Special Project - Codename EF209 - 1/12 Pan Car

[silvertriple 4293]

Hello,

I did a few buggies in CAD, I did reinvent some partially... Next year the first event of the year I intend to attend is going to span over 4 days early May (8th-11th), and the thematic of the event is "Creation and System D". I'm not sure how it would translate in English, but basically, it consist in messing something and the mess works :-)
Therefore, I have to do something for the track side of the even so I have a very special car. I also decided I would focus the track side on 1/12 this year as I have much much much more fun running a 1/12 pan car than an 1/10 touring car...

Anyway, I want to do a special project. It will be a 1/12 pancar very simple. Something that I could do relying on 3D print, a shaft widely available for the rear train, a few cut pannels (either Carbon Fiber, FRP, or other) that can be combined together with the printed parts to make an 1/12 chassis. A quick search shows that the rear shaft of the Fantom is widely available (and you may even have one if you replaced the metal shaft by a carbon shaft). 
The bodyshell will topic will be treated only when we have a chassis plan.

This will be my starting point. Kyosho, part EF209

And I obviously converted in CAD so we can start thinking...

And yes, I have added another project to my already huge project list...

[Pylon80 4426]

Following with interest, in particular I am looking forward to seeing how you build the T-bar, assuming you use one like the Tamiya F1's.

[silvertriple 4293]

5 minutes ago, Pylon80 said:

Following with interest, in particular I am looking forward to seeing how you build the T-bar, assuming you use one like the Tamiya F1's.

I have to think about that. My work plan will be first a rear train, including motor mounts, then the front train. Once there we will be able to identify different options to attach them together (taking into consideration that the bodyshell may also push for some limitations)...

[El Gecko 1770]

1 hour ago, silvertriple said:

This will be my starting point. Kyosho, part EF209

The thread title made me think this was going to be a Robocop sendup

https://en.wikipedia.org/wiki/ED-209

[JimBear 1538]

Yep, I am also interested, I love the Kyosho pan cars but I have also been waffling (mostly to myself, humm, humm) about trying to make something like a simple pan car.

[silvertriple 4293]

The Hirobo project gets closer to print order.
I've decided to draw some parts for this project...

The support of the rear left wheel, and the nut...

I needed to check that my thread is working fine, so I did a test print (have some ideas to play with regarding the wheel nuts, so I had to play with this and get a working nut...

The thread on the shaft works with the adhoc metal machined thread, so it's perfect (no offset, but slicer setting may impact).
The nut was printed with 0, -0.1 and -0.2mm offset to test. (again, slicer setting may impact), but at least that gives a good indication of the tolerance needed for it to work...
0 doesn't work as expected. -0.1 does engage but not possibility to get more than a turn. -0.2 does engage and the thread work. I will have to check if it is the same for power base process, but I would expect it is similar from what i've read somewhere...

That's all for today!

[silvertriple 4293]

I decided to figure out the overall position taken by the motor pod on my shaft

The plan is quite simple actually :
Bring in a differential design I know being tested and validated on one of my cars (spoiler : many :-) ), one I have already the design in Fusion360 : I'll use the one form my Marui 2WD gearset as a basis.

I will have to modify the main gear to be more suitable for the targeted use (let's target the same ratio as the Fantom, that makes less thing to think about )
For the diff itself, the center of the diff gear will be used as is, with the way I use it on Marui cars and same for the small small bevel gears and their shafts.
The big bevel gears will be amended in order to work out with the new shaft : left side will be attached firmly to the shaft, while right side will have to be redefined to position and drive the right wheel attachment...
And all of that should allow to have a proper diff for my chassis...

Looks simple enough in my head, that should work :-)

[silvertriple 4293]

Tonight, the program is to deal with the differential and as well with the right wheel carrier...

I first made the wheel carrier, which is an hex with a thread at the end and two ball bearings : one going at the end of the shaft and the other one going on the shaft. Then I brought in the diff components from my Marui gear set, and defined the way to set the big bevel gears on the hex, the installed the right one, then the diff center, and defined then the hex to push on the other side to fix on the shaft to have the left wheel driven.

