Right Angle Drive Success
Bill Chennault
Posts: 1,198
All--
Some may remember that I want to build an 8-legged walker. It will be like a cat, but with twice as many legs. In fact, it will be the mechanical incarnation of the great Edgar Rice Burroughs' baanth.
But, I am a LONG way from building it.
I need to test motors for a walker. To do this, I need motors and drives; I want to test servos, gear motors, and perhaps steppers. Right now, my odds-on favorite for power and repeatability is the gear motor. However, I need a right angle drive because I do not want·a motor sticking out of each joint.
Here is my first effort using a Banebot 574:1 gear motor with 534 oz-in of stall torque . . .
Here is how I built it . . .
Right angle gear motor.
I built it to merely test motors and leg configurations. I will mill the actual right angle drive cases·out of aluminum and fit the bearings, shafts, and gears. In essence, I think I can cut the length down by about 35 to 40% and the "width" of the right angle drive by about 70%.
Tell me what you think.
--Bill
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You are what you write.
Some may remember that I want to build an 8-legged walker. It will be like a cat, but with twice as many legs. In fact, it will be the mechanical incarnation of the great Edgar Rice Burroughs' baanth.
But, I am a LONG way from building it.
I need to test motors for a walker. To do this, I need motors and drives; I want to test servos, gear motors, and perhaps steppers. Right now, my odds-on favorite for power and repeatability is the gear motor. However, I need a right angle drive because I do not want·a motor sticking out of each joint.
Here is my first effort using a Banebot 574:1 gear motor with 534 oz-in of stall torque . . .
Here is how I built it . . .
Right angle gear motor.
I built it to merely test motors and leg configurations. I will mill the actual right angle drive cases·out of aluminum and fit the bearings, shafts, and gears. In essence, I think I can cut the length down by about 35 to 40% and the "width" of the right angle drive by about 70%.
Tell me what you think.
--Bill
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You are what you write.
Comments
Awsome idea!!! keep us posted on your progress! I have always wanted an 8 legged cat, but my parents would never let me get one [noparse]:)[/noparse]
...now where did I put that "Genetic Engineering for Dummies"....
Looks good, Bill.
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Truly Understand the Fundamentals and the Path will be so much easier...
Modifying the Dremel right angle attachment destroys it for further use on your Dremel tool. I am going to play around with it a bit and probably build at least one more. (However, today I bought the guts for four more which equates to two legs and would let me do more relevant experimentation.)
I am thinking--for experimentation purposes only to determine motors, feedback, CPUs, etc--that I will build some actual test legs out of PVC. A little bit of PVC glue should anchor that big Dremel nut into a correctly sized pipe. I am not quite sure how I will build the joint, yet. But, I will doubtless figure it out.
A hip motor and a knee motor mounted on legs connected to a "spine" via a "vertebra" will give me an excellent test platform for the Banebot motors. Testing those Banebot gear motors is of great interest to me. IF the Banebot motors of some variety prove to be what I need, then I will begin milling right angle drives out of aluminum for testing. EVENTUALLY, the baanth will be constructed as I test components until I find the best for my application. As soon as I have something that actually moves a leg, I will begin taking very short movies and posting links.
If a gear motor will produce 534 oz-in of torque using a 0.125" shaft (which has a 0.0625" radius), is it·correct to assume that the same gear motor with a six inch leg attached (somehow; to·be determined later), will produce 6/0.0625 oz-in of torque, or·96 oz-in at the end of the leg? I think that is·a legitimate computation. However, I do not know how·much--how "strong"--96 oz-in is. Of course, the·completed device·will produce far more than·96 oz-in of "lifting" force, because each leg will have two motors for a total of about·192 oz-in. Then, of course, there will be eight legs for a total of about 1536 oz-in. (This all assumes my guesses about how to figure torque extended from the shaft are correct.)
I do not have a feel for how much this may·actually be in the world of mechanics. That is why I am testing. If nothing else, I'll use the new Banebot RS-550 with 18061 oz-in of stall torque.·That should "get'er done."
--Bill
ps: I have an RS-545 with 2368 oz-in of stall torque. I am thinking of building a lift for my Sportster with it.
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You are what you write.
All electronics has these little motors in, they look brand new, I tested one at the store and they are pretty powerful. I have no idea if they meet your requirements but for the size they may be worth looking at.
Thanks! I'll check them out. The first thing I noticed was that they are made in Japan. That's probably better than the ChiCom Banebots!
--Bill
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You are what you write.
Your right angle drive looks fine as a 1:1 ratio, but I was curious what kind of speed you are getting from the 574:1 motor used in the picture.
Reason I ask, is that you "may" be able to find an off-the-shelf substitution with a cordless screwdriver (adjustable angle). I wouldn't spend
more than $10, but I always check the clearance rack at the hardware store for these sometimes hidden gems.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
The Banebot is an FF-050 geared down 574:1 and provides 26 rpm. I only THINK that is enough. (It may also may be too much for my walker; that is where your MMBe comes in.) Fortuneately, they have a pretty good supply of standardized motors with different ratio gearing, so I can experiment quite a bit.
Standardization is absolutely vital . . . well, at least pretty important! When I attempt to build my device, I will need AT LEAST 16 of these motors, whatever they prove to be. Therefore, the standardization issue is obviously important.
By the way, the Banebot cost me $14.80 without shipping.
--Bill
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You are what you write.