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Re: iwannabetheguy1980's build

Posted: Fri May 21, 2021 9:00 pm
by iwannabetheguy1980
i would note:

If you will be using TPU tires: i would use 3 degree rear blocks, with the spooled main ring gear in the transmission.
it will be like driving on a ice skating ring but at least you will have some stability. The TPU tires are so hard that any extra outside edge wear will have no effect.

If you will be making the Rubber tires then 3 degree rear blocks will cause a lot of outside edge tire wear. I recommend using the open Gear Diff as you will have grip as compared to the TPU tires and it will reduce tire wear, plus using the 2 degree rear bearing blocks or the 1.5 degree rear bearing blocks. there is quite a difference in how the chassis will handle. 1.5 will give you much more oversteer in general and loosen up the rear end and give less outside edge tire wear. 3 degrees will give more stability in the straight line at the cost of some understeer entering the corners. under hard acceleration 3 degree may cause some side to side pull as the tires fight each other a little.
2 degrees seemed a balance between the two and you can equally tune performance with the Tires you cast. a harder tire upfront will reduce steering as a softer rear tire will increase rear traction. having less rear toe will increase the tire life. on my second revision to the cast tire molds i made the tires thicker for more life and it helped de-gas the molds better.

casting the tires may seem overwhelming but this was the first time i made tires this large and it goes pretty smoothly now.
for the Casting rubber you want something between Shore 30A and Shore 60A that is very tear resistant. I'm using Urethan rubber that is 1:1 making it very easy to mix and stable to add things too it like pigment. I'm using VytaFlex 30 and 60 from smooth-on in a trial size you should be able to get at least 8 tires out of the trial bottles.

as far as the printing I've made the tolerances very tight so make sure your extrusion multiplier is set well. you may need to pretap some areas and a set of metric drill bits from 1mm up to 13mm is a good idea.

Re: iwannabetheguy1980's build

Posted: Fri May 21, 2021 11:19 pm
by iwannabetheguy1980
2 long runs tonight.

1) white car chassis #1 had less steering as written on the last page.

Front end suffered a upper ball joint failure, the Brass ball joint snapped at the thread and let go causing loss of steering response.
This was a second type of this ball joint failure I experienced the first failure occurred on the bench not during driving.
The brass is very soft and PLA is transferring shock loads to the joints. option would reprinting the knuckles in Nylon filament not for strength but for the rubbery-ness of the material to reduce vibration and shock damage to these brass joints.

Another option would be finding a similar dimension of ball joint in steel, or a 4mm ball with 2mm hole, the distance between the ball joints is critical to allow the suspension to work correctly.

on the white car the suspension is also new so everything is tighter and that could of contributed to the failure.

Also i could of over tightened the ball joint while installing it.

Gearbox had no issues.

2) green car chassis #2 did fine i had to dial out 10% steering since i got used to the white chassis #1 setup while driving.
no other failures to report battery fully dumped. engine temps got very hot but no gearbox failures to report either.

Re: iwannabetheguy1980's build

Posted: Sat May 22, 2021 3:05 pm
by iwannabetheguy1980
ball joint failure made me change a few things on the knuckles and how they are assembled.

Re: iwannabetheguy1980's build

Posted: Sat May 22, 2021 4:45 pm
by iwannabetheguy1980
tested chassis #1(white) this morning after fixing the ball joint and replacing the steering knuckle, full battery used, no breakage.

ANN is done.

Re: iwannabetheguy1980's build

Posted: Sat May 22, 2021 6:22 pm
by iwannabetheguy1980
Putting together new hardware list: I'm sure I'm missing something.

Motor/ESC: Motor, TrackStar Roar Approved 1/10th Stock Class Brushless ESC and Motor Combo (21.5T)

Steering Servo: Corona DS-843MG

Tamiya Motor Plate 58193

TAMIYA America, Inc CVA Super-Mini Shock (4): TT-02, TAM54753 4 shocks

8x Tamiya 4mm Ball joints.

