Introduction: RC Scout II - 3D Printed From Scratch
I have a long-standing love of International Harvester Scouts. I went years between owning one and now we have four of them in various stages of disassemble. When I saw the Gen 8 Scout II RC crawler you must know that I wanted one, but being a family man I could not justify spending $300 to buy one no matter how cool I think they are.
So, what to do? Make my own of course. I took our Bluetooth Scout II model https://www.instructables.com/Bluetooth-Scout-II/... and cut some weight out of it by redesigning it for use as a RC body. This method of making a RC Scout II cost me a third of what the Gen 8 would have. This was certainly not the path of least resistance, but it was a fun and rewarding experience over-all.
In this Instructable we will explore how I made my own RC body and customized it to my liking. I am not the first to design a new RC body, nor am I claiming to be the best at this game, but I am happy with the end result. I know that it is not 100% accurate as far as Scout II lines go, but it is recognizable and that is good enough for me.
Note: many of the photos contain additional notes added in the boxes.
Music used for the video: "Binder Beats" by Greg Schock. An original track used with permission from the artist.
3D design software
Super Glue and/or 5-minute epoxy
Bondo, wood filler, or plastic weld
Paints and brushes
Drill, wire cutter, paint brushes, hobby knife
I used Iron powder and XTC 3D for effect, but not necessary
Step 1: Design
I already had the primary design work done for this project as I have used these same files twice before. Once on an 1:10 scale Instructables project https://www.instructables.com/Bluetooth-Scout-II/ and once on a 1:25 scale model, teal and white model pictured above. Now here it is as an 1:12 scale RC Crawler body.
I took the existing model and hollowed it out to as thin as I thought I could print it. I then scaled it to 1:12 and cut it up into pieces that would fit on my 3D platform. I also added support to some areas that is to be removed after printing.
I designed a new rear bumper for this version as I had to add support under the tailgate to print the back of the Scout as one unit. Rather than remove the support I thought that it would tie well into a bumper. So I painted it black and did work out well.
I made the battery compartment as large as I could to support a larger battery pack if needed and also to fit in the charging cord for my existing battery pack, so it does not get misplaced.
You can also modify the lights to accept the wire harness off of the original stock body. My lights and lenses are printed and painted, but they could be cut and lenses added. This would give running lights and headlights to the build. I did not choose to do this.
I have included screen shots from Tinkercad to illustrate where I “cut” the model to fit onto my Dremel 3D printer platform.
I printed it in PLA as that is what works best for my printer. I would estimate that it takes about 24 hours to print up the entire model.
Step 2: Assembly
First you need to remove the extra support material from the wheel wells and bulkheads/firewall. I have a little angled wire cutter from Erem that works well for this. A craft knife will not get the job done with the supports that I used nor would it be very safe to use a knife for this task. (Adding support to models for printing is a skill that I need to learn better methods for. I should have learned this process years ago, but hey my method works crude as it is.)
Now you can glue the front section to the mid-section, followed by gluing the rear section to the mid-section. For this I mostly used a medium gel super glue. Making sure to do your best to keep everything in a straight and untwisted line. I then go back over the seams several times from inside of the model to build up the glue and fill in any gaps.
Glue the lower grill valance into place lining it up with the upper grill and the lower part of the front fenders.
Now to install the battery compartment tray. To do this I measured the height of the hood and added to this measurement the height of a magnet: Do not glue the magnets to the hood yet. Then measure down from the top of the fenders and mark where the battery compartment needs to sit for the hood to be level with the top of the fenders. Before gluing the compartment in-place I drilled into the top of the posts that hold the hood and glued inside these holes magnets that will attach to the magnets glued to the underside of the hood.
The next step is kind of tricky but does not need to be exact. I placed a magnet on top of each of the glued in post magnets and colored them in with a black Sharpie pen. While the Sharpie ink was still wet, I set the hood in place and pushed down onto the wet ink. This will mark where the magnets will be glued onto the hood in a position to line up with the magnets on the support posts. Make sure that you have the magnets in proper orientation and then glue them to the hood. For the record I did this wrong the first time and flipped the magnets over to where they repelled with the post magnets and so I had to redo this process. Check twice, Glue once.