Once I had that done, I modified the spur gear to be 71T 48dp because that what it is on the Fantom (I also modified the diff so there is better protection of the gears...

To get the right carrier printable (it has a modeled thread), I had to modify the thread and increase the diameter to make it M10.

I modified the internal thread of the nut to be in correspondance, and I may also change the nut size...

Next step will be to define the motor pod...

[silvertriple 4293]

Before anything else, I decided to print a differential to check everything was fine in the design.

The diff works, and it is no surprise...

I did an adjustment on the wheel carrier (I could have done it somewhere else, but this was what I believed the easiest... Once the adjustment is done, the diff is set in place, the space for the motor pod is as expected and the nut allows to set the diff more or less tighten, just like it is on the Fantom.

This being done and validated, motor pod will be the next piece...

[silvertriple 4293]

Motor pod is mostly easy... I did target pinion range between 14T and 27T (48dp), and made slots accordingly so we can position the motor for this. The reference point is the single hole, and I may adjust the position later on as everything is depending upon the position of this hole and the rear axle, accordingly to the targeted possible interdistances.Everything else is pretty simple. I planed for 2 holes to fix the pod on the chassis plate on each side, and one hole on the top for the upper deck.

Here, this may not be finalised parts : I keep the right to adjust a few things based on what will come next. The chassis plate will require an opening so the motor can be set for the smaller pinion... I will have to focus on the front train next.

[silvertriple 4293]

I started the front to create a derived part from the rear right wheel carrier... Then I set the upright from there. I could have done something different with bearings inserted in the wheels, but this way, I can just do a simple design working for both front and right and giving the possibility to use printed nuts (I really want to play with this).

Then I started to work on the master part of the front train... I have the idea to let people play with the caster angle, and if we want to do this without any impact on the wheelbase, that requires to set the caster setting axis lined up with the wheels center...

Then I prepared basic clamps...

And now that I look at it differently, I'm thinking to change the way I thought the pivot between uprights and the C part : having the ball bearing in the uprights is probably much better, so I'll amend the holes and design accordingly...

[silvertriple 4293]

I modified the upright : bearings are now inserted in the uprights and the screws are in the main arm.

The front train is now complete...

Next activity is related to chassis plates... I will target a wheel base around 200mm in this first version.  I may also add provisions for longer and shorter chassis plates to give room for longer and shorter wheelbases...

I'll need to position the steering servo, esc and battery, for which I'll include more holes, and as well define the bumper fixation area, body mounts and other small elements. I'm also questioning the need of an upper deck or not : i'm actually open to any ideas :-)

[silvertriple 4293]

A quick test print to ensure it is printable, and the clamp works... (and yes, I added some cryptic message on some parts :-) )

I will just modify the master part of the front train in order to make it easier to position within the clamps wihout the risk of it being slightly right or left...

The clamp works perfectly. At the exception of the uprights, everything was printed without supports. Upright were printed with a top spacing over supports of 0.3 mm, which allows an easy removal. I'll think about modifiying those parts to make it better, and eventually without the need for supports...

[silvertriple 4293]

As the Hirobo parts are ready to get ordered, I'm contemplating the idea to add diff, wheel carriers and nuts in my order to save on the shipment costs: those are the parts where I believe it makes sense to work with powder base process for this project. Others will be printed using filament.

As usual, and just to make it more convenient, I grouped the key parts in clusters. The wheel nuts are going to be printed with a 0.05mm offset. The idea is really to confirm the right offset to use, so I will add a set of nuts in 0.1mm offset as well. That's the first time I'm trying to print threads in MJF, so it promise to be interesting. I saw some experiments of threads printed in MJF and I believe it should work as per this experimentation...

Let's see...

[silvertriple 4293]

I ordered those parts while ordering for the Zerda, so they arrived as well...

I did a mistake when doing the order : I completely forgot to use the right nuts version. Nuts are wrong.
But the rest is fine.

As expected (and that what I wanted to check), I'll need to add something to make it right with MJF (the FDM printed parts add some imperfections here and there, which at the end makes a bit of difference when they are added in chain, like in this case...

