Mini/Micro - MOA - Scratch Build

[sweli]

Originally Posted by danielk

I don't think a micro-t trans would be big enough to handle a 130...We are talking 140g/cm+ startup torque...

My bad, thoughts were mini, brain and fingers were stuck on micro.
A 'MINI-T' trans would work great!

Pardon my poor photoshop lite skills.
Reverse the trans with motor between links.
This would give you room for a servo on the front axle.
Green are links.
Blue is axle that passes under trans, uses mounting points that already exist.
Red is approx size of 130 motor in place of 280. For a 130 you should be able to find much fewer tooth pinions to gear it down some more.
Red upper link mount could attach where motor guard would come off.

[itsjust me]

another crazy home made crawler. keep up the inventive stuff.

[sweli]

Originally Posted by itsjust me

another crazy home made crawler. keep up the inventive stuff.

Have to see if it can even touch the 1.9 comp section at Battlefront.
Has Mini-T tires on it.

[sweli]

Cannot decide what axle ratios to run now.
With my new front gearbox and internal alum motor bracket, I need to run slightly larger OD spur and pinion.
If I do not mod the rear gearbox, then I cannot run more then 18/24.

With each axle having it's own ESC and Batt, will there be any clod stall?
Should not, right?

Chart below, yellow shows present ratios, Green shows what I am considering, which is a scratch less ratio on the front.

[sweli]

Rear 150:1 gearmotor installed, with 18T Pinion, 24T Spur.
Front gearmotor installed with new bracket, 19T Pinion, 25T Spur. It feels a lot sturdier.




Got the Losi Mini-T Smashers installed on the front beadlocks. They went on well. Wrapped the rear Mini-T wheels with lead and dryfitted the tires.
Used some soft, molded (with skin) foam I had.
With the narrow rims, I was going for taller foam to keep these tires skinny and bump up the overall OD on them. It worked, but they are a little stiff, and a little rounded.
May attempt at star cutting them to see if that works.
If not, may have to find some softer foam. The stock Mini-T tire foam is too short (OD).



Got started on the body. Had to cut a LOT away. It might not be too bad (smaller body on a supersized 24th chassis). More on that tomorrow.

[sweli]

Got busy with house projects and kids swimming.

Fully assembled with electronics.
Did some wire routing and put micro Deans on the motor wires.
Cut up an old 2.2 memory foam to replace the molded ones under the Losi Mini-T Smashers.

Not happy with the 150:1. I have an email into Pololu. Seems like these have less torque then the 100:1 motors(??). Speed is reduced, so ratio is up (around 200:1). They do make lower current draw motors, but label on bag puts these as the higher draw motors. Wonder if they got mixed up.
Could put a meter inline to measure current draw, but a pain with the micro deans installed.

Considering a single 3s through a Mamba25 into a Punk Dig switch.
The motors are rated to 9v, but couldn't I limit the throttle EPA so they don't see more then 9-10v of the 11.1 avail?

Other idea is two small boost regulators that step the voltage up from 7.4v to whatever I want. Would start with +/-8.4, but would also need to get a better second ESC then the stock RC18T I have, which is flaky already.

Memory foam is better then previous foam. May need softer yet, or less of it, but that will reduce the tire height, and let the width bulge back out.

Enough of my babble...............

[sweli]

http://www.youtube.com/watch?v=LYT6iNBIQg4

[dezrik]

4 Seconds really? Are you still working on this?

[Dillpickle]

Originally Posted by dezrik

4 Seconds really? Are you still working on this?

x2.

[bwm8142]

everybodies bringing up old threads today.

[sweli]

Have not touched it in about a year. Still have the pcs.
Gearboxes on the motors, did not have bearings, but rather shafts through brass plates, to keep the size down. The holes in the brass plates on the output shafts wore after 3-4 runs to the point the pinions began to skip.
Need to either downsize the gears, or better yet - extend the output shafts through some machined fences with bearings in them.
The next size up motors have bearings, but could not fit them in this design.

[Hyde802]

You sir, have crazy skills! Keep up the sick work!

[Drc]

Incredible job. Absolutely amazing. The fab work is outstanding for a prototype looks production ready. I know its an old post, but hope u got to finish it with the body and all. Thanks for posting it.

[mjderstine]

blast from the past