I wasn’t quite sure where to post this, “Uncategorized” seems as good as any. I’m working on a simple project to get familiar with the new machine and software. I needed to drill some shallow 1/4 inch holes for some joinery dowels. I knew that I didn’t have a CNC drill bit, but not to sweat, it should take a regular 1/4 inch twist drill bit in the 1/4 inch arbor, right? Wrong! I tried many different plunge rates and bit speeds, and the holes turned out oversize every time. The same bit in my drill press makes perfect holes. What am I missing?
I wound up pocketing the holes with a 1/8 inch router bit, worked a treat, VERY precise. I’m SUPER impressed with the new machine! Light years ahead of what I had before. ~Mike
I’d say there are a few areas to look at, first what RPM were you using? Twist drills aren’t usually balanced/straight enough where you can spin them at 10,000 RPM and not have wobble and therefore runout.
Second, what operation were you using to drill the holes? Are you using a drilling cycle which pecks and lifts the chips out every 1/4-1/2"?
I frequently drill holes when they’re smaller than 3/16" larger holes I can employ a 1/8" endmill, as you stated, this operation of ‘boring’ a hole will produce an accurate hole. Smaller than 3/16" I’ll usually use a drill bit at 1800 RPM or so with a peck style drill operation to clear the chips out. I normally don’t drill deeper than 1.5 inches for most of my operations.
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