These following items I glued to the model at nearly the very end of the build. That way I had the easiest painting, minimized breaking pieces off and gave me the best access for assembling to the chassis: Painted mirrors and bumper go on after body painting is completed.
The topper was the last thing that I glued to the model and that at the very end of assembly to the chassis. Later I changed this to magnet mounting to add interior parts for topless running.
I also glued the rubber tires to the wheels on the RC car that I bought because the rubber tended to separate from the wheels easily. Super glue seems to have stopped this from happening.
Part list with weights in ounces
Battery Box .6
Body Mounts .3
Mirror, Latch, Steering Wheel .1
Door Panels .7
Roof Rack .2
Roof Panels .8
Seat Bracket .1
Lightest Build 11.5 ounces (Items in bold above)
Heaviest Build (All parts used) 15.5
Step 3: Painting and Rusting
Since Scouts had rust on them even before leaving the factory floor (an old saying) and because I am basing this build somewhat on what is to become our real truck, I chose to add rust to areas of this model where I had printing flaws and to areas that commonly show rust on real rigs. This step of adding metal to rust-out I did after priming the entire model with the base coat.
Body work: What Scout doesn’t have Bondo on it? This model is no different. I was not happy with the meeting of the middle and rear body parts because the glued seams where very noticeable. I filled them in with JB Weld - Plastic Weld. I have used wood putty as filler before and there are other options too. This was a first time that I used Plastic Weld on a 3D print, and it worked and sanded well. My body filler was not completely invisible, but with the paint job that I planned to apply I was fairly confident that it was good enough.
Primer coat: I begin with painting all the parts in a Red Oxide colored enamel primer making sure that I have three coats or more so that everything is well covered. Next you want to add one or more coats of contrasting colors to accent the salt technique, so I took a Hammered Rust-Oleum copper color and quickly sprayed it onto some areas of the model. This color and other colors (if used) are not to provide full coverage but simple to add depth through the removed salt that is to be added later.
For the topper I will stop painting it at this step with only two colors of paint until later when I am going to hand paint the windows in a black enamel. To recap I sprayed on a solid covering of Red Oxide enamel primer and lightly over sprayed that coat with some the copper colored “hammer” effect paint.
Rust effect: After the paint base coats, I am adding real rusted metal to some of the areas of the body. To apply this rusted metal effect, I used a technique that I have used a few times in the past with good success. I illustrated this process before in my Instructable: https://www.instructables.com/Shadow-Box-Grandpas... There I used this same method to rust the 3D printed horseshoes so that they appeared to be real. I have also used this technique on other projects that I did not write up and it produces a believable effect.
I did learn something new about this technique that I think may help me next time so I will share it here. I have done this technique before using both ModPodge and with XTC3D although I am quite confident that it can also be accomplished with super glue, Elmer’s glue, or 5-minute epoxy. In the past I embraced the absorption of the iron powder into the glue. I was mostly shaking off the excess iron then rusting what was left behind and if I sanded an area or buffed it with steel wool, it was not going to show just glue because the metal had saturated the glue as well. On this build I had an indent (hole) in the model just below and behind the passenger door. I decided to fill that hole with XTC3D, which is a paint on leveling glue that works well to remove print lines from 3D printed objects. So now you can imagine that I have a “pool” of epoxy basically to which I added the iron powder. This iron powder absorbed into the pool and expanded so I added more iron powder to cover the top of the pool which in turn expanded the pool even greater. The end result was a blob of rusted iron that protruded and looked out of place on my model. What I would do differently to hopefully prevent this: mix my epoxy and wait until it starts to get a little tacky before applying to the model. That way it is not nearly as absorbent of the iron. This is not necessary unless you have a standing pool of ever-expanding liquid metal as i did. Hopefully this makes some sense to you.
