Assult Sherman, Jumbo build
 

Ok so I finally started on this beast.
I decided to try the all metal Mato lower hull and mato tracks with extended end connectors and mato steel ball bearing 4:1 gear boxes.
The draw back to this hull, was the tracks would not fit over the bogies, I had to literally slide them on and pin them after they were in place.
Talk about a pain in the rear. Its like scale track repair without miniature guys to do it for you.
Its also quite costly compared to getting a HL as a donor tank.
To get the transmission cover to fit on the lower hull I soaked it in hot water and formed it to the hull. Unfortunately though it doesn't meet the upper glacies plate correctly, it also isn't quite thick enough or formed the way photos of the one I saw look so Im going to add a Tamiya bolt bar on top and build up the tranny cover with bondo to thicken it.

http://www.rcuniverse.com/forum/atta...mentid=2123871http://www.rcuniverse.com/forum/atta...mentid=2123872http://www.rcuniverse.com/forum/atta...mentid=2123873

I am planning to use a HL rotation gear box unit and servos for elevation and recoil. Likely a Barc4 and Bendini for operation system.
Im playing around with another mongrel tank to test out the barc and bendini.

Nice, I enjoyed mine very much when building.

http://www.modelersite.com/en/112168...6-scale-for-rc

http://www.rcuniverse.com/forum/atta...mentid=2123886

Great!

I have an Assault JUMBO in the works too, but mine will have the original 75MM gun. :cool:




Jeff

Is that turret that is resin actually modeled for a Jumbo? Because if it isn't and it doesn't look like it is it is too narrow. The Jumbo's turret was 4" inches thick on the sides and actually looks a little rounder in a frontal profile view. I know Nick makes the regular T-23 turret but does he also make a Jumbo specific turret?

Oh another consideration. The Jumbo always used the duckbill track extensions. When you see them with out them they are in transit config. They always used the extensions in combat because of the added weight of the very heavy extra armor. The Mato metal tracks work very well. not really the correct track but they have the duckbills at least.

There are lots of pictues of jumbos with other tracks incombat. One good one I recall has a 76 and flat rubber oad tracks while taking Halle Germany. Others lost their duckbills in places, which seemed common. Whish I could get rubber chevrons with ducbills.

yes this is a real jumbo turret made by Nick, its thicker and has the particulars of the turret.

I was pretty sure Nick did have a true Jumbo turret , when i built mine i literally just added plastic putty to the sides over and over to build it up then i sanded the profile. it came out pretty well for a rough scratch job.

Yes the duckbills did very commonly get broken off all the time but they where still standard on the Jumbo.
If you see pics with out them on a Jumbo it may have actually been one of the feild mod jumbo's they actually made in theater. i know there where quite a few of those too. especially the 76's as the Jumbo originally had the 75 then they up gunned many of them.

JUMBOs without EECs were referred to as Out Of Spec.

http://the.shadock.free.fr/sherman_m...bo/m4a3e2.html




Jeff

I have been thinking about track pads again as I dare to do.
I have a set of the mato rubber chevron tracks that came off the mato 76 M4a1 RTR tank. They are the same width as the metal track pad of the mato metal tracks but the inside of them is hollow, kinda funky. I was thinking of finding a 3d printer that can copy one pad and print them, then I could make a jig and drill them out and swap them out on my metal track set. Yes this is a ton of work, but it would make the tank more accurate and it would look cool, and might be fun too....

Good to see this build moving again. I will be taking notes for when I eventually get back to mine.

Have you put any thought into the best way to attach the upper and lower hulls yet?

I use the tamiya body clips. I made rubber molds of them and then cast them in urethane, works pretty good and have them on all but one of my shermans so far because its a HL upper and lower matched.

If you use the the tamiya bolt strip ontop of the Tran cover it will meet up nicely. At least that what I did on mine.

Yep, i have not had time to body work it yet, but I got one from a forum member to do just that. It should work out nicely, but I need to build up the tranny cover thicker with bondo to make it look right. Ive got picures of the one Jaque had.

been wasting my time on a hl lower with a mato 76 turret conversion. Probably going to sell it.

I finally got around to fabing up the rotation system. I wanted to try to use the HL motor box since the Tamiya one feels a bit fragile, and I have the Hl stuff here. The Tamiya set up would have cost more money. As I was fabbing this all up, I was thinking I should have just bought the Tamiya parts, but I have another kit from nick that is a small hatch Sherman and it doesn't have provisions for the Tamiya system to I figured I would practice setting up the HL system from scratch on this tank.
What a pain in the ass this was to do. The first thing I did was wrap styrene around the inside of the ring of the hull to shim it down to the turret diameter.
I have the gear box mounted on a piece of plexiglass bedded with bondo. That way I can unscrew it and remove it if necessary. The mounts I made for the ring seems really stupid but I couldn't come up with anything better. And then I had to add shims on the 90 degree points between the screw mounts to keep the ring gear level and meshing with the rotation gear box. I decided to make the shims into retainer pins as well so the turret wont just fall out or come loose since I had to cut off the tabs that are cast into the turret ring..
I cant say I am completely satisfied with this fab work, it feels like more of a hack job, but I have way more hours in it than I would like to admit The first time I had it all lined up the gear was off just a tad and lost mesh at one point, so I had to relign it all.
At this point, the whole system works correctly. But I still have that thought that I should have just used a Tamiya system.

http://www.rcuniverse.com/forum/atta...mentid=2132615http://www.rcuniverse.com/forum/atta...mentid=2132616

The Mato metal hull and running gear should be solid. The Mato metal transmission cover was not usable for this project?

i really like the Mato plastic track. Couldn't,t the duck bill connectors be used on that?.

