BluCrawler – LEGO Rock Crawler with BTBox Bluetooth Controller
First off.. I want to give a shout-out (and credit) to PunkTacoNYC as BluCrawler is based off his Chilli Crawler – this is his creation. I’m just taking it down another path. Thanks for waking me up from my Technic sleep! You can also find published instructions if you want to build it yourself. For some time, I wanted to get an RC crawler, but they can be $$$. When I came across PunkTacoNYC’s Chilli Crawler, that was it.. I figured I had 90% of the parts already in my Technic/Mindstorms collection, so off to Bricklink I went… My version is pretty much the same except that I only had the LEGO PF remote and IR receiver (he uses Sbrick). The issue is that the LEGO IR system requires line-of-sight between the remote and receiver. Not very good.. So, I decided to do something about it. Pop over to my write-up of BTBox for more on what I came up with.
Note: This is an active project. I’m making regular changes and updating this page, so keep checking back for updates.
After some crawling, I noticed some challenges with the design that I wanted to improve upon. Namely:
- Links: Connecting links would disconnect from the ball joints during extreme climbing, or stress.
- Steering – the current design uses a M-motor and it drives in either direction based on the joystick. I’d often find myself going too far and grinding gears. I wanted to try the servo so motion would be automatically limited.
- Steering Portals: The original front unit that used a combination of pieces that resulted in more play than I wanted. I wanted to integrate the same steering portals that the back drive unit was using.
- Motors – The XL motors are ideal for this build, but I wanted to try to see if L-motors would do (when geared appropriately).
Links: I’ve just changed this up again. I’m now using Technic Wishbone links which allow direct connections on both sides using axles. This will eliminate the disconnects I continued to have using the ball connector approach. It comes at the expense that there is less side-to-side torsion movement range – but this is buffered by allowing space for the link to slide along the axle.
|Technic Wishbone links connecting the chassis to the drive units.|
Steering: My adventure to modify the steering resulted in my completely rebuilding the front unit. The goal was to integrate the Servo Motor into the design. The challenge was where to put it. I ended up using the space where the XL motor was from the previous design. For the drive motor and gearing, I used a similar approach from the original but with a different combination of gears to allow the lower torque ratings of the L-Motor handle things. I also managed to create a means to easily swap out gear ratios. The current setup has a geared down ratio but allows me to use either a 8 to 24 (3:1) or 16 to 16 (1:1) gear set depending on the terrain. I also replaced the original steering arm components with Technic Steering Portals. Result is a stiffer front drive unit.
|Servo Motor Steering 12 Tooth Direct to Rack Unit
Also Shows L-Motor at Top
I’m currently waiting on a second Servo Motor. Once done, I’ll finish up the rear drive unit (mirror of the front), hook it all up and do some test runs. Will get some videos as well.
Below is info and videos of the original version of BluCrawler – based on PunkTacoNYC’s Chili Crawler.