Sportsman + 3D print: Lil Doggy

[SurlyBurly]

Originally Posted by D440

Pretty impressive stuff man. Did you create that model of the axle and ring gears?

[D440]

Yup - the axle is just a close replica for mocking, the rest is at precise scale. Was required to designed it!

[TheLetterJ]

I like where you're going with that cover... and the whole car for that matter. In the last pic, is the face of the cover 1 piece with the bottom? Are the bearing caps incorporated into the cover now that the lower bearing cap bolt holes have been cut? Is the underside just held on by 2 screws after drilling upwards into the housing? I've got a couple ar60 housings (that I previously wore through the bottom of) laying around that I wouldn't mind experimenting with.

[SurlyBurly]

Originally Posted by D440

Yup - the axle is just a close replica for mocking, the rest is at precise scale. Was required to designed it!

Pretty slick, what do you use to model?

[D440]

Originally Posted by TheLetterJ

I like where you're going with that cover... and the whole car for that matter. In the last pic, is the face of the cover 1 piece with the bottom? Are the bearing caps incorporated into the cover now that the lower bearing cap bolt holes have been cut? Is the underside just held on by 2 screws after drilling upwards into the housing? I've got a couple ar60 housings (that I previously wore through the bottom of) laying around that I wouldn't mind experimenting with.

The cover is 1 piece, yep (front and bottom). Now the cover takes care of holding the bearing, no internal brackets anymore. I'm still developing this model, I think I can cut the housing further to get even more clearance. The other thing I wanted to do, is to cover the rear of the housing a bit, so when you run backwards the bottom won't get hung up. Still some tweaking pending!

About your question SurlyBurly, I simply use Tinkercad.

[pcgab]

Awesome rig, really like all the custom printed components you've made!

I'm using the Progress RC barber mod covers on my sporty. I made a quick jig to attach the ar60's to that I can run against the fence of my bandsaw to get the desired cutoff, 33mm in the case of the Progress RC covers.

Once you get your covers for AR44's how you like it, do you plan to put it on Shapeways?

Cheers,
Gable

[D440]

Hey pcgab, yes I would be fine putting them in shapeways. I'm still not done with the AR60 tho, I want to get more clearance out of it, trimming the housing further (more to come on this soon).

I like the idea of doing the same on the AR44, I will probably do that next. Need to check how much clearance is there to gain actually. AR44 housing has a smaller pumpkin so not sure if needed.

[D440]

Watching the axle cover I was pretty sure it can be trimmed quite a bit more. Took a stab and trimmed all the way up to the bearing!







Next step: changing the design to match the extra ~4mm of clearance!





I'll call it "Pacman" LoL - eating the gears!
I think it's ready, now will do some field testing!

[D440]

Got this HR Diff Locker in the mail.



It's way thinner than the stock one. So updated my cover to take advantage of the extra clearance!





At this point the bottom of the the AR60 axle is basically completely flat besides the bevel gear cover!

[D440]

Got 3S batteries of 450mAh, 650mAh and 850mAh. All of them fit behind the servo. The 850mAh tho has a very tight fit, almost rubbing with the drive shaft and the lower links. Decided to build some sort of plate.

Took a piece of this really strong plastics that I got, don't remember exactly the name, but is stronger than lexan. Cut a piece, flipped the truck and lay down the plate somewhat aligned with the axle, battery and servo. Then applied the heat gun and let it melt a bit to take the shape of the bottom. Worked flawlessly.

[D440]

I created a Shapeways shop in case anyone wants the pieces I've built.

https://www.shapeways.com/shops/d440rc-designs

Fill free to ping me with comments/suggestions.

[D440]

I made a video to explain how to mod the AR60 axle and install the Pacman!

https://www.youtube.com/watch?v=mLcVg_PISLg

[TheLetterJ]

What happened to the diff covers on your Shapeways? I saw them earlier, then refreshed the page and they're gone. I'd really like to give one a try and if it goes smoothly on my worn out plastic axle, maybe even try it on a Chinese "steel" (potmetal) housing. I think with a full width truss on top, it could still stand up to some abuse.

edit: I see now after reading the comments on your install video

[D440]

Originally Posted by TheLetterJ

What happened to the diff covers on your Shapeways? I saw them earlier, then refreshed the page and they're gone. I'd really like to give one a try and if it goes smoothly on my worn out plastic axle, maybe even try it on a Chinese "steel" (potmetal) housing. I think with a full width truss on top, it could still stand up to some abuse.

Hey. The folk from Progressive RC didn't like that I a made copy of their design (The Barber), so I'm checking how to share my version without going over them. You can still buy theirs in the meantime.

[HumboldtEF]

You could share just the design on someplace like Thingiverse

[D440]

Realized ny wheelbase was way far from comp specs! The rig was at 13.75" ! LOL. Had to do some link work. Overall wasn't that bad.



Now I'm exactly at 12.5" at max stretch.

Also took some time to shave the HB White dot Rovers. They look very narrow now! And I have full clearance for steering! Also checked the width of the front and I'm getting 11", which I think is perfect and on the rear 10". I like it narrower in the rear, will see how it goes, I may add 1/2" if I see challenges.





Finally been thinking of different wheel designs, and did some testing. I might install one of these...





Sent from my GM1917 using Tapatalk

[D440]

Wanted to change the transfer case as I think the axial is too wide, but also didn't wanted to change the gears as other options are usually hard to find and expensive, while standard axial scx10 are everywhere and super cheap. Designed a new transfer to also mount the motor forward, which will better balance the rig, also putting the motor as centered as possible. Tested out and working!

[D440]

Doing more thinking i would like to also make the skid plate smaller along the way... This is where I'm at now, a transfer case that includes the skid plate.. next will be to tested out and modify the chassis and links to fit the new skid.

[D440]

People asked me "whats the difference with a simple axial transfer?", ""At a glance, looks the same!". Well, it's quite different, here's a picture to illustrate. Can you tell the difference?



The gears sit lower and closer (narrower) so the front motor mount will locate the motor at the bottom of the skid and beside the shaft. I think having a front axle with pumpkin offset (like AR60) it's a must to make it work. Basically, the spur sits ~5mm lower and ~12mm closer to the center compared to a standard Axial gearbox, using less space overall and allowing locating the motor low at the skid level and as centered as possible.





Printed it out, and works! Looks way smaller than I expected , really narrow and centered. Realized of couple tweaks I want to do to make assembly easier.. improvement opportunities never end I guess...

[D440]

Did some tunning on the design and I think is ready to be tested in the real world. Side by side with the standard tranny looks great.