JMS1972
Member
- Messages
- 1,208
- Location
- NW Leicestershire, UK
I read a few articles on 4 facet drill grinding quite a few years ago and was intrigued. The fact I wasn't very good at off hand drill gauging and had scored a biscuit tin full of Morse taper dills had something to do with it. 
I cobbled together a bit of tooling for my terrible old Union T&C grinder then, it kind of worked but was pretty limited. Especially in length of drill.
Design is based around 1" diameter Morse taper sleeves, these are held in place by a plain collar at the business end and an index collar at the rear.
The index collar is held in place with an Allen screw which is loosened to get the cutting edge vertical.
I use a large square and a mirror to do this at the moment. The angle on the Wixey is 31 degrees which is 90-59. So the usual 118 degrees drill point.
Room for improvement there
I had a pile of crusty drills to grind recently so had a sudden burst of enthusiasm and made a base plate for it this allows some adjustment for length but also has the two important angles set with a pin. (10 and 25 degrees)
The two rows of four holes allow considerable overhang. Pivot and tee bolts are all M12. The M6 bolt is spring loaded and is pressed into one of two holes to set the angle. I'll make this a brass handled pin at some point.
I've managed to sharpen all of the Dodgy drills now and it was much more efficient being seconds to change angle. I had to fiddle with a protractor each time with the original setup.
To give some idea of how nice they are to use, the 8 holes were drilled in two steps. 8mm and 12mm the 8mm didn't need a pilot hole it was straight through no problems.
If you get it right you end up with a central point like a pyramid. So minimal friction and it doesn't wander much.
One issue with this set-up is it relies on the drill being straight.
I have ordered a ER25 collet chuck with a 32mm shank so should eventually be able to hold drills by the flutes which will improve this.
I cobbled together a bit of tooling for my terrible old Union T&C grinder then, it kind of worked but was pretty limited. Especially in length of drill.
Design is based around 1" diameter Morse taper sleeves, these are held in place by a plain collar at the business end and an index collar at the rear.
The index collar is held in place with an Allen screw which is loosened to get the cutting edge vertical.
I use a large square and a mirror to do this at the moment. The angle on the Wixey is 31 degrees which is 90-59. So the usual 118 degrees drill point.
Room for improvement there
I had a pile of crusty drills to grind recently so had a sudden burst of enthusiasm and made a base plate for it this allows some adjustment for length but also has the two important angles set with a pin. (10 and 25 degrees)
The two rows of four holes allow considerable overhang. Pivot and tee bolts are all M12. The M6 bolt is spring loaded and is pressed into one of two holes to set the angle. I'll make this a brass handled pin at some point.
I've managed to sharpen all of the Dodgy drills now and it was much more efficient being seconds to change angle. I had to fiddle with a protractor each time with the original setup.
To give some idea of how nice they are to use, the 8 holes were drilled in two steps. 8mm and 12mm the 8mm didn't need a pilot hole it was straight through no problems.
If you get it right you end up with a central point like a pyramid. So minimal friction and it doesn't wander much.
One issue with this set-up is it relies on the drill being straight.
I have ordered a ER25 collet chuck with a 32mm shank so should eventually be able to hold drills by the flutes which will improve this.
maybe that's why I got them cheaply 
but I do this as a hobby and I like to get things done to the best of my ability. Purely for the satisfaction of doing a good job.
