I've been researching this subject for ages as this D bit grinder comes with a "drill sharpening" attachment and (of course) no instructions...
I've been using Luc Wybo method that works great for drills of 5mm and bigger, but I can't get 4mm and smaller to work despite adding an extra 3 degrees clearance as described in the pdf doc. If anyone knows how to get those smaller drills to work please let me know.
First let me clarify for those that don't know what I'm talking about.
This is the tool cutter grinder I'm talking about:
This is the attachment:
Now, there are various videos online showing drill sharpening on it, but most of them are quite useless. They omit a lot of info, they obscure what they're doing etc. But, there is one youtube creator that took the time to write a pdf document alongside his video. His english is ok-ish. I can understand what he says and writes, but his written descriptions could be better. Still, he is the only person in the know that took the time to share this knowledge so he has my thanks for it. His youtube channel (and I assume his name) is Luc Wybo. I strongly recommend anyone interested to start by reading the pdf here: https://drive.google.com/file/d/11gtweV-mVcSftFvA3ZSR8xOS-gqZyFhX/view
Also attached.
Then the youtube video here
will make a lot more sense.
The method can be briefly described as:
- 3 small 1.5mm (60 thou) sheet metal plates have to be made, drawings are in the pdf document as stops to replace the useless stock plate. Those plates are used to position the drill flutes in the attachment. There are 3, one for small drills, one for medium, one for large
- a set of tables with precise dimensions was created (also in the pdf) that specify stick out (flute edge to plate) based on helix rate, and attachment stick out (based on drill diameter)
- the main angle is set to 14 degrees for 118 degree drills and 22 degrees for 135 degree cobalt drills
- secondary angle is set square to the wheel with a help of a test rod that is accurately faced. Allegedly extra 3 degrees are added there for drills under 5mm
- a method to grind additional faces on cobalt drills (6 face method) is described. I haven't tried it. I'm sticking to 4 face method as it is much easier.
The 4 face grinding process requires no repositioning for each face. The settings are set. Then one feeds the wheel in and makes a swinging motion with the attachment. Both faces on one side of the drill are ground as well as the web is defined. Then one turns the drill around, repeats those moves and it's done. It's a very quick method if one has a printout of those tables on hand. It is even faster if multiple drills of the same diameter are sharpened.
There are drawings in the pdf that describe all the angles, the relations etc.
As mentioned I've had very good results with this method with drills over 5mm. Initially I had my drills cut oversize, but then I got the hang of it and they're right on point. However I can't get 4mm drill to work. It looks the part, but it gets destroyed when entering the material (mild steel plate).
So I wonder, how many of you know and use this method? How many of you have this attachment and not use it due to a lack of proper instructions. Hopefully this information will spread further and it will be refined to make small drills to work too.
I'm also interested if there are any hss end mill sharpening manuals for this grinder
I've been using Luc Wybo method that works great for drills of 5mm and bigger, but I can't get 4mm and smaller to work despite adding an extra 3 degrees clearance as described in the pdf doc. If anyone knows how to get those smaller drills to work please let me know.
First let me clarify for those that don't know what I'm talking about.
This is the tool cutter grinder I'm talking about:
This is the attachment:
Now, there are various videos online showing drill sharpening on it, but most of them are quite useless. They omit a lot of info, they obscure what they're doing etc. But, there is one youtube creator that took the time to write a pdf document alongside his video. His english is ok-ish. I can understand what he says and writes, but his written descriptions could be better. Still, he is the only person in the know that took the time to share this knowledge so he has my thanks for it. His youtube channel (and I assume his name) is Luc Wybo. I strongly recommend anyone interested to start by reading the pdf here: https://drive.google.com/file/d/11gtweV-mVcSftFvA3ZSR8xOS-gqZyFhX/view
Also attached.
Then the youtube video here
The method can be briefly described as:
- 3 small 1.5mm (60 thou) sheet metal plates have to be made, drawings are in the pdf document as stops to replace the useless stock plate. Those plates are used to position the drill flutes in the attachment. There are 3, one for small drills, one for medium, one for large
- a set of tables with precise dimensions was created (also in the pdf) that specify stick out (flute edge to plate) based on helix rate, and attachment stick out (based on drill diameter)
- the main angle is set to 14 degrees for 118 degree drills and 22 degrees for 135 degree cobalt drills
- secondary angle is set square to the wheel with a help of a test rod that is accurately faced. Allegedly extra 3 degrees are added there for drills under 5mm
- a method to grind additional faces on cobalt drills (6 face method) is described. I haven't tried it. I'm sticking to 4 face method as it is much easier.
The 4 face grinding process requires no repositioning for each face. The settings are set. Then one feeds the wheel in and makes a swinging motion with the attachment. Both faces on one side of the drill are ground as well as the web is defined. Then one turns the drill around, repeats those moves and it's done. It's a very quick method if one has a printout of those tables on hand. It is even faster if multiple drills of the same diameter are sharpened.
There are drawings in the pdf that describe all the angles, the relations etc.
As mentioned I've had very good results with this method with drills over 5mm. Initially I had my drills cut oversize, but then I got the hang of it and they're right on point. However I can't get 4mm drill to work. It looks the part, but it gets destroyed when entering the material (mild steel plate).
So I wonder, how many of you know and use this method? How many of you have this attachment and not use it due to a lack of proper instructions. Hopefully this information will spread further and it will be refined to make small drills to work too.
I'm also interested if there are any hss end mill sharpening manuals for this grinder