Build Thread D3MON's D-28 Drift

[D3MON]

Buy you a couple of these for now. Then, if you really love drifting, you can always upgrade your electronics.

https://a.co/d/6aRoA5l

Thanks! Funnily enough that's what i use to check the battery and cells. i just do not have a spot or enough room to put it on the chassis lol.
for the time being, i am just going to be checking every 10 or so minutes, especially as it gets closer and closer to a safe LVC to see if it does or not.
yeah thats the plan. depending if 2.0 is the final version where i top out on my design skills for or not, plan is to keep the 1.0 as the friends ride, then have this as my main.

 

[D3MON]

Update:

as i was expecting the 5mm OD 4mm ID tube i was using for the spool shaft is starting to show signs of wear from the driveshafts. this was expected and depending on how option #2 goes, might be what i go back to or try to find some brass/steel tube of similar sizing.

i did have something i wanted to try with the WL Toys diff i got, once i realized it was an actual ball diff, even though it came in locked so tight i thought it was just a spool.
original worm/bevel gear (i think?)

New spur gear style ball diff gear:

partially assembled:

I dont know if i want to recommend this if i share the build as re-assembling the diff was absolute hell, but TBD.

Removed old trans assembly:

installing new ball diff trans assembly:

dont really think diffs are preferred for drift but figured why not test it? if it really is bad going to just crank down the ball diff and run it as a spool, but will have more resilient diff cups.
awaiting testing for tomorrow! still hvae the old assembly in case this is an absolute flop.

also playing around with printing new shock bodies for the wltoys shocks, so far showing alot of promise and alot smoother than the stock aluminum bodies, just need to dial in size for the threads of the shock caps.

 

[D3MON]

unfortunately the Ball diff being a "diff" did not last long, between them being so tightened down to where the diff balls grooved the aluminum, there being no thrust bearing, and my inability to tune ball diffs (probably the biggest reason), it came loose within a minute or two and just slipped. given it being a ball diff needed some gap to not allow binding on the internal diameter, i did have to re-print it so when locking it down it would be perfectly centered.

Upon assembly i have also discovered i will either have to re-evaluate the diff housing/motor mount to be able to use the set screw to fix the spur to the to the "shaft" as the shortest grub screw i have is 2.5mm and it sticks out just far enough to impact the screw heads for the motor mount. i am planning on trying to implement a "rotating" motor mount to allow flexibility for motor location, i do think I'm going to have to use some sort of metal for this though as i will need to notch it around the upper link mount. (not a priority)

received Micro T ball studs and those other shocks today, shocks are considerably ( i say that but its only like 3mm lol) shorter, i cannot recommend them anyways especially with the springs they come with, they dont even fit the perches, it is funny though as the springs from the other ones i had before fit perfectly in the perches, and seems semi decent like that.

going to be testing out rod ends tomorrow to fit the smaller ones for the micro T, they are approximately 2.8mm diameter compared to the 3.5s of the scx24, going to be tiny and a little worried printed parts arent going to cut it. injora does sell a turnbuckle and rod end set for the micro T which i might give a go with. the kit comes with exactly how many rod ends and balls one car will take so it is tempting if 3d printed doesn't work. but i am sceptical that they will give enough articulation.

sorry not much for pics this time around.

 

[CertifiedMike]

Is there some point where these parts get too small to see and just go on faith that they are there and doing as expected?

I had to put cone washers and spacers under a few ball studs that were getting interfered with on suspension stroke. 1 was causing a shock spring collar to just barely hit the shock tower. It drove me nuts looking for that!

 

[D3MON]

Is there some point where these parts get too small to see and just go on faith that they are there and doing as expected?

I had to put cone washers and spacers under a few ball studs that were getting interfered with on suspension stroke. 1 was causing a shock spring collar to just barely hit the shock tower. It drove me nuts looking for that!

haha my eyes suck so doesn't take much for that to happen!

dropped one of the 2mm diff balls on first assembly yesterday and.. yeah that diff is one short. My floor got some iron supplements apparently.

 

[HPIguy]

I use one of these a lot on the small scale sutff. And also just got glasses so. LOL

 

[D3MON]

have learned that this ESC does have LVC of sorts, set at 3.6V, it is strange as it doesn't cut off throttle completely, just stutters alot.

