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CNC Drilling

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LotsaChips

Iron
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Mar 22, 2017
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#1
I have an Industrial Hobbies CNC mill. Just recently I needed to drill several 7/32 holes in 1020 steel. I
ran it at 1600 rpm with 3 ipm speed, with a stub drill bit in a keyless chuck. I like the keyless chuck because my stub drill bits bottom out in the chuck, maintaining my tool offsets. I manually tightened the bit as hard as I could. In the first hole at about 3/16 deep, my drill bit stopped rotating, slipping in the chuck. Needless to say, I hit the E-Stop button real fast.

Just thought I would see if anyone on this forum has experienced this problem before and what might have caused the slippage.
 

mikey

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#2
What brand of chuck do you have? If it was an Albecht, there is oil on the threads of the spindle so it cannot resist the cutting forces and the drill will slip.
 

LotsaChips

Iron
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#3
What brand of chuck do you have? If it was an Albecht, there is oil on the threads of the spindle so it cannot resist the cutting forces and the drill will slip.
Thank you! I think I will chalk this up to dane bramage! I have always used mist coolant when drilling holes, especially in steel. This time, for whatever reason, I just sprayed some WD40 on the bit, something I have never done before.....viola, instant slip of the drill bit.
 

TomS

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#4
I've had the same problem with my keyless chucks. One is an Albrecht and the other two are cheapo imports. For spot drilling the keyless chucks work fine. For hole drilling I use a keyed chuck and have had no slipping problems.

Tom S.
 

mikey

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#5
I've had the same problem with my keyless chucks. One is an Albrecht and the other two are cheapo imports. For spot drilling the keyless chucks work fine. For hole drilling I use a keyed chuck and have had no slipping problems.

Tom S.
Funny you mentioned this. I never get slippage with my Albrechts but junk keyed chucks slip for me. It led me to buying a Jacobs Super Chuck at retail price - that sucker don't slip!
 

cmantunes

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#6
I have a keyless chuck from Shars that exhibits the exact same problem. I ended buying a hook spanner wrench (the chuck has a hole for this purpose) and I am now able to torque the crap out of it: no more slippage. Of course, it totally defeats the purpose of the stupid chuck.
 

EmilioG

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#7
Albrecht recommends against bottoming out the drill bit. The Albrecht is designed to get tighter as it drills and keyless design
will pull the bit up and may get stuck. Leaving a few millimeters of space allows you to release the grip after drilling. A lot of ALbrecht owners have gotten their drill bits stuck in these tight gripping chucks. There is no need to crank down to initially hold the drill. I bottom out the drill then back it off slightly and never have a problem. I own 4 Albrechts.
 
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