Re: Z-Axis Knee Woes

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dan Mauch" <dmauch@s...>
wrote:

> I have one of those 600 oz in motors on my 8X36 knee mill. I am

using a

> 2.5/1 ratio timing pulley. I would recommend a 3/1 ratio. I can

raise

> and lower my knee with a #105 mill vice on it all day long without

the

> motor getting warm and at good speed. The G320's never fault except

when

> I run the knee into the stops. (AAAARRRGGGHH I hate it when I do

that)

> The trick is make sure you have a 3/1 and I also put a lower encoder
> count onto that motor so that I would not have a larger count on

the Z

> axis. I ended up using a 60X037 pulley on the handshaft and a

24XL037

> pulley on the motor. These are not that expensive! But I would

recommend

> a full 3/1 ratio and possibly a 4/1.
> Dan
>
>
>
> -----Original Message-----
> From: jbordens <jake@a...> [mailto:jake@a...]
> Sent: Monday, January 13, 2003 4:59 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> 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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