Denso motor Lead Gear specs?

[billbo911]

I am wondering if anyone has already determined the specifications for the Lead Gear in the Left or Right Denso Window motors. Specifically, I am looking for: pitch, angle and possibly the number of teeth.

"Why" you might ask?

If my insanity hasn't taken over, I am hoping to have the lead gear drive an encoder pot through a small hole or slot in the side of the frame of the gear assembly.

[Joe Johnson]

Originally Posted by billbo911

I am wondering if anyone has already determined the specifications for the Lead Gear in the Left or Right Denso Window motors. Specifically, I am looking for: pitch, angle and possibly the number of teeth.

"Why" you might ask?

If my insanity hasn't taken over, I am hoping to have the lead gear drive an encoder pot through a small hole or slot in the side of the frame of the gear assembly.

I can't answer your question directly, but I think that even your modification to allow a gear to mate with this worm or wormgear would illegal. I don't have chapter and verse in my hand, but I am pretty sure this would be an illegal modification to a motor. Motors are pretty tricky. Only things that are explicitly allowed are legal. I don't think this type of modification is specifically allowed.

As to your question. The worm and worm gear are designed to mate together and are not likely to be a easily matched by an "off the shelf" type standard pitch gear. The reason is complex but basically, they have to trade off a lot of things in a worm/wormgear design (tooth thicknesses, helix angle, center distance, etc.) Since the parts are no longer cut from standard hobs, there is no reason to stick to a standard pitch (even in the plane of the cutter -- the so called normal plane), standard pitches are almost always a last priority.

Joe J.

[Andy A.]

<R36><R36> So that every robot’s maximum power level is the same, the motors in the kit may not be modified in any
way, except as follows:
• The mounting brackets and/or output shaft/interface of the motors may be modified to facilitate the
physical connection of the motor to the robot and actuated part.
• The gearboxes for the Fisher-Price, and Globe motors are not considered “integral” and may be separated
from the motors. FIRST will not provide replacements for parts that fail due to modification.
• The electrical input leads on the motors may be trimmed to length as necessary.
The intent is to allow teams to modify mounting tabs and the like, not to gain a weight reduction by
potentially compromising the structural integrity of any motor. The integral mechanical and electrical system
of the motor is not to be modified.

I read this as ruling that no, you may not modify the window motor in this way. The modification you propose would go beyond "facilitating the
physical connection of the motor to the robot and actuated part".

Although, I had to play around with the Window motor last night, and I can't see why the gearbox is considered integral this year. It connects with 3 screws, and thats it. The output shaft of the motor is a little (really little!) shaft with two flats on it. There is a funky radiation symbol type dog and adapter that connects the gearbox and motor, but certainly nothing more integral then the Globe or FP setups. While I don't see many teams using the window motor alone, there is plenty of room for modifying that gearbox if it where legal.

I don't have an older window motor to compare to the new ones, but perhaps they where integral in previous years (like the van door motor), and have changed this year?

The key here is as Dr. Joe said- It's not explicitly allowed, so it ain't legal when it comes to motors.

-Andy A.

[billbo911]

Andy and Joe,
Thanks for your complete and detailed responses. I have to admit, all of your details have gone through my mind in the last 48 hours. I fully agree that the gear box is not an integral part of the motor, but a rule is a rule and we comply with the rules.
So, that being said, now I have to find a way to encode the azimuth of our turret. Without revealing too many secrets (Just kidding) I am currently baffled as to how to do it. We have no external ring gears to connect to. No central shaft exposed enough to tie into and the only point where the turret pivots around is in a location where a pot connected to it would not be able to be held to a reference point. Oh well, this isn't the biggest obstacle we have had to overcome.

Thanks again!!

[Joe Johnson]

Originally Posted by billbo911

Andy and Joe,
Thanks for your complete and detailed responses. I have to admit, all of your details have gone through my mind in the last 48 hours. I fully agree that the gear box is not an integral part of the motor, but a rule is a rule and we comply with the rules.
So, that being said, now I have to find a way to encode the azimuth of our turret. Without revealing too many secrets (Just kidding) I am currently baffled as to how to do it. We have no external ring gears to connect to. No central shaft exposed enough to tie into and the only point where the turret pivots around is in a location where a pot connected to it would not be able to be held to a reference point. Oh well, this isn't the biggest obstacle we have had to overcome.

Thanks again!!

Have you considered a string pot?



I have not used them but Delphi's test lab swears by them.

I also don't know if you can find a cheap one. But, if you could use one, you'd have a 1 to 1 mapping of azimuth angle and pot output. You could use a lookup table to linearize and/or convert back to true azimuth angle.

Here are some more pictures. Anybody have success with these products?

Begin Edit:
Lets take the conversation about strinp pots to a new thread: String Pots: Good, Bad or Mixed Bag?

Feel free to continue to discuss the Denso motor modes but take any string pot discussion to the other thread. Thanks JJ
End Edit

Joe J.

[billbo911]

Originally Posted by Joe Johnson

Have you considered a string pot?



I have not used them but Delphi's test lab swears by them.

I also don't know if you can find a cheap one. But, if you could use one, you'd have a 1 to 1 mapping of azimuth angle and pot output. You could use a lookup table to linearize and/or convert back to true azimuth angle.

Joe J.

Wow, what a cool idea. I'll keep that in mind for future designs.

Honestly, shortly after I publicly announced my inability to figure out a way to encode it, I had a Brain Flash. All I had to do was look at it upside down. Now I know exactly how I'm going to pull it off. It will be very simple to do, easy to calibrate, and quick to replace should something go wrong.

I would love to show you, but that would require you to come to the Davis/Sacramento Regional, either that or we make it to Atlanta. Hope we see you there!!!!!!