Need a secondary face angle gauge, and benefits in time

[Mackdan]

I'm new to the forum. I've had a DBS-22 for about 2 weeks, but I've been sharpening all my metric and standard bits (about 300).  On  a T-7.

The secondary angle grinding is somewhat random. Its based on setting the slider table at a not quite horizontal position. I've been setting it by putting the drill bit holder onto the secondary position and bringing the table up so the bit starts to hit the grinding wheel. Again this is still somewhat random based on the protrusion of the bit from the bit holder and the size of the bit and the position of the adjustment for the primary facet grind.
The secondary face just needs to be at a greater angle to the cutting edge than the primary angle. Using the recommended procedure I would guess that the secondary angle is about 28 degrees (very rough estimate) down from perpendicular to the grinding face. The jig gives us settings of 7, 9, 11, and 14 degrees down from perpendicular to the grinding face.
So i tried sharpening some of my good german metric bits with a 130 point angle, and using the 9 degree primary facet angle, then setting the secondary angle at 14 degrees. (5 degree delta) I also tried 9 and 11 (2 degree delta) but the line between primary and secondary faces is not really discernible so its hard to get a good center point.
Advantages: 1. This allows me to have a very repeatable secondary angle, so in the future I will hopefully be able to grind on the bits less to achieve both a new sharp primary facet, and the secondary facet.
2. I can set the DBS-22 base plate angle, sharpen one bit, primary, then adjust angle for the secondary facet, and using the Primary Stop, finish the 1st bit; then immediately start on the second bit with the secondary facet. When that is finished, I turn off the machine, reset to the primary angle and finish grinding that bit, and then start on the next bit. This saves a lot of time in resetting the DBS-22 table 2x for each bit. Instead of setting the angle 2x for each bit (primary and secondary), I only set it 1x for each new bit, thus saving time.

Problem:
A.  I noticed that while the angles were cut, the bits didn't seem right. The secondary cut heel (lowest part) wasn't really the lowest part of the bit. So the bits weren't cutting, they were riding on the heel of the secondary cut. I attribute this to the curved surface of the grinding stone and the long edge at the outer edge of the bit, and the low secondary angle.

So I went back to the original method, and recut those bits with a larger secondary angle. They work great.
I think the secondary angle needs to be more than 5 degrees, and probably more than 7 degrees (7-14=7), because I tried that set up too.
So how much difference is required between the primary and secondary facets when using a DBS-22 on a T-7 type machine?

I 3d print stuff. So I'm going to make a ~ 20 degree delta plastic guide (27, 29, 31, 35) and maybe a 28 degree delta plastic guide and try those out. In the mean time, lets hear some thoughts.

[RichColvin]

Dan,

The document, "Drill Bit Geometry", by Joseph Mazoff is a truly great reference about drill bit geometry.  Here's a link:

http://www.newmantools.com/machines/drillpoint.html

May not answer your question, but it is the best I've seen yet.

Kind regards,
Rich

[Jan]

Mackdan, I do not have the DBS-22, I use my simple homemade jig for drill bit sharpening. https://forum.tormek.com/index.php?topic=3226.msg26866#msg26866

Following Joseph Mazoff I use 20° clearance angle for the secondary facets.
(Quote from J. Mazoff: "Primary facet angles is determined by the nature of the material being drilled while secondary facet angles are at 20°.")

Jan

P.S.: Currently I use the diamond wheel DF-250, the platform is mounted to the side of the diamond wheel using multi base MB-100.

[RickKrung]

Mackdan, I do not have the DBS-22, I use my simple homemade jig for drill bit sharpening. https://forum.tormek.com/index.php?topic=3226.msg26866#msg26866

Following Joseph Mazoff I use 20° clearance angle for the secondary facets.
(Quote from J. Mazoff: "Primary facet angles is determined by the nature of the material being drilled while secondary facet angles are at 20°.")

Jan

P.S.: Currently I use the diamond wheel DF-250, the platform is mounted to the side of the diamond wheel using multi base MB-100.

