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1/18 chassis build need motor/gearing and tires for

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1/18 chassis build need motor/gearing and tires for

Old 12-19-2022, 12:12 PM
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testfly
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Default 1/18 chassis build need motor/gearing and tires for

I am creating a 1/18 scale onroad chassis that I need to source some parts for. Mainly the motor, gears, ESC, rims and tires. The chassis design is cut from G-10 and has some 3D printed parts.
I am looking for info on where I can get the items needed to complete this project. I have included a image of some of the chassis parts. At the moment I have 7mm holes for the rear axle bearings. (3mm axle)
I need a motor and gears so I can add the holes in the frame rail for the motor. I am happy to share more details of this project if there is any interest.
I am also willing to share the stl and dxf files as soon as I have the car running.


Old 12-19-2022, 09:37 PM
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kistner
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Not sure what you are looking for in 'gears'
this transmission comes with a motor, designed for a crawler, meaning not built for speed RC4WD R5 V2 1/18 Mini Transmission
this transmission should be much quicker - ECX Transmission Set Smash also Fits Team Losi Mini T 1.0 1/18th
the 2nd one is probably along the lines of what you probably want. But for that price you could probably pick up a 1/18 roller off ebay, facebook, etc.

There are a ton of motors that will fit, look at 24mm to 28mm diameter motors
Old 12-20-2022, 02:23 AM
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Default TPU Tire Print Sample Image

Originally Posted by kistner View Post
Not sure what you are looking for in 'gears'
this transmission comes with a motor, designed for a crawler, meaning not built for speed RC4WD R5 V2 1/18 Mini Transmission
this transmission should be much quicker - ECX Transmission Set Smash also Fits Team Losi Mini T 1.0 1/18th
the 2nd one is probably along the lines of what you probably want. But for that price you could probably pick up a 1/18 roller off ebay, facebook, etc.

There are a ton of motors that will fit, look at 24mm to 28mm diameter motors

I am looking for a simple spur gear and pinion type setup really.

My goal is to build a simple car that I can cut or 3D print parts for when needed. 1/18th scale would be the perfect size for my front yard. The area we will be racing/running on is concrete.
We have run 1/10 scale trucks there but it is a bit tight but it is a lot of fun so I am willing to design a chassis that uses G10 and 3D printed parts so when something is broken it can be replaced after it is printed.
Here is a video showing the size of the concrete and some of the racing.

I have also been looking for tires and rims but not having much luck so I am working on TPU tires now. I just need to get them to the proper size and get a car completed so I can do some tire testing.
Below is a tire test print.





I did get a frame cut and it went together very well.






There is one cut flaw that has been corrected in the tool path. So that cut is no longer there.




Here you can see the PETG 3D printed spindles and how they are mounted.

Once I get this project done I might create a sprint car version.
I built some wing sets for the 1/10th Bandit brushless cars and a buddy and I had a blast with them as seen here
.





Old 12-20-2022, 04:42 AM
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If you pick a motor I can suggest a pinion and spur. Quite a variety in 48p is available. Although 1/18 typically uses a smaller pitch.
24mm or 28mm, also sometimes referred to 380 or 390 motors.
Old 12-20-2022, 11:43 AM
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Originally Posted by kistner View Post
If you pick a motor I can suggest a pinion and spur. Quite a variety in 48p is available. Although 1/18 typically uses a smaller pitch.
24mm or 28mm, also sometimes referred to 380 or 390 motors.
Honestly, I am open to suggestions as I have not cut the holes in the frame yet for a motor so I am willing to use what ever will work. If you can provide a link to the items that will work together (motor/pinion,spur and maybe ESC)
I will get them on order so I can continue the project. I think I will use a .125 axle but I am open on that as well. I don't really know what is out there or what will work, But, clearly by what I have shown so far I am serious about this project.
I am working on the tires at the moment but I would like to order what I need and get it on the way.

I plan to run 2 or 3 cell lipo batteries because I have a lot of them (40 to 50 of them) But I am open on that too.

