Honza

@BuggyGuy Thank you, I wanted to make it look like something that could be made by Tamiya as a side effect, it also saved some material, since most parts don't need any infill.

Hi, I'm currently working on a design, that's going to use M0x gears. Problem is, that I don't have them yet and I'd like to do some work before I get them. I could get some measurements from the manual, but since it's generally poor resolution (why Tamiya just cannot export vector files, like others do?) it wouldn't be as precise as I want.. so I would like to ask for help, could anyone measure the spur gear and counter gear dimensions shown in the picture? Thanks for help

@Willy iine ah, sorry about that. In that case, it's just another Tamiya thing... Apparently, they have capacity for surface treatment of aluminium parts, so they could do better pinions, if they wanted. 😀 @No Slack I think that heat treatment is not needed, we use soft plastic gears and they work well. Problem is with surface treatment, or lack of thereof in case of Tamiya. Anodising drastically improves surface hardness of aluminium. It can be even done at home.

For me, PLA+ works pretty well on many parts, it has good Z-layer strength and it's less brittle than a standard PLA. But it may degrade over time, although most parts I printed still work. PETG is softer and has higher melting point, so it's great for gears or parts surrounding hot components, but, at least one I use, has a bit worse layer adhesion, so it's not as suitable for more complex parts with horizontal holes - but it may still work with a proper design.

I think it's caused by lack of anodising on Tamiya pinions. Anodised aluminium pinion I had in one Chinese kit didn't wear as fast as Tamiya...

A little update The most problematic part during the race was a steering, dirt could get stuck between arms and chassis. I did a quick hotfix, which helped me to finish the race, but I needed to do it properly So I made a new bridge and steering spacer The purpose of the spacer is to make a flat plane under arms. hopefully, that should help to sweep debris out of the mechanism instead of getting stuck. Now I'm waiting for some parts to improve steering angle...

PS: @Grumpy pants I also put the car on scales, the car weights 1630g with body

Report from yesterdays race Well, results were.. underwhelming - as expected But most was due to drivers errors or electronics issues, mechanics mostly worked well. And nothing broke I even got some nice comments and ideas from fellow racers, so the first race was success. I identified some issues, around steering (I definitely need more steering lock) and the center diff, so these areas will be modified, soon. I have a few photos, but my phone's camera wasn't up to task, so quality is pretty bad...

@Grumpy pants Thank you Performance will be very limited by me, it's my first race after 2 years 😀 So even finishing the race will be success 😀

Getting ready for the weekend race The chassis is now ready to run. I also added chassis cover mounts on the top chassis plate, but I underestimated motor cable thickness, so cover doesn't fit as tightly as I would like - but I don't have time to reprint it. And installed body. And this is what development looks like. Several iterations of prototypes and damaged/misprinted parts

XV01 is a little odd - rear XV01 axles are ~2mm longer than fronts. Also, rear swing shafts are 39mm, while fronts are 42mm. @DuntmatterReally The bearing you used with the XV01 axles is same as one you used with the GPM parts? It looks like the inner bearing wasn't fit properly in the previous photo.

And here it is mounted in the chassis. Councan notice thet the ARB mount is higher than in the rear gearbox. That is to make more clearance for the suspension mount, which can be moved upwards to create a kick-up angle. Here is the very short front driveshaft, 20mm long. You can imagine angle that would've been there, if the gearbox outdrive was 7mm off-centre. The top deck looks massive, but it's actually hollow, with added support in the center section - as a result, it's quite flexible, but only in the straight sections. And completed chassis. At least for today 🙂 Please let me know what do you think, any idea will be appreciated I plan to release the files in the future, once everything's sorted out.

The front gearbox is a bit more interesting. I needed to open it to clean it, so I made a few pictures in the process. You can see 3D printed gears there. While I wanted to use TL01 gears, like in the back, it'd make the front driveshaft run under quite extreme angle and in possible collision with the motor tabs, so I decided to print 7mm shorter variant of the gears from PETG, which allowed me to move the outdrive closer towards the centre of the chassis. The differential is taken from my MF-01X - FF03 ball diff outdrives combined with 3Racing diff gear. Like in the MF-01X, the front gearbox can fit 1510 bearings to make this work. Here you can see why I printed the gears from PETG - during initial assembly, I put temporary 3D printed shafts in the gearbox - and then forgot about that until a test drive. Of course the shaft broke and gear got in contact with the gearcase. PLA melted away, but there is no sign of wear on the gear. Just like in the center gearbox, gearcase are held to the chassis through embedded nuts - in this case it's because of print orientation and high loads from the dampers. The two halves are held together with two 3x15mm screws - they are there mostly to bear axialnload from the bevel gear. Additional support is provided by damper mount, chassis, top plate and ARB mount.