Jan, what do you do for small/tiny drills?  Asked another way, what is the smallest drill you can effectively sharpen with your platform?  I would think they would have to be long enough to stick out the end so they can be gripped. 

I have the DBS-22 and while it says it goes down to 1/8", I have found it difficult to use with that small of drill.  Mostly, my difficulty is with getting the drill lined up properly.  A while ago, I came up with the idea of using a pin vise for holding small drill, even smaller than 1/8".  I've not found commercially available pin vises that work well enough, mostly due to the fact that they come with some form of knurling, which doesn't work well with gripping them in the clamp/holder.  It is pretty far down the heap of things to do at this point, but I figured I'd have to make a pin vise without the knurls. 

In regard to using the diamond wheels, how are you finding them for flatness on the side?  I was very excited to get the diamond wheels, thinking they would be great for drill bits, particularly for getting to the 1200 grit.  I was dismayed to find the outer surface flat across it, at least for the DF wheel.  I got pulled away and haven't gotten back to it and I believe that was before I had the MB-100 Multi-Base. 

Hand holding, you may not have the same circumstance to feel whether it is flat or not.  The DBS is guided by a stop while the holder passes across the wheel, resulting in the bit to travel in a true flat plane (assumed) and allow for the detection of the unevenness of the wheel surface. 

I have been following Mapzoff's process since coming across the article, even before I had the DBS-22, which was almost immediately upon getting a Tormek, as drill bit sharpening was a major rationalization point for getting one. 

Rick

[Jan]

Rick, the smallest drills I sharpen are 4 mm = 1/6" provided they are long enough to be gripped. I have the same difficulties you have, namely to line up the drill bit correctly. I have an additional difficulty to flip the drill bit exactly by 180⁰. For this reason I purchased hand wise with rotating handle but I have not used it until now.

I am quite satisfied with the flatness of the side of my diamond wheel. The major advantage for me is that the angle setting is very simple and transparent.

Jan

[RickKrung]

Rick, the smallest drills I sharpen are 4 mm = 1/6" provided they are long enough to be gripped. I have the same difficulties you have, namely to line up the drill bit correctly. I have an additional difficulty to flip the drill bit exactly by 180⁰. For this reason I purchased hand wise with rotating handle but I have not used it until now.

I am quite satisfied with the flatness of the side of my diamond wheel. The major advantage for me is that the angle setting is very simple and transparent.

Jan

Interesting vise.  I like it for the clamping force it looks like it would exert.  It looks like it would be very handy for for holding small parts, particularly for grinding/sanding, etc.  I would like to have one, I think.  Is there a name on it?  Where did you get it? 

I am not sure how you would use it for drill sharpening, for a couple reasons.  First, how would you hold a small drill bit in the center?  Does the screw shaft have a center hole that the drill shank would go into?  I see the handle has the flats.  How well centered are they with how the drill would be held? 

Are you familiar with collet blocks?  I have a cheapo asian set, square and hex.  They are very handy for holding round things when you want to perform operations on particular sides with precision on the angles of those sides.  I would think a square one would be quite the ticket for working with all sized drills, but especially small ones where you cannot easily see how the lips are oriented and equally difficult to maintain said orientation.  If I were using a platform jig for drill sharpening, you can bet I'd be using one of these. 


I know only of these for 5C collets, which are quite ubiquitous in the machine tool industry.  5C collets come in 1/64" increments in imperial units.  I do not know what the increments are in metric. 

Rick

[Mackdan]

Rich,
Thanks, I've read that document several times. I was going to try and build a semi automated drill sharpener with a computer controller. But then if found and decided to just get a Tormek. I have to many other things to do right now. However I have a lot of bits to sharpen so being efficient is a key right now. Once I get them sharpened, then I can spend time occasionally resharpening as needed. That resharpening will go faster if I write down the primary and secondary angles on the box of bits.

