tap & die question

Yep, the dies too. My favorite are the two flute gun taps.

Jim

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My Britmobile ( Austin ) mechanic's solution to this, 45 years ago, was to arc weld bits of rod across the head of these screws and use a hammer to loosen/tighten them. Gerry :-)} London, Canada

Chuckle..as a Master Scrounger, I tend to wind up with a handful of taps, here and there, and I cant read the sizes either. I recall somewhere a thread about some chemical, vinegar or something that could be put on the shank of a tap, and it would make the writing more visible. Anyone recall this?

Gunner

Confronting Liberals with the facts of reality is very much akin to clubbing baby seals. It gets boring after a while, but because Liberals are so stupid it is easy work." Steven M. Barry

And lo, it came about, that on Mon, 27 Oct 2003 22:00:11 GMT in rec.crafts.metalworking , "Boris Beizer" was inspired to utter:

What about left hand drill bits and "reversible" drill motors?

"worked for me" the couple times I've done it. Either I drill out the screw, or it catches in the screw and "backs" it out under power.

Does have the drawback of needing a separate set of left hand drill bits.

Absolutely correct and left handed bits work pretty darned well for this. I have one drill press that I can put on a longer motor drive belt and twist it..Figure 8, and while the belt rubs, its great for the rare occasion you have to try to drill out a screw.

A note to those whom may not know..there are a couple of brands of screw machines, that turn the spindle in the opposite direction then normal, so have to use left handed drill bits. As I scrounge..I have to use some care when I get a box of bits, as there is inevitably some left handed ones and they dont work very well when stuck in a drill press and run. The red glow is your first indication that something is amiss

Gunner

Confronting Liberals with the facts of reality is very much akin to clubbing baby seals. It gets boring after a while, but because Liberals are so stupid it is easy work." Steven M. Barry

I bought a set of import screw machine length drills from KBC a while ago. I went to use the .25" drill, and it wouldn't cut, so I said "Ha, import quality, sure..", but these were from Pland, which is usually good. I would keep trying it, having forgotten that it was no good. Practicing sharpening drills one day, I remembered it. turns out it was a left hand twist drill that had been sharpened as a right hand twister...no wonder it wouldn't work for anything!

inspired

When I was gunsmithing I eventually got and started using the Brownells Magna-tips (1/4" hex tips). I have about 60 different basic tips and many that were ground to different thicknesses and widths as needed. Replacements bits are free if you break one.

For a screwdriver I used to chuck a 1/4" hex bit holder up in the drill press and lay the gun on a well padded drill press table, put a

I had to do this most frequently on old S&W revolvers to get the side cover screws loose. Second most use was almost any screw on old single and double barreled shotguns.

Everyone knows how to get S&W side plate covers off right? After the screws are out and with the grips removed, hold the pistol in the flat of your hand and rap the grip frame (below the cover plates) with a rolled leather hammer with a clean face. I don't know how those guys fitted those plates that well but if you try to pry them up you'll leave burrs and they'll never be the same again. And the value of the gun just went down about 25 percent.

I have resharpened taps with a Dremel tool using the small abrasive cylinders that fit over a rubber expanding mandrel. Pick a mandrel that was smaller than the flute and carefully bring it up to the cutting tips while drawing it down the flute. Do it so the rotation of the cylinder off the cutting tips, not onto them.

I did that as a measure of desperation when I had a tap that was obviously dull and no spare on hand. Worked better than I thought it would.

And if you want a source of good quality carbon steel taps for most common machine screw sizes and some real oddballs too, check out Brownells.

I use to buy my 6-48 taps by the dozen and use a new one for each hole. You got your $800 rifle, you're about to put four holes in it that sell for $20 each, and the taps (back then) were about $1.00 each. Using a tap twice did not make sense. Especially after I broke my first one.

But don't forget that a carbon steel tap with not handle as much incidental flexing without shattering as a HSS one if you use them freehand.

