Beetleweight Drive motors:
Beetleweight builders often have problems finding suitable motors to power their wheels. Many of the choices are meant for Ants and are too wimpy, or more suitable for Hobbyweights and too heavy. You also need suitable gearing and that can be even harder to find. Below are some likely choices and my comments on them:
Why not start off with the Ferrari of small motors? The Maxon motors come in a huge variety of interchangeable options and are made like Swiss watches. Hardly surprising, since they come from Sachseln, Switzerland.
These motors come in a range of sizes and have a matching range of planetary gearheads. The A-Max range is the most affordable and the ones to find on the surplus market. The common sizes are the 22mm and 32 diameter motors. The 32mm models will drive a 4 wheel bot via belts, as demonstrated in JR's Mini-Moo: http://www.teammadcow.com/mini_moo.htm∞
The 22mm model is better suited for driving individual wheels. The gearboxes come in a huge range of reductions. Ratios around 17 & 19:1 seem popular, then the 60 to 80:1 gearing is sometimes used.
The US site is the best place to go for more info, just don't get lost in the catalogue! http://www.maxonmotorusa.com/∞
The Australian distributor isn't much interested in selling to hobbyists but if you want a standard model and know all the part numbers, they would be worth a try: http://www.mrutty.com.au/∞
You can get Maxons delivered next day in Sydney, if you don't mind paying RS Overcharge: http://www.rsaustralia.com/cgi-bin/bv/browse/Browse.jsp?catoid=-87821956&cacheID=auie∞
A 22mm maxon and 19:1 gearbox from RS will set you back about $250 Needless to say, I want a set!
You can also get the 22mm / 19:1 Maxon from Acroname for $145 US: http://www.acroname.com/robotics/parts/R179-6V-ENC-MOTOR.html∞
. Take off the encoder and its the same but cheaper than RSC
For smaller and Much cheaper 19mm Maxons, try Bane Bots: http://banebots.com/osc/product_info.php?cPath=36_64&products_id=66∞
. The supply is limited, so don't be surprised if they have sold out!
B series Motors
Can't quite afford the Maxons? the next best could be the B series motors from the Robot Marketplace: http://www.robotcombat.com/marketplace_ant_motors.html∞
. I am using these in my first beetleweight and they are clearly a low cost copy of the Maxon range. After importing a pair, you would be up for around $115 AUD including postage - still not cheap. Jim at the RMP has won events with these motors in Wallop http://www.robotcombat.com/wallop.html∞
- I believe he uses the 12V 62:1 version, over-volted to 24V. I will have more to report on these when my set arrives. The RMP seems to be the only source of these motors at the moment.
UPDATE: I now have a set of the B16 motors and they definitely live up to the hype. The the only problem is that the motor's rated voltage is just 6V, so running them at 12V is significantly over-volting them and anything more is likely to blow the brushes. compared to the closest priced motors (the small Lynxmotions) the B16 motors are a little smaller, 14 grams lighter and twice as fast.
These are almost as high quality as the Maxons, but are hard to find at the moment. They are made by Portescap http://www.portescap.com/Sections/Products/products_main.asp?PC=10003000&CL=3&L1=10000000&L2=10001000&L3=10003000&L4=&L5=&L6=&IT=Descrip&lang=1∞
You can get some of the range locally at RS Components and I am researching other suppliers, so stay tuned. These occasionally turn up on US surplus sites.
Mounts for Escaps are available at CNCbotparts: http://www.cncbotparts.com/escap_mount.htm∞
Jaycar electric screwdriver
I have always wanted to hack one of these cheap screwdrivers – they look like a great value if some way to attach a wheel can be found.
These guys have some very worthy looking planetary motors. They are often geared far too low but the 19 and 27:1 ratio models are quite useable. All the motors are standard sizes so you can replace them with faster, more powerful models. The smaller models look very comparable to the B series motors from RMP and at $9.15 US they are very cheap although Lynmotion's shipping is incredibly expensive. The description says the gears are all metal, but the photos make them look plastic…
UPDATE: I have run the small Lynxmotion motors in Slash for several tests and while they are a bit slower than I wanted, they have excelent torque, pushing large objects (a vacuum cleaner) around the arena. The foam wheels have quite good grip too.
Lynxmotion have very strange international shipping policies; they only use expensive UPS shipping and that will easily double the cost of the parts. I recommend giving these guys a miss in favour of the RMP.
Motors with spur gear reduction
These are a cheap but fragile option. The gears never seem to hold up and stories of gears stripping during the first match are common. I will find links to the best options.
This could be a topic all by itself - hacking a servo is common in antweights, but the bigger servos have plenty of power for a beetle and can be fairly cheap. The main problem with servos is the plastic reduction spur gears and the weak output shaft. If you have exposed wheels, one hit from a spinner will surely break them!
One of the best places for servos and cool accessories is Servo City http://www.servocity.com/∞
. They have an amazing range of servos and accessories to make them more useful.
Acroname have a range of wheels for servos http://www.acroname.com/robotics/parts/c_Locomotion.html∞
They look to be very light, but fragile too - definitely for use inboard!
One of the main problems with modified servos is that they are SLOW! The link mentioned in the next post is about the best description of speeding up a servo on the web.
Some good servo hacking guides and tips can be found at: http://www.teamkiss.com/antweight.html∞
Bane Bots gearbox's
These drives are fairly new to the robot drive market, and there is yet to be much information on how well they work.
However with all metal gears and a significantly lower price tag than any other comparable beetleweight drive, they seem promising. www.banebots.com