SCX 24 - Layer by Layer

[Bray D]

It's been a while since I've made a proper build thread. I picked up an Axial SCX 24 this past weekend and it's shaping up to be the perfect test bed for a pretty extreme build.

After seeing the relatively small aftermarket offering for these rigs, I decided to splurge on a 3D printer (Creality Ender 3 V2). I plan to flex the capabilities of FDM printing as I work through various build iterations. I have no idea where this will ultimately lead, but I love building and having the ability to make parts on the fly is going to be awesome. Being able to test and tune in my living room is pretty solid too, haha.

Anyways, on to the build!


Next to my 2.2 Creeper






This thing is tiny






And the machine that will be doing all of the labor

[Bray D]

I started by playing with the printer and getting the slicer settings dialed in pretty good. I made a filament guide, tolerance test block, Benchy, etc. The machine met all of my expectations. I think it'll be pretty solid.

Then I moved on to actual parts. I'm more-so a fan of performance rather than scale accuracy, so the first thing to address was the tires. I opt'd for the RC4WD Scramblers for their size and rubber compound. Looks like they'll conform pretty well under the light rig. Unfortunately the stock tires are glued to the wheels, so I needed to print some new wheels for the Scramblers.

15mm wide. 0mm offset. Two piece double beadlock. I just modeled it based on my size requirements, then added some features until I liked the way they looked. I plan to machine some brass for the internal locking sleeve to add some weight while I'm at it.




Fits the tire pretty well. I need to print 3 more then I can mount them up for good.




I also printed a straight cage bar to replace the baja style lights up top.





Aaaaand a couple pics showing the test fit for the Scramblers. Part of me wants to print the wheels with more offset to make it wider, but I think I'll roll with it at the current width for now to see how I like it. 0 offset will make the steering happy, and with the wider wheel it'll be slightly wider than stock anyways.






That's where I'm at right now. Finishing the wheels is on the immediate list, and I'd like to start experimenting with printing full cages to see how that goes. This massive cage has to go!

[spoo76]

Sounds interesting, but none of your pictures seem to be working

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[Bray D]

Originally Posted by spoo76

Sounds interesting, but none of your pictures seem to be working

Uh oh. I pulled them from my Google Photo location. It's likely a private album so no one can see it.

I'll fix that pronto.

Edit: So many hosting issues today. I think that should work. Let me know if they're still broken.

[spoo76]

They work now!

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[zjcrazy94]

Looks good!


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[Bray D]

Good deal. Quick update to put us back on track -

I machined the lock sleeves tonight and learned a thing or two about wheel / tire design. Turns out my lock sleeves are too narrow, but rather than machining replacements I've decided to print narrower wheels. I have a 13mm version printing beside me as I type. Sticking with 0mm offset. We'll see how they look when they're done.

I had some leaded bronze stock on hand, so that's going in the front. I made some thinner steel sleeves for the rear. I have no idea if this is too much weight, but I may as well try it and see how it does. I'm used to my 1:10 rig that literally weighs 10 times this thing, haha.

[Bray D]

The 13mm test wheel turned out great. I increased the flange diameter a bit compared to the previous one, and it obviously only has 13mm flange to flange opposed to 15mm. It squeezes the tire a bit more when assembled, but I'm cool with skinnies.

13mm vs 15mm





13mm assembly





With a successful prototype, I went ahead and printed a full set (with slightly more hex engagement).

[Bray D]

They all assembled well and look great. They added significant weight too, though it doesn’t feel too extreme.



I’m diggin’ the width with 0 offset. No immediate desire to change anything with the wheels.



I will, however, have to do some body chopping or push the axle forward as I have some interference with the tires. I have essentially a 90 degree approach right now without the bumper, so there’s not really a functional need to push the front end out. I feel like the wheelbase is pretty long as-is too.

I’ll probably have to get out the sawzall.



The steering servo and motor are pretty weak with the bigger tires and added weight. That needs remedied ASAP.

I’m familiar with the EMAX servos. What motors are people swapping into these little guys?

[HumboldtEF]

I like where this is going. 3D printer + Lathe seems like a very powerful combo.

Good choice not going for a wider offset, steering is terrible enough as it is.

