My research assistant on this was the email Pololu sent me.....I'm sure The Erco Bargainmatic 650 has fancy Internet web crawler algorithms to find these deals.
It's a neat little chassis, but it comes without motors. It is designed for the Pololu micrometal motors which are about $20 or so a pair. So it's a bit over $40 in the end. But it is designed for micro- sumo and will be a beast in the ring.
Finally got my 4WD chassis assembled this morning. The motors are those 48:1 jobs erco mentioned in the $30 4WD Chassis... I'm guessing those will go away soon. :-|
The aluminum parts came with a =generous= coating of silver paint... on aluminum!? How much paint was there you might ask! Paint was so thick I had to file it off mating areas to get the parts to fit together and tap out the 3mm mounting holes to get the screws started. A few hours in a bag of paint stripper took care of all the paint issues and I still have a "silver" vehicle. (Of course I ordered the black one! :-< )
You can get similar-sized gearmotors with lower gearing which will work a lot better. I don't know why anyone specs 48:1 gearmotors unless they're so cheap because no one wants them. Also, those wheels & tires aren't always concentric, so double check everything!
Of course if you put much smaller wheels & ties on, the 48:1 motors would work proportionally better, but there goes your ground clearance.
Comments
This is a very tempting chassis to play with!
Neat! Hope it'll be around for a while... I'm working on one of these right now.
http://www.ebay.com/itm/SainSmart-4WD-Drive-Aluminum-Mobile-Car-Black-Robot-Platform-for-Arduino-Motor-/271028929584?pt=BI_Robotics&hash=item3f1a954430
The aluminum parts came with a =generous= coating of silver paint... on aluminum!? How much paint was there you might ask! Paint was so thick I had to file it off mating areas to get the parts to fit together and tap out the 3mm mounting holes to get the screws started. A few hours in a bag of paint stripper took care of all the paint issues and I still have a "silver" vehicle. (Of course I ordered the black one! :-< )
Of course if you put much smaller wheels & ties on, the 48:1 motors would work proportionally better, but there goes your ground clearance.