I know I could just go buy a car and run it. But what fun is there in that when you enjoy designing and building from scratch. I have all the tools so I might as well use them.
Old 12-20-2022, 12:27 PM
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It sounds like you are doing a bit of a direct drive, no transmission? Just motor, pinion, spur, axle. You are a little out of my wheelhouse as far as what to suggest. Seems like a low kv motor would be in order, maybe an outrunner or if brushed, a 380 silver can.
Old 12-20-2022, 01:29 PM
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Originally Posted by kistner View Post
It sounds like you are doing a bit of a direct drive, no transmission? Just motor, pinion, spur, axle. You are a little out of my wheelhouse as far as what to suggest. Seems like a low kv motor would be in order, maybe an outrunner or if brushed, a 380 silver can.
Pretty much a 2 gear setup correct.
Old 12-20-2022, 02:23 PM
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well, like I said, this is outside of my general rc knowledge so I will throw a few things at you

here's an inrunner from hobbyking.com, 1980kv
they have a bunch of outrunners ranging in kv from 1000 to 2000. I have found outrunners with the wires near the shaft end easiest to mount in an rc car.
you dont have to buy there, amazon has similar motors at similar prices (after you factor in shipping), I have ordered these little motors from aliexpress before also. hobbyking was just easy to find a bunch in one place.
your basic brushed 380 silver can would work too - but I am not positive on the motor mount size. I do have one floating around somewhere so if that interests you I can measure.
most of the hobbyking motors are 1/8 or 3.2mm shaft (same thing). The 380 brushed is probably 2.3mm shaft. 48p gears are very plentiful in many sizes and very commonly found for 1/8 shaft. I'm not sure what the availability is for the 2.3mm shaft motors. I have a couple small scale rc that use .5mod pitch, pretty sure that was on the 2.3mm shaft, maybe 3.2mm, I dont recall, maybe/probably they have them for both.

does that help at all?

Last edited by kistner; 12-20-2022 at 02:26 PM.
Old 12-20-2022, 02:42 PM
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for an esc I'd probably go with a hobbywing 30amp. or if you went with the brushed motor I'd look at this one. there are tons of esc options - I almost always gravitate to the lower priced but still decent quality units. I'm kinda cheap that way.
Old 12-21-2022, 11:49 PM
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I have some parts coming so now in hopes that I am able to at least get a car built for testing.

While I am waiting I am working on tires. Here is a look at the progress on the tires.

I am having trouble finding the proper size tire so I am working on a rim and tire that can be 3D printed. The rim is no issue but I am concerned about the tire. I will be 3D printing TPU tires with different walls and infill amounts to see if there is any difference in traction. Also with tread and no tread. I have added nubs to the rims so tires do not have to be glued in place. This means I can have one set of rims and test many different tire prints.

Below are a few pictures to show the progress.



Here is my rim design.


Here is a look at the first rim I printed.


Then I created a tire that fit the rim.



Here the rim and tire are mounted to the car. I re-printed the rim in yellow so it would show up better in the pictures.


Then I created a tire with a tread pattern that I am still working on with the help of a "Rocket Scientist". Literally LOL.

I needed a way to hold the tire on the rim so it does not have to be glued in place. The way I did this on the front tires was to add 3 nubs and then put 3 pockets in the tire so they fit together.




Here you can see the nubs as the updated rim was printed.


Here is a look at the rim after it was printed.


Here is a look at the updated 3D printed TPU tire. You can see one of the three nub pockets that will help keep the tire firmly on the rim.



One thing is for sure, If the TPU tires do not work out for racing at least I know I can print tires for display cause I think they look pretty good and worth the effort it has taken to get them printed.
Look close and you will see the rims are designed to use a 3X7X3 flanged bearing. (2 per rim)


Old 12-21-2022, 11:59 PM
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Here is a short video that shows how the tire is snapped onto the rim.
Old 12-22-2022, 01:34 AM
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Here is a look at one of the tread designs.



Here you can see the two ways I am testing to keep the TPU 3D printed tire from slipping on the rim.
Old 12-22-2022, 04:36 AM
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Nice work.
Old 12-23-2022, 10:49 PM
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Originally Posted by kistner View Post
Nice work.
Thanks.
It is coming out nicely so far.
Old 12-24-2022, 01:00 AM
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Default Rim Versions 1 & 2

Here is a look at 2 rim designs I have created. Both use my nub tire mount design so the tire can be mounted or removed from the rim without any issue.