[silvertriple 4293]

I spend a bit of the day today on this project, with the overall idea I want to be able to make it quite versatile in terms of battery configurations, and I also planned for mini and standard servo (mini servo is better, though), with a bit of flexibility as not all servos are exactly the same size.

I still need to deal with the Bumper and bodyposts but the overal idea is here...

[silvertriple 4293]

I'm questionning myself about keep the chassis the way it is now. I intend to use the same holes than for the Bumper as mounting points for the front bodypost (I may even think about include them in the Bumper design, using some magnets to fix the bodyshell).And for the rear, the original idea was basically to use the front top of the motor pod (where I have holes already set in order to deal with the bodyposts fixations)... And since bumper and bodypost will be bodyshell dependant, it looks like chassis design could be frozen...

I also made sure there is enough material around each holes so they can be countersunk as it will be definitely nicer to have them this way...

Next will be to get two (maybe three) chassis cut in G10 2.5mm thickness. I've check everything twice, it should be good. Hope I don't forget anything important...

[silvertriple 4293]

Just received chassis parts today thanks to Jeff from Factory Works

I will have to print my parts in final mode soon so I can check everything and make them available...

[silvertriple 4293]

I thought I could move on the Zerda soon, but I did a miscalculation for the belt length, apparently. Ordered new ones, longer. And in the meantime, this mean I need to do something...

A friend has fed me with ideas in my reflexion, and he will work with the red parts for the chassis he is going to build. On my side, the target was to make another color...

I printed the parts today, and in particular for 2 parts, I allowed me some fun

I lined all the key parts on the table. I have the ball bearings and the RX (not on the picture). I'll need to take care of the ESC and motor. And remains the hardware : normally, I should have everything I need, but I still need to check. In the first test, everything will be assembled with button head screws. I'll change for countersunck screws once I have the possibility to rework the holes. And there I few sleeves I need to take care for the front shafts, but nothing too difficult...

[silvertriple 4293]

Time to check the assembly is going to go easy...

First front train bar... I straight away noticed that I need to review the bottom part of the clamp either to introduce the nuts by a pause during the print or either reviewing the design to make it easier to insert (it was a bit too hard to my taste. Almost everything is mounted with M3x8 machines screws (not yet countersunk, but that would not change the dims required). 4 M3x8 screws + 4 M3 nuts

One of the exceptions to this is the screws required when using a mini servo (M2.5x8)

Rear train is also mounted with 4M3x8 under the chassis and 4 M3x8 countersunk for the rear side

One of the things I needed to absolutely check was my rear axle : the flat area of the hex is at equal distances on both side (an adjustment will be made to the design of the hex as I did adjust that therorically after the initial mount of the diff - I'll adjust that once I have the motor and pinion in).

I also mounted the carrier on the knucles... 2 M3 Nuts, 2 M3x20 screws (used as shafts)

The initial design I made includes a sleeve 3x4x11 which one would need to cut to be able to mount both carriers. Maybe this is a bit too much of DYI for most (I don't know, I'm not sure, but I doubt most would be happy to do this). I'm considering to remove this and replace the sleeve and the ball bearing by another simple ball bearing. Don't hesitate to shime in, especially if you are interested by making a derivative of this project...

Next is the battery mount : 6M3x8 screws and 2 M3 nuts for the center part (which is going to be removed more often as it is the battery retainer). I noticed I made a mistake on this part, I'll review it...

I still need to deal with the steering links (but that will be easy) and then it will be wheels, bumper and bodymounts...

[silvertriple 4293]

Berfore dealing with the bodyshells, it is time to deal with the wheels... The simple way to have proper foam tire easy to source is to rely on Kyosho Fantom wheels. The carrier would simply required to be drilled with a 10mm diameter for the center hole, the carrier has the same hex definition.

On my side, I'll have at least a set of printed rims/tires for the shelves (not sure the Recreus Filaflex 60A would be good enough to run the car), so I designed something in CAD.

