Sumbot - Build Thread - By Quadiak
I don't ask much from my Summit, just that it bash, crawl, swim, jump, roll, crash, etc. and all with the flick of a couple switches. I don't think this is unreasonable for a RC monster truck, at least not for a Summit. So as I near achieving all the goals I have set for my ever evolving "Sumbot," I thought I might share my build with everyone.
The specs :
Name : Sumbot
Motor : Novak 7.5 HV(sensored)
ESC : Mamba Max Pro
BEC : CCBEC
Spur\Pinion : 12/68
Batts : 2 SMC - 2s 9000 Mah Lipo in series(4s 9000 Mah 28C)
Speeds : 32 Mph(calculated seems close)
Run time : 1 1/2 Hrs bashing - 4-5 Hrs crawling/hiking(estimated)
Wheels/Tires : RPM Revolver/Losi Claw MT's
Body : Proline 2007 Silverado
Suspension : LT with Double orange springs front and rear, 70 Wt shock oil
Radio : Traxxas Link HO (modified for 3 position 3rd and 4th channels)
Servo(s) : Hi-Tec 7980(front) - Hi-Tec 7955(rear)
Programmable Digital Components : MMP, CCBECm, Hi-Tec 7980, Hi-Tec 7955t
Custom : Front mounted motor, front mounted ESC, 2 water proof boxes, Servo saver spacer, Single front steering servo, 4WS(front and rear), TRX front toe links.
All of the exposed electronics are listed as water resistant, everything else is mounted inside the water proof boxes. I believe it to be quite reasonably water tight. As far as swimming goes, it is certainly not as water proof yet as I would it like to be. but I'm sure I will test it at least once:D
Starting at the front:
The front bumper mount is turned upside down in order to properly place the body and bring CG down
I used a Proline Silverado body and trimmed down E-Maxx body mounts. I also trimmed the front bumper section off of the Silverado body and matched it as well as I could with the Summit bumper.
I machined a piece of heavy plastic into a angle bracket and mounted it to the front body mount and attached the MMPro with 2 sided tape and zip ties for back-up:D
The MMPro is absolutely awesome, some of the features it has make it the perfect choice for the Summit, it seems to be able to handle the Summit just fine running 12/68 gearing. Speeds around 30 Mph are all I expect from my Summit, it can easily bash equally with a brushed E-Revo.
There is however, a Rock Crawler setting on the drag brake which, in combination with the sensored motor, will not allow the truck to roll down hill when in neutral/low gear. This drag brake setting makes it a little difficult bashing, because every time I let off the trigger, the brakes lock solid(and not gradually either). However, I found a remarkable way around this without having to reprogram between bashing and crawling. I set dead band to the largest setting and set the multifunction knob on my Traxxas Link Tx to throttle trim. Now by simply by turning the throttle trim to a more forward position it doesn't actually go into neutral, but deactivates the drag brake or can be set for a very slight drag brake. A simple return of the throttle trim to the center position and the rock solid, rock crawling drag brake is re-engaged.
It also has no reverse delay which is completely necessary for any technical rock crawling. Both the VXL and Novak ESC's had terrible delays into reverse. At the time of this righting the MMPro has had very little testing so I will update later on.
The ESC is hard wired directly to a Novak 7.5 HV motor. The Novak motor is a 3000 Kv, sensored brushless motor with a 5mm rotor and was used in Novaks 1/8th scale Brushless conversion kits. I choose this motor partly because of its size, I wanted to mount it in the front position on my E-Revo dual motor plate, but mostly because it was Sensored and also should be a lot more efficient when geared properly. I really do expect to get 4 or 5 Hours of crawling/hiking from a single charge of my 9000 Mah LiPos. However long the packs do last, I'm sure it will outlast a hike with me:cool: