3D printed Ultima ST "Type-R"

[HiTec]

Hey all. I thought to dedicate an own topic for this car.

I started to model some parts to my ST GP some time ago and the things just went out of control when i win a bid on BNIB Ultima ST Type-R EP. Before assembling it, i recreated all the Type-R specific parts to my PC, so i could easily print spares for it (so rare car nowadays, that parts arent easily available.).

Well, then i thought that i should do a "beater" version of that Type-R. So i basically reinforced all the parts to be compatible with 3D printing and also durable when printed with FDM printer.

The transmission was the most difficult part of the project i think, because Type-R transmission is not available anymore. I can get the transmission case halfs, diff and idler, but not the input gear, or diff cups, or the motor mount. So i re-modelled the rear end of the car to use RB5/RB6 rear mount transmission, with custom rear chassis plate, rear shock tower mount, motor mount and rear bumper.

All the parts except the front body holder are printed from 20% Carbon fiber / 80% PETG (edit! Forgot that the wheels were printed from red transparent PETG). Only parts that have not been printed are the ball cup ends, servo arm, metal parts (except the motor mount and rear chassis), and lower control arms.

End result:





Sorry about the rear tires, no ST tyres in stock in local suppliers, so i need to wait.

Rear chassis plate:



Transponder holder and other 3D printed parts visible:



Custom rear end and gear cover

[Dadio]

Looks really good , I did virtually the same thing with the Yokomo YZ-834b so I could have a beater ( see my YO-CLONE-OH project ) .
How's the CF PETG ? I never really liked PETG but I've not tried CF PETG , my project was in CF Nylon but its expensive stuff so if CF PETG is better I might give it a try .

[JackOTrades]

Looks like a lot of work. Looks good!

What’s your process for reverse engineering the parts? CMM, Optical Comparator, Calipers....?

Also would be interest in what printer was used and your settings. I don’t know if this is closely guarded, but I’ve been getting into printing in the last month but have yet to get away from PLA into the more robust materials. It seems like some of the SLA filaments are also pretty robust and would yield finer parts but I have yet to explore these as well.

Thanks for the share.

[HiTec]

Wow! Just checked out the whole YO-CLONE-OH project, nice work there!

I was forced to use PETG/CF, as i couldn´t get my Nylon CF to adhere to Prusa powder coated steel bed no matter what i did. Warped off like crazy. I like the CF/PETG. Not as good layer adhesion as Nylon i think, but the parts are very rigid and awesome looking. I have tested my development parts in the original Type-R in winter (no fear of dust or scratches). And they hold up well at least in normal driving. Havent tested the crashing I still need a longer dog bones than stock because of the RB6 ball diff, so i havent driven this car.

For reverse engineering, i only use caliper. I dont have any of those fancy scanners or other devices. Then i just think of the forces and direction of force when reinforcing parts. I´m no expert in these things, just self taught Fusion 360 user.

And yea, no secrets here:

- Printer is Prusa i3 MK3s.
- Slicer is Prusaslicer
- Design software: Fusion 360
- Filament is fillamentum carbonfill black (i literally have to rip this out from print bed, sticks like crazy)
- Print setting for most of the parts: 0,20mm speed settings (the chassis was 0,30mm draft as well as the front upper chassis) 100% infill.
- 270c nozzle, 85c bed, cooling on auto mode


If you need anything else, just ask (y).

Here you can find most of the design files: https://www.thingiverse.com/jiipeee/designs

Im not making money with these files/parts and i expect that people wont make money with my files (because of that the licence is what it is). I recreated these parts just for the love for this chassis. GP version of this car was my childhoods second "real" RC-car after Marui Hunter and i have really nice memories with this chassis, even though the Racing Sports version was far from optimal. If even one people can get his/hers old Ultima ST running again with my parts, im happy. I remember the pain when my old ST GP was "dead" after the RS-147 spur gear was discontinued and impossible to get about 16 years ago.

[HiTec]

First drive with this was today! Weather was -15 degree celcius.

Everything worked as it should! Even my RB6 input shaft slipper eliminator held on!

I crashed the car once during the test drive. Some radio-interference with those old AM27 MHz Hitec radios that i just tossed in. (Futaba is installed to the "real" Type-R".) I was 100% sure that side impact would have cracked the steering arms, expecially when its cold outside, but no.

Very happy with the results.

Next test will be the "Ultimate" test. 60A brushless ESC with 4000KV motor with 3S LiPo. Im pretty sure there will be pieces flying around, but lets see.

Edit: First brushless/ 3S LiPo test was also success! No problems in jumps yet.

[HiTec]

Swapped in a brand new Team Orion 4300mAh 3S 55C LiPo, swapped the rear tires to more gripper ones, turned the ESC punch all the way to the "punchiest setting" and gave it a go in -16C.

I broke the slipper eliminator groove after 5 minutes (i didnt remember to tighten up the eliminator set screws, so the input shaft and the eliminator was "paired together" with just the 3D printed groove part of the eliminator). After tightening the set screws up, the eliminator held just fine.

The car was crazy fast, i can say that i have never ever driven this fast RC-car.

Drove it for 10 more minutes, crashed/rolled it over 3 times.

After the last roll over ( it was dark and i hit a lump of ice from full speed), the car rolled over four or five times. After that there was first visible damage. The C-hub upper ball joint attachment point was cracked ( i didnt have the "L" style ball joints, i only had the short ones).

