Q: How to make a micro sized nut driver?

[mmagliaro]

Heat the thing up and quench it in oil.  I think sometimes we overplay wear on these tiny devices that do not see grease monkey torques or real life loads.  It sounded like it was so easy to make you could make a lifetime's supply anyhow.

I do think however, had you heated the brass in advance, it would not have shaved material into the tube as the picture shows.

John, true if I had annealed it beforehand, it would have been "softer" and formed with shaving, although I'm not too worried about the shaving.  But if I heat and quench it now, it's not going to harden is it?  Brass doesn't harden from doing that the way steel does.

[narrowminded]

I did think about this (reenforcing my nut driver with another layer of tube around the outside wall).
I wonder.... is that how it will really give, or will the straight faces on the inside just kind of round off over time?

Just make it out of a bigger round and if the end result is larger than you'd like, turn it down after the hex is in.  Enough material in your blank and it supports itself in the process, pushing ALL of the material ahead of itself instead of just some.  As I look closer at your picture I see the bulging and that's no surprise.  It's reshaping by SHARING the distortion of the wall with the shearing action at the tool edge.  It's loaded up and finding the weak spot.  In this case, it was a combination of the wall giving up some, reducing the load at the shearing face in proportion to how much material got out of the way in the wall bulging process, then once the equilibrium is found the shearing action occurs at the tool face, taking the rest.  A thicker wall will force ALL of the action to the shearing edge, not just some.

If you determine that the socket wear or strength is a problem (I doubt it), make it in mild steel.  You might get away with using the SS bolt head as your tool AND if you're SURE that it's mild steel (below 20 points carbon, 1018, 1020, etc, very common).  I only mention that because, while most steel used is mild steel, machine shop scraps can easily be something else and when picking through scraps you just can't be sure. And higher carbon alloys DO show up in what might seem like the strangest places, like coat hanger wire.  Remember, the strongest material wins!  And in spite of a fairly common perception, 300 series SS isn't all that strong.  It's similar to a medium carbon steel, and not even on the upper end of that spectrum.  That's why you MIGHT get away with it (probably will) as long as you assuredly are pressing in to MILD steel, not something stronger.  IF the SS doesn't handle it for a one time hit, the hex key material WILL and it will proceed much like it did in brass.

I hope this isn't seeming like too much and if the sole purpose is JUST the tool, then I'll be the first to say, it is.  BUT, since it's a new concept to many readers I see it as an opportunity to both get THIS job done (and QUITE efficiently) but also to learn a TON that can be used another day in a similar fashion, by style, but adding a whole new technique for... who knows what the next obstacle will be?  Once this concept is understood the imagination can put it to use another day.

[peteski]

Max, you have perfect little socket wrench. I would leave it alone for now. If it wears out, you can easily make another one (since you now know how and you know how easy it it to make).  How many times will you use it on your model?  Do you think enough to cause it to wear out? 

[narrowminded]

John, true if I had annealed it beforehand, it would have been "softer" and formed with shaving, although I'm not too worried about the shaving.  But if I heat and quench it now, it's not going to harden is it?  Brass doesn't harden from doing that the way steel does.

That is correct.  Copper and its alloys, which brass is, act directly opposite carbon steel in this regard.  They can only be hardened by cold working them.  That is why you see brass material sold as dead soft (fully annealed), quarter hard, half hard, and full hard.  That is accomplished as a side benefit to the rolling and shaping processes and actually requires an anneal step to get rid of it.  The good news is you can do that yourself as the temperatures required for the small sizes of material we use are attainable with normal home type heat sources.  Heating and quenching that material for the socket would have just softened it, although some of that would be back by the process of forcing the tool in.  And it's amazing how soft (not rigid) "dead soft" is compared to even "half hard".  If you want to see that first hand, take a piece of brass wire that's listed as hard, cut off two samples and heat the one up pretty good in something as simple as a candle, then quench it in water.  Check out how it bends compared to the unheated one.  Then, think about when that might be beneficial to know, like bending intricate wire form details.  Or when it's NOT desired, maybe some of those same wire form details but this time, they need to stand a load.  Or a tool.   And make sure you're working with brass and not bronze.  Bronze can be the same but also, in alloys with high zinc content the procedure changes slightly and might require holding at temp alittle while then skipping the quench step.  It's the zinc that gets weird in the mess.   If you need to know or are just technically curious, there's some search topics.  Have at it.

