Q: How to make a micro sized nut driver?

[up1950s]

http://www.microfasteners.com/metric-screws-nuts-washers-set-screws-socket-cup-point-metric-alloy.html

Max , they don't say , at least I think they do , the allen key size needed . But the smallest hex holes I ever dealt with were on set screws .

[narrowminded]

OK, Max.  Ready to have some fun and impress the ladies?

No index head or rotary table, right?   That's OK.  Cut off a piece of 1.3mm hex key (.051"), as long as it can be.  Set down on flats in your mill, tapping down to be sure you have it solidly down on the flats, gripping the corners, and with a mounted stone, grind down each side, one at a time, until you have the finished hex dimension, +.0005" to .001" large.  (The highest speed you've got or make a holder for your high speed grinder to the spindle.)  The amount you'll be removing is only about .004" per side and about 1/16" long and because each step is from a uniform hex dimension the center never moves.  A better holder for rigidity, squareness, and cutter access, might be a block gripped in your vise, milled flat with a step left to square the part against, and a tapped hole and bridge clamp that will afford a solid grip right up against the area where the cut will be made.  Also easier to see what's happening and easier to rotate the part assuredly.

You might first try a carbide end mill as it may have a decent chance on hex key stock which is hard, for sure, and desired, but it isn't glass hard like a drill or high speed tool steel.  Keep oil on it.  If that works, and only needing a few thousandths a side I think you've got a chance, it'll be done pretty quickly.  Also, you only need about a 1/16" long cut to the new hex size for the socket depth so the overhang won't be too bad. 

With your hex finished, grind the face leaving sharp, square edges, much like a cutter.  That's your basic tool.  Mounting it in a bigger piece of round might be handy and could be done by drilling a piece of round stock (3/8" maybe?) to the corners which will be .050".  That tool will mount in your spindle and be pressed into the socket material leaving that finished shape.

The socket will be made by drilling to at least the 1.1mm flats size but I would plan on a drill that was slightly oversized as it leaves less metal to move and the effective gripping occurs up the flank towards the corners, anyways.  The actual core hole size would probably be nice at .047" or so which is conveniently 3/64" (.046875") as the corners (sharp) for an .045" flat will be .052" (.051963").  That will leave evidence of a small radius relief at the center of your internal flats but with good effective corners.  The core hole should be drilled MINIMUM about twice the depth that you'll be pressing the hex shape in to provide space for the removed material to flow.  3 times depth would be safer.  The material will flow down into that void and will remain there.  You could also add a small pilot drill at the entry just to be sure you're started straight and help the tool to get the material flowing by virtue of the drill point affording a tapered tool entry at the start of the cut.  That pilot diameter would be .050" so it would seem a #55 drill at .051" would do the trick.  .005" depth at full diameter should suffice but a little more wouldn't hurt.  Just make sure you're not using up your coring hole reserve at full depth.  Once blanked, you can face the finished part to remove the pilot.

For the socket, try aluminum or brass as they should flow easily and be adequate for the torque and use.  The wall  for the blank would probably be OK in 1/8" material but 3/16" or more might be nicer to grip in your tools.  You can always turn down the finished part and make it sexy as you want it to be.

Additionally, I didn't lay this out so the diameters for the holes, the pilots, and the hex shapes will be correct but I didn't look at the pilot hole depth angles or really consider the hex height (for engagement depth) or any of the other details so a good drawing would probably be warranted.  Even if just as an aid to become familiar with what you're doing.

Also, if your effort seems tight on the screw, before to panic try rotating the hex tool one flat and pressing it back in, repeating for each set of flats.  The tolerances of the flats may just get you the extra tenth or so that you need. 

[up1950s]

Ok here is a M1.6 and a M1.7 set screw , both have a 0.7MM hex hole .

http://www.del-screw.com/(hex)flat-point.htm

I would be looking for something you can grind , as most set screws have a cone where the allen key enters . You will need to grind that inverted cone away so you can tighten the nut flush .

[mmagliaro]

Ok here is a M1.6 and a M1.7 set screw , both have a 0.7MM hex hole .

http://www.del-screw.com/(hex)flat-point.htm

Richie, the problem is that I don't need a 0.7mm hex hole.  I need a 1.1mm hex hole, and none of those set screws have that.
My crank screw is M0.7, but that's the thread on it, not the size of the head.

[narrowminded]

I did a couple of edits so maybe it's a little clearer.  That kind of rig works, is a method I've actually used, and is basically one of the ways sockets are made in production, especially older ones.  If you look up in the end you'll see the flowed material curled up in there.

[Missaberoad]

An old mechanics trick i use is to use a piece of paper in a socket to allow a more snug fit on the bolt. Would a piece of tissue paper fill enough of the slop on a 1.3mm head set screw to allow it to turn the screw? Or grind the set screw slightly to create a burr...

or would the set screw shrink with freezing?

I know its a little low tech compared to some of the other solutions but might be worth exploring... 

[Spades]

From: http://www.macsmodeling.com/Tuner%20MM%20Detail%20Parts.htm the etched sheet http://www.macsmodeling.com/T2m%201020.jpg   On the etched sheet the second and fourth etching bottom right?  If they truly are to be used for adjusting could they be chucked in a pin vise?

[up1950s]

Max , maybe the set screw with a 1.3 hole will work .