Old 12-25-2022, 11:04 PM
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Default Rear Tire / Rim Design

Still waiting on some parts to arrive.

I have started work on the rear rim and tire setup.

The rear rim will be mounted to the rear axle using a collar and 2 long set screws. The rim will be 3D printed and then the collar will be inserted from the back side and the long set screws will lock the collar to the rim.

Below are a few images of my rear rim and tire design.




TPU tire, PETG rim and the collar with two long set screws.

Wheel collars mounted in the PETG rims.

TPU tires pushed onto the rims.


Rear rim and tire set mount on the axle.



Checking the fit of the rear axle rim and tires. Still waiting on rear axle bearings to arrive.


It just looks like the gear in hitting the lock nut.


Here you can see the collars I am using to locate the rear axle while I wait on flanged axle bearings to arrive.


I do have a rolling chassis at this point.

More details coming soon.

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Old 12-27-2022, 10:45 AM
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Default Tires

Not sure if it helps, I have n.o.s wheels and tires. I thought the scale was 1/18 over all hight of tire is about 2.25in
Old 12-27-2022, 10:47 AM
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Default Wheel

The wheel is about 1.5in and I have a few sets with different tires.
Old 12-28-2022, 03:15 PM
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Originally Posted by Jjj1080 View Post
Not sure if it helps, I have n.o.s wheels and tires. I thought the scale was 1/18 over all hight of tire is about 2.25in
The tire is about 1.40in OD.
Old 12-28-2022, 03:29 PM
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Originally Posted by Jjj1080 View Post
The wheel is about 1.5in and I have a few sets with different tires.
I can design a rim to fit the tire. I just need to come up with a tire that will have grip on concrete.
Old 12-28-2022, 04:11 PM
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At this point I have the car ready to do a small amount of testing. I am still waiting on the rear axle bearings to arrive so for now I just have bushings there.



I was able to test the slicks and they had zero grip on the concrete so it looks as if I am going to need another type of tire material for concrete.


The good news is I did create a tire for the carpet I have in my house and after printing 2 tires and a few minutes of testing I thought it would be worth printing 2 more.


The grip is so good on my carpet that the tire stands the fibers in the carpet up and it leaves them looking like scratch off marks when getting on the throttle hard.
Traction Test:




TPU Carpet tire.

I will try a few more tread patterns but I may need something else for concrete.
I am open to suggestions. The tire is 1.40in OD.
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Old 12-31-2022, 12:00 AM
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Default Tire Information

I have looked hard for a better tire for concrete then the TPU I have been printing. Still no luck. But, I may have a simple solution. I will it cover here with a few images.
The quick test run on the concrete in the dark was much better than I was expecting. This may be what I end up with in the end. The good news is the bands are less than $10.00 for 30 of them so tire cost will be pretty low.
In fact a rim and tire as one unit may be printed in PETG and a cap added so TPU may not even be needed. I will report back on this later.

Now with what I have so far:



"A" My TPU tire
"B" Skog Bands: Heavy Duty Rubber Bands Made from EPDM Rubber - 5col Survival Supply (Medium)
"C" Place a band centered on the TPU tire.
"D" CA glue one edge of the band to the tire. (here I clued the left edge)
"E" Then roll the other edge back to get to the center of the band and run a small bead of CA glue around the center of the tire.
"F" Roll the band back in place and once the CA glue dries the tire is ready for some hot laps to scuff it.
"G" Once the tire has had a few laps it is ready for the big race.

Scuffing the tire (running hot laps) removes any CA on the outside of the band.

Below are closer images of the steps I take to mount a band on a TPU tire.



Roll the cap back in place and remove any CA glue while it is still wet. Let the CA dry before scuffing in the tire. (Running a few hot laps)

The first run of tires I printed were smooth across the top.
I am going to create a tire that has a slight step where the band will set to make it easy to locate the band on the tire for gluing.

The bands I am testing are made from black EPDM rubber, an extra tough material that is stronger and less stretchy than regular rubber bands. They are called "Skog Bands".
The EPDM rubber used in Skog Bands provides excellent durability, with strong resistance to UV light, moisture, heat, and cold. EPDM rubber is also used for applications like commercial roofing, long-term resistance to environment conditions is mandatory.
The bands I have are not very thick so not sure how long they will last but they do seam to be tough and they also have a lot of grip. I will report back when I have more tire info to share.

