I looked around for gearboxes and applications for the throttle motors we get in the KOP each year and came up empty handed. Eventhough vetran teams have heaps of these motors nobody uses them because they are utterly useless. I have decided to make a few different 3D printable gearbox solutions for the Denso throttle motors. I plan on using herringbone (double helical) gears in all the designs. I’m working on a 16/1 two stage planetary gearbox that is 50mm in diameter and about 30mm long. It currently utilizes one 608zz bearing, eight short pieces of 1/4" aluminium, and a 5/16 threaded rod output shaft. I opened this thread for suggestions, requests, questions, and general criticism:] .
The biggest problem with using these motors is the placement of the electrical connectors rather close to the output shaft. You probably already have something in mind, but if the gearbox extended or redirected these connectors so that either spade lugs or screw down lugs could be used, these things could be powering hundreds of active pickups and other small tasks typically done today with a PG27.
You might also consider finding a manufacturer who would build these things for sale, giving the team a royalty. This way, teams without 3D printers could utilize the design, and you would help your team financially in future years. It’s been done before, here are two examples:
IIRC planetary gearboxes are tricky to design. How about just a simple printable gearbox for like a 1:10 or 1:5 reduction? I could go for that.
It would be nice if there was a COTS solution for those motors. I’ve yet to see one actually used on a robot in person. A gear box for them would preferably use the included gear. I’m a bit surprised that VEX hasn’t made a plate to adapt them to the VersaPlanetary. There are certainly thousands of them out there sitting around especially since there were 8 in this year’s KOP.
What is the benefit of these motors? Yes, they are free in that they come in the kit but when it comes to value for a FIRST Team, I recommend Banebot 775 with a Versaplanetary with a 1/2" hex output. The Banebot provides up to 270W of Mechanical Power. The Versaplanetary’s hex output shaft is SO easy to use. It also lets you be “wrong late” in that you can discover that you need more or less ratio and just swap out gearsets to achieve your goal*.
Yes, the Throttle Motors are a little lighter but I just don’t see any reason** to use them when there are so many better solutions available.
Dr. Joe J.
*Case in Point: After Week 1, Overclocked decided our lift was too slow. We had a 120:1 ratio in Nashua. Last night we used 10 minutes of our unbag time to go to 48:1 and bang zoom! we’ll be stacking 50% more totes in Week 2 with a faster lift. We have 14 Banebot motors on our robot this year. 11 of them are connected to Versaplanetaries (the other 3 are driving our Wild Swerve modules via CIM-iles).
**I know that many teams are cost sensitive, but honestly, it is a false economy not to spend money on motors and gearboxes. Teams would be wells served to find the money to make their motor/gearbox solutions robust. FIRST is not a cheap activity. In the total scheme of things, having powerful, robust drive solutions (drive meaning more than just wheels) is the right place to spend your robotic dollars.
P.S. I have no financial interest in any of the products I have discussed. JJ
Also, while I understand that herringbone gears work well for softer materials like 3-d printing stock, it would be best if you utilized the COTS pinion; it would simplify installation to a screwdriver job.
You could do both, by having your sun gear or reduction pinion have an extension which fits over the TMs pinion like a spline, rather than (as I was first thinking, maybe you weren’t) having to pull one pinion and press the other. This would also help move the gears away from the electrical contacts.
Not everything needs as much power as a 775. Granted this season motors other than CIMS are unlimited but I don’t know how long that will last. In some ways I liked the restrictions on each style of motor because it increases the challenge since you need to choose which applications require the greater power motors and which applications can be done with the lower power motors. On the other hand I do like that you can essentially standardize on one style/model of motor for everything that you are not using a CIM for.
I am a big fan of the Versa Planetary and the quickness with which you can change the ratio, the choice of motor, or even double up on the motor with the new dual input. So the ultimate to me would be a kit to mount the throttle motor to the Versa Planetary or another planetary that had the ability to swap ratios and add reduction stages like the Versa Planetary. I also prefer the 1/2" hex output version of the Versa Planetary.
All that said teams have at least 8 of the throttle motors and for some with tight budgets a reasonable cost COTS solution to actually use them would be very welcome.
I agree. We need some gearboxes for these things. More motor and gearbox options can’t hurt teams, it can only help. Inspiration comes in a lot of different forms and not every operation needs a 200+ watt motor behind it.
The 775 from Andymark, or the 12V banebots 775 fill the lower power role better (as they mount to COTS items).
Don’t see any point to chasing down an option for the throttle motors.
Near the end of the fall, one of our students designed an adapter that could be used to connect these gear boxes to the landmark planetary gearboxes. We never ended up printing it out to test, but maybe we should now that we have some spare time…
Motors lose their lives in strange and unimaginable ways* because of which, I insist that our team have several spares of each motor on the robot. Having 14 of the exact same motor is a huge benefit in terms of managing our spare parts inventory.
As to not needing 270W of mechanical power, of course that is true for nearly all of the 14 motors**. But there is little to be gained by using lower power motor like the Andymark 775, which has 1/7th the peak power yet has the same form factor & weighs almost the same.
Also, just because it is a 270W peak power motor, that doesn’t mean that it HAS to be providing that much power. We can give it less voltage or even if we give it full voltage, it may be working near free speed which means that it is providing very little power.
I WOULD like to have the access to those sexy seven pole AndyMark 775 Hall Encoder*** but the ability to have common motors trumped my desire to have this very nice encoder option.
As usual, YMMV.
Dr. Joe J.
*The link is to one of my favorite poems which is not about motors at all. For a real motor death reference, look no further than Overclocked’s first match at the Granite State District last week – they almost took a fire extinguisher to our smoking drive motor. In all our practice and in all our subsequent matches, we never had another motor problem. But for a time, I was deathly afraid that I didn’t have enough stock of the 775 motors.
**We have counterbalance designed into the lift and all 3 joints of our “Standard Three Joint Arm” which basically means that these motors are used to overcome friction and to accel/decel. Other than that they are just hang out. Our lift and arm motors essentially don’t even get warm.
***Banebots, you should offer a long rear shaft options next year and perhaps your own Hall Encoder, yes?
The mane reason for herringbone gears is that the whole stage assembly is pre-assembled and doesn’t come apart.
Yes, they are a bit tricky. I will explain in my next post why I am going this rout.
This was exactly what I was going to do.
Okay so I am going to throw my $0.02 into this. Who cares about the practicality or the possible future uses of this gearbox, for this motor. A student saw a problem and would like to solve it to see if it can be done, period. Who knows what it could lead too and who it could inspire. Practical or not we should not be discouraging students on what could be a very interesting project. I would kill for kids who want to do stuff like this on my team. Again that is just my $0.02
My local high school team (5464) has 3 members that used to be on my team (3840). They won the rookie award but came in 56th place out of 59. I don’t want to see them get crushed at Einstein, just creamed. They want to put wheels on their intake but they are a rookie team and don’t have anymore motors besides the throttle motors. Given the incredibly high cost of going to internationals, they don’t have any spare money. I calculated that the throttle motors, once gear reduced, should have enough torque to suck in totes. Thanks for the input everyone.
Here is the first part: http://www.thingiverse.com/thing:710907
Looks good so far. How is that mounted?
I haven’t decided yet.
Given that the PDP only has 16 spots for motors, I assume you are using 3 CIMs or MiniCIMs as drive motors, R42 limits you to 1 motor per speed controller, how are you using 17+ high power motors in 16 PDP spots?
I’d also love to hear what each motor is powering, sounds like a complicated robot.