35326Re: [MILL_DRILL] how to drill deep holes
- Feb 2, 2014I've been lucky so far with metals, and haven't needed to drill anything really deep, but years ago I needed to drill some very long holes in oak. I have a 3/8"x about 18" brace bit, but needed either 1/4" or 3/16" (I forget which). I ended up welding a bit to a piece of random rod. It worked, but took a long time to drill. The rod twisted a lot, and it was hard to "feel" the bit because of all the friction.-Dave
From: Rgsparber <rgsparber@...>
To: "MILL_DRILL@yahoogroups.com" <MILL_DRILL@yahoogroups.com>
Sent: Sunday, February 2, 2014 10:34 AM
Subject: Re: [MILL_DRILL] how to drill deep holes
This is turning into a rather useful collection of pointers. Maybe I'll turn it into an article with a rather large Acknowledgement section.Keep those ideas coming!
On Feb 2, 2014, at 10:35 AM, Bill <bill_1955@...> wrote:I drill a lot of long holes for grease passages in cylinder pins.Start with a spotter, then a jobber length, and then to a 6” or 8”, sometimes a 12”. About all the long holes I do are 3/16” in diameter. A few are 1/8”, but are 3” L or less. Pins are 4140/4142 Q&T.The deeper you get, the more you need to pull the bit out, clean the chips, and give it another shot of lube.The hole in the long pins in the pic are about 5-1/2̶ 1; L. I always take a peak in the cross drilled hole when I’m done, to see if I wandered at all. I have had that happen a bit a few times, nothing extreme, but it’s always caused by a dull bit, not cleaning the flutes often enough, and/or being in a hurry and crowding the bit. Best to take one’s time…..JBillWith peck drilling on a lathe I've gone beyond the flutes with just a
bit of the shank in the tailstock chuck.
On 02/02/2014 04:55 AM, lists wrote:
> That is the normal procedure. When you've used your "long" bit you move to
> the "extra long" series.
> Interestingly, anything deeper than three times the drill diameter is
> considered a "deep" hole", though I th ink most of us would cheerfully
> drill almost to full flute depth without much thought.
Jerry Durand, Durand Interstellar, Inc. www.interstellar.com
tel: +1 408 356-3886, USA toll free: 1 866 356-3886
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