Re: [CAD_CAM_EDM_DRO] Climb milling was feeds and speeds.

Hello Woody Woodpecker,
Here the response why you were told never to climb mill:
In one occasion I nearly paid it with my life!
When You climb mill the cutting edge of the mill tends to pull in the material.
So when there is backlash in the machines lead screw it can overcome the friction of the table and suck it in. The next cutting edge
will have to cut a cut of the full backlash distance. Sometimes it may pull out even the work peace out of the vice.
On good quality conventional mills in the 60's and 70's there you could find a knob to catch up the backlash so you could climb
mill. Since on CNC mills ball screws are used they are more suitable for climb milling.

Ok the incident I mentioned above was like this. I had to mill deep steps into a lot of 6 mm plates (15 pieces packed together) and
made it with a 3" semi roughing shell mill. I wasn't used to that mill and the backlash was about 0,5 mm. I took of
wiping back and forth 2,5" by 5/8" deep. In one moment while I checked the adjustment above my head it said bang. The pieces flew
through the whole shop!
The rest of that day I felt like I would have had 5 gallons of coffee!
Since then I never use a machine of somebody else in automatic feeding, always only with hand feed. And I am very jealous with the
fixtures.

Climb milling indeed is not that bad as long you take care of the machine not to permit jumps or pull out the work piece. It
specially is very useful for finishing and on aluminium.
Good Luck
Sven Peter

Woody wrote:

> Jon Elson Wrote:
>
> >
> > You can't climb mill safely on machines with sloppy leadscrews.
> >
> OK. This is something I was taught in High School (ok I was taught
> NEVER to climb mill)
> But nobody ever told me WHY. I THINK I can understand the change in
> forces in the system but not exactly how they relate to a sloppy leadscrew
> and why a tight ballscrew is OK.
>
> Yeah, I know, dumb question. But still...
>
> -G
>
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