Hello everyone,
I'm new here. Just purchased a T8 :-)
I wonder how I can sharpen a countersinck.
Anybody?
Thanks a lot!
Serge
Welcome to the forum, Serge. I believe you will find your new T8 is a very versatile machine. I don't know if could be used to sharpen a countersink. I would probably start with my file drawer. If a metal file didn't do the trick, I would use an India or Arkansas file.
Enjoy your new Tormek, and keep posting.
Ken
Welcome to the forum, Serge! :)
I think TORMEK is not entirely suitable for sharpening countersink. However, you can try the following method of freehand sharpening:
1) Draw a line on the stone along the lowered USB
2) Use the USB as a tool rest
3) Align the cutting edge to the line on the stone
4) Use the marker method to set the angle
5) Remove the burr
Jan
Quote from: Jan on December 28, 2016, 12:52:11 PM
Welcome to the forum, Serge! :)
I think TORMEK is not entirely suitable for sharpening countersink. However, you can try the following method of freehand sharpening:
1) Draw a line on the stone along the lowered USB
2) Use the USB as a tool rest
3) Align the cutting edge to the line on the stone
4) Use the marker method to set the angle
5) Remove the burr
I am thinking that without turning the countersink as it is being ground, you are going to create a flat or at least a concavity behind the cutting edge of the countersink. In so doing, the rest of the countersink that was not ground in sync with the edge will be a raised area. The raised area would then prevent the countersink from contacting the hole the be countersunk. Unless of course you "wallowed" out the hole by not holding the countersink at a 90 degree angle to the target. So, if I am right, then the Tormek is not the best choice for this. If however, you chucked the countersink into a drill and maintained concentric contact with the spinning grinding wheel, I can see it working although over time the size of the countersink would be reduced.
Jan
Yes Jeff, you are correct, when we remove too much steel from a conical countersink cutting edge the tool may be destroyed. :( Thank you for pointing it out! :)
What I recommend is only to touch the stone along the edge of the tool under an angle shown by the marker method. I recommend sharpening away from the edge on a stone graded fine.
It is important to sharpen the inner side of the cutting edge also. For this I use a fine triangular ceramic file.
In this way I have prolonged the life of two countersink cutters. They do not cut iron as new but they serve quite well.
Jan
P.S.: Using the base of the scissors jig as a tool rest helps to maintain the same angle for all flutes of the countersink.
Which type of countersink? I agree that none would be easily done. :(
A couple more.
You are correct, Elden, they are many types of countersink cutters.
My experience is limited to 3-fluted countersink cutters of about 1" diameter and 90° chamfer angle.
Jan
Quote from: Jan on December 28, 2016, 08:31:29 PM
Yes Jeff, you are correct, when we remove too much steel from a conical countersink cutting edge the tool may be destroyed. :( Thank you for pointing it out! :)
Jan
Jan, I just realized a problem with my comment. I am sure that you caught it but others may not have. I assumed that you were going to be sharpening on the conical part of the countersink. Whereas the proper sharpening position would be on the vertical plane which is 90 degrees to the conical portion. Well, actually it could be 45 for a 45 degree countersink or various other degrees depending on the desired outcome. In other words, the cone is half the degree of angle of the countersink. So, if you sharpen the vertical plane; you eventually reduce the size of the countersink but do not decrease the angle of the cut. At some point if you wanted a one inch wide countersink and you have repeatedly sharpened the cutting edge from the vertical, you would come up short.
The attached pictures show 3-fluted countersink. The blued area shows the inner side of the cutting edge which I sharpened using fine triangular ceramic file. The red line shows the outer side of the cutting edge which I have sharpened/flattened by touching the grinding wheel.
Jan
Yes, inner edge from the inside. I am wrong again.
No problem, Jeff! :) It is best to think about the issue from all sides.
Once Herman wrote, "I find it hard to think in three dimensions". Most certain for me is to hold the 3D object in my hand.
Jan
Hi guys!
Thanks for your input.