2x 4M locknuts

2x 3M locking nuts

8x M2 Locking nuts

4x M4 x 22mm bolt for wheel axle front and rear

6X M1.4 x 4mm self taping screws. Door handles and front fender Flaps left and right

1x M1.6x6mm comes with the servo

2x M1.6 x 10mm socket head bolts for removable roof

Pinion gear
1x M3 Standard Hex Nut
1x M3 X 6mm Grub Screw

1mm Steel Rod
Used in upper window frame

5mm Steel Rod
1x M5 x 18.2mm long

2mm Steel Rod
M2 Rod prepared as:

2x M2 x 13.5mm long;
2x M2 x 15mm long,
4x M2 x 6mm long


4x 10 x 15 x 4mm Rear Bearing blocks
3x 9 x 5 x 3mm Inner Diff
3x 15 x 21 x 4mm Outer Diff / Pinion
4x 4 x 8 x 3mm Front rims



2x M2 x 4mm
16x M2 x 6mm
12x M2 x 8mm
18x M2 x 10mm
8x M2 x 12mm
16x M2 x 14mm
20x M2 x 20mm

2X M3 x 13mm


6x M2 x 3mm
12x M2 x 6mm
2x M2 x 8mm
22x M2 x 10mm
2x M2 x 14mm
9x M2 x 16mm
4x M2 x 25mm

5X M3 x 6mm
4x M3 x 8mm
2x M3 x 10mm
2X M3 x 14mm
2x M3 x 16mm


Button head

4X M3 x 20mm
4x M3 x 40mm
2X M3 x 45mm

Re: iwannabetheguy1980's build

Posted: Sat May 22, 2021 8:22 pm
by iwannabetheguy1980

I had a long run and suddenly the car stopped and wouldn't move.
figured driveline failed. Took it inside and started to see what happened.

Turned out a rock got stuck behind the wheel and jammed the wheel from turning


Driveline is fine, no damage to anything other then the rock getting stuck in the wheel.

here is the excessive outer edge tire wear from the 3 degrees of rear toe-in


Testing changes to make:

* slightly lower front ride height on both cars pulling a ride height wedge out.

* change Chassis #1 White to 2 degree rear bearing blocks.

* Rebuild front shocks both cars; change internal Piston to 2 hole instead of 3 hole front end is bouncing a little too much and needs more dampening.

Re: iwannabetheguy1980's build

Posted: Sun May 23, 2021 1:45 am
by iwannabetheguy1980
made some dash decals

Re: iwannabetheguy1980's build

Posted: Sun May 23, 2021 3:16 am
by iwannabetheguy1980
parking brake

Re: iwannabetheguy1980's build

Posted: Sun May 23, 2021 8:56 am
by admin
Looking good! :)

Re: iwannabetheguy1980's build

Posted: Mon May 24, 2021 3:42 pm
by iwannabetheguy1980
I think I'm going to "STOP" at this point and lock in my changes. it is death by 1000 knives if i keep going.

I changed the door hinge a little over the weekend but it goes together with my redesign of the rocker and door system together.

I locked in that 2 degree rear bearing block.

i made the changes to the front suspension which was an improvement.

I had a couple of nice calm runs of each chassis where nothing broke.

i really have one last thing i need to do which is complete a second casting of front and rear 30A tires for chassis #1 White and make sure it drives the same as chassis #2 green.

as for the files: its 102MB of changes to the original model :)
it is broken into sections and now i need to work on the assembly manual.

I didn't completely redesign the original model so you will still need supports on almost everything and to get best results you will need to make custom supports in your slicers. i tried to keep the integrity of the original design and improve on what was there.

Also my changes are not a complete car you will still need the original STL files to fill in the missing pieces. for the many STLS i changed there are many that have not been altered.

There are many parts that are Right and Left Specific but look very similar i thought about marking them left and right but that might make some unhappy that are building more of a model then a R/C car. so if you assemble the project and something isn't right or is jammed chances are you mixed up left and right and you will have to go back and correct it. I guess it adds to the project being a bit of a puzzle to assemble.

I aimed for making the mechanical and body serviceable and it really is. The body is completely modular and you can get to the main frame easily just removing a few bolts. if something is damaged you can get to the sub assembly and reprint as needed.
For example if you damage the windshield you can easily remove the lower and upper window frame just print 2 new parts and bolt it to the dashboard without having to reprint a new dash assembly because you glued it together. same with the body panels the hoods now bolt together so if you crash you can reuse many of the parts and save printing and repair time.