Re: [CAD_CAM_EDM_DRO] Re: Z-Axis problem - Not Enough Torque?

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





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