I was talking about 3 fluted countersinks.
I thought I had to sharpen the cone, but some say I should sharpen the flat inner side. Are they right?
Thanks,
Serge
I found this pic on the site of a manufacturer of professional grinding machines...
(http://kaindl.de/media/catalog/product/cache/1/image/487x487/91425abecabbe831b2f095c8fd88309a/b/s/bsg-60-1-hp-kopie-kopie.jpg)
Serge, both sides of the cutting edges should be sharpen. The outer (conical) side can be sharpen on Tormek along the red line. The inner side shown in blue can be sharpen using a file.
Do not remove much steel from the conical outer side, touch the grindstone only.
Jan
Jan... shapen by hand? No jig availale?
Serge, you are correct, without special sharpening device, the described procedure is only an attempt to prolong the life of the countersink not its real sharpening. :-\
I do not have the Tormek Drill Bit Sharpening Attachment so I cannot tell you if this could be used for countersink sharpening or not. Do not hesitate to answer the Tormek support.
Jan
I once watched a knowledgeable Tormek sharpener fumble with trying to sharpen a very dull small parting tool. He was trying to follow the standard Tormek practice of using the multi jig. That procedure works well with standard parting tools. This smaller parting tool did not stay secure in the jig.
I was the junior member, so I did not speak up. I would have just rested the parting tool on the support bar and sharpened it freehand. It would have been sharp "in no time".
I like jig sharpening. However, sometimes it is more efficient to carefully freehand sharpen something. With thought, care, a fine graded wheel and a light touch, the job is usually quickly done.
Do not sell handheld sharpening short.
Ken
I'm going to make my own jig...
When it's finished I'll show pictures :)
Great idea, Serge. Several of us have made and shared jigs. We all benefit from this!
Ken
Here is one person's approach to sharpening a single fluted countersink. While not a rock solid approach as the machines that can be seen from doing a search for "sharpening a counteracting", he achieved good cutting results.
https://m.youtube.com/watch?v=26DSNBclJKk
Thank you Elden for posting the link to this video. I like the fence used to guide the chuck with the countersink at the desired angle. Clever and inspiring solution. :)
Jan
Quote from: Ken S on January 01, 2017, 05:06:50 PM
Do not sell handheld sharpening short.
Ken,
I am a HUGE fan of
repeatability. With the cutting edge consistently the same, I get consistent results when turning. So I'm not a fan of freehand sharpening.
The Tormek jigs make repeatability possible. I have great luck when using them.
Kind regards,
Rich
Rich,
I totally agree, however, at this point, and the foreseeable future, there is no Tormek jig for countersinks. For a one off, or rarely needed sharpening job, I have no problems with skillful handheld sharpening. In my pre Tormek, pre Veritas sharpening jig days, I did a lot of handheld shsrpening. Like you, I prefer the precision of a well designed jig.
Ken
Ken,
Sounds like an opportunity for the KenJig developer...
Rich
Good idea, Rich. Unfortunately, unlike Thomas Edison, I don't have the luxury of making simple drawings and turning them over to John Kruesi (Edison's chief machinist). Edison also had almost thirty machinists on his staff at Menlo Park. Edison's phonograph was one of those sketches given to Kruesi.
And, unlike some of our members, I don't have the luxury of having a machinist in the family....... :)
Ken
I bought a set of these three-fluted countersinks and I find that they do not produce a very smooth bore. Are these intended only for use on a drill press?
Quote from: Jan on December 29, 2016, 05:28:44 PM
Once Herman wrote, "I find it hard to think in three dimensions". Most certain for me is to hold the 3D object in my hand.
Just so you know, Jan, I stole that from Stephen Hawking. In his book,
A Brief History of Time, he talks about the difficulty of thinking in four dimensions, stating that he already has a hard enough time thinking in three.
Explanation appreciated, Herman! :)
Quote from: Herman Trivilino on January 10, 2017, 01:46:48 AM
I bought a set of these three-fluted countersinks and I find that they do not produce a very smooth bore. Are these intended only for use on a drill press?