Cheers

That is a question I asked when MATO first introduced the new metal track with the Duck Bills but I think someone tried it and found that there is a slight difference in the pin to pin dimension that makes them incompatible, Which really is a poor idea by MATO if you ask me. Why would you do that, especially when the metal track you are making is the LEAST common of all the Sherman track. Dumb.

I had Woz desing and print the plastic chevron pads for me to change out the metal pads in the Mato track. That is going to be a nightmare of a job, but he did print the pin holes so I just have to ream them out. The big pain is going to be taking the whole thing apart link by link.

The metal tranny front cover was not suitable for two reasons. The width is the big one, the gap on the Nick jumbo hull would have left a gap on both sides of the metal tranny cover. Believe me, I was disapointed with this but its the difference between manufacturers. Nick formed his up from the Tamiya brand parts so I had to use the cast cover he provided. Also the tranny cover has to be much thicker on a jumbo. Im going to build up the cover with more bondo too to make it a bit thicker to visually match the jumbo I took pictures of from the Tomlin collection.

Forming the urethane cover to the metal hull changed it a bit and the bolt bar no longer meets at the correct position, hence I needed a Tamiya bolt bar to glue over the one cast in after I sand it back a bit.

Here are the awesome "Rubber" chevron track pads Woz printed for me. They replace the metal T-74 pads.

http://www.rcuniverse.com/forum/atta...mentid=2132959

I made a paper template and cut out and glued 5/32 plexi glass down both sides. The urethane hulls can sometimes get soft and warp in the hot sun. I did this from experience with my A1 cast hull, it bowed a little.
http://www.rcuniverse.com/forum/atta...mentid=2132960

The metal hull has screw holes in the sides to catch the top of the tranny cover so I made plexi brackets and screwed them into the hull for support.
http://www.rcuniverse.com/forum/atta...mentid=2132961

Ive been working slowly. I got the elevation servo bracket fabbed and installed but haven't hooked the servo arm to the barrel carriage yet. I still have to make the recoil servo mount too.
Then I focused on the tranny cover, I felt the nick urethane one was too thin compared to my photos, also the bolt bar was too low after I made the tranny cover fit the metal mato hull so I had to file down the urethane cast on bolt bar and glue a Tamiya over it. Then I began building up the thickness with bondo and got some texture in it too. I might sand it a little more but I am super happy with the results.
http://www.rcuniverse.com/forum/atta...mentid=2135326http://www.rcuniverse.com/forum/atta...mentid=2135327http://www.rcuniverse.com/forum/atta...mentid=2135328http://www.rcuniverse.com/forum/atta...mentid=2135329http://www.rcuniverse.com/forum/atta...mentid=2135330http://www.rcuniverse.com/forum/atta...mentid=2135331http://www.rcuniverse.com/forum/atta...mentid=2135332http://www.rcuniverse.com/forum/atta...mentid=2135333http://www.rcuniverse.com/forum/atta...mentid=2135334http://www.rcuniverse.com/forum/atta...mentid=2135335http://www.rcuniverse.com/forum/atta...mentid=2135336http://www.rcuniverse.com/forum/atta...mentid=2135337http://www.rcuniverse.com/forum/atta...mentid=2135338

https://www.youtube.com/watch?v=JP0WEEWN1aE Jumbos of the world unite.

Might be too late, but when I was working on the trunion base for my wrecker I just couldn't get it completely true. Decided to spring load the traverse unit to keep it engaged. Just thought I'd throw the idea your way if the turret ring doesn't cooperate down the road.

I must confess a dirty trick.... my M50 process was delayed a bit as I am using an old Clutch Steer hull with modified heng long traverse. I used a turret lower from an old WSN T34 85 as the spacer and everything looked hunky---dory until the vehicle was buttoned up. The turret stuck at multiple points around the circle no matter how much I sanded and buffed the plastic.

I cheated.

I sprayed WD-40 on the ring from below.

No more problems.... for now.

(don't forget to wipe the excess off...)

https://farm6.staticflickr.com/5803/...73903db3_c.jpgIMG_7202 by Ethan Dunsford, on Flickr

Good video ethan. I photoed that tank a day later at the ball park. Then got the other photos from the site where it was auctioned. 800k. Wish I could have afforded it

any way, yes, I was so close to putting the turret motor box on a pivot and spring pull, I mean so close as ihad a template made up. But the first time I moved the turret gear, I nailed it, so i let it go.

The mato gear boxes are super rough and noisy. The steel gears are horrid. So im going to pull the tracks, lube up the shafts and put valve lapping compound on all the gears and run the hell out of it to lap the gear teeth in and hope it queits down. Right now it is seriously nasty.

has anybody found a good speaker in a box ? I tried to fit a tamiya sherman speaker but its just not going to fit, but buy did it sound good.

The twin Mato speakers aren't bad. Not up to par with a tamiya speaker/box but gives you some freedom of mounting in smaller areas. Otherwise hearing good things about the visaton speakers though you'll have to build your own box.