[WIP] Rock-Bouncer RC

[mktechniccreations]

Some time ago there was a thread about not so many MOCs, so i decided to share my side project from scale modeling. And its more sophisticated version of my previous model which i called rock-bouncer 2L or 3L depending on the numbers of motors, now i made it larger and RC motor driven, but i dont know how to make suspension travell so long with only 9.5L absorbers, since there is potential for much more travel. I would love to see some recomendations. 

Original Thread : 

[Zerobricks]

If you want more suspension travel, than i suggest you attach the shock absorbers to the control arms.

[mktechniccreations]

Just now, Zerobricks said:

If you want more suspension travel, than i suggest you attach the shock absorbers to the control arms.

I was expecting your response, hmm so swap few of those 9L links with liftarm with sockets and place Shock absorbers somewhere in the middle ? 

[TeamThrifty]

This is awesome. Its a chassis design i'm totally unfamiliar with, love seeing new things! Brilliant!!

[2GodBDGlory]

Another option for increased travel is to create custom shock absorbers by taking apart a few 6.5L shock absorbers, taking the springs, placing them on an axle, and building a shock out of it.

I don't know what your feeling is about taking shocks apart, though.

Otherwise, it looks like a fun, powerful model with a sophisticated suspension design!

[Lira_Bricks]

Nice car! I really like the look with all the tubes :)

Small question: I see a few pins being filled with bars (like with the exo force hands or the joysticks). Is that to make it stronger, so chances of the pin getting loose are smaller?

 

[amorti]

3 hours ago, Lira_Bricks said:

Small question: I see a few pins being filled with bars (like with the exo force hands or the joysticks). Is that to make it stronger, so chances of the pin getting loose are smaller?

Look again, it's (mostly/all?) Ball joints being held in. The bar (or equivalent) stops the end of the pin compressing so the ridges can't get into the pin hole and it can't fall out.

I hadn't spotted it, but now you point it out, I like it. Smart move, otherwise this would forever be popping ball joints.

[astyanax]

It looks to me like this thing is not gonna bounce; it's gonna fly when it hits a rock!

You're going from buggy motor inner (fast) output, to 20/12 gearing UP, to planetary hubs. Now, I've previously done some experiments with connecting a buggy motor's inner output directly to a planetary hub, and I was surprised how fast that was! And this is gonna be even faster...

[mktechniccreations]

14 hours ago, 2GodBDGlory said:

Another option for increased travel is to create custom shock absorbers by taking apart a few 6.5L shock absorbers, taking the springs, placing them on an axle, and building a shock out of it.

I don't know what your feeling is about taking shocks apart, though.

Otherwise, it looks like a fun, powerful model with a sophisticated suspension design!

I will not do it, i rather work with parts that i already have and are original, these absorbers are rare and i dont want to destroy them, but i may found solution. 

 

10 hours ago, amorti said:

Look again, it's (mostly/all?) Ball joints being held in. The bar (or equivalent) stops the end of the pin compressing so the ridges can't get into the pin hole and it can't fall out.

I hadn't spotted it, but now you point it out, I like it. Smart move, otherwise this would forever be popping ball joints.

Yes i saw it on zerobricks models first, and i had to try it, it prevent ball joints from popping from pin holes, but there are 3 types i found, 1st is exo-force robot arm, this is the weakest of the bunch, then its 3L tiny bar with end pin or i dont know how to call it, it is quite secure but large, and i thing the most tight fir is the bar with small ball at the end. 

 

9 hours ago, astyanax said:

It looks to me like this thing is not gonna bounce; it's gonna fly when it hits a rock!

You're going from buggy motor inner (fast) output, to 20/12 gearing UP, to planetary hubs. Now, I've previously done some experiments with connecting a buggy motor's inner output directly to a planetary hub, and I was surprised how fast that was! And this is gonna be even faster...

And about this, yes but i am worrying about torque that it will twist the entire model, or model will not handle any hits, with those ball/9L link connections. 