Based on my experience countersinks require firm pressure and perfect perpendicular alignment what is tough to do by hand. For smooth bore the countersinks should be run very slowly and a cutting fluid should be used. ;)
Similarly to drill bit, countersink cutting edge must have a relief angle also (typically 5 to 8°). Relief behind the cutting edge has even to be slightly larger and must continue around the conical surface segment of the countersink's tip.
Jan
Serge, I was inspired by the videos mentioned in this topic and prepared very simple jig for countersink sharpening on Tormek.
The most important is that the jig enables to set the relief angle of the cutting edge. I have used 7°. ;)
The first picture shows that the jig consists of short Al rod attached to the tool rest.
The second picture shows that the countersink really cuts with the cutting edge and the relief behind the edge is sufficient. After test countersinking the marker was removed only along the cutting edge and not from the conical surface behind it. :)
Jan
Excellent work, Jan!
Ken
Thank you, Ken! :)
To set the lip relief (clearance) angle Tormek uses the DBS-22 setting template. This may be used in our case only if the height of the countersink centre above the USB is near to the corresponding height of the DBS-22.
My clearance angle setting method takes the drill bit diameter or height of the countersink centre above the base/USB into account. http://forum.tormek.com/index.php?topic=3226.0
Jan
Prototype almost ready!
Pictures follow soon.
Serge
Here it is!
Assemble 2 tool supports like this...
Pic 1 normal view
Pic 2 top view
Pic 3 front view
Pic 4 side view
Pic 5 bottom view
A steel tube, 12mm external, 10mm internal diameter
Pic 6
Place the tube in the upper tool support. Stick out in front 1mm to avoid friction with the tool support. Pay attention that the tool support has been shortened 15mm (otherwise long counter sinks won't fit)
Pic 7
The tube should stick out about 15mm at the back.
Pic 8
Make an 'L', as wide as the sharpening stone, height 77mm, as deep as the tool support. And 2 bolts 3mm diam. Pay attention to the white line, this will be the reference to the top of the tool support.
Pic 9
Fix the 'L' to the upper tool support. The height of the 'L' above the upper tool support must be 51.5mm (explanation later)
Pic 10
Make a ruler, 30 cm long, 4 cm high, 4-5mm thick and provide a hook.
Pic 11
This is the ring between the grinding stone and the machine. We are going to use it to set a correct angle of the tool support so that the axis of the countersink goes through the axis of the grinding stone. This ring is 36mm in diameter And the height of the axis of the countersink is 33.5mm. 33.5 + 36/2 = 51.5mm. This is the height of the 'L'.
Pic 12
Now, use the ruler you made, put it on the 'ring' and align the tool support with the ruler. Now we are sure the axis of the counter sink goes through the axis of the machine. This is needed to correctly set the horizontal angle for the counter sink conus.
Pic 13
Then, take a steel bar, 10mm diam. ⅜ thread in front for a chuck, M10 thread at the end. Fix a chuck as short as possible (I found one from Makita).
Pic 14
Place the steel bar with chuck in the jig.
Pic 15
Place a spring, a washer and a nut.
Pic 16
Assemble and fix a hand wheel. Ready!
Pic 17
Pictures: https://www.dropbox.com/sh/veofqyl9pnkzfcq/AACdxjfexZaYbzP5bZqOfHeoa?dl=0 (https://www.dropbox.com/sh/veofqyl9pnkzfcq/AACdxjfexZaYbzP5bZqOfHeoa?dl=0)
How does it work? Tomorrow...
Serge
Oh, I forgot the last picture... This is how it looks like as a whole:
https://www.dropbox.com/s/htttsm12riyq7r4/Jig-18.jpg?dl=0 (https://www.dropbox.com/s/htttsm12riyq7r4/Jig-18.jpg?dl=0)
Since the jig can't move sideways during sharpening and because countersinks are hard, a standard grinding stone soon shows scores. Therefore I think a black stone is recommended.