[PFongemie]

Ecx barrage motor works well. You could drop in a sidewinder micro and run a small brushless. Just beware things will break. Throttle control is a must. I tried it, it was fun, but after breaking a few driveshafts and a axle I switched back to the barrage motor. As far as the steering replace the rear axle with a front one and go with 4ws.



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[Bray D]

Originally Posted by HumboldtEF

I like where this is going. 3D printer + Lathe seems like a very powerful combo.

Good choice not going for a wider offset, steering is terrible enough as it is.

I’m a tool junkie. I typically jump at the chance to increase my shop capabilities, as seen by the 3D printer purchase for this build, haha. I also have a small mill that comes in handy pretty often.

The stock steering is certainly lacking. I’ll do my research and put an adequate servo on it. Either way, I really like the stance right now.

[Bray D]

Originally Posted by PFongemie

Ecx barrage motor works well. You could drop in a sidewinder micro and run a small brushless. Just beware things will break. Throttle control is a must. I tried it, it was fun, but after breaking a few driveshafts and a axle I switched back to the barrage motor. As far as the steering replace the rear axle with a front one and go with 4ws.

Nice. I’ll look into the barrage motor. I have no real desire to go brushless, but I do plan to eventually run a separate receiver and ESC so I can use my nicer transmitter (for what that’s worth).

I’m very much a low speed technical driver, so hopefully I can keep the mechanicals alive. It needs to be able to pull itself through obstacles though, haha.

The only wheel speed requirement for my 1:10 is that it’s fast enough to throttle out of a roll. A similar requirement would be nice for this one, but it wouldn’t be a deal breaker if I have to slow it down further to get the torque and modulation I want.

The 4ws setup looks legit. My 1:10 is setup with 4ws and I’m not sure if I’ll go that direction with this build or not. I’ll keep building and driving and we’ll see where the journey leads!

While I’m still playing with the tires, I figured I’d vent them and cut the foams.

I had no plans when it came to the foam, but I hacked them up pretty good. It’s hard to tell, but I cut 8 radial sipes in them and 1 circumferential sipe around the OD. All of those cuts run to a depth that’s approximately 1/2 of the foam thickness.



It’s still not as soft as I’d like, but it’s starting to squat a little when fully flexed.

Driver front at full compression causing the passenger rear to squat:




At rest:

[PFongemie]

I tried brushless just to see if I could do it. While it was fun, it was just to much.

I did keep the sidewinder micro (programmed to run brushed motors) mounted it under the battery tray. Fits perfectly. Mounted my receiver in the stock location.


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[Bray D]

Originally Posted by PFongemie

I tried brushless just to see if I could do it. While it was fun, it was just to much.

I did keep the sidewinder micro (programmed to run brushed motors) mounted it under the battery tray. Fits perfectly. Mounted my receiver in the stock location.

Good to know. Research shows that the Barrage motor is a pretty popular swap and motors are super cheap. I may end up going that route.

I just ordered a receiver so I can use my GT5 transmitter. I need to decide on an ESC and get that on order as well. Once I have that swapped over, I can see how it influences performance and go from there.

Edit: Sidewinder Micro 2 and Barrage motor are on their way. I'll likely toss the motor in it before I do the ESC swap as it'll get here sooner and it'll be good for science.

[Bray D]

On tonight’s edition of ‘3D printing FTW’ you’ll find Bray’s whiskey fueled implementation of a steering solution.

I modeled this solely on intuition and printed it fully expecting to have to make another after I learned something about the spherical bolt fit. I was pleasantly surprised when everything snapped together beautifully.

20% infill PLA. I was worried about it’s strength, but after seeing how much force was required to set the TRE’s, I have much more confidence. If it fails, I’ll print with 100% infill. If that breaks I’ll experiment with PETG.

Maximized drag link length and threaded it vertically into the tie rod. Plenty of clearance for the diff and no more floppy steering.




Old





New

[Gramps]

Looks good will be interesting to see how well it holds up. If you want to strengthen it more you can anneal it. This is how I do it Annealing PLA - Gramps Ramblings

[Bray D]

Nice. I didn't know annealing plastic was possible! I learned something today.

[HumboldtEF]

Just keep in mind the dimensions will change and some parts will warp a fair bit. CNC kitchen on Youtube has some good video's on Annealing.

https://www.youtube.com/watch?v=dOzVuoBP9gY

[chaotic_life]

Thats pretty cool... would you mind sharing the STLs for the linkage?