[nathan]

I have heard a phrase when using a mill or drill press called "reading the chips." Can anyone give me a source on how to do this? I'll be using my big new drill press for some bolt holes on an upcoming job, and I'd like to know what I'm doing lol
I have used a drill press before, but never had 16 speeds to choose from and never had my own semi-perfectionist ego to please. I have plenty of scrap to practice and learn and play.

[AdVirMachina]

When you hit the sweet combination of speed and feed, the chips will come out as a long spiral on most materials. Iron comes out as short curls. If you aren't getting a spiral, you have start with drill speed. Bigger bits have to turn slower or they don't cut. You just soften the tip. If the speed seems right, slowly increase the feed (How hard you press). If neither has any effect, your bit is usually dull.

Irving, TX. Epicenter of the Metroplex!

[AdVirMachina]

On a mill with a milling cutter, you are looking for dark blue chips shaped like a 9. That's right at the point of the mill/tool's capabilities.

Irving, TX. Epicenter of the Metroplex!

[Arno]

Marc L'Ecuyer does some great machining background and 'howtos' on his Youtube channel: https://www.youtube.com/user/THATLAZYMACHINIST

Specifically some on drills: https://www.youtube.com/watch?v=UO_B78jUoII

But he also has made video's on chips and how to read them.. Eg. optimum color also depends on the type of tool used.

BYe, Arno.

[nathan]

AVM, howdy. Thanks for the info. I see you're in Irving. I run my little shop out of my garage in Sanger, just north of Denton.

Arno, that guy is awesome. I had no idea there was so much science and physics in drilling and machining. This is very interesting. I am going to start investing in good drill bits, as I have cheap one that came in sets from various places. The quality of your bit seems to have a big effect on your hole quality. I never had to think about that yet, as most of my personal bits have been for drywall. Do you have any recommendations for places to get quality bits?

[Arno]

As you're in the US I guess something like McMaster-Carr is a good option to get some decent quality ones:

http://www.mcmaster.com/#standard-drill-bits/=yf2bfv

Otherwise a regular builder's supply shop who has metal-drills will do as well. They usually only have HSS drills which are fine for plain steel but when used on stainless tend to wear out fast. Cobalt alloyed drills usually last longer on stainless. Some decent drill sets and some cutting oil (esp. when using cobalt bits that's pretty much required) should last you a long time when they are treated properly.

Bye, Arno.

[AndersK]

I too preffer the cobalt bits.
Dont go for carbide if you dont have a stable mill. They will shatter if used in a cheap drill press.

[AdVirMachina]

I live in Irving, but I do have a shop in Keller.

Irving, TX. Epicenter of the Metroplex!

[nathan]

I live in Irving, but I do have a shop in Keller.

Irving, TX. Epicenter of the Metroplex!

Cool! We just moved from Euless to Sanger in the spring.

I've found that all my drill bits are crap. Most of them are brand new, and none of them are sharp. I will be going and getting drill bits for specific jobs as I need them.

[noddybrian]

Back when we were in school there was a general rule for R.P.M on lathes / drills based on cutting speed in meter / min for HSS tools - it's still a good starting point if you don't have experience - I'm sure there are online charts giving similar guidelines much like the Miller weld calculator - maybe a member here already found one.

so spindle speed R.P.M is cutting speed for material in meters/min * 1000 / work diameter in mm * Pi.

ballpark cutting speed for low strength steels 20 > 30 M/min.

Hope this helps.