I did a few tests... although the cones are perfectly sharpened, the sinks don't cut well. I know why: in between 2 flutes, the sink drops to the grinding stone and the cutting edge is rounded. I see 2 solutions:
1 after sharpening the cone, sharpen the inner side of the cutting edges with the jig in a 90° position and at the edge of the grinding stone. Difficult to do well!
2 modify the jig so it retracts the sink just at the cutting edge. I don't know yet how to do that :)
Serge, excellent countersink jig, congrats!.
Thanks for posting the detailed description and many pictures. Appreciated. :)
In my opinion the reason why the countersinks do no cut well may be absence of sufficient relief behind the cutting edges. Similarly to drill bit, countersink cutting edge must have a relief angle also (typically 5 to 8°). Relief behind the cutting edge has even to be slightly larger and must continue around the "conical" surface segment of the countersink's tip. Strictly speaking it is not an exact right cone!
I have used the marker method to find spots where additional steel has to be removed. ;)
Good luck in tuning the final details!
Jan
Hello Jan,
Any idea how a m
Hello Jan,
Any idea how a relief angle can be achieved? I have no idea (yet).
Serge
Serge, in my case there was some play in the jig, so it was sufficient to apply more pressure behind the cutting edge.
In your case the jig play is probably much smaller and so you can proceed similarly as when grinding a secondary facet on a drill bit. It means you enlarge the clearance angle by some 10 degrees and grind off segment of the "conical" surface behind the edge. It may be necessary to repeat this procedure for larger countersinks.
Use the marker, blacken the whole countersink surface and make a test countersinking. If the marker is removed from the conical surface you need to remove more steel here.
Jan
You were right about the relief angle Jan! It now cuts like crazy :)
Here is the proof with the marker: https://www.dropbox.com/s/dn9dwqv05fwynkv/jig-19.jpg?dl=0 (https://www.dropbox.com/s/dn9dwqv05fwynkv/jig-19.jpg?dl=0)
Serge
You are welcome, Serge, I rejoice with you that the added relief helped to resolve the issue! :)
Jan
Quote from: Jan on April 28, 2017, 09:51:37 AM
In my opinion the reason why the countersinks do no cut well may be absence of sufficient relief behind the cutting edges. Similarly to drill bit, countersink cutting edge must have a relief angle also (typically 5 to 8°). Relief behind the cutting edge has even to be slightly larger and must continue around the "conical" surface segment of the countersink's tip. Strictly speaking it is not an exact right cone!
Jan
Quote from: Serge Nelissen on April 28, 2017, 12:16:46 PM
Hello Jan,
Any idea how a relief angle can be achieved? I have no idea (yet).
Serge
Quote from: Jan on April 28, 2017, 01:42:32 PM
Serge, in my case there was some play in the jig, so it was sufficient to apply more pressure behind the cutting edge.
In your case the jig play is probably much smaller and so you can proceed similarly as when grinding a secondary facet on a drill bit. It means you enlarge the clearance angle by some 10 degrees and grind off segment of the "conical" surface behind the edge. It may be necessary to repeat this procedure for larger countersinks.
Use the marker, blacken the whole countersink surface and make a test countersinking. If the marker is removed from the conical surface you need to remove more steel here.
Jan
I didn't really follow the above conversation. But, I believe what you need is some sort of cam that guides the countersink in that conical path, although it is a gradually changing conical shape and needs to continue for around 270 deg. in the case of a single fluted countersink. This is how Drill Doctor does it (see photo) (except the DD photo shows a cam designed for a two fluted drill, so it is much shorter.
Rick
Rick, you are, of course, correct! :)
My approach was guided by the idea to keep the solution versatile (e.g. what concerns the number of flutes) but as simple as possible. My intention was to replicate the existing edges only. Countersinks are usually made off hard steel and so my wish was to remove minimum amount of steel.
In my opinion the cam guiding approach may result in in re-grounding the countersink.
Jan