HPA

One of my bugbears is finding that the drill I need to use is blunt. Above 3 mm I can use the Drill Doctor that I invested in when woodwork was my main hobby. However, model aeroplanes often require smaller diameter drills.

Often the suggestion is made that a replacement drill is cheap, so just get another one. That's true, although it offends my desire to be economical with resources and I am impatient waiting for the new drill to turn up! Also, for reasons best known to the suppliers, there seems to be a rash of small drills produced already blunt!. So I have been searching for a convenient way of sharpening them.

Scouring the model engineering websites, I came across a device called the Wishbone. I also discovered that this can be made for yourself if you have a 3D printer and can be bothered getting from the Internet the bearings, collet equipment and dowel pins needed to assemble the plastic device that you print.

Here's a link to the Thingiverse web page for the Wishbone sharpener:
thingiverse.com/thing:5849174

There is also a purpose designed case to keep it in. The 118° and 135° angles to set the grind are my own design.

I attach some self explanatory photos.

There is no doubt that the device works well.

Never having thrown away a blunt drill I have a small box of them that I could be let loose with this tool. :D

I have an original commercial wishbone and one made by a friend to plans and the latter is much better. But yes, superb for sharpening for drill BUT ONLY IF you get the orientation of the flutes correct; if not it will be useless. There used to be a small insert that helps do this I think.

Anyway, a good tip.

CHE

An alternative solution to the same problem.

4 Facet Sharpening (https://www.modelenginenews.org/meng/smalldrilljig.html)

Steve

Thanks for the great info.

John