Seriously, I don't know how I would do it if I didn't have an air sander. I'm going to shave the front fenders on this one as I like that look.

RE: SU-100 Build Thread
 

Yes I know what you mean. I used epoxy putty to stiffen the stock plastic on my first T-34