1/35 E-KAT

[Frank3k]

I recently bought the AMT 1/25 Sandkat last released in 1969.



The first step was to scale it up to 1/35. The vehicle is pretty small even in this scale. The easiest solution is to source a 1/35 engine, slap in a slightly smaller seat (or use the existing one) and call it a day... but I can't leave well enough alone.
I'm still undecided if it's going to be a post apocalyptic vehicle, or some sort of military FAV.

The double rear tires are cool, but I want double front tires as well (even though that would make it a bit tough to steer). I haven't found a suitable 1/35 replacement, so I found some interesting tire treads online and I'm in the process of building them in Rhino3D. Both tires are big - about 45" in dia. and around 20" wide. This image shows the tires with their tread patterns:



Just tires:


The tire to the left reminds me of the Aliens APC tire tread, the one on the right is an interesting sand tire tread I found online. I haven't decided which to go with - I may print both styles and see which looks best on the vehicle. I still have to design the hub.

I found a 1/35 engine to fit in the rear, but it and its transmission take up most of the rear space. I thought of using spares from my Theseus 8x8 Amphibious cargo hauler and a large box to represent the battery box. The steering wheel is from one of the trumpeter Aerosan kits I built last year. Thankfully, it's not very wide. The bench seat is the rear seat from a Tamiya Jeep kit, cut and trimmed to fit. I changed the front wheels and they can now turn:



Those two electric engines probably put out as much power as the V-8 it may replace. Now there's cargo space or room for one or two passengers.


I'll move the battery box forward to keep the center of gravity closer to the middle of the vehicle.

[LemonJello]

When I first saw the box art of this kit, I thought it needed double front tires as well!

You're off to a good start, for sure.

[apophenia]

I like where this is going Frank!

When you say "there's cargo space or room for one or two passengers", do you mean additional passengers behind the turn-over cage?

If so, maybe leave the battery box where it is now. Not so good for c/g but it does provide footwell space for the GIBs.

[Frank3k]

I spent a few hours on this model today, with not much to show.

Here's "Nigel" (the driver from the Tamiya Quad tractor) showing how small this vehicle is, even when scaled to 1/35. Changes/additions are:
- two small plastic tubes to act as guides for the steering track rod - the brass wire kept popping out. The whole front end will be somewhat hidden, so the primitive steering mechanism will be mostly hidden
- thin plastic crossbeams in the rear
- suspension and mount for the twin electric motors. They're modified M113 wheel arms.



Slightly better view of the motor mounts:



I'll probably add a support rod to connect the ends, but for now I like the Blade Runner Spinner look.

@apophenia

While there is just some space behind the seat and roll cage, I meant at the very rear. Here's Nigel modelling the position of the two rear passengers/cargo area:




I'm running some exposure test on the resin I'm going to use, since I noticed that the ideal exposures for my printer have been shorter than typical (a good thing). If they are shorter for this resin, I should get nice crisp prints, so it'll still be a few days before the tire designs are finished and printed.

[ChernayaAkula]

The Sandkat box-art has some Batman Tumbler vibes. Applied Sciences Dvision test rig?

[apophenia]

... While there is just some space behind the seat and roll cage, I meant at the very rear. Here's Nigel modelling the position of the two rear passengers/cargo area...

Ah, gotcha Frank. So, actually, moving the battery box forward both improves vehicle balance and gives Nigel et al more foot room. Bonus 

[Gingie]

  first thing I thought of "Those could make good Aliens APC wheels!"

Love this scale bash as I plan on doing it with a 25th scale monster truck, but without the body cover, just all that exposed tube steel is too awesome to hide.

Are you going to add some kind of fenders?

[Frank3k]

I'll add fenders, front and back. This project is on hold because it's too cold up in my lab (72F) for the resin printer. I'll have to blast the area with a space heater to bring it up to 74F-78F before I can print successfully.

[robunos]

I'll add fenders, front and back. This project is on hold because it's too cold up in my lab (72F) for the resin printer. I'll have to blast the area with a space heater to bring it up to 74F-78F before I can print successfully.

This is how you know that resin 3D printers were invented in California . . .      


cheers,
Robin.

[Frank3k]

This is how you know that resin 3D printers were invented in California . . .      

Moderate year round weather is a cross I'll have to bear, I guess.

[Story]

Mediocre!

[Frank3k]

I finally printed the wheels. I should have looked at the original tire dimensions, because I either scaled the tires incorrectly, or they're small. Luckily I also printed a set of generic truck tires:



The resin in a clear blue-black color.

They looks small on the vehicle. The front tires aren't all the way on because they're a bit tight and didn't want to break the wheels or axles taking them off:





The generic tires look OK:



The wonky rear motor/wheels are easy to fix:



If I shorten the vehicle frame the smaller tires look fine.

[Buzzbomb]

... or the dual tyres on the rear option, rather than make it shorter

[Story]

Belly wheels?

[Frank3k]

Brian - thanks for the suggestion to double up the tires. I tried it with six of the sand tires:



Then four generic truck tires in the rear:



Finally, six of the truck tires:



I think the truck tires look the best - without shortening the vehicle. I guess the sand tires are about the right scale size - the vehicle is just long (not surprising, since it's being rescaled)

Story is right; I have to think of something to keep it from getting high centered/bottoming out. Maybe I can use the sand tires there, or go the BRDM route and source some smaller tires.

[Jeffry Fontaine]

Glad you sorted out the tire issue.  But the high-centering thing may not be so simple.  A thought, though, what about cutting the frame behind the passenger compartment, removing a section of the frame from the bottom to create an angle to the frame that would make it appear as an upside down "V" shape? 

[Old Wombat]

Story is right; I have to think of something to keep it from getting high centered/bottoming out. Maybe I can use the sand tires there, or go the BRDM route and source some smaller tires.

Or proper driver training, where they're taught not to go straight over the top of hills/dunes/etc &, instead, to go over diagonally, like you should anyway?

BTW, if you moved the driver forward a bit, you'd have enough room behind him to fit a gunner/observer/passenger.

[Frank3k]

I cut the frame like Jeff suggested and it gives it a bug like stance that I like. I also inverted the front axle to put the front wheels closer to the ground.

I'll try moving the driver forward. There may be enough room.

[Story]

What about small wheels (like rollerblades) inset into the belly skid plate?
https://rmsoffroad.com/images/IMG_6039012022.jpg

[Frank3k]

Here's what I have so far - I don't think skates will work for high centering now. Maybe some 1/72 aircraft wheels, or the sand wheels I printed. I moved Nigel forward as well:





For the number of mods and evergreen rod I've used, I wonder if it would have been easier to just scratchbuild this vehicle. Not much is going to be left of the original! Still need to make some fixes to the bend area - like replace the bent yellow "tube" with yet more evergreen.

[Jeffry Fontaine]

Well that certainly addresses the issue of getting high-centered but it does look odd.  Without the benefit of lifting the suspension that is probably the best option. 

[Old Wombat]

Still need to make some fixes to the bend area - like replace the bent yellow "tube" with yet more evergreen.

I'd just reinforce the joins with wire pins, rather than replace the original plastic. That would (should?) make it even stronger.

[raafif]

Jacked-up looks good to me !  No more bum-dragging & you won't get stuck see-sawing on the tops of dunes as you go over

[Story]

Don't forget to pack sand mats. Maybe integral, like roofing sections?

[Gingie]

Very nice!


If Nigel moves any farther forward, we're going to start called him "No Jewels"