And since this topic has been opened and in a thread where some folks might be interested (I hope), there was a recent mention of heating and quenching SS to harden it.  I skipped over it because it wasn't critical and wouldn't hurt anything, but...  Again, no hardening benefit at all if it's a 300 series (18-8 or better).  It cannot be hardened with heating and quenching, EVER.  There simply isn't enough carbon in it, nor the "room" to have enough carbon when it's 18-8 or more.  On the other hand, it is NOTORIOUSLY prone to work hardening.  It CAN be annealed but it's not likely that will be accomplished too easily in the home environment as it needs to be much hotter AND held at temperature for a time.  NOW, some 400 series CAN be heat hardened, is stronger on average than 300 series, but is less corrosion resistant.  And all due to the lower chrome/ nickel alloy leaving room for more carbon.  SS knives are usually 400 series for this reason.  Bolts are usually 300 series for the corrosion reason.

And for common materials that can't be heated and quenched to harden, add mild steel to that list, too.  CANNOT be hardened by heating and quenching.  That's what makes it so handy around welding.  Almost can't hurt it.  It's not as strong as higher carbon as that's the main ingredient that imparts strength in steel.  Mild steel CAN be case hardened which places just a hard shell on the mild steel core.  That is accomplished by getting it screaming hot (about 1725F) in surface contact with carbon.  The carbon is absorbed into the outermost shell and makes a high carbon content in the surface only, leaving the original core material as it was.... sorta.   Then it's quenched.  Then there's annealing of steel which also requires a lot of heat, but not as much as hardening (1450F or so).  Then there's drawing back which helps impart toughness back into through hardenable products (higher carbon content) that will see shock loads (like metal punches) and the brittleness can cause fracturing.  Those temps can be as low as a few hundred degrees F but are generally up around 800 degreesF up to about 1350 degrees F with the degree of change, draw back, directly effected by what temperature was used.  600, 700, 800, each effect how far back you took it.

OK, so what's the point for the hobbyist?  You can grind your drills or grind high speed steel cutting edges on your grinder and not wreck the material is a quick one that's often heard.  Any amount of control and caution that you need to make a good cutting edge will by default have you well below those temps where bad (or good, depending on what you're trying to accomplish) things happen.  An occasional dip in some water makes it comfortable to hold the part and FURTHER assures you're not in the temp ranges that will have an effect.  Another one, you won't soften your already marginally strong enough brass tool by trying to harden it with a quench.  You WILL anneal the brass half hard wire when you've had some trouble getting the detailed wire form shape you wanted.The knowledge can be helpful with how to approach a problem and can often be JUST as helpful in knowing when to quit.  When you're trying to defy gravity.   And if you've seen enough, maybe you'll not be as afraid to try some machining for yourself. 

And by NO MEANS is that intended to be the begin all and end all for all things metal.  It's some quick rule of thumb concepts that have surfaced in these discussions that can be right damn handy to know. Just a few markers that can help you dismiss the absurd while recognizing when you're approaching the point where something matters, and then have an idea what searches you might do or what expertise you might seek to get the nitty gritty you need.  Hope that helped somebody.

[Lemosteam]

Take a brass tube and put your nuts in it then convince the tube to be be a hex tube with this .

http://g01.a.alicdn.com/kf/HTB1M7ZsIFXXXXXvXpXXq6xXFXXXy/Coaxial-font-b-crimper-b-font-crimping-Tool-LS-02H1-for-coaxial-cable-BNC-fiber-optic.jpg

Wait was this a Freudian slip? 

[mmagliaro]

Max, you have perfect little socket wrench. I would leave it alone for now. If it wears out, you can easily make another one (since you now know how and you know how easy it it to make).  How many times will you use it on your model?  Do you think enough to cause it to wear out? 

+1
(oh oh... we're not supposed to do that anymore....)