Are you new to Black Crow models? All the STL files are here free on Printables.com. A non printed parts list is below along with easy step by step assembly videos. Help is available, usually within 24hrs. You can contact me thru private message or comments on the makes and comments tab. File updates are always listed at the bottom of each description page. Ways you can help my efforts to provide free models to everyone include, informing me of mistakes and subscribing to my YouTube channel. I need 1,000 subs.
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Now, I am proud to introduce Thumper. Thumper is a scaled CJ7 rock crawler. These crawlers are common in the western and south eastern USA. This model is very close in build to the real thing. Scale puts the 120mm tires at the standard 37" tall. The front axle has been moved forward about 10 inches and the back axle moved back about 9 inches. The seats have been moved back and mounted to the roll bars for safety. A race fuel cell has been added and raised above the frame for clearance. Without a trailer hitch the approach and and departure angles are 90 degrees. The ramp over angle could be better. You can't have everything.
When building a real rock crawler you want the tires to be as big as you can swing while keeping the body and center of gravity as low as possible. You want lots of power while staying light and nimble. Cooling the engine is usually an issue and it has to practically run upside down without leaking fluids. To be honest the CJ7 is not the best choice for this and they are becoming too valuable to destroy. You could technically buy every part of a CJ7 without buying any actual AMC or Jeep parts using 100% catalog aftermarket parts. This model is a fully home built custom crawler.
This 3D printed build was designed to be strong and easy to work on. I appreciate the “fully 3D printed” models put out by others however I tend to be a bit more utilitarian. This model uses RC hobby standard metal axle gears and drive shafts. The transmissions use an amazingly strong belt system that is very quit. The motor/transmission sets are easily removed and swapped without removing axle links or suspension. The battery module slides out the back for easy charging or swapping. This model has room for one or two 2S 7.4 volt shorty Lipo batteries.
Before building please read carefully. This model has options. In an attempt to keep things simple the motor/transmission build options and other options are in separate listings. Build this Jeep chassis, pick your motor/transmission setup. Then combined or swap out Motor/transmissions. You also have door and top options along with custom options in the Thumper aftermarket store. The half top option requires a different rear tub found in the Door and Top Shop. The Four Wheel Steer option also has a separate listing for it's custom parts. All the STL files you need are listed with links below. Parts are numbered in order of use. Parts files are in proper orientation to print. Assembly videos at the very bottom of this page.
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Videos: Introduction here. **Assembly videos at bottom of this page!!**
Introduction to Four Wheel Steer version. **Assembly videos at bottom of this page!!**
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Action Video below by independent Builder Lasz YouTube channel here
Top and doors in this video by MaSt52 here
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Links to Transmissions and options:
Metal Gear Motor/Transmissions - Coming very soon
Printer Gear Motor/Transmissions
https://www.printables.com/model/356820-thumpers-transmission-shop-for-18-scale-rock-crawl
Four Wheel Steer Option
https://www.printables.com/model/394110-thumper-4ws-rear-steer-mod-18-scale-rock-crawler-b
Optional doors and tops https://www.printables.com/model/629922-thumper-door-and-top-shop
Aftermarket Parts Shop
https://www.printables.com/model/356827-thumpers-after-market-shop
Requested and Retired parts
https://www.printables.com/model/396992-requested-and-retired-parts
Top Shop
https://www.printables.com/model/629922-thumper-door-and-top-shop
GoPro Mount
https://www.printables.com/model/372044-thumper-gopro-mount-by-black-crow
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Motor Transmission Options
You have a wide verity of options when it comes to motor transmission setups. First choose from printed gears or metal gears. Then see more options on Transmission pages.
3D printed gear transmissions here: https://www.printables.com/model/356820-thumpers-and-morrigans-transmission-shop-for-18-sc
The 3D printed gears work very well unless you stay in the throttle for an extended period of time or use high rpm motors.
Metal gear transmissions here: https://www.printables.com/model/769045-thumper-and-morrigan-cheater-metal-gear-transmissi
The metal gears are better for people that push the limits. This is the better choice for 540 motors. The Fusion SE 1,200kv is awesome! This is also better if experimenting with 3S batteries.