Fast rust: Now that I have added the rust effects, I want to rust this iron out ASAP, because I do not wish to wait months or years for rust to form naturally. To speed up rusting I use a formula that I want to caution you about. It uses Hydrogen Peroxide, Vinegar and Table salt. This may or may not be a toxic combination so mix it and use it in a well-ventilated area and use at your own risk. I am not a chemist or anything close to one so do your homework as to safety of this combination of chemicals and minerals. To make the solution mix roughly 5 parts Hydrogen Peroxide to 1-part vinegar and add some table salt. I have it in a little spray bottle and spray it over the iron areas.
Salt technique: Now I want to add some table salt to the paint. I used this same technique in https://www.instructables.com/Model-Safe-Hidden-i... , but with this one I did not want the large blobs of paint removed as I did there.
I let the overspray from the rusting solution stay on the model and added water splayed on with a model paint brush to other areas. I made sure that I had a heavy coat of water over the rusted areas to cover them so that it would mostly let the rusted iron show through. I then coated all of the wetted areas with table salt and let it set up for hours to dry. Initially I add some more salt to the larger wet blobs to make sure they are well saturated with salt although not really nessesary. The folks who are really good at this technique recommend different sizes of salt grains ranging from coarse to fine. I agree with them, but I only used what I had on hand. Which was iodized table salt. After the salt dries you can shake off any excess or lightly go over it with a soft dry paint brush. I even chose to rub some off with my fingers and fingernails.
When it comes to salting you can see that often less coverage is better than more coverage. I got the desired effect for this paint job, but I think that if I did it again I would go with even less areas of salt.
Topcoat: For my topcoat I am using an Almond Satin enamel spray paint. This is applied in two or three light coats over the top of the salt and base coat(s). Then after the paint has fully dried you rub off the salt exposing the base coats beneath. As I started to remove the salt from mine, I decided that I was going to have too much base coat showing through, so I removed about half the salt and sprayed a very light coat of the Almond Satin over it before removing the remaining salt. This gave even more depth to the coloration. There are people out there who have this process down to a science, so I recommend looking at this technique from other perspectives as I have not fully mastered it yet.
It takes some effort but you can remove the salt in several ways. I used fingernails, toothpicks, rubbed with fingers and a stiff bristle brush. Note that it is not really fun to wedge salt up under your fingernails though so I do not really recommend this method.
Step 4: Attaching the Body to the Donor RC Chasis
Truth be told here I was blessed with a lot of dumb luck. I scaled the initial body to measurements that a friend took from his daughter’s RC. I already had everything completely painted and ready to go before I even explored how to remove the existing Rover body from the RC chassis. I was very fortunate that everything fit and cleared as needed. Changes at this point would have been devastating as everything was glued and finished. So, this is not the pathway that I would recommend.
I was a little perplexed as to how the stock body would need to come off, but I was pleasantly surprised that it was held on by only 4 small screws. I will reuse two of these screws and take two from the front bumper assembly to attach my front mounts because they have larger heads.
I am sure that there are better ways of attaching the body, but my method worked, and it did not add much weight to the RC.
I used one of the screws and turned it into each of the mounting holes on the rear bracket to "cut the threads". I then screwed the rear mounting bracket to the chassis and held the front mounting bracket in place with toothpick studs that were cut off flush at the top of the bracket and fit firmly into the mounting posts to prevent movement. I then placed the body resting onto the front bracket and I made the back bracket fit tight enough to hold the body in place with tension. After careful measurement of the front and the rear wheel wells from the desk surface to the top of the wheel well (keeping them the same at just under 4 inches each) I glued the rear bracket to the body at the four attachment points.
