Re: [CAD_CAM_EDM_DRO] Re: What kind of motor should I use?

One of the fellows where I worked accidently flipped the switch on for a 3hp
Perske. What he forgot was, that he left a Dial Indicater and Flex Arm in the
chuck. As one could expect, the last rpm setting was sky high. The Dial came
off rather quickly, the arm was hanging for dear life. Vibration was felt
thruout the shop.

As I am on my knees crawling at the "below projectile zone" heading for the
Main Power Switch ( the guy that turned it on was no where to be found !),
one of the knuckle joints let go and launched itself across the room into the
vertical steel pole barn siding that lined the inside of the shop. The
5/8"-3/4" dent from the hit is clearly visable to this day !

That would be a shallow dent compared to flesh......

There are two glass windows on each side of the machine to keep it seperated
from other workers in the building and keep noise under control with the
ability to see what goes on. Those windows never looked as "safe" after that.
Should have wire reinforced glass at least.

So, watch your speeds, and keep a lookout on those dials when they are in the
chuck.

Centrifugally speaking, May the "force" work with you, not against you.

Chris L

Dan Mauch wrote:

> Good points and one other problem is most people don't consider when
> running spindles at much higher speeds than designed is the significant
> safety factor problem of running a large pulley that was designed to run
> at 1/4 that speed. Have you ever seen a 7"D pulley come apart? I would
> think the centrifugal forces would be enormous. I have not seen one do
> this either but would not want to be in the general area when it did
> come apart.
> Dan
>
> -----Original Message-----
> From: Peter Seddon [mailto:peter@...]
> Sent: Tuesday, February 05, 2002 2:14 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] Re: What kind of motor should I use?
>
> The thought of running a motor rated at 3000rev/min at 14,400rev/min is
> terrifying:
> 1. Bearing capability
> 2. Rotor integrity and possible bursting
> 3. Out of balance problems
> 4. Overal efficiency and heating problems
>
> Stick with motors designed for the task and go for longevity of your own
> life !!
>
> Regards Peter
>
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