[astyanax]

4 minutes ago, mktechniccreations said:

And about this, yes but i am worrying about torque that it will twist the entire model, or model will not handle any hits, with those ball/9L link connections. 

Well, you've chosen a very extreme setup by combining 2x buggy motor with light-weight model and planetary hubs... So somewhere some plastic is gonna suffer!

(I mean this as an encouragement haha!)

[mktechniccreations]

I solved it kind of, made same technique as in the previous rock bouncer, just changed angles etc, it may not have insane twist angles like other rock crawlers, but it will do, any it has other strong sides. 

[braker23]

Very complex suspension and RC motor placement is great, hope the large u-joints will handle that stress. Good luck and hope to see that video :)

[mktechniccreations]

3 minutes ago, braker23 said:

Very complex suspension and RC motor placement is great, hope the large u-joints will handle that stress. Good luck and hope to see that video :)

there should be almost no stress, since joints are handling RPMs not high Torque 

[AndyCW]

This thing looks awesome and will give you a lot of enjoyment.

Having built many similar vehicles, I can give you a couple of heads up on what to expect as you test and develop.

• The links will pop off of the ball joints unless you 'trap' the link and even then it will still happen a little.
• During suspension droop, the springs will separate from the chassis.  They only appear to be connected via the friction of the 3l axle into the top of the spring.  Incorporate the side mount on the spring as a retainer and not as a stressed item.
• You will overheat the motors.  My buggies with 4x 5292 and 107mm tires overheat the motors on anything less than 4:1 overall from the slow output, but I run 3 cell Lipo and with lower voltage, you may have some success.

 

[mktechniccreations]

Just now, AndyCW said:

This thing looks awesome and will give you a lot of enjoyment.

Having built many similar vehicles, I can give you a couple of heads up on what to expect as you test and develop.

• The links will pop off of the ball joints unless you 'trap' the link and even then it will still happen a little.
• During suspension droop, the springs will separate from the chassis.  They only appear to be connected via the friction of the 3l axle into the top of the spring.  Incorporate the side mount on the spring as a retainer and not as a stressed item.
• You will overheat the motors.  My buggies with 4x 5292 and 107mm tires overheat the motors on anything less than 4:1 overall from the slow output, but I run 3 cell Lipo and with lower voltage, you may have some success.

 

glad you pointed out these 3 things, first thing is good to know, but i dont know how to cover them from underside, since the links are the lowest point of vehicle pointing downwards, second thing is also good point, and i will take a look at it, i already tried to put there OX technic connector to make 2x lenght so more friction is there, but then the absorber cant twist, so ill figure something else, and third, i thing i will run out of buwizz battery sooner than motor starts to heat up.

[AndyCW]

By rotating the links and ball joints 90 degrees, trapping them can be done without compromising the ground clearance.  However, it will make things wider and mandate a rebuild.

Eagerly awaiting a video of the performance and carnage.

[mktechniccreations]

1 hour ago, AndyCW said:

By rotating the links and ball joints 90 degrees, trapping them can be done without compromising the ground clearance.  However, it will make things wider and mandate a rebuild.

Eagerly awaiting a video of the performance and carnage.

i cant, if you seen photo from bottom, they are aranged in tiangular shape, so there is no sideways movement of the axle, three point of contact, thats why there can be just links and it will not slide to the side freely, there is a bit tension but it holds up nice. 

1 hour ago, AndyCW said:

By rotating the links and ball joints 90 degrees, trapping them can be done without compromising the ground clearance.  However, it will make things wider and mandate a rebuild.

Eagerly awaiting a video of the performance and carnage.

Or ...you might be genius

[mktechniccreations]

Moded, this thing is going nowhere, but my fingers are dead after those axle pusning manuevers. 

[AndyCW]

That looks much more robust.  I'm not sure you need four lower links though.  Two upper and two lower are plenty to locate the axle provided they are 'triangulated'.  Keep at it.

Have you seen Attika's truck with the planetary hubs?