Why do slotted taper screwdrivers exist?

[HanShotFirst]

I know that if I use the tapered screwdriver for gun smithing, the screws will be ruined very quickly because the driver will slip.

Using my gun smithing screwdrivers, which have zero taper, keeps them from slipping. Very important when working on antiques with irreplaceable or rare screws.

I'm a gunsmith and I have a LOT of screwdrivers. I have oodles of bits, and I keep a drawer full of screwdrivers for when something needs to be filed to fit. And you file a screwdriver, not grind it. If you grind a screwdriver you'll lose the temper at the tip and it will bend.

I use some of the Brownells bits, I have some Grace hollow ground, and I have drivers I've made from Lasalle "FatigueProof" barstock, but I don't have time to do that anymore.

I always have tapered screwdrivers on hand because when you get to pre-1900 guns, most screws are tapered.

The Brownells set is a great start, but they're pricey and they DO break. You have to take very careful care in using the screwdriver properly, get a good deal of downward pressure before cracking anything lose.

 

[neophyte]

Can't find that at brownwell's ..... they still offer that for sale?

On brownells do a search for "Magna-Tip set".

http://www.brownells.com/search/index.htm?k=magna+tip+set&ksubmit=y

 

[partsproduction]

HanShotFirst, if you practice religiously grinding very short duration and lightly, immediately swish in water, grind lightly again etc you won't effect the temper. I do this all the time, the temperature has to get above 350 degrees or so before further tempering takes place. As long as your ground surfaces don't show any discoloration (Carbon and alloy steels) you won't damage the steel.
With HSS I've read that internal stressing is the demon to avoid while grinding, but again, that implies higher temperatures that can be avoided by making the grinding time very short and with low pressure. I've never seen evidence from either hand or machine grinding of HSS drill bits that I've induced any micro cracking.
My personal observation is that the thinner the object being ground the harder it is to avoid overheating the steel, even with copious coolant right on the wheel and workpiece. That's a situation that speaks directly to screwdriver grinding, and I hate to grind screwdrivers for that reason.

And has anyone else noticed that belt sanders tend to grind faster and cooler than wheels? I hardly use a wheel anymore except get into a corner. The belt spends more time out of the cut than the wheel, since in effect it is the same thing as a huge wheel to the workpiece, the same as if that belts length would equal a very large wheel.

90% of the cutting tools we use are insert type, either carbide or cobalt inserts we don't grind ever.

 

[Adam.C]

If you can file a screwdriver tip, it's too soft, throw it away.

Grind-quench-grind is a bad idea. If the stone is freshly dressed it will cut, not abrade, and much less heat will be generated. The reason your belt sander works better is because it probably isn't clogged and the grinder is.

When you grind a tool, the corners are easy to overheat. Heat collects there and can't get it out as easily because there's no place for it to go. This often happens with screwdrivers. Any tiny bluing has damaged the temper. And the damage isn't skin deep.

Old fashioned high carbon tool steels (1077, 1095) can become super hard. But the temper temperatures can be low, like 350F. If the tool becomes too hot to hold and sizzles in your quench cup, you are already over 200F. Very likely some tiny corner is much hotter than that.

Using a light touch on a dressed stone, you can grind for minutes without ever over heating your tool. Start with a diamond dressing tool. And don't use too fine a stone 60grit is fine enough.

 

[gtae07]

IMHO slotted and phillips screws should have been phased out decades ago. They are both real crappy designs.

Agreed. I try to avoid buying fasteners or items that require those bits; my airplane will use hex and torx head fasteners wherever possible.

 

[JR 42]

No molecules? Huh? I think all matter except pure materials are formed of molecules, am I wrong?
Pure iron or gold is atom upon atom, but I'm not sure even that is not part of a molecular formation. I'm waiting to be schooled.

I'm no chemist, but steel is like your pure iron or gold example, with more than one element forming the "atom on atom" structure (at a minimum, steel is iron and carbon). Adding more elements and heat change the shape (and some properties) of the structure formed by the various atoms.

Here's a link to some google image results:

linky

It's all way more complicated than what I wrote... here's another link:

wikipedia's steel entry

JR

 

[ScottsGT]

I always thought those were made for gunsmith's.

I bought a small set from Brownells when I did an upgrade on mu Uberti 1866 yellowboy. The upgrade kit warned purchasers to not even attempt to remove the screws without the "Gunsmithing" screwdriver. It even came with replacement screws since the factory was known to over torque them.

 

[JR 42]

Reed and Prince
those odd Japanese Phillips. ...

Thats two more.

And those horrible Phillips / square drive combinations (abominations?) on some deck screws, always seemed to strip those when taking them out.

And Frearson (cheating a little, it's a modified Reed and Prince).

JR

 

[PFSard]

If you can file a screwdriver tip, it's too soft, throw it away.

I'll probably get my head handed to me, but.... it wouldn't be the first time.

I have Craftsman screwdrivers that I bought new 40 years ago. I have dressed these up with files occasionally with standard files (as in NOT diamond files). They still work great. I won't be throwing them away.

 

[partsproduction]

No Adam C, heat builds, it can build quickly or slowly depending on many parameters, the thickness of the base metal is a big part. With a surface grinder the workpiece is constantly deluged with water, but it makes no difference if it is constant or intermittent, the important thing is that the temperature is not allowed to rise. I've been doing this for over 30 years.
Also, I have many dressing tools for my grinders, I do not allow my wheels to get clogged.

 

[balane]

No way could I scratch my ear canal with that bit!

 

[partsproduction]

JR42, Steels (And that is what we are talking about here of course) are molecules of mostly groups of iron atoms with structural atoms of carbon and or other additives, which is what my understanding of what a molecule is.

 

[partsproduction]

Wow, I take it back. https://www.physforum.com/index.php?showtopic=41333 and https://www.physicsforums.com/threads/are-metal-molecules-actually-molecules.13028/

It isn't the component mix that makes it a molecule, it is the bond. Hat off to you JR42.