RC tank-steering Rock Crawler by danjr1

Last crawled date: 3 years, 3 months ago

3/10/20 Update - All seems to work well but I'm questioning the strength of the PLA+ chassis so in future I might print it in PETG.
Rather than buy an expensive RC Crawler, I thought I'd have a go at making one! As I have a background in combat robots (and couldn't be bothered with the complexity), it uses tank, rather than conventional, steering. The rear axle also can technically spin 360 degrees if it wasn't for the wiring. The link below will take you to the fusion 360 design that I might update over time and below that is the list of parts required. Feel free to remix this and add your own twist!
Link to Fusion 360 Design ...... https://a360.co/31HT7ua . I may do some build instructions if there's enough interest.
Bill of Materials (BOM)
Printed parts
1x Chassis
1x Battery strap
1x Rear axle support
1x Rear axle carrier
4x Outer mounts
4x Inner mounts
1 of each of the rear M5 bolt holder parts
4x Goodson's Hobbies 2.2 Beadlock Wheel 06 - "Super 5" (https://www.thingiverse.com/thing:3402987) - you'll need extra m3 button bolts if you use these
1x Bodyshell if you want to print it. The body I've used is here ... https://www.thingiverse.com/thing:4584559
Electronics
1x 4s lipo. I've used a Turnigy nano-tech 4s 2200mah and that looks like the biggest that would fit.
2x reversible brushed ESCs. For testing I used cheap 7.2v-16v 320a ESCs but they have a brake-before-reverse so steering is a little weird. I'm going to upgrade to some 30a brushless ESCs that have been converted to brushed operation which are commonly used in combot robots so forward to reverse is instantaneous. You can buy these from various places or make them yourself.
1x Transmitter and Receiver. Anything will do really.
1x RC signal mixer but only if your transmitter doesn't do channel mixing. Mine didn't so I've used a Fingertech TinyMixer.
4x 300rpm 12v 25mm gearmotors (https://www.aliexpress.com/item/32776557759.html?trace=wwwdetail2mobilesitedetail&spm=a2g0o.productlist.0.0.75b663a0I5cilv&algo_pvid=25879370-b82f-4a8a-8a9c-601c2d8e694b&algo_expid=25879370-b82f-4a8a-8a9c-601c2d8e694b-10&btsid=0ab6f82415899108943085094e6826&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_)
12x 3.5mm bullet connector pairs
1x XT60 battery connector pair
I used 12v speaker wire for most wiring then some normal rc wiring for the lipo-to-ESC wiring.
Heat-shrink
Other Components
4x 2.2" Crawler tyres (https://www.ebay.co.uk/itm/4PCS-120MM-2-2INCH-Rubber-Rocks-Tyres-Wheel-Tires-For-1-10-RC-Rock-Crawler-Axial/392341138167?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649)
4x Pololu 12mm hex 4mm shaft adapters (https://www.pololu.com/product/2684). The grub screws that come with these don't seem that great so I may change them out for some longer pointed ones so they dig into the gearbox output shaft.
20x M3 25mm button head allen bolts
2x M3 25mm countersunk allen bolts
11x M3 8mm countersunk bolts
3x M3 10mm button head allen bolts
4x M3 washers for the printed wheels if you use them
18x M3 nyloc nuts
4x M3 nuts
3x M3 aluminium standoffs
2x 86mm long 12mm O/D aluminium tube. Wall thickness should be above 1mm
1x 139mm long, 14mm O/D aluminium tube. Wall thickness should be above 1mm
1x M5x60mm allen bolt
1x M5 nut
7x M5 washers
1x spring that can go over the M5 bolt (I used a 20mm long, 12mm O/D, 6mm I/D spring like this https://www.ebay.co.uk/itm/Heavy-Load-Duty-Compression-Die-Spring-8-18mm-Diameter-Up-To-55mm-Long-JIS/223584768462?ssPageName=STRK%3AMEBIDX%3AIT&var=522328127518&_trksid=p2060353.m2749.l2649)
10mm wide self adhesive velcro for the bodyshell if you use it.
Some self adhesive 3mm thick foam to help protect the better
Something to stick the ESCs and Receiver to the chassis. I use double sided no more nails tape.
Tools needed (other than the printer and filaments)
Drill
Drill bits up to 5mm
Allen keys/ drivers
Some grease for the washer arrangement around the rear axle M5 bolt
Pliers
Various files
Soldering Iron
Solder
Heat gun or lighter for the heat-shrink
Threadlocker
Hammer and punch for marking the aluminium tubing
CA glue
A vice is useful for forcing and clamping the rear bolt holders together when gluing them.
Hacksaw to cut the aluminium tubes
Usual marker pens and measuring tools