Society of Robots - Robot Forum

General Misc => Misc => Topic started by: GeorgeBA13 on March 10, 2012, 02:41:02 PM

Title: How to extend a drill motor?
Post by: GeorgeBA13 on March 10, 2012, 02:41:02 PM

Hello Everybody!

Sorry I just wanted to try that effect.
Anyways, I am trying to build a combat robot and I am going to use two drill motors. But I have found that the spinny bit on the end of the motor is too short to add a sprocket so I can add a chain to connect the wheels. How can I extend this. (sorry for the lack of technical vocab!)

George

Title: Re: How to extend a drill motor?
Post by: Soeren on March 10, 2012, 03:30:37 PM

Hi,

Quote from: GeorgeBA13 on March 10, 2012, 02:41:02 PM

[...] But I have found that the spinny bit on the end of the motor is too short to add a sprocket so I can add a chain to connect the wheels. How can I extend this. (sorry for the lack of technical vocab!)

Mount an axle coupler (http://www.servocity.com/html/set_screw_shaft_couplers.html) on the "spinny bit" (using the included lock screws) and either put the sprocket on the coupler or connect another axle to the coupler.

Use bearings or bushings (http://www.servocity.com/html/bearings___bushings.html) for this extra axle if you want to make it strong.

Title: Re: How to extend a drill motor?
Post by: GeorgeBA13 on March 11, 2012, 08:58:49 AM

Great, thanks!

Sorry about all the questions through this last week but have one LAST question:
 I was wondering if I wanted to build a robot with a spinning disk do I want a motor with a lot of torque or hi RPM?

Thanks

Title: Re: How to extend a drill motor?
Post by: Soeren on March 11, 2012, 01:13:55 PM

Hi,

Quote from: GeorgeBA13 on March 11, 2012, 08:58:49 AM

[...] have one LAST question:

I'm a bit sceptical here ;)

Quote from: GeorgeBA13 on March 11, 2012, 08:58:49 AM

I was wondering if I wanted to build a robot with a spinning disk do I want a motor with a lot of torque or hi RPM?

That depends on several factors.
High RPM is good (up to a point) for wreaking carnage, but the faster you want it, the more important the balancing and strong perfect bearings becomes.

The damage you can do with a given shape of disc depends on its speed and weight (inertia).
How fast you get it up to those RPMs (after an attack that slows it down or stops it completely) depends on the torque of the motor.

So, you need to consider how heavy you want the disc. Calculate how much speed is needed to reach a certain inertia (then you know the needed RPM) and then decide how fast you want it to be ready again and calculate the torque needed.

Don't forget Google :)

Title: Re: How to extend a drill motor?
Post by: GeorgeBA13 on March 12, 2012, 11:17:43 AM

Thanks,
I had checked google but I couldn't find anything.

I know I said that was the last question but as you predicted I have one more.

I was looking around at combat robots and thought that a honda lawnmower engine to power a metal bar would be really cool. But people say this is not for beginners. I was thinking that this is pretty simple isn't it? You just need a servo to pull the accelerator chain. Is this a good option?

Thanks

Title: Re: How to extend a drill motor?
Post by: newInRobotics on March 12, 2012, 02:49:27 PM

Quote from: GeorgeBA13 on March 12, 2012, 11:17:43 AM

I was looking around at combat robots and thought that a honda lawnmower engine to power a metal bar would be really cool. But people say this is not for beginners. I was thinking that this is pretty simple isn't it? You just need a servo to pull the accelerator chain. Is this a good option?

Did You consider what would You do when motor gets stalled? Have You considered how would You start the motor? Have You considered how would You actuate clutch?

Title: Re: How to extend a drill motor?
Post by: GeorgeBA13 on March 12, 2012, 05:02:50 PM

As a experienced karter I know that these motors rarely stall. I would start it before the start by hand. There is no clutch on a GX 5.5hp engine.   
 :D