Home Forums Hunting & Shooting Hunter's Campfire Drill Bits

Other than a little deburring, this one's done. I'll try a steady rest on the next one I do. I'm stuffing 40-something extra cubic inches into a stock-appearing 216 cubic inch engine that can't be identified as being different from an original from the outside. It's a "sleeper" hotrod engine for antique Chevy truck restorers.
Jerry

Listen to Ted.

Buy a drill point gauge and learn how to use it, and cut margins.

If you think you're feeding too hard, you're probably not. If you hear ANY high pitched noise STOP. Regrind and try again.

If you can get a good grind on marginal HSS bits and nail the feed and speed, you'll win. If you screw those up with quality bits....you'll lose.

I don't consider myself a machinist but I have done quite a bit of machining on lathes, drill presses and milling machines. I have machined mild steel, stainless steel, aluminum, delrin, pvc and several other materials. It seems to me when cutting something the last thing you want is lubrication. Cutting fluid is designed to cool the cutting tool not lubricate it. I have seen people use motor oil, WD40, grease and other lubricants when trying to cut metal. This seems counterproductive to me. The reason I bring this up is to emphasize you need to use a coolant designed for the material you are machining. Am I missing something here?

Good information here. Colbalt 8% min up to 12%. Good drills arent cheap! Industrial supply houses usually carry , or can get you good HSS jobber bits. Drilling isnt milling, cutting oil for drilling, coolent for milling is what i was taught. Im not a machinest! Just a lowly millwright! Carbide drill will also cut stainless well, but get you wallet out if going to buy carbide drill indexs!

That is complete BS. We hand drill C/T holes all the time!

Thanks Fellers.

The harder the material, the shallower the angle. Cobalt drills are generally preferred for stainless and have shallower angle.

Lubricity helps the chip flow over the cutting edge of the tool. It also helps prevent a built up edge just behind the cutting edge of the tool. Try single point threading stainless steel on a lathe using water for coolant and then use the dark resulfurized oil. You'll see how the chip tears and destroys the flank of the thread. Or you can try to machine aluminum without using lubricant. The endmill will become impacted with aluminum almost instantly.

Another thing, when we machined forged cranks we ran them separately from cast iron. A different grade of carbide inserts were used in the crankshaft lathes, setup men had to switch tooling for the changeover.

reading all this explains why i have a pile of useless bits and pieces of metal with shiny dimples. maybe i'll use some of my 'rona money to get a good set. designing my new shop and plan on getting a decent press for the first time in my life.

Thank you for that explanation.

Sharpening a drill is a muscle memory skill that is deeply embedded in my soul.

Over the course of the past 34 years I've probably ground away several feet worth of twist drills.

Stuff under .5 and I don't even get a gauge out of my box

Big stuff I use a point gauge if it isn't a clearance hole

My favorite tool to sharpen is a 6" belt sander

My favorite tool to split a point and or thin the web is by hand with a hard sharp 90º wheel on a surface grinder with the gaurd rotated up out of my way

I virtually never use lubricant when milling aluminum. Two flute endmills stay cooler and not as prone to load up as multi flute endmills,...so I only use 2 flute endmills on aluminum.

Also, I usually save .002" for a clean up cut then climb mill it off. In fact, that's a habit of mine with pretty much any material I mill. Climb milling the final .002" or so causes the endmill to throw the chip behind it instead of pushing them off in front of the flute,....turn the spindle speed up and creep across it slow,...leaves a very fine finish.

Drilling, reaming, and tapping is a different matter, however. Crisco is excellent for drilling, reaming, or tapping aluminum.

Some of the best drilling lube I've used is unsalted lard, with just enough 30 weight motor oil mixed in to make it easy to apply with a small fiber-bristle brush like sheet metal workers use for tinner's flux. When the bit warms up a little, it smells like bacon cooking!
Jerry

That will work on a Bridgeport...

Running a CNC mill I'm pushing 150~200 surface feet with a good cobalt four flute endmill at .02"~.024" per rev feed rate. That would be running a 1/2" endmill 1200rpm @ 29" of feed, 75% depth of cut, 75% side engagement. All climb milling, .005" finish stock on the side and .01" on the floor. I've got to get those chips out of the way using coolant blast. Recutting chips kills a cutting edge.

Jet A works good for cutting aluminium.
Heavy high-sulfur cutting oil mixed 55-50 with trichloroethylene works really good on mild gummy steel. I really like Boelube when drilling with small diameter cobalt drills ( I mostly use #40, 30 and 21)

Cheap and available

WD-40 for Aluminum

Yup!

In the field I've had good success with a cutoff wheel on a 4" grinder. I'll clamp the grinder and go to town. The cool part of a thin disc is the ability to split the point cleanly.