Minibot motors

[baroneje]

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

[Ether]

Originally Posted by baroneje

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

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

[Colin P]

Originally Posted by Ether

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

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?

[baroneje]

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.

[Al Skierkiewicz]

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.

[Dad1279]

Originally Posted by Ether

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

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

[Dad1279]

Originally Posted by Colin P

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?

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

[Ether]

Originally Posted by Colin P

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

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

[sanddrag]

Originally Posted by Ether

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

http://www.chiefdelphi.com/forums/sh...8&postcount=15

[DonRotolo]

Originally Posted by baroneje

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

Back to the original request now:

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

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.

[Ether]

Originally Posted by sanddrag

http://www.chiefdelphi.com/forums/sh...8&postcount=15

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.

[Chris is me]

Originally Posted by Ether

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.

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

[JB987]

Originally Posted by Dad1279

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

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.

[WileyB-J]

Originally Posted by JB987

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.

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

[EricH]

Originally Posted by WileyB-J

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

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