I am puzzled as to why our Asian cousins have never reproduced this design of drill grinding jig which is far superior and simpler in operation than the ‘Picador’ type that they have copied.

On 10 October 2024 at 23:46 Chris Crew Said:

I am puzzled as to why our Asian cousins have never reproduced this design of drill grinding jig which is far superior and simpler in operation than the ‘Picador’ type that they have copied.

The Asian copies are generally not of the Picador type with its vertical pivot axis requiring a “5 to 5″ drill lip angle.

Mostly they are a version of the General (USA) / Spiralux (UK) type with the pivot at an angle and vertical drill lip setting.

Usually made with little attention to detail concerning the vital angles and offset of the drill carrier trough relative to the pivot axis. There is an extensive internet literature chronicling the failings of the devices as built and various descriptions of how to get sensible results from them. As usual Graham Meek nailed it with a more comprehensive rework than most to produce something that does work reliably.

Bottom line is all the die cast alloy versions are basically attempting to do the job with a too cheaply made device. Although the Picador wasn’t, objectively, cheap in relation to 18 or 19 year old Clives wages when he bought his.

In practice the major alignment problem is with small drills where the Picador sliding lip gauge is less than satisfactory due to poor contact and limited drill projection. Easy to grind the lip gauge!

Frankly the only satisfactory drill position setting gauge I’ve encountered is on the original even more cheaply made, all plastic, Plasplugs version which works unreasonably well and allows the drill to be flipped to do the second edge whilst still in its Vee trough. Repositioning errors during flipping being, to my mind, the most likely source of errors with trough type drill carrier. It’s quite tricky to get small drills right.

Before getting the drill sharpening attachment for my Clarkson T&C grinder I took a hard look at the Plasplugs drill carrier system with a view to reproducing it in more engineered fashion. The fundamental disadvantage is that it can only cover a limited range of drill sizes before the fixed projection results in angular errors. probably need three carriers to cover 1/8″ to 1/2”, 3 mm to 13 mm, drills although two might work.

Clive

Further to the drill projection when using the Reliance jig here is one of the pictures from the photographic instructions showing the drill position before grinding.

Makes the “push the drill forward until the centre of the first indent is aligned with the front of the trough” a bit clearer. The faint white line shows the position of the front of the trough. Not as clear as you’d ideally like. Probably a not too good scan of a second generation photocopy.

As ever nice and clear with a bigger drill in places but probably less clear with a small one up.

Agree with Noel about a Brierley being the Rolls Royce solution for Home Shop folks but they are pretty big. As far as ease of use is concerned the original Plasplugs device stands out as being stupidly easy to use with no user judgement needed. Push the drill up to the stop, rotate it until the angle detector drops to its lowest position, lock holder, transfer to pivot position and grind. Any engineering analysis shows all sorts of limitations. Like what happens when the wheel wears? But what it does do it does well just like it says on the tin or, rather, cardboard box.

The fundamental issue with all one lip at time swing over the wheel drill sharpening devices has always been how to affordably hold the drill on centre with its point correctly located in relation to the sweep movement geometry and accurately flip it to do the second lip. It’s the affordable bit that trips Home Shop friendly devices up! Mr Clarkson used a 6 jaw chuck, Brierley and the other professional systems generally use collets. Back in the day just too expensive for the likes of us.

These days Asian import 6 jaw chucks can be gotten “not silly expensive” and ER collet sets with their long closure range can also be within budget. Especially so if the collets can do double duty on the mill. Given this I’m surprised that no on has yet replicated the Clarkson attachment geometry for home construction. The Clarkson seems to be the professional standard type most suitable to use as a basis for a “bring your own grinder” device.

Alternatively the Kaindl with its “toast rack” style interlocking Vee block holder looks to be a promising inspiration for a home shop project.

Clive

That’s a neat job Bernard !

Clive,  my Brierleys have a six jaw chuck, like the Clarkson, though the Brierley point splitter uses fixed size collets, you need to make one for every size you sharpen. Noel.