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[DPRG] I bought the wrong gearmotors

Subject: [DPRG] I bought the wrong gearmotors
From: Kipton Moravec kip at kdream.com
Date: Sat Feb 26 06:57:39 CST 2005

In my opinion I would use them, and not send them back.  The extra
torque is probably better as opposed to being bad because you can
respond faster to small variations. And I doubt you will see the speed


On Fri, 2005-02-25 at 23:17 -0800, Rick Mann wrote:
> I have two shiny new Pittman GM8724S021-R1 60.5:1 12V gearmotors with 
> 500 CPR encoders. I bought them for a project similar to DPA's nBot. On 
> his website, he mentioned how he used similar 19.1 V motors. For a long 
> time I put off buying motors because of the price ($195 each), but I 
> finally decided to go for it.
> Unfortunately, I didn't check the specs carefully enough, and my output 
> shaft no-load speed is about 75 RPM, whereas nBot has more like 128.
> The worst part is that the distributor wants a 50% restocking fee.
> So, what are my options? A) I can sell them at a small discount to 
> someone on the list, and buy new ones. B) I was going to drive my 'bots 
> wheels with a timing belt & pulleys, so I can put a larger pulley on 
> the shaft and recover some of the speed (not sure what this does to the 
> efficiency). C) I can drive the motors at a higher voltage, but part of 
> the reason I wanted 12 V motors was to not have to have a higher source 
> of voltage, and I don't know what overdriving these will do.
> Any ideas? Anyone want a beautiful pair of motors (they're really quite 
> nice)?
> TIA,
Kipton Moravec <kip at kdream.com>

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