I intend to provide the files for the tires, and for the rims in 2 versions. If someone have a way to make proper foam tires, he could ultimately using printed rims for that... The version I'll use for the TPU tires have some areas designed to lock the tires on. I also designed a nut which won't require any tool.

I printed the rim, and also the nut to check everything was fine...

But the nut color was not standing out enough... I printed all nuts in orange for that reason.

I'll print the tires in TPU by the end of the week, and will add the tie rods very soon. Then it will be time to work out Bumper, led supports and bodymounts...

[silvertriple 4293]

I printed tires with Recreus Filaflex 60A.

From what I can see on my desk, it could actually work, so I'm eager to try them on asphalt to see if workable this way. Backup plan will be Fantom EP-4WD re-release wheels...

I do still have to do something about the holes in the chassis. This is not complex, but if we want to make all the holes similar, this is just about having the right tooling...
First iteration.

Then a second one, with a centering tool and a way to fix the ball bearing in place to drill at the right place.

It will be soon time to work out the bodyshells topic. I plan for 2 bodyshells. The fist one is already in.

I satrted to work out a bumper... Bodyshells will be mounted with screws, removing the issue with the body post being too fragile due to weak point in Z.


I planned for a lip under the bumper at the front of the chassis to protect it...

Next : rear bodymounts and leds holder...

[silvertriple 4293]

I did a rear body mount that is targeted to be printed in TPU and will include leds holder, exhaust, and flaps behind the rear wheels...

I believe the inspiration of this bodyshell is a Ferrari 333SP, but I decided to not use any wing for some reason (something I'll precise once I come to the bodyshell paintwork because the reason wil become clearer - spoiler there is 2 cars, one will be blue, and the other one will be red )
The part was slowly printed (TPU is slow)...

... and quickly put on the chassis

Although the bodyshell is not trimmed we can already do some checks...

This morning I designed washers with a slop on the bodyshell side (printed in TPU) to fix the bodyshell using 4 M3 screws. And the fit is perfect (I made 4 holes with 3mm drill bit)...

I will need to trim the bodyshell next... And for this I may need to design some guides for the blade, at least for the arches...

[silvertriple 4293]

My last post on this topic was last Sunday... Since then, I had quite a time to move some stuff around...

First, arches were unmarked on the bodyshell. I did a small tool (and I believe I can improve it for next time)...

The principle is simple : mark, drill, fix, cut following the line.

And the result is a near perfect arch marked and it is easy to cut. Small note for next application : reduce the gap for the blade as 1mm gives to much space....

Initially, I thought about not installing any wing neither roll bar... But the fact is, I know this bodyshell is highly inspired from the Ferrari 333 SP, and each time I went next to the car, I could see there is something missing... I had to do something, and this meant a wing and a roll bar.

The roll bar was printed in TPU

The first version of the wing showed me that something was missing to maintain proper position.  The wing is printed in TPU so it doesn't break in case of roll over...

I then added two parts to fix the position of the side wing, fixed on the top of the led holder... The roll bar is fixed with screws/nuts on the bodyshell

I will need to find a driver and do the paintjob next...




 

[silvertriple 4293]

After the bodyshell, I decided to extend a bit the chassis project: create a forked version of the project with no dependancy on Kyosho EF-209 Fantom rear shaft, with the target to allow more people to access this chassis and to print it.

For that, I decided to use a long M3x70 full threaded screw and 2 M3 locnuts as a basis : i needed to have the right side allowing the use of a modified carrier and the modified diff main gear. I had a solution in mind, and I had to try... The two nyloc nuts are set precisely distant of 20mm, the screw being fully engaged in the first one. The shaft will be made of 2 parts, and will be ketp together by the carrier, ball bearings and bevel gear on the left side.

I've printed it and proceeded to the assembly to check

The left end is a square driver, and I included a hole to fix the carrier.

And I designed the carrier to keep this together...

At the end, I had just to modify the diff to allow for the different shaft diameter : I included 2 flanged ball bearings 3x6x2.5mm on each side of the main diff, and the carrier uses the same ball bearings on both ends (while it is a different one on the version with the Kyosho shaft.

Should I consider a printed version of the chassis plate next?