Scrapheap Junior

[Coelacanth]

I just used a 4-40 screw to create the rest of the thread.

I've made my own 3mm thread taps from 3mm screws. I carefully cut notches on opposite ends of the screw tip with a Dremel cut-off disk. Kinda hard to describe, but it ends up looking like a tap and works pretty well. I've used it to tap my own 3mm holes in plastic and aluminum parts. I'll take a picture of one and add it tonight.

EDIT: Here is one of my 3mm screw taps. I have another made from a long 3mm button-hex-head screw, I recommend going with that because it won't slip while tapping threads like this first one I made with a Philips-head screw. I can't seem to find it however. Anyway, I just used the thinnest Dremel cutting disk I had to gradually cut a groove on opposite sites of the machine screw, deepening as it got closer to the tip. This particular one I've been using for many years, including to tap aluminum, hence it's a bit scuffed up. It still works like a charm to make threads, though. If you don't have a tap & die set and you need to cut threads in a pinch, this will get the job done.

[jwscab]

Nice work on that motor plate!

Yep I can't imagine the difficulty in the rest of the world vs U.S. to find some of these things. It has to be frustrating.

[Johanp]

The build goes on.

Since I had Pro SE front and rear shock towers I decided to use them instead of the plastic Junior ones.

But I ran into a clearance issue.
The front shock springs rubs the shock tower when using original arms.

Had to 3D print Pro SE front arms. I found the files (including front bulkhead) on the web.
Added a quick layer of black paint.

I didn´t know, but the swept front arms actually mounts the lower shock attachment further forward than the original arms.
No more rubbing.

Will be very interesting to se how the 3D printed arms will hold when I take the car for a testrun.

[matt1ptkn]

I didn´t know, but the swept front arms actually mounts the lower shock attachment further forward than the original arms.
No more rubbing.

I never knew that either; I learned something new! Thank you.

[Johanp]

EDIT: Here is one of my 3mm screw taps. I have another made from a long 3mm button-hex-head screw, I recommend going with that because it won't slip while tapping threads like this first one I made with a Philips-head screw. I can't seem to find it however. Anyway, I just used the thinnest Dremel cutting disk I had to gradually cut a groove on opposite sites of the machine screw, deepening as it got closer to the tip. This particular one I've been using for many years, including to tap aluminum, hence it's a bit scuffed up. It still works like a charm to make threads, though. If you don't have a tap & die set and you need to cut threads in a pinch, this will get the job done.

That is a clever way to do it. Never came to my mind that you can actually make your own taps that way. Thanks!



Finished assembly of the chassis including 3D printed Pro SE geometry front arms. Doesn´t seen very easy to find genuine arms. Or does someone have a spare set?
Maybe I should stick to the 3D printed ones. They look kind of cool.

On to the body. There was a couple of bodies in the parts lot that I bought.
The least sad one was this black one:

It had pink window mask and was broken (and repaired with CA glue and white plastic strips) at the rear shock mount.

I used flexible glue (like shoe goo) and some leftover carbon fibre weave to patch the broken halves together.
Not very pretty, but functional and is seems strong enough.

Then I covered the worst cracks with flat black vinyl wrap

The body still has to trimmed and fitted to the car, so it is not the final result in the pictures.

//Johan

[Coelacanth]

Nice body repair, Johan...you did it right by using Shoe Goo. CA glue is not the right adhesive to repair Lexan as it's hard and brittle when dried. You need a flexible cement.

[aconsola]

looks great, what 3d printer did you print the arms and bulkhead with?

[Johanp]

looks great, what 3d printer did you print the arms and bulkhead with?

Thanks!
They are printed in a 3D Systems Projet 2500 Plus. It is unfortunately not mine, I have access to it via a friends workplace.

I decided to make this one into a runner. I got some modern electronics for it, but still using a brushed motor.
The Radiolink controller I had since before, but I had to visit the local hobbystore to get a Tritronic 1060 ESC, a Hackmoto 13T brushed motor and a SRT servo.
Batteries are NiMH. I actually got a shorty LiPo, but I preferred the look of the NiMH. Call me old fashioned if you like!
The front tires are new, but the rears are NIP Yokomo Hotlaps TR-39 that I had in my old racing stuff.

