Barn find - Estate sale - Steel M5 Stuart

[RC_BobM]

Hello Minipansar,
I picked up another project - because I'm very good at starting and never finishing.

This is an all Steel M5 hull made by guy in California in 2009. He made exactly 5 of these hulls and never finished them. It has no motors or electronics or turret. I was able to pick this up cheap and hope to get it running soon. Its heavy - 80-85 lbs (176 -187 kg) with nothing inside! I made a scratch build M5A1 some time ago, so the CAD for that can be used for this one.

Craftsmanship is pretty nice overall.

Motors are 12V robot motors will all steel gears. I will remove output shaft on one side to make Left and Right.

Rear idler - works like real tank

48975930-DA2A-4B4E-B792-79ACBCDBDE20.jpeg (50.02 KiB) Viewed 1142 times

Track and bogey wheels

C5F047E4-C9A3-466A-A48C-6AA8275C0EBB.jpeg (48.46 KiB) Viewed 1142 times

Sprocket

642F87E3-E7B0-4C30-AEE1-0A9A2B685217.jpeg (46.13 KiB) Viewed 1142 times

Hull with fresh paint

Motor layout

NPC motor

Hull CAD model

Turret CAD model

Hopefully someday it will look like this.

[Hans K]

Nice Works

Hans K.

[cahlfors]

Holy cow, Bob! You are good at CAD!

Fantastic project!

Don't forget that this is a hobby! We start and finish projects as we like!
//

[RC_BobM]

Thanks guys, Chris doing this stuff for living (Engineering) helps with the hobbies! I like to know what I'm making before I try and make it - hopefully prevents some do overs!

[mrTyko]

Another great work from you Bob

[Erik]

Wow! And the Stuart is such a cool model! Congrats to a great find!

[RC_BobM]

Thanks for nice comments guys. Yes Erik this hull is one of 5 ever made. I feel lucky to hopefully finish it.

Making some parts on CNC mill:

Got motors and chain sprocket installed

test fit the battery, will have 2X 12V battery for juice.

Hope to test drive soon.
-Bob

CAD continues

Machine motor mount plate

Motor mount / floor plate

Motor installation with chain sprockets

Test fit of batteries

[RC_BobM]

August 23rd little Stewey got its first RC drive. Everything went really well - until it didn't. All part of the fun.

Motors all connected up.

Motors ready

Nice side view

Side view

Nice three quarter

Three quarter vieww

In the yard

In the back yard

Run Aug 23 2.jpg (202.9 KiB) Viewed 1022 times

Track separation. The end connector came apart and the track jammed.

Track separation

TRack separate 2

Tank cart to the rescue!

Rescue cart

Got some good dirt on it at least.

Dirt on tracks

Unfortunately I lost some of the end connector pieces and there are no spares. Time to make some! I found one of the Achilles Heals for this model!

In the back yard

Till next time,
Bob

[mrTyko]

Great modell you have there, pretty good job on the mill.
Everyone has had your problems, try something. And it goes wrong, redo and fix it so it gets better.
I think you say try, try and try again.

Have a nice day
Robert

[cahlfors]

"...came apart..." Does that mean that it broke, or just that the fastener unscrewed itself?

Hoping for the best!
//

[RC_BobM]

Hey Chris and Robert
Yes this thing is very tank like - quite fun to drive. Even squeek like real tank.

Nothing broke - just came apart. The little "C" shape piece on end connector fell out. Fortunately I found it by putting small magnets on tips of garden rake - good thing about steel.

The end connector are really poor design with many tiny parts. Each track weigh over 10lbs (~5 kg) so it needs to be strong. The end connector should be one piece like AT Sterman (tooth piece and C shape = one piece) like shown below.

One piece end connector 2.jpg (44.75 KiB) Viewed 1007 times

Also of poor design is the use of really thin plastic bushing instead of bearings. The model weigh nearly 100lbs as is, no turret, and using tiny plastic bushings in the wheels is absurd. At the very least they should be bronze bearing. So I replaced the idler wheel bushing with custom bronze bearing. Lots of things to fix!

Still fun tho!

Cheers Bob

[RC_BobM]

Phase II - Design of 24V motor mounting. The 12V motor I have installed run really great and have plenty of torque, but they get extremely hot. I think they are over worked for weight of model. So got some 350Watt 24V scooter motor from AMZN. Very inexpensive, but they are a little heavier than the 12V motor. They should run much cooler hopefully, they were 4X less expensive than the 12V motors. Right side chain length is a little long, but should work fine. Will be nice to run on 24V like all the Armortek models.

Some CAD images

350 W motors -L

Motors from R

top view

350W motor install -TOP.jpg (38.01 KiB) Viewed 915 times

With top deck plate;

overall

Almost ready to start machining parts....
All for now.
B

[mrTyko]

Nice work you make there.

[RC_BobM]

Minor update. New 3D printed stainless steel end connectors to fix me Stuart. Very nice quality. Yahoo!

Printed End Connector

[mrTyko]

Impressive Most Impressive...