While the right and front section of the left guard are screwed directly to the chassis, rear left part also serves as a battery clamp held by clips - as there will be driveshaft above the battery, I needed it to be removable on the side, but I didn't want any holes in the chassis side. Rear gearbox uses standard TL01 gears and gear differential. I chose this drivetrain to raise the driveshaft above the chassis. You can also see one of the few non-tamiya parts (apart from 3D printed ones) - the outdrive comes from Maverick/Himoto chassis. As I didn't need to do anything with it, it went in assembled, including YeahRacing shocks. The top link mounts might be critical part of the gearbox, as they contain holes horizontal with printing plane. On one half of the gearbox, they delaminated during assembly, but after reprint, they were able to withstand some crashes, so I'm not sure whether I should change the design or not..

Now motor mount. I really liked design of last shaft driven tamiyas, with easily removable center gearbox - so I made my own version. It makes servicing much easier. The green part on the spur is a center differential. More on that later 😉. Motor plate is printed from PETG, as PLA, used on the rest of the chassis, has too low melting point and tends to creep. The mount has embedded M3 nuts to make sure that it will survive multiple disassembles. And here is the chassis with all central components mounted. The picture demonstrates that there are no need for additional braces to hold it together... ..so these side guards are there purely to protect the components from a direct hit. It's not really visible from the photo, but they are angled upwards at around 10 degree, gaining additional 5mm of ride height.

So, I already posted a few pictures of my rally chassis before, but since I needed to rebuild the chassis because of new chassis plate, I thought that I could make a proper build thread with some more details I've been experimenting with 3D printed parts for a few years, with my last car being MF-01X with a custom middle section, containing motor, and some parts around the axles. I also tried feasibility of 3D printed gears there. The chassis worked pretty well, but there were still some issues, and I wanted to experiment with a center diff, which couldn't fit in the chassis. So, I decided to make a fully printed chassis. well, fully.. almost The bottom plate is 3mm thick aluminium plate. A bit overkill, but I wanted a rigid "backbone" that will take forces from the bumper and axles. Here with suspension and steering. The suspension is short reversible type, it so far worked the best for me. However, I used MF-01X knuckles to get a bit better steering geometry withou collisions with the arms. In the future, I plan to get TRF420 knuckles and make a custom arm. Steering has 50 degree throw - well beyond capacity of Tamiya CVDs (future proofing 😉) . The servo is mounted on a floating mount. I wanted to mount all components to the aluminium plate, however it backfired a little here, the servo mount is a bit too flexible, so I need to come up with a better solution. The battery is mounted in a little frame, which also makes connection point to the top deck. The connection was necessary for the temporary printed deck, aluminium plate doesn't flex as much. The honeycomb pattern on the bottom should help with debris, that could get between the battery and plate, so battery won't jam in its slot.

Finally designed and printed chassis cover, it still needs some mods for better fit.. Getting ready for next week's race :-)

It looks awesome! Now I'm thinking about revisiting my old project once I'm done with the rally chassis

It looks like an F1 from this angle maybe you could move the battery a bit rearwards and lay the servo flat in front of it to further lower cog? It looks like it'd have enough weight on front.

Load from the droop screw is just load from the spring + some inertia of wheel, but here it acts against the damper, which means significantly greater force and it'll be moving at the same time. Although the onrad chassis won't experience large bumps that often and YR-F's original solution is quite similar and works, too.

Wouldn't that make the car around 200mm wide? The TCR has 5mm shorter driveshafts. I can see potential issue with the damping solution - it created a lever, which multiplies force that goes into the arm's pivot ball.

Very interesting. It is great to see a FWD that's not just a TC with removed rear belt what driveshafts do you use?

Unfortunately, it didn't get past early CAD. My requirement to make it rally-capable (i.e. - long suspension travel and wide steering angle) further complicated things. But I might try it again my idea was using an FF03 ball diff, which is fairly narrow, and mount it between motor mount and spur cover (which also acted as a bearing holder and top link mount). That created free space behind the motor, so it could be slightly off-centre, which allows for slightly longer arms and right-hand drive shaft (I wanted to use a 30mm M0x shaft) I think that I scraped the concept, because suspension arm mounts ended up being pretty far from the bulkheads, held only by chassis bottom plate (which was planned to be 2mm GF composite, so quite flexible) . Otherwise, it was doable.

Looking forward, it sounds like an interesting project. Direct drive with an independent suspension is quite challenging to design, I played with that idea, too. Have you considered different lengths of the driveshafts, like the real cars have? I was wondering, if there would be any adverse effects.

No need to apologies, there's nearly nothing left out of TL01 I even 3D printed some gears, luckily, these old models have large 32p gearing, which is doable even with cheap FDM printer and basic materials. M03 very close to TL01 and it is quite close to what I'm planning as my next project Tamiya cars might not be perfect, but they provide lots of inspiration