In a curious coincident, shortly after I posted to this thread the mailman brought me the latest Lee Valley & Veritas catalog, and when thumbing through it I noticed a product called "Screw Grab":

Jeff

Are they OK for aluminum?

Sears was selling something like this for a while... may still for all I know. Never tried it though.

Erik

And lo, it came about, that on Tue, 28 Oct 2003 17:06:49 GMT in rec.crafts.metalworking , Gunner was inspired to utter:

That and the fact they cut for shit.

My dad discovered reversible drills when he couldn't get the borrowed drill to work. It would go round and round and ... nothing. Mark up the wood, but no hole. Said, finally, "Charlie, it doesn't work." That's when Charlie introduced my Dad ( a mere yout' of 75) to the wonders of reversible drills.

I've done plenty of tapping in aluminum and it works just fine. My steel 8-32 tap is a bit worn out from 10 holes it had to do in some HRS, hope I can get the Dremel down into its fine flutes. ;)

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

That stuff might help with the tapered screw driver seen in the photos. The screwdriver bits from Brownells were ground at a radius so the was some taper in the slot but very little. A well fitted screwdriver touches the bottom of the slot, is within a few thousandths of the same width as the slot, fills nearly the entire length of the slot, and does not touch any part but the screw itself (i.e., will not mark anything as it is turned).

Brownells sells a small round stone with a shank on it that you can chuck up in a drill press and use for thinning or cleaning up the Magna-Tip bits. I even made a piece of tooling (a piece of 1" square stock with a small chuck on a floating straight shank in a reamed hole) so that when the bits were brought up against stone, they could self-align the existing flat with the stone.

After the tips were clean and straight I would take a 1/4" round white synthetic stone and carefully break the sharp corners on the ends and sides of the bit. It was nearly impossible to see the radius but it took away the edges that would quickly damage blueing.

I had a real paranoia about marking up screws. People used to ask me how to evaluate gunsmiths or become a good gunsmith and I used to tell them the initial qualification was to be able to disassemble and reassemble guns with damaging any pins or screws or leaving any other evidence of having worked on the gun.

I'm not saying I never damaged or caused any marks on screws or pins but I restored them to as close to original as I could and/or touched up any minor scratches in the screw slots when I was done. There are some guns that are simply impossible to take apart and put back together without causing some marks and unless you know the "tricks" for doing it. I used a lot of reference materials and drew on the heads of a lot of old timers when I could find them.

There are a couple of other posts here that explain or justify the existence of carbon steel taps. My experience with them is that a new, good quality, carbon steel tap has a sharpness to it that seems superior to HSS taps when working in harder materials. But they break more easily and I prefer to use the carbon steel taps only in perfectly aligned and rigid setup.

As you use taps there is a little "windup" as you apply turning forces to the tap. Carbon steel taps appear to me to tolerate less windup than HSS taps. And after a while you get a feel for how much windup can be applied before the tap shatters.

Applying some turning force will raise but not sever a nearly imperceptible chip at the cut. So you can back off 1/8th turn or so, cut the chip and, and do it again. It can take a lot of cuts to get a thread cut.

If I was tapping freehand I would prefer to use a HSS tap if I had one. But the technique of watching the windup and reversing to cut off the chips would be the same. I think taps are almost as likely to break on removal as during the cutting feed because they have to sever a berm of displaced metal when reversed.

When you get to the point where there is little or no resistance when the tap is reversed, that is you signal that it is okay to take longer or even continuous feeding cuts. And there are some taps and materials that will let you simply wind the tap into the hole to produce the cut.

Ordinary, soft aluminum? Sure. Some aluminum alloys can be surprizingly hard, though. Boris

I have a Tapper, hand tapping device, and made an adapter to use the bits in it. Very rigid, stable, and bolted to the bench top and easy to provide down pressure while turning.

Gunner

Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

Thanks all, especially for these tips.