The first time i saw K9 in Dr.Who series, i knew i just had to make one. Finally, i did. It took a month to get completed. Well actually longer because i dont really have the fun to get it done a.s.a.p. and i do wish i could get it done way faster than that. Anyway, back about K9.
This build is mainly out of foam. I used 4mm foam for the whole body construction. The bumpers are foam tubes used for wrapping air-conditioning pipes. I downloaded a pepakura K9 file and moded the file a little bit to make it lesser pieces (file is attached below). Pep files are printed on a A3 paper and traced on a big sheet of 4mm foam piece. After cutting , the body is assembled with contact glue. Way cleaner then hot glue but it stinks !
The inner chasis are made of MDF plates and dowel rods. Just enough to keep the whole body steady. I dont want it to weight too much. K9 only weight 8kg with two of 12v SLA batteries. Most of the weight are from the batteries. using Lipo batteries would weight way less but wont last long.
The body is then sealed with latex glue to make sure paint has something to hold on to the body. Foam are famous with paint not sticking to it. Usual method are modpodge / pva glue and latex glue. I like using latex glue more due to it's consistency. Three coats of latex glue and it was ready for painting. I used Dark Grey for the main colour. The rust is a mixture of Burnt Sienna and Raw Umber. For rust texture, i added small pieces of tissue paper and glue it on randomly. Not really accurate looking rust but it works for me XD
The electronics are pretty much simple. LED strips are used for almost every lights. Why solder individual LED's when you can just buy one strip of ready-to-use LED strip? Hahaha. Im such a lazy person. The ears and tail are powered by two separate servos that take CH3 and CH4 on the receiver. Installation was pretty straight forward. Installed on a single axis and servo lever turn it left and right.
The drive system is a typical RC system just like any other RC tank. Since K9 doesn't have a steering system like a car, It move left and right by distributing more power to the corresponding motor. Transmitter (controller) send signals to the receiver and it send signal to Electronic Speed Controller (ESC) to how much to move. You can find all sort of instructables specifically on RC here. Do check out my facebook for more updates on my projects :)
Note: Too bad this guy is up for sale to fund another bigger project :(
K9 Specs :
- Lighted eyes
- Manual retractable sensor
- Lighted laser gun (below the nose)
- Motorized ears (antenna)
- Moving blinking top control panel
- Motorized Tail
- Paint scheme : rusted battle damaged
Drive System Specs :
- Two 7.2AH 12V batteies
- Two 10A voltage regulator (fused)
- Two 40A Electronic Speed Controller
- Two 9.6v brushed motors
- Three servos
- One transmitter
- One receiver