If you know of a source for a 1/18th scale foam tire let me know as I sure would like to use something off the shelf if it is out there.

I have more updates on this project coming soon.


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Old 12-31-2022, 07:55 AM
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Default Tire CA

This tire is being created to run on concrete.

I have created a new TPU tire design with a small pocket for the EPDM band to lay in. It is not very deep but it does allow me to fit the band and roll one edge back add a bead of STARBOND CA to the center and then roll it back. At that point I can roll the other side back and glue it as well. With a little effort it works very well.


I should be clear that I am using a CA that is made for gluing tires. For the record, The STARBOND CA glue was moved to a different CA bottle as it is much easier for me to apply it from the INSTA-CURE+ bottle.
Amazon Amazon



Here is a look at the new tire with the band pocket.


TPU tires with EPDM bands CA glued in place.


With a few sets glued up I will be ready to do some tire testing soon.

More updates coming!



Old 01-01-2023, 01:53 AM
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Default It's Go Time

I am happy to report that the EPDM bands are working great on concrete. They are low cost and are easy to install. The grip level is just what I was looking for.


I had noticed the motor getting very hot when I was testing the carpet tire I created. So I bought some 30X30X10 12vdc fans and designed a mount for it that holds it just above the motor.
I used one of these fans on a G scale Christmas train because the motor was getting very hot. It made a huge difference in motor temp on the train motor so I thought I would try one on the car.

I have a few things I need to update on the chassis side frames but I want to do some testing to be sure there are no other changes I need to make.

Below are pictures that show the tires after testing traction today as well as the cooling fan and how it was mounted.


The cooling fan was mounted after the tire test. I will report back if it helps to keep the motor temp down.

Note how clean the steering linkage is. This offers much better steering control. (more on this later)


The top of the fan mount is going to be close to the body hints why I have the holes in the side of the mount. That should help with air flow.


The tires look good after testing, Note the different width bands. I could not tell any difference.

Here is a quick video of the car as I try to keep it in the frame. It had rained so the concrete was not fully dry. It was also getting dark and I was not setup to take any video.
But I did get a little to post here. Also the throttle was cut back to 47%. This is a good way to learn to drive. As the driver gets better just keep turning the throttle up.


Fan mounted to the mount.


Simple to install.


The cooling fan rest just above the motor. Note the cooling fan mount replaces the rear chassis spacer.


Bottom view with the cooling fan mounted.



Here are a few more pictures of the steering linkage and how it is setup.


The linkage is almost straight across which offers much better steering control.


Steering linkage from the front looking back.



I designed the steering servo mount so that it was easy to mount the servo to it and then drop the servo mount in the chassis and bolt it it place.I have also pre-bent the steering linkage
so setting the linkage up is as simple as putting everything together and bolting it in place. Note the mount fits those three servos as well as many others I am sure.


BTW if you have input or know of a motor/ESC I should run on this model, by all means let me know as I am open to suggestions. I have designed and built many types of RC models but never a car this small.
I am guessing by now it is pretty clear a lot of effort has been put into this little project.
It is a project I have wanted to do for many years. I have thought through many of the details before I even started the project. Which is why it is coming along pretty fast.
My only real concern was the rims and tires. But clearly I have that issue taken care of at least when it comes to running on the concrete I have in my front yard.

That is all for now.
More updates coming soon.



HAPPY NEW YEAR

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Old 01-02-2023, 05:43 PM
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Default Track Layout ideas

The car is coming along great. So it may be time to start thinking about a track layout. When we ran 10th scale cars we ran around 2 markers we put down on the concrete which made a oval track.
I think this car build needs more race track then that. So I have come up with two track layouts. I have also included the size of my concrete area just in case someone wants to suggest a layout.

My next build will be a Sprint Car version so I need a 2 in 1 track design. 1) being an oval track and 2) being a road course option as shown in my design.
I would like the track to have a good flow to it. If you have an idea for a track layout that will fit my concrete area I would enjoy seeing it. It don't have to be a fancy drawing either. Sketch it out
and I will make the fancy drawing of it if need be.






Last edited by testfly; 01-02-2023 at 11:46 PM.

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