Next you have the option of Four Wheel Steer
Parts marked Not 4WS will not be used on 4WS. Additional parts needed found in 4WS post
https://www.printables.com/model/394110-thumper-4ws-rear-steer-mod-18-scale-rock-crawler-b
This option is intended for the Crawlers. Keep in mind this option works best on rocks, dirt and slippery surfaces. If reduces the turning radius by about 70%. With locked axles it is not practical on carpet and other sticky surfaces. The good news is that you can turn it off. With just a flip of a switch you are back to front steering only. See more info on the 4WS Page listed above.
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Wheel base 12 ¾" (325mm)
Wide (Narrow tires) 10" (255mm) (Wide tires) 10 ¾" 274mm
Long 17 ½" (445mm) without trailer hitch.
Tall 9" ( 229mm) 90mm shocks stiff for basher or 100mm sagging for crawling.
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Supports:
No supports needed EVER! Supports are built into the Model.
(Because of the built in supports and fine detailed areas a 0.4 nozzle or Adaptive slicer must be used)
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Printer Settings:
0.4 nozzle (no bigger because of built in supports)
.2 layer Hight (no bigger)
Infill:
Normal parts - 15%
Roll bars - 25%
Axles, links, hubs and wheels -80% (100% can exaggerate over extrusion problems)
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Special settings for radiator:
Infill: Rectilinear 30%
Layers top 0
Layers bottom 0
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Filament:
Models are designed around the use of a strong PLA. For best results use Prusa PLA, Inland Plus, CC3D Max, ( Hatchbox PLA does not test well with my models)
Warping - Prusa printers with PLA plus - adjust bed temp to 65 degrees.
Creality printers with PLA plus - adjust bed to 60 - 65 degrees.
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Parts Needed:
Links are US Amazon Affiliates
Axles :
Axle Bearings: 4 bearings 7x14x3.5 ( 687) https://amzn.to/3W1t3Xs
2 bearings 10x15x4 (6700-2RS) https://amzn.to/4cPEnfx
10 bearings 5x11x4 (MR115-2RS) https://amzn.to/3VTBK68
Steering Servo: https://amzn.to/4cVPt2r
Battery- 2S Hard Case Shorty https://amzn.to/43ZbhpT
XT60 connectors - https://amzn.to/4fX27Qi
4mm Banana 90 - https://amzn.to/40Br12r
Wire - 12 AWG .6M (2 feet) - https://amzn.to/3TadxGy
Tires:
1.9 inch center 120mm outer diameter.
Red Jeep has 43mm wide. https://amzn.to/3PVOCF2
Yellow jeep has 52mm wide. https://amzn.to/4cRYoSu
Note two size wheels. Narrow for 43mm and Wide for 52mm.
Shocks: Important!!! 90mm - 100mm only !!
Shocks more than 100mm long will over extend the stock steering. Shocks under 90mm are too short to reach the axles.
Rock Crawlers- I suggest 100mm on Rock Crawlers. Just let the shocks sag and articulate.
100mm internal spring- https://amzn.to/43XIEJz
100mm Exterior spring- https://amzn.to/4aThfLs
Bashers- I suggest 90mm on bashers. 90mm lets you increase the spring tension without raising the center of gravity too high. Shocks more than 100mm long will over extend the stock steering. You can Use 100mm shocks on Bashers. It just raises the center of gravity and flips over more easily.
90mm internal spring- https://amzn.to/3JdtPsW
90mm Exterior spring- https://amzn.to/49tllbW
Acrylic
0.4mm thick acrylic sheet for window glass
My Favorite Radio TX for the money Spektrum DX5C 5 - https://amzn.to/3xoIGOv
---Transmission Bearings and more parts needed. Go to Motor/Transmission page---
https://www.printables.com/model/356820-thumpers-and-morrigans-transmission-shop-for-18-sc
Screws:
M2 nuts 11
M2 x 4mm 48
M2 x 6mm 60
M2 x 8mm 42
M2 x 10mm 71
M2 x 12mm 5
M2 x 16mm 2
M2 x 18mm 4
M2 x 20mm 5
M2 x 25mm 4
32 M2 screws optional lengths from 8mm to 12mm for wheels.
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M2.5 x4mm 3 socket head (for Flash hobby motors) or use new no screw option
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M3 eye bolts (optional) 2 https://amzn.to/3TViAui
M3 nuts 37
M3 Nylock nuts 8
M3 x 4mm 4
M3 x 6mm 2
M3 x 8mm 4
M3 x 10mm 35
M3 x 12mm 16
M3 x 14mm 30
M3 x 16mm 5
M3 x 20mm 10
M4 Nylock nuts 4 ( wheel axle nuts)
Thread Locker (Loctite)
( Additional parts needed in transmission/Motor build.)