I broke down and bought myself a more standard sized battery for these cars, a little Adventure 400Mah, oh my is this thing tiny!

the Adventure 1100 completely fills this space,

drove it a bit wit new battery and makes a very large difference in weight, i dont have to get wheelspeed up so high so allows for more slow controlled drifts.

on another note, decided to weigh the car today.
Car: ~143grams
adventure 1100: ~57grams
Adventure 400: ~17grams

i unfortunately do not have a way to weigh the front to rear bias or the side to side, but the balance point is roughly 33-35mm from the rear axle in a 102mm wheelbase. still havent messed with those new rod ends, but hopefully tomorrow can and will test them out on the old v1 frame for articulation to make sure i get enough movement with the arms.

so far really happy with how it is turning out, definitely a few impacts from driving it yet everything is still holding up decently well.
the gears even though 3d printed and mine isnt the most calibrated, spin very free and just dragging the rear wheels on my glass table spin the motor.
there were a few burs i had to remove but i was fearing it was going to be almost impossible for that smooth of engagement.

have one more major problem area that i do need to design better is the upper front a-arms, though it hasn't gotten much worse and its not "alot"(maybe 0.75mm at the wheel) , they have some front back wobble. i am not expecting to be able to completely resolve this as it needs to be slightly oversized for them to pivot on the screw.
tempted to pull a page from the Drift art book and have a horizontal link forward and back that attaches to the upper arm to prevent this.

 

[D3MON]

Not a ton of progress as of late, been testing and testing rod ends, trying to keep them strong enough and well captured, but i am running into issues where they are either too tight and don't allow movement enough and require quite a bit of post processing, or they are too lose and allow too much play or just come apart. slow going of adjustments to make them both thicker around the ball vertically and spherically trying to retain enough movement. finally settled on a happy medium i believe.
i did come across some Injora ones for the Micro T, which i believe in the future will be the recommended end result. 25 ball studs for the micro T are approx $10, and the ballstuds and rod ends are $13 for all that is needed.

for my own personal until i get the injora going to still use the SCX24 ballstuds, the Micro T ones i ordered require using a 3mm hex socket.

Decided to price out materials that would be needed, and came close to my goal, all parts (excluding m2 screws and the one m3 screw) comes out to a total of ~$55 on amazon, screws bump the total up by approx $20.
Now this does include the rod ends/ball studs from injora, and also using only the WLtoys shocks, which did work decently well. but the SCX24 shocks are definitely preferred though need different springs.
this does not include any electronics/wheels/magnets obviously.

I did find out that WL toys cars also have a variety of driveshaft lengths, which does open up the options for wider track width, but was also annoying trying to figure out why the second car wasn't matching the first lol.

anyways all the updates for now, really want to start getting into other materials like CF for it. also i am going to try doing it in full PETG before long, primarily to see what the pros are compared to the PLA+ i have been using.

 

[D3MON]

Few more major flaw Fixes:

Rear Toe- realized that when i designed the chassis in the first place i didn't make an adjustment for toe, now most of the cars i run and am used to either already have the toe built in either at the hub carrier or the inner hinge pin block, have adjustable toe either via inserts for the inner hinge pin block or tie rod ends in the rear.
few problems with some of those options:
1: I don't really want to have it fixed or adjustable at the inner hinge pins as that will affect wheelbase.
2: I like the idea for adjustable but ball/rod ends always end up getting loose so going to attempt to try to reduce maintenance parts and a big issue is room.
3: i know some drift cars nowadays have "active toe" (fancy term for bump steer) but honestly i don't know how "active" the rear suspension is, and not something i want to get into yet, and issue #2 as well.

i believe i am settling with non-adjustable and changed via rear hub carriers for a few reasons, mainly because just printing new hubs is pretty quick and painless. i know its probably not the best way, but for now i am just rotating the hub itself not the hinge point where it connects to the arms. In full scale I'm sure this would cause some binding with torque as its not at the same angle as the hub, but i believe it will be fine for this (will re-visit if necessary).

Until more tuning commences, i am going to start with 3deg rear toe, also going to try 1.5deg.

