Rock Buggy Body for RedCat Gen7

Inspiration

3D Printing accessories and even whole bodies is very popular among the RC community, especially in the genre of RC Crawlers. Myself and others have released all sorts of free projects, but what is unheard of is for manufacturers to released their own 3D printable files for modifications and upgrades, so when RedCat Racing started releasing files for their "Everest Gen7" crawler it really piqued my interest.

In the end I got hold of a Gen7 myself and started designing parts... next thing you know, kerblam, countless hours of Fusion360 later and I have built a fully-printable body which is tightly integrated into the stock roll-cage of the "pro" version and styled after a Meyers Manx (if that buggy had been involved in some kind of industrial accident involving mutants and toxic waste).

What you need

Files

STL files for the body

STL files for the wheels

STL files for sound module bracket

Materials

I printed in Rigid.ink red ABS, silver ABS, natural PETG and black TPU

I would strongly recommend ABS or PETG for strength. Some parts are long and thin which makes PETG far easier to use, but I like the ability to bond and smooth ABS with acetone.

Hardware

Assorted M3 screws and nuts (you can always cut to the appropriate length)

15mm x 4mm 5mm Ring Magnet (qty 12)

M4 countersunk screws (qty 12)

Miscellaneous

Acetone for bonding ABS of appropriate glue

Spray Paint (Recommend Rustoleum 2x Cover)

Video

I strongly recommend that you watch the build video, it should contain almost everything that you need to know.

Follow

If you like this sort of thing then please follow along for more at MyMiniFactory, Facebook, Youtube, Instagram or wherever else you can find Ossum Designs. If you really like it then please consider leaving a tip to help fund future projects.

Design Tools

All of the design was done in Fusion360 in the model environment (I imagine the spline and sculpt tools would have made it the curvy body much easier but my PC is way too slow to handle those).

I did play around with pieces of card zip-tied to the body before I was able to really decide on a look, never underestimate the power of Cardboard Aided Design.

You can see some of my design progression in the pictures attached to this step. I always start by mocking up the immovables (axles, chassis, cage, etc.) before designing a body around them.

Goals

I find that it is helpful to set myself specific design goals and restrictions when starting a project, these were the goals that I set:

Aesthetics

• I wanted to create a buggy inspired by my all-time favorite car, the Meyer's Manx Beach Buggy, but re-imagine it into a functional rock crawler.

Function

• The Gen7 has a very cool feature where the entire roll-cage hinges upwards, giving easy access to the electronics and mechanicals, I wanted to maintain this

Capability

• Although this will never be a competition crawler due to the weight of the printed hard-body, it still needs to be fun to drive. The excellent approach and departure angles provided by my design certainly help with that.

Printability

• The design should require minimal support material
• All parts must be easy to print
• Body must be as strong as possible.

Files

You will need one of each of the following

• under panel - left
• under panel - right
• wheel well - front - left
• wheel well - front - right
• wheel well rear - left
• wheel well rear - right

Filament Choice

The undercarriage and wheel wells are going to take the most abuse out on the trail, so I choose to print them in

rigid.ink black TPU.

The design will work just fine in other plastics too though, and if I was building for pure crawling performance then I would probably consider a PETG which would slip over rocks better than the TPU does, and still be very tough.

Support

A very small amount of support is needed in some of these parts, for example, the recesses in the wheel wells, as seen in the attached picture from my slicer.

Assembly

The under panels are attached to each other using M3 nuts and bolts, and attached to the frame rails using the same screws that were in the stock panels.

Filament Choice

Normally I print RC bodies in natural PETG for resiliency and ease of painting (it helps that when the paint scratches off there is no distinct colour underneath), but this time I chose to print the body in rigid.ink red ABS and smooth it with acetone because I wanted it too look like a fiberglass body

Supports and Orientation

All of the body parts except for the rear sections print without support material, and are designed to print in the orientation that minimizes layer lines on the body. By default they should load in the correct orientation, but if not, just look for the flat side which presents no overhangs over 45 degrees.

Assembly

The body is assembled using M3 screws, and optionally for strength, glue. Because I was using ABS I was able to use acetone as a solvent and bond each piece together for extra strength. I also used ABS slurry as filler in the seams.

My design makes provision for up to 12 mounting magnets, although I only used the front four locations and it was strong enough.

The recesses are designed to accept 15mm x 4mm 5mm Ring Magnets, held in place by an M4 countersunk screw.

Make sure to choose your magnet pairs correctly so that they attract when the body is closed!

Hood (file: body - hood insert)

Because the hood is such a large flat piece it is not really suitable for printing in ABS, which would be highly likely to warp or crack, so I printed it in natural PETG and painted it black.

The hood can be glued in place which will provide a lot of strength for the body, otherwise you can choose scale hinges that suit you (there are printable hinges available in the usual repositories of course too).

Grille (file: body - grille)

The grille is purely decorative, so I printed it silver ABS (and then changed my mind and sprayed it black). The grille is attached with screws which tap directly into the plastic from the inside of the body.

Roof Mesh (file: roof mesh)

If you choose to use this part I recommend printing in PETG. Make sure that supports are turned off or you are likely to end up with a big mess!

Engine (file: not yet released, follow on MyMiniFactory or Facebook to be notified)

The engine, inspired by a Meteor V12 is placed on top of the sound module bracket. I attached mine with velcro so that the sound module was still easy to remove.

Surface Finish

This depends very much on what filament you use. If you have used PETG you will be doing a lot of sanding.

If you used ABS then you can do some light sanding and smooth the surface by brushing (or sponging) on acetone (see my build video in the first step). The acetone will also increase the strength of the body since the layer lines (at least externally) will be bonded together.

Paint

I ended up spray painting the body as well, since I made the mistake of driving the buggy in an area that was full of ash before doing the acetone treatment, I ended up with discoloured sections where the ash was embedded into the plastic. Fortunately Rustoleum 2x Cover is an identical colour to the red rigid.ink filament I used, so much so that you could not see what was painted and what wasn't.

Decals

This part is up to you of course, but I decided it was a good opportunity for me to stray from my norm and go with some big "sponsor" graphics as though it was a race car. I made vinyl stencils and stickers for all the brands used in the build and plastered them all over.

Since the whole interior is now exposed I chose to remove the electronics bracket from over the transmission and relocate the ESC to the front, hidden under the hood.

The front body mounts are no longer used, so I flipped them upside down and attached the ESC.

The receiver is located in the passenger footwell, zip-tied to one of the mounting holes.

Print Headlight Lenses (file: detail - headlight lens)

The headlight lenses must be printed in a transparent material (I used natural PETG) with very little infill (or none)

Electronics

Any super bright 5mm LED will do the trick, choose an appropriate resistor to limit the current (here is a good guide if you need one) depending on where you connect it.

I chose to wire my LEDs in to the 5V output of the ESC since they draw very little current and it means that I can run 2S or 3S batteries without any change to the lights.

Of course this step is optional, but I love having a quality sound module in my rigs, the ESS ONE 2017 is my weapon of choice.

Unfortunately the sound module is not waterproof so I designed this simple bracket which allows me to clip the module in and out easily, depending where I am driving.

Print the bracket (get file here)

The bracket can be printed in any material, I always use ABS but I have heard good reports of it working just fine in PLA too.