Taps, stepdrills, pivots, etc.

[Jeff Higgins]

Originally Posted by Osprey Guy

Grizzly's great catalog, my new "LittleMachineShop.com" flyer/catalog, and of course all the various knife supply house catalogs (Texas knife Suply, Koval, Jantz, K&G, etc, etc). I always get a kick going through all of these...especially if I have some extra $$$ earmarked for knife supplies.

Oh yeah... you got it bad now! McMaster-Carr is a great catalog too, Dennis. Between that and MSC there isn't much I can't find. Hey those small step-drills really set you back a few bucks, huh! Want a tip to prolong the life of them? Pre-drill the smaller diameter first, then use the small-diameter of the step drill as a pilot with plenty of good drilling lubricant. That keeps the heat off of the drill bit, especially when drilling Ti.

[Osprey Guy]

Hey Jeff-

I like that helpful little tidbit...thanks!


Dennis Greenbaum

Yeah Baby!

[Osprey Guy]

Jeff-

I've been giving some additional consideration to your suggestion for saving wear and tear on the stepdrills...

Upon further thought, I'm not so sure I'll use the suggestion.

It seems to me that the whole point of using a stepdrill is to save the extra steps...and time (and of course the inherent accuracy achieved through use of the stepdrill). Using your suggestion requires that I add another step back into the process (having to now pre-drill the smaller hole,...and that's after drilling the initial pivot hole!). That strikes me as being kind of counterproductive to the whole stepdrill concept.

While it's true that the stepdrills are rather pricey at around $15 bucks apiece, if I can get (let's say) 30-50 holes out of one stepdrill, that works out to $.30 or $.40 per hole... I consider that to be very fair in exchange for what is gained.


Dennis Greenbaum

Yeah Baby!

[Jeff Higgins]

Originally Posted by Osprey Guy

It seems to me that the whole point of using a stepdrill is to save the extra steps...and time (and of course the inherent accuracy achieved through use of the stepdrill). Using your suggestion requires that I add another step back into the process (having to now pre-drill the smaller hole,...and that's after drilling the initial pivot hole!). That strikes me as being kind of counterproductive to the whole stepdrill concept.

No problem, Dennis.

I'll only say that I truly believe better accuracy is attained through the use of my predrilling method. I think essentially that the true purpose of the step drill for OUR application is to provide that second, larger diameter, or counterbore for the screw head to fit into. If we take into consideration the small diameter of the 0-80 step drill, we are looking at a very small amount of material actually being removed. By my calculations, that small diameter must be moving around 3000 rpms faster than the larger diameter to cut efficiently. But the time the large diameter hits the bore, there just HAS to me a large amount of deflection, thus some amount of eccentricity to the hole. Frankly, all this is inconsequential to the 0-80 size. Let's remember we aren't building watches here, and all we are doing is joining pieces of material together in an asthetically-pleasing process.

When I went to machinist school, one of the main things that always stuck in my head was why we needed piloted bits to make a counterbore. When the instructor taought us about tooling deflection, that's when it began to make sense. Do people use the step drills for one-step drilling? Sure they do! Is it the absolute best way? Subject to theory I guess, but I'm sure that if I really wanted to get anal, an end-mill and a drill bit would outperform a step drill tolerances.

[Ray Rogers]

I suspect Jeff is right. It also has a lot to do with what you learn to use efficienty. I have never used step drills for general drilling and yet have no trouble drilling countersunk holes with plain drill bits. I think there is an economic advantage to this method as well as far more flexibilty relative to the combinations that can be achieved. After Dennis has time to become comfortable with his accuracy and speed with individual drill bits - as he surely will due to not having a step drill for every possible combo - I wouldn't be surprised to learn that his use of step drills drops drmatically.......

[Jeff Higgins]

Thanks for the piggyback, Ray. While I got you, I just want to applaud you on your method of slitting. That is almost exactly like the setup I use. It's quick and simple. I bought an old Burke #4 horizonalt mill to do that type of slitting and in the process of rebuilding that machine and getting it all pristine again (bad habit of mine), I discovered that using an arbor and the mill worked even better and quicker. The only advantage to my Burke is a small dedicated hold-down just for slitting liners, and the fact that its powerfeed and fully-adjustable stops. I can put a liner in there, start it and forget it while I do somethign else.

[Ray Rogers]

"and the fact that its powerfeed and fully-adjustable stops. I can put a liner in there, start it and forget it while I do somethign else."

Drool.........