I then removed the body and the now attached rear bracket assembly from the chassis. Then I added super glue to the bracket up front where it attaches to the battery compartment. I left the front bracket held in place to the chassis for now with the toothpick studs with the super glue applied to the top of this bracket where it will meet up with the battery compartment. Placing the body back in place making sure the rear bracket was locked into the chassis posts and adequate pressure applied to the front to adhere the bracket to the compartment in the proper place. After dry time I removed the body from the chassis again and drilled through front bracket holes up into the battery compartment tray with the same size drill bit as the bracket holes.
After removing the front wooden pins from the two mounting posts on the chassis the entire body can be screwed into place and everything should line up nicely.
For the record this did not go well on the first install. I measured everything and dropped the model as low as I could onto the chassis. I had everything fully glued and was excited to try out my new toy. I installed the battery pack and started to roll it across my office floor. As I begun my first turn to the right the left front tire hit the fender and it stopped all movement forward. What I had failed to test or realize is that the servo on this RC car pulls the entire suspension way up when making a right-hand turn. In fact, right up into my body works unfortunately. My first thought was oh no (G-rated version) this is an insurmountable movement to overcome without greatly messing up the looks and fitment of my design. In addition to this everything was already glued solid and fully finished.
Dang what now? I ended up lifting the body upward something like 3mm and forward on the chassis by roughly 2mm from center. I was fortunate to be able to break the super glue bonds holding both the front and rear supports to the body. I then clipped and sanded material away from the area where the front tire hits the body at. The removed material is underneath and mostly invisible from above. Even looking from below it does not detract much as this is a rusted and aged-out old vehicle made to resemble something that is nearly 50 years old and untouched.
The other thing that I discovered is that chassis sits 1/8” higher on the left side than it does on the right side. I went with this so that my front mounts were flush but now my RC lists to the right. Not uncommon for these old trucks with their broken body mounts and the like. This could be corrected by lengthening the body mount connection on the front right side of the battery bay and adjusting the fit of the rear mount before gluing it in place. I contemplated doing so, but then I would have had to get a longer screw for that fright front mount. Not a big deal to buy a longer screw, but with COVID-19 I am still trying to limit unnecessary trips into the public.
Another thing about using the existing screws on the front mounts is that after raising the body up to compensate for tire travel, I had to drill out most to the battery compartment material above the mounting bracket to be confident that I had enough threads grabbing into the chassis mounting posts.
It is at this time that you can finish the assembly by gluing the topper to the body. I contemplated mounting the top to the body with magnets instead of glue to make future repairs easier if needed, but initially I decided to glue it on because I wanted the best rigidity that I could achieve because it will tumble and roll with almost every use. (See Update below in Conclusion: I did end up going with magnetic mounting system afterall, but gluing it worked well and if you don't wish to run topless and with added weight of interior this is a good method.
Step 5: Conclusion
I tried to push myself on this build by using and expanding upon techniques that I have used in the past. I am pleased with the results and will enjoy playing with this RC car.
The end weight of the body ended up slightly less than the stock body. The stock Rover body was around 14.1 ounces and the Scout II body is about 13.7 ounces before adding the topper panels and interior. Putting an interior into it made the total weight at 18 ounces much of which is the weight of the seat.
My best guess is that this project cost me about $100 total with the stock RC chassis, paint, glue, salt, iron powder, and other materials that were used. I could have pulled it off with materials that I had on hand for just the initial $70 purchase of the donner RC car, but I wanted something close in appearance to one of our existing project trucks.
I may add better shocks in the future and that will add about $20 more to the cost, but that will probably be the extent of my upgrades beyond lubing the running gear for better performance and longevity.
One day our ’72 Scout II will be running too, and it will look a lot like this remote controlled toy when done. At that time this model may just live inside that truck at all times. Performance for this “cheap” RC crawler is not bad at all. It would be better served with quality shocks as it bounces around quite a bit. By design hard right turns pulls the left side front tire upward hard towards the body as stated, and I am not experienced enough with RC steering options to know if there is a fix for that.
