its possible that the drill orientation is slightly off, to get parallel primary facet the drill face needs to be exactly horizontal. I use a jig on my stent but would imagine its similar.

I have a Worden and use one of the accessories to four facet grind drills.

The technique is to mount the drill on a 31 degree wedge (118 /2 = 59. 90 – 59 = 31 )

With the table set square to the wheel, and the cutting edge of the drill set vertical, the jig can be swung to the 30 degree position to grind the secondary clearance. The drill should be rotated through 80 degrees, frequently to ensure that the lips are the same length, without abusing the wheel too much.

Once the secondary clearance has been ground, the jig is set to 10 degrees for grinding the primary clearance. This will almost certainly require the table to be repositioned to clear the wheel.

I unknowingly followed the late Giles Parkes and made up a holder for ER collets (ER20 in my case ) from inch square bar, to hold the drills, rather than an individual collet for each drill.

To save space, I turned the back of the clamp nut at 59 degrees so that the face was parallel to the front face of the jig, and gave a more positive location, which helps with accuracy..

With the cutting edge set vertical, turning the block over frequently allows the lips to be kept to the same length without having to take deep cuts, and heat the drill, or wear the wheel.

The result is like that shown by Bernard Towers.

The drills perform extremely well!

By the looks of it, we have all found slightly different means of achieving the same end..

It helps to mark the square, so that you can keep track of where you are!

Howard

I have 4 facet set up, problems later, but if you set the cutting edge to be vertical and then grind a bit off, it isn't vertical any more. I find I have to set it a bit off so that once it's sharp it is also vertical. More guess than science. My problem is turning the drill exactly 180 degrees. Tooth rest in the flutes is a bit hit and miss with small drills. I like the square shank collet chuck mentioned by Howard, it's now on the to-do list

Has any body tried to replicate the Clarkson or Brierley set ups ? Anybody wishing to try, I can help with sketches and dimensions. Noel.

I've just about finished a set of drawings, in Alibre, for a 2:1 scale version of the 'Duplex' drill sharpening jig, as detailed in ME during 1951. That's because my Picador jig only just goes up to 3/4"

Just throwing in some alternatives to the process..The jigs above work well for the larger drill I find – 3mm or larger, but I never came right with the small ones – Like Duncan – a hit and miss affair. So I made aup this microscope alignment aid, drill in collet block, which them fits a custom mount on my T&C grinder..Align the drill edges horizontal with a viewing reticle and then the block is just rotated 180deg in the grinder.

The Grinder motion tables are simply set to the required drill edge angles and the result is on the nose 99% of the time. A micrometer thimble sets the grind depth.