Trans/Diff:
Originally as it was designed there is no brace at or near the top of the trans case halves, and in testing up until now it didnt pose an issue.
That is until i have removed and re-installed the spur gear so many times that it doesn't have as snug a fit on the shaft, and now clamps down on the trans case which causes binding.
Ultimately the ideal way to rectify this by eliminating any axial load, would be to not rely on threads for the gears at all, and use a pin, or some other way to fix the gears to the jack shaft, but i don't really have a way to machine this, and through my searching i have not found a shaft that close enough resembled what i need to make it work.
In light of this i am going to add a spanner brace on the front of the case, and try a slightly different approach for the spacer on the spur gear so that i can use a set screw as well.

as you can probably notice, i swapped out the rear upper links for the ball ends to fit 2mm rod (the turnbuckles that hate change), and swapped to the SCX24 ball studs (also fits the Losi Micro T ones), i had to shorten the threaded portion so i can shorten more to achieve negative rear camber instead of 0deg.

Thats it so far, planning on testing tonight and tomorrow a bit to see how well these changes helped. i need to get some m2 grub screws for the spur so i can get more threads to bite. once i settle on exactly how far out the spur has to be i plan on filing a smooth spot on the m3 screw to help even further.

 

[Doom!]

Just the fact that you know what to change, and when to change it impresses me. Then the fact you can draw it up, and print it out in a functioning model is double impressive.

 

[D3MON]

Just the fact that you know what to change, and when to change it impresses me. Then the fact you can draw it up, and print it out in a functioning model is double impressive.

Thanks! i appreciate that. Honestly kind of flying by the seat of my pants for most issues, a few i was expecting to cause problems but put on the back burner until it was a priority, or had an idea how to fix.

 

[D3MON]

unfortunately, i corrected half the issue with the binding in the diff, the other half is the idler gear backing off, modified the idler gear and diff gear to try to allow a set screw to hold that gear on as well. will try to post an update tomorrow.

 

[D3MON]

with enough back and forth i believe i decided on a design. once testing has been done to make sure no more issues arise, i am planning on filing down the threads on the "shaft" where the grub screw is so that the grub screw can seat further in, and so there is no possibility of the gear moving.

Got the gearbox assembled with the new set screw design. using the set screw i am going to lose some tooth area, but hoping there is enough left for it to still last. on the previous set there is still not visible wear on the teeth even with approx an hour of driving, surprisingly even on the spur gear where it is the plastic tooth against the metal pinion.

unfortunately because the size of the area where the grub screw sits i am going to have to come up with something different for the chassis spanner/brace.

as you can see there is that broken rod end, that part "floats" on supports and there is not quite exact spacing for the supports to sit below the end so it becomes quite attached, and i hadn't removed enough of what was part of the actual "support" left over and snapped when popping it onto the ball. it holds for now so haven't replaced it yet.

 

[D3MON]

had a short test run on my lunch break and i must say, WOW the rear toe really made a huge difference! alot easier to control, not as much feeling like I'm "chasing" the drift. the gears are definitely a bit louder, but i believe it is similar to how the older ones were and just need to break in a bit.
as far as the trans brace, i believe i am going to try to get some aluminum tube i can thread into. dont really have room for a 3d printed part that is going to have enough material to actually brace anything without blowing out the threads.

 

[Spksh]

Loving watching your process from the inside. Thanks for sharing.

 

[D3MON]

Loving watching your process from the inside. Thanks for sharing.

thanks! been quite a learning process and tons of back and forth for sure. glad you are enjoying it!

 

[D3MON]

haven't made a ton of progress as of late, mostly been just trying to learn to drift, found a few training videos online that i am working through.
i will say the the videos from Timmy Woo are a great watch.
That said, i have been noticing as expected some parts wearing faster than id like. i know i won't ever get replacement/maintenance parts down to zero, but i want them to last longer than a few hours of drive time.
I've had a roll of PETG for quite some time but never got around to actually using it mainly because just the ease of use with PLA+, and I'm terrible about planning ahead and using my filament dryer as a dryer and not just a spool holder for the printer.
in running some calibrations still running into a few issues in what feels like at random with layer adhesion and separation, especially if only a few walls. upping the nozzle temp to 260C seems to help but still happens occasionally.
first thing is printing the high wear areas in PETG to see if it lasts longer and the biggest wear areas i am seeing so far is the rear hubs where they connect to the arms, and the ball ends on the rear. amazingly enough the front has not developed nearly as much play as the rear.
test parts printed:

will report back with the findings. eventually i want to play around with aluminum hubs, and use the Micro T rod ends so its true nylon, but for now just want to get some parts that last that are 3d printed.