This test was a success!







Im actually very happy, that the part didn´t crack between the layers. This means that the printing orientation was right, i just need to beef the upper ball joint attachment point slightly. Couldnt be more happy with this test, because i was 100% sure that the rear chassis plate would be the first one to crack.

Some measurements about the part that cracked: The ball joint hole was 3mm and the "outer" dimensions of the area that was cracked was 7mm. Fusion 360 tells i had 2,2mm of material around the ball joint. I have extra 3mm to play around with, so this is the easy one. After the reinforcement process, i suspect something else is going to break, but thats normal stuff.

So, lets test this:



Edit: Im also re-creating the Marui Hunter:

[HiTec]

Alright new test -> Full speed crash to snow/icy road "bank" (sorry i dont know the right word for it).

I think im actually going to wrong direction on this reinforcement project. Im now breaking the original moulded parts. The second crash test result was kind of success.

The front part of the car sufferered broken shock absorber upper ball joint part (thats part of the shock) = fail -> this is not acceptable as moulded "hard to get part" shouldn´t break -> I should make the front bulkhead "weaker".

Front lower control arm (OEM molded) broke -> also not acceptable -> the 3D printed front bulkhead is too strong. -> I should make the front bulkhead "weaker".

The rear section:

The rear chassis teared up, to save the OEM moulded lower rear control arms -> success.

[Dadio]

At first with the Yo-clone-oh project 5 min running was good , it brakes , you redesign and go again ...... Secondly vintage plastic parts and extreme cold weather is a bad mix , they can be so hard and brittle in cold weather its frightening !
Keep up the good work and enjoy it .

[HiTec]

You are absolutely right my friend! Its a constant neverending process when trying to develop things like these!

My goal is to achieve a chassis that is durable enough, but that will give up before the OEM parts crack (because its always easier and cheaper to print some parts).

Thanks for the reply!

I already designed the front bulkhead to be much more weaker and also draw the replacement part for the shock upper balljoint attachment. These will also go to thingiverse once i have tested them. I already uploaded the reinforced front C-hubs.

[HiTec]

Now it holds up normal 3S driving and jumps (if you land it correctly). Also seems to hold up with "soft" crashes.

I think i will now package all the parts and release it as a whole set.

[adam lancia]

That's some very cool work you've done!

[HiTec]

Thanks Adam!

This has been a very nice Fusion 360 learning project. I was able to 3D print the rear and front lower arms also, so they are durable enough for normal driving and jumps. The printing orientation of the arm is horrible, lots of supports and cleaning after printing, but thats the only way they are durable enough for beater.

I have now broken 2 OEM Kyosho front lower arms and i dont want to break any, as i only have one full set stocked and i now know that my front bulkhead and the whole front chassis is too durable for even the OEM arms to last in crashes. I fiddled around with weakening the front bulkhead hinge pin area. Bulkhead would be easier to print, but its time consuming to swap instead of arms, so...

If you print the arms 100% infill 0,20mm layer height from PETG, you will get the same stiffness than the OEM optional soft arms have (example UMW-116.)
Same settings, but printed from CF PETG -> they feel the same than the "hard arms" (UM-102).

Rear arm v.1.3.1:



Front arm v1:

[HiTec]

Small update. I think i have successfully created Kyosho plastic shock body with 3D printer.

I copied the original design from the Racing Sport chassis shock body, but designed the whole shock body around the ORG03X X-Groove Kyosho "O"-Rings.

The test shock body had setup like this (from bottom to top):

- 3x6x1mm aluminum collar
- ORG03X
- 3x6x1mm aluminum collar
- ORG03X
- 3x7x1mm aluminum collar
- Star washer

To set everything up goes like this. Shock shaft needs to have piston installed, then goes the 4mm installation shim collar, then the o-ring/collar packet as a whole. Then just assemble the shock like in the Racing Sports manual says, but pull the shaft tight against the shock body end, so the star washer locks the o-ring/collar packet to the shock body. When the star washer grabs the shock body flange, pull the shaft out, remove the 4mm installation shim, reinstall the shaft, fill it with silicone oil and install the upper parts.

I kind of copied the Type-R style/Racing Sports style combination and designed it to be printable.

I have one shock assembled on my desk right now. I dont know how durable it is, but it doesnt leak yet. Assembled with "Graupner 20 Winter" silicone oil. Feels great also! It isnt like the Kyoshos velvet coated damper, but its absolutely the same as the Kyoshos stock plastic damper body with X- "o-rings).

Edit: Oh shiii, i forgot the print settings:

- Printed from prototype style clear PETG (accurate).
- 0,15 layer height (final would be 0,10)
- Seam position outer and random
- Speed = Quality
- 230c / 80C.

Some pics without the upper part (installation collars still visible):





Small air bubble visible (proofs that its really filled with silicone oil):



Im really surprised that i cant feel the print layers when i move the shock shaft up and down. Even if i try to bend it the shaft to one direction or another. The ID of the shock body is the stock 10mm and the piston is something like 9,8mm.

[coxbros1]

wish i had your skillset....i couldn't even turn one of the printers on...let alone make a part

[HiTec]

Thanks for the reply! About an year ago i could draw anything. Luckily the Fusion 360 is easy to learn, you should try it out!

Here is a cutout from the shock i designed:



I have now have three runs driven with this shock, still holds the oil and hasnt cracked.