Printed gears transmission- https://www.printables.com/model/356820-thumpers-transmission-shop-for-18-scale-rock-crawl
Metal gear transmission- https://www.printables.com/model/769045-thumper-and-morrigan-cheater-metal-gear-transmissi
*All parts for this model were purchased on Amazon
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Tools: Drill with 2.5 bit, File, Vice or clamps, plyers, utility knife, screw drivers, wiring tools, soldering tools
cutting: Hack saw or Dremel ( cutting 5mm rods)
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More info:
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Assembly Video 1
Assembly Video 2
Assembly Video 3
Assembly Video 4
Assembly Video 5
Rear Axle Assembly Video 6-A
Front Axle Assembly Video 6-B
4WS Axle Assembly Video 6-C
Assembly Video 7
Assembly Video 8
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Optional Four Wheel Steer Assembly Video
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Disclaimer - Lipo Batteries can be dangerous. Build at your own risk.
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Before you build:
Update: Jan-25-2023 adjusted 30-60Amp ESC mount. 60amp ESC sits on it's side with fan facing perforated radiator, ( see special radiator printer settings above) On Off switch goes to either side. Receiver mounts on top of steering servo with double sided tape.
Update: Jan-31-2023 Added 3 part roll bar for Ender3.
Update: Feb-10-2023 Improved rear frame- (048FrameRearLeft 049FrameRearRight)
Update: Feb-14-2023 Improved roll bar supports
Update: Feb-17-2023 007Cowl fixed hole alignment issue
Special thanks to Brace91 for catching many mistakes and beta testing the 4WS option.
Update: Mar-23-2023 updated axles for tighter fit with axle nuts
Update: Mar-23-2023 Added 4WS option
Update: May- 29-2023 Much needed update to seat. Old seat mover to retired parts post
Update Oct- 24 2023 045FrameFrontLeft - Added option for servo reinforcement screws. (1x- M2 x 25mm, 1x- M2 x 15mm) These screws reinforce layer line weakness at servo mount.
Update Nov-12 2023 Front Fenders -Added layer adhesion screw above shock mounts for greater strength.
Update Dec-10-2023 Axles and axle videos have been updated to the heavy duty Morrigan style axles. ( I had to move a lot of things and update links. If I missed something tell me please.)
Update Jan-12-2024 Added Top Shop here
Update March-17-2024 Added Metal Gear Transmissions here
Update Aug-9-2024 (rear non steer axle) 201AxleHousingRearRight, 203AxleHousingRearLeft- added option to reinforce with 5mm x 63mm rod for extra strength _________________________________________________________________________________________________________________
Builder Videos:
LegoManiacman Video 1
RN's RC Inaugural, Hill Climb
MAX3DRC- Video1 ,Fusion SE Video2, cruise control Radiomaster Video3 Stuck in the mud Video4
FPV Parts 1, 2 Steve Eckerlien Video1, Video2
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Parts designed by others:
Half Door that work with original roll bars by MaSt52 here
Top That works with original roll bars by MaSt52 here
Extended battery compartment by Steve Eckerlein here
1.9 to 2.2 Wheel adapters by Steve Eckerlein here
FPV camera mount by Steve Eckerlein here
Bumper with light mount by Steve Eckerlein here
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Prusa and Bambu printers usually print this model without any problems. Other printers might need to be dialed in. I picked this video because it explains all of the horizontal expansion settings. In most cases you will need to set to -0.1 to -0.3.
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License- Some file sharing platforms are taking files off sites and placing them on their sites without the knowledge of the designer. I am not OK with that. These models are updated here with the feedback given here. I intend to keep the home of this model here. This is the reason for the strict license of this model. I am not concerned with hobbyists sharing and remixing this model, Enjoy
The author marked this model as their own original creation.