Re: [CAD_CAM_EDM_DRO] Z-Axis Knee Woes

Hi, several on this list have used gas struts to help balance up the knee
weight. take a look in the files. cul brian f.

----- Original Message -----
From: <jake@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, January 13, 2003 7:58 PM
Subject: [CAD_CAM_EDM_DRO] Z-Axis Knee Woes


> Hi folks. I'm retrofitting a G3102 Grizzly Knee Mill, a smaller type
> mill somewhere bigger than a drill mill, but smaller than a full
> bridgeport.
>
> I just finished my Z-axis, after success with X and Y. I decided to
> motorize the knee for various reasons. I'm using Camtronics 600-in-oz
> motors and a 2:1 ratio on the pulleys.
>
> The knee is driven by a shaft that is at 90-degrees to a jackscrew.
> The shaft is connected to the jackscrew via a set of helical spur gears.
>
> Here are my problems:
>
> (1) the motors aren't powerful enough, apparently, to raise the knee.
> They stall and eventually cause my geckos to fault. I'm pretty sure
> I have the "limit" set to Max on the geckos.
>
> (2) when lowering the knee, the motor turns and every now again
> there's a 'thump' from the mill, as if the knee is not lowering
> smoothly, but in little increments.
>
>
> I guess I have two options:
>
> (a) go to a higher ratio, but 2:1 was the most practical. 3:1 is
> possible but expensive, and anything more is really not possible due
> to pulley size constraints.
>
> (b) counterweight the knee. I think this is complicated and probably
> not a good idea.
>
> In either case I'm not sure it would solve problem #2. I'm currently
> at a loss on how to proceed. Any suggestions are greatly apprecaited.
>
> Thanks,
> Jake
>
>
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