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Author Topic: Pecking  (Read 2940 times)

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Offline Keith

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Pecking
« on: January 13, 2015, 05:56:06 PM »
I'm having a bit of a problem peck milling. I've had recent success with some relatively larger hole. This time around, I'm drilling down .375" into a .0555 diameter piece of polycarbonate with a .031" drill (of high quality). I'm using the longer retract method. The hole comes through okay (the fixturing is a bear) but the inside walls seem to have a spiral cut into them looking a lot like the spiral of the drill bit (but probably just an artifact of whatever is not right).
Any suggestions are appreciated. I read some where this might be an anomaly of not enough dwell at the end of a peck and then rapid-ing above the last height.-Keith
Re: Pecking
« Reply #1 on: January 13, 2015, 07:01:51 PM »
I would think this happens because one flute of the drill is dragging on the way out.  Maybe the spindle isn't perfectly square to the Z axis.

Offline BR549

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Re: Pecking
« Reply #2 on: January 13, 2015, 07:16:57 PM »
What RPM are you drilling at ?  A drill that small needs to be zinging along RPM wise to cut smooth.

Just a thought, (;-) TP

Offline Keith

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Re: Pecking
« Reply #3 on: January 13, 2015, 08:59:39 PM »
I was going quite slowly because I thought a high speed would melt the polycarbonate. So then what about a 'feed' on this; fast as well?

Offline BR549

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Re: Pecking
« Reply #4 on: January 13, 2015, 10:20:04 PM »
This may help

« Last Edit: January 13, 2015, 10:23:34 PM by BR549 »

Offline Keith

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Re: Pecking
« Reply #5 on: January 14, 2015, 08:46:17 AM »
Thanks, that 'puts a face on' what I was missing. I'll experiment with these ideas.-Keith

Offline Tweakie.CNC

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Re: Pecking
« Reply #6 on: January 15, 2015, 07:50:19 AM »
Thanks for the PDF link Terry - I have just learnt things I did not know about drilling acrylic.

Tweakie.
PEACE