Minibot motors
 

Does anyone know how to attach an 3in. long axle directly to the tetrix motor, no gearbox at all?

Re: Minibot motors
 

Is it legal to remove the gearbox from the P/N 739023 Tetrix motor, and use the motor (without the gearbox) on the MINIBOT ?

Re: Minibot motors
 

Yes, that's pretty much the only way to get up in less than 3 seconds.


I saw a team put shaft collars onto the remaining gear and then tinker around with that, but it kills the gear.

PVC and (lots of) PVC cement?

Re: Minibot motors
 

It doesn't say you can't. I saw team 16, 148, and 118 at the Alamo regional with these modified motors and the officials didn't say anything.

Re: Minibot motors
 

Ether,
It is legal to remove the gearbox and use the Tetrix motor alone.
From the Q&A...

Tetrix Motor/Gearbox
Posted by 2011FRC2775 at 01/13/2011 05:10:19 pm
In regards to to R47 and R93 Is the Gearbox on the Tetrix motor considered to be integral to the motor? Can the gearbox be removed and/or modified as long as the motor itself is not changed.

Posted by GDC at 01/16/2011 11:47:05 am
No, the gearbox is not considered integral to the motor. Yes, the gearbox may be removed and modified.

Re: Minibot motors
 

Modify Gearbox: http://forums.usfirst.org/showthread.php?t=16779
Remove Gearbx: http://forums.usfirst.org/showthread.php?t=16187

Re: Minibot motors
 

Off the shelf collars would not be legal. We made them by machining a bolt.

Re: Minibot motors
 

Does anybody have a link to the motor curves of the motor without the gearbox?

Re: Minibot motors
 

Re: Minibot motors
 

Back to the original request now:

Yes, we do. I suppose you want us to tell you?:p

Here is an example, you can experiment from here:
Take a Tetrix metal shaft. Carefully drill a hole with a #40 drill bit into the very center of one end. Press this onto the motor shaft carefully, to avoid damage to the motor (meaning: Hammering is bad).

Some tips:
Hot metal expands, which may make an interference fit easier to assemble.
Long shafts under radial load must be supported at the far end.
Latex tubing is not very abrasion-resistant.
Rubbing alcohol makes a fine lubricant for assembling rubber onto metal.

Good luck.

Re: Minibot motors
 

Thanks. I just found this, which has speed and current in addition to power and efficiency.

The gear ratio is 52:1, so the motor free speed is something >8000 rpm.

Re: Minibot motors
 

Do keep in mind the motor gearbox is almost laughably inefficient (hovering around 50%)

Re: Minibot motors
 

R92, S. Indicates "mechanical fasteners" are allowed. A shaft coupler/collar mechanically fastens two shafts together...there were several examples of minibots that passed inspection with such couplers/collars this weekend.

Re: Minibot motors
 

Pretty sure they changed that to "mechanical hardware" in an early update, might wanna check the current version manual.

Re: Minibot motors
 

Nope, they changed it from "mechanical hardware" because all sorts of people were getting confused. It reads "mechanical fasteners".