Page 2 of 2 FirstFirst 12
Results 16 to 29 of 29

Thread: Skew grind Angle - newbie Here!

  1. #16
    Join Date
    Sep 2013
    Location
    Wayland, MA
    Posts
    1,057
    It's one of these: https://www.sharpeningsupplies.com/N...tone-P180.aspx in medium or fine grit--the markings on it are long gone.

    Probably not ideal, it is just a stone that I've had around the shop since who knows when that is a convenient pocket size. I'm sure there are better choices!

  2. #17
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    4,794
    Quote Originally Posted by roger wiegand View Post
    It's one of these: https://www.sharpeningsupplies.com/N...tone-P180.aspx in medium or fine grit--the markings on it are long gone.
    Probably not ideal, it is just a stone that I've had around the shop since who knows when that is a convenient pocket size. I'm sure there are better choices!
    I used the Eze-Lap diamond paddle-shaped hones (the blue, extra fine) for refreshing turning tools. I like the control I get by putting my forefinger above the active honing area which lets me feel for the contact with both the edge and the heel of the bevel. I use these so often I bought a lifetime supply directly from the manufacturer at a significant discount.

    hones.gif

    I knock off any burr on the inside of the flute of gouges using a tapered round diamond hone: https://www.amazon.com/DMT-DCSFH-Dia.../dp/B00004WFT1
    I also rub polishing compound on the rougher side of a piece of resawn MDF and strop the cutting edges of skew chisels for a polished edge.

    After several honings the flat on the hollow-ground edge gets wider and changes the geometry of the tools a bit so I go back to the bench grinder.

    JKJ

  3. #18
    Join Date
    Sep 2013
    Location
    Wayland, MA
    Posts
    1,057
    That's a good idea-- I even already have a set of them!

  4. #19
    This is a go to video for me and the skew. First half is with the skew and catches, well, how to cut as well, second half is with bowls and gouges. Richard's skew does not appear to be a 20/20 grind, but more blunt, maybe 25/25 or even 30/30, not sure. None of my skews are in the 20/20 category, and I am pretty sure most of them came with a 30/30 grind. Also not mentioned here is the convex grind that Eli Avesera uses. I found it easier to cut shallow curves when compared to a concave/standard grind skew, but not as good for long straight cuts. I may have to regrind another skew for the 20/20 grind...

    https://www.youtube.com/watch?v=jOvF5f1phhY

    robo hippy

  5. #20
    Join Date
    Feb 2008
    Location
    lufkin tx
    Posts
    1,881
    Skews make me nervous yeah.

  6. #21
    Quote Originally Posted by John K Jordan View Post
    .....

    After several honings the flat on the hollow-ground edge gets wider and changes the geometry of the tools a bit so I go back to the bench grinder.

    JKJ
    I've only been turning for about 12 months and am not a skilled operator with the skew but I do use one regularly. I have found that I have been getting a smoother planing cut since I started sharpening the skew on the side of the CBN wheel to give a flat rather than a hollow ground edge. That's a 1200 grit wheel on a tormek. I had been getting little vibrations, particularly on wood with irregular or interlocked grain, that was resulting in little spiral ridges on the surface. Dont know which deveolped first, the vibration or the uneven surface.
    My observation may be complete rubbish and the improve results could simply coincide with improving skill levels be I would be interested in comments of others.

    Tony

  7. #22
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    4,794
    Quote Originally Posted by Tony Allwright View Post
    I've only been turning for about 12 months and am not a skilled operator with the skew but I do use one regularly. I have found that I have been getting a smoother planing cut since I started sharpening the skew on the side of the CBN wheel to give a flat rather than a hollow ground edge. That's a 1200 grit wheel on a tormek. I had been getting little vibrations, particularly on wood with irregular or interlocked grain, that was resulting in little spiral ridges on the surface. Dont know which deveolped first, the vibration or the uneven surface.
    My observation may be complete rubbish and the improve results could simply coincide with improving skill levels be I would be interested in comments of others.
    Tony
    That's a very interesting observation! Gives me things to think about and experiments to do.

    I hate those spiral ridges but fortunately they are pretty rare. Once the wavy ridges start they are hard to get rid of since the bevel of the skew rides on the waves. I'll have to try sharpening one that way. I also have a 1200 grit wheel on a Tormek with grit on the side. It seems like sharpening a wide skew or one with a curved edge would be harder to do that way.

    I have always used a hollow ground bevel. It does make it easier to hone the skew by hand - you can press a flat hone between the sharp edge and the heel of the bevel to control the honing. If the heel of the bevel is riding on irregularities and amplifying the wave on the next pass it would make sense that the flat bevel might work better. Perhaps softening/rounding the heel of the bevel would help, the same as we do with spindle and bowl gouges - I might try that too.

    For the hollow-ground bevels I don't have any magic fix but I try different things until I find what works. Sometimes the fix does seem like voodoo. I think the waves can come from grain issues, flexing in the spindle, resonance, tool flexing, tool control, edge not quite sharp enough, or maybe an evil spirit. Or maybe two or three things at once, or something I haven't thought of. I had the same problem with a thin spindle and got a clean cut with turning the speed wide open, planing slower, and switching skews - I don't know which one of these did the trick, if it was one.