Put the mildly restored body on it. I decided to keep most of the original decals, including the French/Canadian (Les miniatures) in memory of where I got this car from.

And I took it for a short run in our gravel paddock. Way to bumpy for this car, but it was fun!

I never realized how much I missed these old Losi cars!

[Johanp]

The car has been sitting on the floor in my home office for a while now. Was looking at it the other day and something in the front end was a bit off.

Had a closer look and I think I found the problem.

3D printed arms using SLA (I don´t know what material was used) might not be optimal. They bend over time!

So let´s try FDM this time. Printed using PETG filament. Not the same finish, but they seems stronger.
Quite rough from the printer.

Somewhat cleaned up and on the car.

Let´s see if this works better.

[Dadio]

those look good , did you model them yourself or download the file ?

[Johanp]

those look good , did you model them yourself or download the file ?

The one I got printed in my first attempt was a downloaded file. Can´t remember where I found it, but they are out there.
I never really liked the look of all the extra strengthening, although I totally understand why they are there. And the arms where totally ok after some light running.

For the secont print I did my own model. I skipped the strengthening and made them look more like the original arms. But they are not exactly like the original since I don´t have any to take actual measurements from.
I figured since I´m only doing some occasional running the arms should be ok for that.


Orange in picture is the downloaded one. My model is the grey one.

[Dadio]

Nice , well done

[Johanp]

Autum is here and I decided to make some upgrades during the winter.
Got some new parts to put on the car.

Complete Friction slipper
Swept front A-arms
Front axles
Front outer hinge pins



The slipper came from the US and the rest from Germany.
Note that the original price tags on the parts from Germany are still in place and they are in DM (Deutsche Mark). I think Germany went to the Euro currency in 2002.

[Sasha8066]

Apologies on only coming across this thread recently. Those Pro-SE swept A-arm files are my design. They can probably be found via Yeggi, but they were originally posted to the Thingiverse site here: https://www.thingiverse.com/thing:4348333

Free to use for all - I only ask that you give credit for the effort to create the files . If there's ever something that someone is looking for in a particular line-up, feel free to PM me, and I will add it to the queue. I've posted quite a few files based on requests, I only ask that you provide the info for others. This helps others find the information (and saves people a lot of time).

Some background into the design, I modeled this arm 4 years ago. My original printer (a M3D) was not capable of producing particularly great parts at the time due to some of the limitations of the printer. A couple printers later, and the file was posted after some successful tinkering. I may post the non-webbed version at some point, as I think it makes the car look more like the XX prototypes run at the 91 Worlds and allows for users to manipulate infill to adjust flex/weight.

While I have modeled/designed quite a few 3D printed parts, the process does have some inherent weaknesses for parts that are not produced with a higher end printer if the original designs are copied 100%. Weight was given priority to strength on many of the designs from early 1990's through the 2000's. Ideally, if parts are copied 100%, they should be printed in a nylon / glass-filled nylon or via a resin printer in a nylon-esque material for maximum strength. Shapeways is a good option for that (as most people do not have access to a commercial printer). For most typical individuals, a personal 3D printer is a reasonable option. Nylon or polycarbonate can be printed on a personal 3D printer but can be difficult to work with if you do not have a humidity/temperature-controlled location. Because of this, most of the parts that I have modeled/modified are designed to be useable with filaments that most users can print (i.e., PETG or ASA) - and may have some additional tweaks to improve strength or remove B-side features that are unnecessary with a 3D printed part. Generally, I avoid PLA (weakens/becomes brittle over time) and typical SLA resins (brittle/sags with exposure to heat).

[Johanp]

Apologies on only coming across this thread recently. Those Pro-SE swept A-arm files are my design.

Free to use for all - I only ask that you give credit for the effort to create the files .

I only ask that you provide the info for others. This helps others find the information (and saves people a lot of time).

Hi Sasha,
Yours are nice arms and they seems to work great.
I believe I just searched for something like "Losi arm" on stlfinder.com when I found them. Had no idea they were yours.

Keep up the good work!

Since I'm a mechanical engineer and have been using 3D cad since 1999 I did my own model as you can see in a previous post. A model I intended to test and update, but since I found a pair of original swept Pro-se arms I use them instead.