Re: Z-Axis problem - Not Enough Torque?

I did something similar, using a short section of 4" PVC
with two end caps with an eye bolt through one of the caps.
I filled it with big chunks of scrap steel til it was close
then "fine tuned" it with a box of b.b.'s from walmart.
I painted it to match then it did'nt look so bad.

John


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Jim Fleig - CNC Services"
<jim@...> wrote:

>
> To couterweight the head, lead shot and hot melt glue work well.

Believe it or not, on a large bed mill I was troubleshooting for
mispositioning in the Z axis I discovered the counterweight was not
heavy enough. I built a sheet metal box on top of the existing
counterweight, sealed the bottom with hotmelt glue, put in a layer of
lead shot, some glue to keep it from shifting, more shot and more glue
while watching the current draw on the motor in both directions. When
the current draw was almost equal (slightly heavier to the head to aid
in drilling on this mill) I was finished. Z mispositioning went away
and as far as I know the mill has run well since.

>
> 2 cents for what its worth,
>
> Jim
>
> ----- Original Message -----
> From: WT
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Sent: Thursday, November 09, 2006 6:11 AM
> Subject: Re: [CAD_CAM_EDM_DRO] Re: Z-Axis problem - Not Enough Torque?
>
>
> Hi, Chris.
>
> 1. I noticed a lot of advise from others regarding counterweighing the
> Z-axis head as well. Maybe I am missing something here. Is it a

must or a

> better solution to do a Z-axis by counterweighing? Kindly look at

my earlier

> post reply to "Brian Worth" regarding this.
>
> 2. Timing belt/pulley reduction may be the first thing I will try.
>
> Talking of pulley, can someone point me to a web resource where I

can get

> the DXF or SolidWorks file for an XL timing pulley for CNC GCodes
> generation?
>
> Thanks,
> WT
>
> ----- Original Message -----
> From: Chris Horne
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Sent: Thursday, November 09, 2006 7:28 AM
> Subject: [CAD_CAM_EDM_DRO] Re: Z-Axis problem - Not Enough Torque?
>
> In your shoes I would try the following in this order.
>
> 1. Counterweight the head with a weight, steel cable and a couple of
> pulleys. Make the counterweight greater in weight than the head.
> The exact amount more than the weight of the head you can find by
> experimentation, but at some point it will take up the backlash on the
> leadscrew, killing two birds with one stone...
>
> 2. Toothed belt drive reduction on the 'Z'.. most of the time you
> will hardly notice the reduction in speed..
>
> I can't stress enough that the counterweight actually works... and it
> is also probably the most effective, easiest and cheapest option.
>
> Chris
>
>
>
>
>
> [Non-text portions of this message have been removed]
>