My goal from the start of the Scout II designing process was to make a model that can easily be identified as an International Harvester by most people. Initially it was designed to be a “model kit” to be assembled as a 1:25 scale representation of a Scout II. That model was completed, and photo shared above. Secondly the files were used in a joint venture with my Brother and assembled as a 1:10 scale Bluetooth radio which was gifted to our Sister for Christmas 2020. Now finally the files are used for an RC crawler.
The modeling of a Scout II is not perfect, and I am fine with that. This RC toy represents the best of my current abilities using only Tinkercad to work with. I can see Scout 80/800, Scout II and maybe even Traveler influences in it. I feel that I have taken the evolution of this concept as far as I desire, and now I need to move onto wrenching on the big trucks.
UPDATE: After I did the original write-up, I decided that the Scout had to be able to roll topless and it needed a better topper design to closer resemble the real deal. So, I made the following changes: I added an interior, redesigned the topper, added two mm to the overall wheelbase length for future builds, added magnets to the top for mounting it to the body for easy removal and modified the rear bracket to better clear the new wheel well dimensions. Photos in the next section can be used to see how the interior was assembled after painting it. I glued the front floor holding the seat to the brackets which are glued to the battery compartment and the front underside of the rear floor and front top of rear bracket. Door panels were glued to the door pocket at the top and bottom. The entire body and interior are now one piece.
If you wish to keep the weight as low as possible do not add the interior parts or the top effects to the roof top and simply glue the topper to the body as I originally built it.
Step 7: Interior Added: After Build Was Completed and the Instructable Written
Of course after the original model was completed and the Instructable written I decided that I had to make changes to it for my own satisfaction. One of the cool things about a Scout is the ability to run topless. Well that would not work with the original design as the topper was glued on. Also originally I left the interior out of it for weight reduction and it would require interior pieces for topless running.
So off came the topper by breaking the glue bond and an interior was designed to fit into this model. I hollowed out the seat and made everything as light as I could, but it still added a substantial 1.5 ounces to the overal weight.
Assembly went like this: I glued the door panels in, followed by the seat brackets, seat, and then rear floor. I added a piece to cover between the rear floor and the seats last.
I added magnets to the topper as seen in the photos. Something to note is that I do not like the paint job on the replacement topper as much as the original topper paint job. The reason is that I printed the original topper in black and I lightly sprayed it in the colors so that some of the black pla still came through. The replacement topper was printed in white filament and fully covered in paint.
As I made changes I also wanted a topper that closer resembeled a Scout II topper so I rounded out the corners, changed up the rear hatch area and added top effects (panels). This took a lot of time and work to complete. I then mounted the topper to the body with magnets so that it can be quickly removed to run it topless. Most of this process is shown in the photos in this section. It adds nearly one ounce by adding the top roof panels. So be aware that the more detail you add the higher the weight will be.
A word of caution. You should not pick up the RC by the topper with only 8 magnets attaching it. It will come off and the body can fall. This would not be a good thing for a glued together model. You also should not hold it by the hood as those magnets slip easy too. It is best to pick up the RC by the running gear to avoid any chance of dropping it.
A special thanks to Greg Schock for letting me use the original track, Binder Beats, in the video.
I am open to questions and comments that you might have.
All the best to you and your projects.
Step 8: STL Files
- RC Topper.stl
- RC Topper Rib.stl
- RC Steering Wheel.stl
- RC Seat.stl
- RC Seat Mounts.stl
- RC Roof Rack.stl
- RC Rear Bumper.stl
- RC Rear Body Mounts.stl
- RC Mirrors and Handle.stl
- RC Lower Grill.stl
- RC Front Bumper.stl
- RC Front Body Mount.stl
- RC Floor Panel.stl
- RC Door Panel Passenger.stl
- RC Door Panel Driver.stl
- RC Body Front.stl
- RC Bed.stl
- RC Rear Body.stl
- RC Hood.stl
- RC Battery Box.stl
- RC Body Cab Rework.stl
- RC Body Back and cab together.stl
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