3D printed screwdriver sharpener jig to fix blade angle and orientation

[GregG]

I recently purchased some surprisingly high quality screwdrivers from AliExpress that have the exact same design as the Bergeon 30081 series, but at a quarter of the price.  Unfortunately, the blades tips were flattened too much during manufacture, which meant that I could barely use anything other than the 0.6 mm to 1 mm screwdrivers, because the blades wouldn't fit into any screw slots.  I've sharpened screwdrivers in the past, but I've never done it very well.  The angle of the wedge was never quite the same, and I couldn't never quite get the orientation correct, meaning that I was cutting a new blade face rotated by a few degrees rather than sharpening the existing one.

I have the Bergeon screwdriver sharpening tool holder (https://www.cousinsuk.com/sku/details/screwdriver-sharpeners/s1521?skuId=26987).  The problem is, when sharpening, your screwdriver blade angle will change depending on how far into the holder you place your screwdriver.  If you put the screwdriver in too far, your blade angle will be very narrow, travel further down the shaft, and the blade will be very thin at the tip, possibly risking breaking.  Not far enough, and your blade will be fat and you won't be able to fit the tip into any screw slots.

So, I endeavored to create a solution...

Judging by the picture of the replacement blades, the tip angle looks to be 26 degrees total included.  The goal here is to then create something which limits the length of screwdriver that you can insert into the sharpener, and which results in the screwdriver sitting at 13 degrees to the horizontal.  Without getting into the trigonometry, you need to extend the screwdriver about 30 mm from the sharpeners pivot point in order to reach 13 degrees.

I sketched it up in Tinkercad (attached picture).  The curvature of the sharpener fits onto the top, and the screwdriver points down.  There is a V-notch at the bottom that orients the blade so that you're always resharpening the existing faces of the blade, rather than having the blade rotated slightly, which would cause you to cut a new face.  And I'm happy to report that it worked extremely well, probably within 1 to 2 degrees of what I calculated.  The blades were sharpened precisely over the old face, and the end was perfectly perpendicular.

And that 1-2 degree error is not down to a lack of theory, but rather the realities of 3D printing; that you'll always get layer lines, and that corners can never be truly sharp.  I think what was happening is that in the initial version, the blade-orienting slot was designed as a sharp V-notch.  But since 3D printers can't print infinitely sharp slots, the screwdriver didn't fit into it exactly as intended.  So I made a follow up version (haven't tested it yet) that includes a small recess at the bottom of the V to allow the very end of the blade to fit in.

If you would like to try it, the file is available at https://drive.google.com/file/d/1mWjxi0HUs9jL55ysQaSV2xnyMiAOS29Y/view?usp=drive_link.  Just note that this was built to fit the Bergeon screwdriver sharpener.  Other brands might have different geometries which might result in different blade angles, though I don't think this will be so drastically different. 

Edited March 8 by GregG

[RichardHarris123]

Great idea and will help in most cases, however the blade angle needs to change to fit the screw.  The blade should wedge in and not bottom out on the screw. 

[GregG]

1 hour ago, RichardHarris123 said:

Great idea and will help in most cases, however the blade angle needs to change to fit the screw.  The blade should wedge in and not bottom out on the screw. 

Thank you.  For the longest time I was using a set of cheapo Indian screwdrivers, which I had eventually swapped Bergeon blades into.  They never gave me a day of trouble with slotting into screws so I figured I'd just emulate what I already knew worked.