Crazy axles idea design

[gonper]

I managed to print one of the gear boxes, now is time to check tolerances, interferences, etc. quite long and tedious process.
As well I started to design the chassis.

The 3D prime of the gear box, it is a quick print so quality is not great.

[Highmark]

This is bad-ass! If you run into strength problems with your prints you can look into having someone print your parts in Markforged onyx. Also, have you thought about using a small brushless outrunner on a gear-head? That might be a good path to research if you run into gearing problems.

[gonper]

Originally Posted by Highmark

This is bad-ass! If you run into strength problems with your prints you can look into having someone print your parts in Markforged onyx. Also, have you thought about using a small brushless outrunner on a gear-head? That might be a good path to research if you run into gearing problems.

Thank you Highmark,
It is beefy designed and I was planing to test Nylon, PC and PETG to see which one is the better suited for the task and my printer. Last option will be if someone can print it on a Markforged one as you say.

The first idea was to use brushless motors but I was not able to find small sensored ones.
And because efficiency is not an issue in this case, and more weight where they are located is not a problem as well, I decided go brushed way...

[gonper]

All linkages are set up now.
I do not know how to proceed with the chassis. Going the standard way with plates and cross-members or doing something more creative.




The steering that is posible with this setup is almost ridiculou , 70º on both axles.

[WHITE-TRASH]

70* is pretty standard these days. Make the axle "tubes" smaller and go for 80* and really prove something.

[gonper]

Originally Posted by WHITE-TRASH

70* is pretty standard these days. Make the axle "tubes" smaller and go for 80* and really prove something.

I though that the actual range was about 50º-60º most.
Actually it can goes a bit more than 70º, around 72-73º and yes certainly it will be able to go even more with more scrub and reducing the axles sizes, but I do not know if I want to start redesign so much, it means lots of work

I will let that for next version update.

[filotr14lsdude]

Originally Posted by WHITE-TRASH

70* is pretty standard these days. Make the axle "tubes" smaller and go for 80* and really prove something.

While 70degrees is a standard these days. This won’t have the speed up and slow down that you tend to get with the current products available.

The other main issue is that when your running that much steering you get really bad pushing forward. The only way to stop it, would be to work out some fancy radio mixing to overdrive the outside wheel at full lock.

To the original poster. Keep up the great work.

Looks like your going to need at least a quad stick radio. Might as well have is so you can mix the steering so both front wheels can go opposite each other.

[gonper]

Yes, plan to use stick radio, with one axle steering and gas on each stick.
Similar to helicopter flying
Then both steering axles can be controlled differently and even the throttle of each axle can be controlled separately so each axle can go on reverse direction than the other. Do not know what weird effects this will cause

[gonper]

Finally decided to go on a fancy chassis design.
It is the first version with lot of holes in order to test different configurations.
Depending what holes are used on the chassis and other changes on the wheel shafts, different setups can be achieved:
- 0º to 30º Caster angle.
- 15mm to 25mm positive Scrub radius
- Multiple Antisquat Antidive positions for the links arms
- +-30mm wheel base adjustment
- 0 Akerman (Can not adjust)
- 0º Camber angle (Can not adjust)
When geometry defined I will modify that chassis to make it lighter and simpler.

I know that every one uses different geometries, but if you do not mind to share the ones you are using on your rigs, it will give me at least some ideas where to start.

[gonper]

And here is the final full assembly. I did not draw the shock absorbers, as I do not think it is need, they are represented by the red links.
As well I did not added the screws, nuts washers, as it is just a hobby design.
Now it is time to start ordering parts.
First I will order gears bearings and motor to check if gear box works ok.

[Tzi]

Awesome idea!
I think It needs a pimp-cane chassis
That would really flip people out.
Do you foresee the instant-brake of a worm drive to be an issue? It’s like having 100% drag brake

[gonper]

Awesome idea!
I think It needs a pimp-cane chassis
That would really flip people out.

Thank you for the input Tzi
Although I like the simplicity of a pimp-cane chassis, I think it does not work very well. Because it does not flex on its length.
Anyway you made me think that I could go more radical on the chassis.
So I have spent some hours doing maths and geometry... will post about my hypothesis soon.

Do you foresee the instant-brake of a worm drive to be an issue? It’s like having 100% drag brake

Yes it will probably be an issue, and will require special TX mixings and an especial driving license

[Gandalf The White]

I don't think that's enough adjustable mounting positions... Looks great, cant wait to see how the gearbox works.

Would you ever consider making the files for some/any of these parts available for others to use?

[gonper]

Originally Posted by Gandalf The White

I don't think that's enough adjustable mounting positions... Looks great, cant wait to see how the gearbox works.

yes you are right, I have reduced the number of holes on the final version, after checking all adjustments and clearances.
Will post final version latter.

Would you ever consider making the files for some/any of these parts available for others to use?

I will print and check functionality first, modify if necessary (for sure...) and then will post files and designs on thingiverse or somewhere else.

[Gandalf The White]

Originally Posted by gonper

I will print and check functionality first, modify if necessary (for sure...) and then will post files and designs on thingiverse or somewhere else.

That would be awesome! You have put in a lot of work on the CAD for this project, I hope everything goes together IRL as well as the CAD model.

[gonper]

I thought that I already had posted this, but apparently went missing on the internet ocean...

I have checked tolerances, interferences and other issues so here is the final version V1 that I have named Gosainthan, it is a quite standard chassis that can be 3D printed. I reduced the number of holes to just the most usable ones but still a lot to play with. Now it looks more slick and cool and it is lighter. As well I added holes on the top axle link mount so there is more possibilities for adjust the caster angle.
It can use one way or two way shock absorbers from 80 to 110mm.

Provably after printing and testing will need some redesign and adjustments.




Later I will post V2 Gasherbrum version.

[gonper]

As Tzi sugested on a previous post, I went a bit wild on chasis design and decided to design something more radical, well actually it is almost no chassis at all. So this is the V2 version, named Gasherbrum
It share the same axles as the

As it is just some small 3D printed parts and some links will try it and if it does not work I can always go back to Gosainthan version.

Let me know your thoughts.

[filotr14lsdude]

One thing I would look at is your upper link mounts.
I’d consider adding some more holes on the other side of the current mounting bolt.

I know for the front it’s not required as the caster will go the wrong way, however on the rear you would be able to position the caster angle closer to the same as the front axle.

I used to run zero degree caster in the rear, but has been playing around with caster on the rear and found it can be handy for a little bit more traction on the edge of the Tyre.

[Gandalf The White]

If my brain is seeing that very cool second chassis right, you would need some very stiff springs in order to keep it from being super floppy. The links sharing the same mounting holes on the chassis means that blue "chassis" can just rotate forward an backward (on an axis similar to the wheels spinning, if driving straight), taking the axle with it. This will make the caster change as the load on the axles change.

I could be wrong, but figured I would let you know.

[gonper]

Originally Posted by filotr14lsdude

One thing I would look at is your upper link mounts.
I’d consider adding some more holes on the other side of the current mounting bolt.

I know for the front it’s not required as the caster will go the wrong way, however on the rear you would be able to position the caster angle closer to the same as the front axle.

I used to run zero degree caster in the rear, but has been playing around with caster on the rear and found it can be handy for a little bit more traction on the edge of the Tyre.

It is already thought, the red part that looks like an spur can be mounted on both directions so you can have positive or negative camber (0º to +-25º) on both axles.