 

[D3MON]

unfortunately havent been able to do alot of testing, but so far from the testing i have done, approx 2 packs, the PETG has held up better for the rod ends, rear hub carriers, and a-arms.
a tuning issue i believe i have found is that i think my gearing quite off. i had a feeling in the beginning but didnt know for sure.
i am realizing that most of the time my drifting is doing ok i am between 25-50% throttle. i am used to bashers so precise throttle control is not something i have learned yet or adapted to, coupled with the fact this thing cogs pretty good at low throttle input i want to give myself the best chance to learn this right.
From what i can find in pictures and still frames from videos, most 1/24 scale chassis use approx ~0.13 approx 7.7 motor rotations for the wheel to turn once, mine is ~0.187 approx 5.33 motor rotations to spin the wheels once.

going to be re-designing the transmission to accommodate the larger spur and diff gear to get a closer to correct ratio with the pinion i have (16t).
i could probably also help offset this by using a much smaller pinion, but they are alot more agressive and i would anticipate would get considerably more wear on the 3d printed spur gear because of it.

In testing i am still getting more play than i would like with the front upper arms. PETG might help with this, but i think its mostly the tolerances between the "hinge pin" holes and the "hinge pin" (screws). i believe the fix for this is going to be pulling the front shock tower forward a few MM and lengthening the arms. The car has definitely taken some hard hits to objects in the garage, and am quite pleased with how everything has stayed together.

I am tossing around the idea of forgoing the old battery compartment size in the process of the trans re-sizing and moving the chassis to 3.0 keeping the 2.0 to fall back on. the full size scx24 battery is just very large but more importantly heavy, and made control quite a bit more difficult. This might have been exacerbated by the gearing issue as well though.

will post some pics as soon as design/printing continues. work has been quite busy so haven't had much extra time to work on this.

 

[D3MON]

Modified the trans cases with some cleanup to the motor mounts:

size difference pretty noticeable here:

in increasing the size of the gears i had to move the front idler gear/jack shaft gear as the distance between the gears needed +2mm. i could have revolved it up and out 2mm, but for this version i am planning on reducing the battery compartment size anyways. this is going to add the weight 2mm forward. hoping the feel is going to be negligible, but i do have the option to revise and go up instead.
side note probably my ineptness with 3d printing, but with PETG gears i did have to space the gears 0.2mm further than what ideal would be.

Everything installed in the trans. had a small chip out in the one side of the trans half but wont really affect anything so still using it as test piece.
slight revision for design of the chassis:

rework of the front bulkhead/shock tower:

extended the arms 2mm to try to get more leverage against deflection.

going to be printing it all up tonight and tomorrow, hope next post is putting it all back together!
going to be printing everything new in PETG, firstly because i want to learn it, and second i am wanting to test to see how it does, i know its slightly more flexible than PLA, and want to see if that will help out.

Thanks for reading!

 

[D3MON]

got everything printed and fitted.

as you can see alot of it is now printed in black filament, pretty much everything was adjusted between the battery compartment resizing, rear trans, and the front upper a-arms. i did opt to rotate the motor mount so the motor is in a similar position as it was before i moved everything forward for the larger gears.
Not necessarily crazy about it all printed in black as it dulls the details and all kinda blends together aesthetically and tryting to keep an eye on things.
with PETG i have also been having semi weak layer adhesion, at least compared to PLA. already running at 260F, though i have been reading that fan speed may also be too high so will have to play with that.

Going to be trying this ECO 827 digital servo as opposed to the Emax ES08MA II.
ultimately if i still stick with non-drift specific servo i will try to source an Emax ES08MD as its the digital variant and i like the size of the Emax for this.

Primary reason for switching servos is that i want to try a digital servo with this gyro, another reason is that i need to re-solder the wires to the board of the Emax as well.
Some issues with doing this, the height is different between them, i had to add approx 3.5mm of extra height, lifting the servo up, and the housing is about 3mm taller too. totaling 6.5mm of extra height, so unfortunately the body will not fit. this will play into tuning but given i am starting from ground zero anyways will get there when i get there.

Hoping to be able to test run it tomorrow, hoping for some promising results with the gearing and servo.
as always thanks for reading along (if you did) even when i write a chapter book lol