I made a plastic guide that looks like a bigger version of the Tormek primary face angle guide and 3d printed it. It actually didn't turn out very well, my printer nozzle was getting clogged up with something (dirt most likely). Its a +20 degrees to primary angle guide. (27, 29, 31, 34 degrees). That was pretty close to the secondary angle I was getting by just setting the secondary angle manually. I then made a +13 degree guide, which I'm trying out right now. So its 20, 22, 24, and 27 degrees down from perpendicular to the grind stone.

Dan,

The document, "Drill Bit Geometry", by Joseph Mazoff is a truly great reference about drill bit geometry.  Here's a link:

http://www.newmantools.com/machines/drillpoint.html

May not answer your question, but it is the best I've seen yet.

Kind regards,
Rich

[Jan]

Rick, my small hand vise clamp you can find e.g. here"
https://www.amazon.com/slp/hand-vise/jrgkh85f7nfc4s4
The clamp for small drill bits only, the jaws open to some 6 mm = 1/4" and the central hole entrance is only some 4 mm = 1/6".

Thanks for your suggestion to use the collet blocks. I think that the square collet block with a suitable set of collets may solve my problem. It will allow to line up the drill bit properly and also flip to the other cutting lip easily.

Small drill bits are so inexpensive that I have inhibitions to invest too much money and energy in the drill bit sharpening equipment. Even more the factory sharpened small drill bits usually drill better than after my sharpening.

Jan

[RickKrung]

Rick, my small hand vise clamp you can find e.g. here"
https://www.amazon.com/slp/hand-vise/jrgkh85f7nfc4s4
The clamp for small drill bits only, the jaws open to some 6 mm = 1/4" and the central hole entrance is only some 4 mm = 1/6".

Thanks for your suggestion to use the collet blocks. I think that the square collet block with a suitable set of collets may solve my problem. It will allow to line up the drill bit properly and also flip to the other cutting lip easily.

Small drill bits are so inexpensive that I have inhibitions to invest too much money and energy in the drill bit sharpening equipment. Even more the factory sharpened small drill bits usually drill better than after my sharpening.

Jan

Thank you for the link. I have ordered one.

5C collets are the most common and the least expensive, but given the narrow gripping range require a few more collets to cover the range.  I have found the collet block to be a must have for certain types of operations.  I do understand that it is a significant investment, so not as easily justified for many. 

I am with you on the relative worth of trying to sharpen small drills vs buying new ones.  Perhaps the matter with sharpened ones not cutting as well is more an issue with how they are sharpened and could be rectified with better holding mechanism/device, such as the collet block.  Alas, even with something like the collet block, there is still the matter of getting uniform lips.  I think this is why, when I ever get back to messing with small drills, I'll be glad for the DBS-22 jig as it attempts to control uniformity of the two lips.  The mass of a collet block setup may hinder the "feel" of grinding on such small points/surfaces as small drills and the DBS-22 jig has this situation as well.  A 5C collet block is also a bit large and may block visibility of the drill bit point, hindering effective sharpening. 

3C collets are a good bit smaller than 5C.  Unfortunately, I do not know of any collet blocks available for 3C, so one would have to make their own.  Same goes for the jeweler's or "Wire Collets", which are very much smaller.  I was on the hunt for some of the latter.  They are available, but this is low on the priority list right now.   

Rick

[Elden]

Here is fellow's approach to small bits.

https://www.homemadetools.net/forum/sharpening-tiny-drills-27187#post36588

Here is a thread about small bits.

http://www.chaski.org/homemachinist/viewtopic.php?t=103087

[Jan]

Thank you Elden for the interesting links!

Jan

[Jan]

Rick, the inspiring discussion with you concerning collet blocks moved me to finish my older idea to guide the drill bit in an aluminium block. The drill bit is fixed by a small set screw. This simple solution will help me with proper drill bit alignment and also with the proper flipping of the drill bit. It would be optimal to prepare the drill bit guides for several diameters.

Jan