Then again there is these
http://www.west-op.com/opticalhexdriv.html

Or this , just don't apply the heat to mold the plastic as desgined .
http://hlj.com/product/brfb432/Sup

[narrowminded]

Max , maybe the set screw with a 1.3 hole will work .

That idea is great!  The only problem is that the sizes miss completely.  A 1.1mm hex is 1.27mm on the corners so 1.3mm will just spin.  Knowing that the standard hex keys were either too small or too large and by a good margin is why I was explaining how to make one with his mill.  In these tiny sizes the corners of the hex are only about .003" larger than their adjacent face so there really isn't any breathing room. 

Then again there is these
http://www.west-op.com/opticalhexdriv.html

Being that the screw size is 1.1mm I doubt that the hex on top would be the same but I don't know that for sure.  Might be a weird piece of hardware which industries do sometimes have but I highly doubt it.

Or this , just don't apply the heat to mold the plastic as desgined .
http://hlj.com/product/brfb432/Sup

That actually looks like it could work!  But tolerance is everything and Max's measured hex is already just over a true 1.1mm.  Then there's $28 plus shipping while Max has a mill and probably has the materials and cutters laying around.  The finished part I was describing how to make would look pretty much like that one in the picture. 

It's a shame the hex is an odd size because that socket head bolt deal would totally do the job otherwise.

[Lemosteam]

@mmagliaro , i have an etching going to PPD very soon.  If you could wait, I can make you a multi-layer hex etch at 1.14mm across flats that you could solder together and solder to a brass rod.

[mmagliaro]

Narrowminded... I get what you are trying to have me make - a hex-shaped ram to press into a tube to cut/shape/form the
hexagonal inner faces, the trick being that the ram is from hardened tool steel and the tube is softer (brass or something similar).

I do think that would work.

You guys have all given me way more ideas than I even dreamed you would, and I really appreciate it.
Let me experiment for a bit and see if I can make something that works.
The idea of shimming the inside of a larger nut driver with thin brass strip also occurred to me and that might well work.
Thin brass shim stock at .003" or .001" is might malleable.  I might be able to place a small piece of that over the head of one of the bolts, held in a vise under the mill head, and just press the larger nut driver over it, forming an inner liner inside the nut driver that
would fit the bolt perfectly.

1.5mm nut drivers are commonly available.  That's .059".  I need .045".  So a .005" sheet, if it would press in, would get me .049.
Then I finish up with some .001 or .002 and press again.  It might be sloppy, but I kind of doubt it.  I think pressing that metal in there around the actual steel head would not give much room for slop.

[narrowminded]

Max, if you want to try out the concept just take a small hex key (1.3mm is in one of my sets), cut off a long piece, and grind the end square on your bench grinder.  Then place a drop piece of any aluminum in the vise in your machine, drill a hole in it .001" or so larger than the hex flat size. Without moving the X/Y to maintain alignment, chuck up the hex piece and push it into the hole.  If necessary place a blank up in your chuck to make it a solid stop not relying solely on the drill chuck grip. You might also break the hole entry to the corner diameter with another drill or countersink to aid alignment on entry.  That should take all of about fifteen minutes to try and even if not chosen as viable for this project it won't be a bad trick to have in your extensive bag of tricks.  Plus, you'll have a 1.3mm socket, too!  

In this size I suspect your mill will have the necessary force to push that without abusing it.  In larger sizes you would really need a press or rig up holders for your vice.  Also, if the force seems high, drill one number drill size larger and see if that's still adequate to drive a hex properly.  It will dramatically reduce the force required to push it in.

[mark.hinds]

and Mark suggests the perfect place to find one.... Have an old flip phone? Torx could work and some even had hex screws.

Ryan, I suspect that some of these guys either don't know what a torx screw is, or missed the point of the suggestion, which is to use the 6-pointed depression in the screw head as a socket. 

So, in case either of the above surmises are correct, here is a torx screw in an old cell phone.  They come in various sizes, but note how the depression in the head *seems* as if it could be used to turn a hex nut of an appropriate size.  So my original post above was suggesting finding such a torx screw, and using it as a nut driver.  You can of course buy them, but you could possibly salvage one from an old microelectronic device, such as the one pictured, in which case it would be free.  In either case, no machining is required. 



MH

[mmagliaro]

I knew what a torx screw was   

I just didn't think there would be a size that would work, similar to the quandry we have with the allen screws.
BUT...

I may be wrong about that.
Here's a chart:
http://www.newmantools.com/tech/torxspecs.htm

Looks like a T3 or T4 torx head  might work.  The point-to-point dimension is 1.17mm and 1.28mm respectively.
That might mean that "across the flats" might be close enough to 1.1mm to actually work.

Time to grab some T3 and T4 and try this.

[Lemosteam]

I knew what a torx screw was   

I just didn't think there would be a size that would work, similar to the quandry we have with the allen screws.
BUT...

I may be wrong about that.
Here's a chart:
http://www.newmantools.com/tech/torxspecs.htm

Looks like a T3 or T4 torx head  might work.  The point-to-point dimension is 1.17mm and 1.28mm respectively.
That might mean that "across the flats" might be close enough to 1.1mm to actually work.

Time to grab some T3 and T4 and try this.

Now the trick is to try and find a screw THAT USES that size torx feature...  Been searching all day for ya Max!  Nada so far.