    If flexing, it might be controllable by better support (I use the left hand steady rest method), otherwise by planing at a different speed (perhaps much faster?) or by consciously pressing the skew more firmly into the tool rest while making the cut (and make sure the overhang is not too great). Sometimes a different size skew works better - thicker, smaller (smaller bevel), wider. A different speed can change the resonance.

    Since riding the bevel on the spirals just make it worse sometimes I'll make a cleanup cut with a method not usually recommended: with the very point of the short point of the skew. This will roll up fibers and may not leave a smooth surface but it can also take out the spirals and make the next cut better.

    Another thing I try when I run into a particular spindle that seems out to get me - a different skew with a larger or smaller included angle. Another thing that may help is varying the angle of the edge with the work, normally at about 45-deg, try making it larger or smaller. (Making it closer to perpendicular to the axis cuts poorly but can help with things like grain tearout on certain brittle woods.)

    If the piece permits I might also try planing the other direction and/or making the pass much slower.

    I've had others tell me about problems with these spiral waves. Maybe someone else has a suggestion. (I must consult with my favorite skew expert when I see him next week.)

    Anyone else using flat bevels, perhaps from sharpening on a belt sander?

    JKJ

  8. #23
    Join Date
    Jan 2018
    Location
    West Coast of WI
    Posts
    6
    Here's a thought

    If a skew is sharpened with either a hollow or convex grind you're going to have variable angles along the bevel. Add any small vibration of the work piece and it would be very feasible for any operator to have difficulty maintaining the exact angle / point of contact on the bevel. That could cause spiral ridges perhaps??? With additional passes over the ridges, the act of maintaining the same angle / point of contact would be magnified. A full flat grind would eliminate part of the problem by giving the user a consistent angle no matter what part of the bevel is touching the work.

    I sharpen with a belt grinder / sander because that is what I have from my knife making escapades along with a plethora of belts ranging from 36 grit ceramic all the way to leather impregnated with Tripoli compound. Whenever I resharpen a tool I start with a full flat grind. My process has been 60 grit ceramic belt if reshaping is needed, otherwise 240 grit, 400 grit, and 600 grit ceramic belts followed by leather belt honing. Touch ups and additional honing are done flat on the platen for gouges and skews get touched up on the slack portions of the belt. This means the skews end up developing a secondary convex bevel as they get used. If/when the secondary bevel grows more to more than about 1/8" I'll hit them with the 60 grit on the platen and take them back to flat again.

    Being new to the hobby, I've been very curious about the majority of people that turn sharpening on wheels rather than a belt grinder. I assumed it was because the cost for a bench grinder and wheels was less than a belt grinder and belts, is there something I'm missing?

    I've noticed the spiral like crazy when using a roughing gouge and drawing it away from the cutting edge. (i.e. gouge open to the left while drawing it to the right along the work)

  9. #24
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    4,794
    Quote Originally Posted by Smitty Searles View Post
    ...
    I sharpen with a belt grinder / sander because that is what I have from my knife making escapades ... Whenever I resharpen a tool I start with a full flat grind....Touch ups and additional honing are done flat on the platen for gouges and skews get touched up on the slack portions of the belt ... the skews end up developing a secondary convex bevel as they get used. If/when the secondary bevel grows more to more than about 1/8" I'll ... take them back to flat again....

    I've noticed the spiral like crazy when using a roughing gouge and drawing it away from the cutting edge. (i.e. gouge open to the left while drawing it to the right along the work)
    A convex grind is not often attempted. Some people round the bevel almost completely to allow a continuous cut even on the transition at the bottom of a bowl, but even then there is a "nearly flat" bevel although it is pretty narrow - maybe 1/16" wide or less. For example, Chris Ramsey teaches this grind for turning cowboy hats - it doesn't get much more challenging than that! This is a poor cell phone photo of Chris's gouge - I highlighted the bevel in red since it's hard to see. If I remember correctly this is a 3/8" bowl gouge. (He sharpens free-hand with no jig.)

    Ramsey_gouge_comp.jpg

    Mike Darlow, in his book Fundamentals of Woodturning, describes using a belt grinder for sharpening. Where he comes from they call it a "linisher". I tried to buy one once and it was too expensive so I think cost is part of the issue for woodturners. Another issue is as mentioned, the ability to easily hone an convex grind multiple times before resharpening. Sorby markets their ProEdge belt sander to woodturners but it is pretty pricey, even before buying the accessories and spare belts. I'm sure some that read this forum have one.

    I also have a belt machine made for sharpening knives and it puts an incredible edge on them. It uses two "sanding" belts, one ceramic one very fine, and a buffing belt. The belt is only 1" wide. It is made for knives so I would have to devise some kind of tool rest for lathe tools.

    For me the grinders and the Tormek work very well. Don't misunderstand, as I mentioned, the spiral issue is pretty rare and it may be somewhat related to experience. To test different grinds I was imagining it might even be difficult to recreate for testing without picking the right wood.

    I'm trying to imagine a sharp skew with a secondary convex bevel added to a flat bevel. Seems like that would significantly change the geometry of the cut which might make interesting issues at high speed with hard woods. I don't know anyone who sharpens that way for turning. Exactly what happens to the cut and the tool control (for planing, peeling, facing cuts, pommels, and deep v-grooves) when the smooth convex secondary bevel reaches 1/8"?

    You should not get a significant spiral with a roughing gouge if moved with the spindle turning at high speed, best either angled into the cut or 90-deg to the axis. The wavy spiral with the skew is a different issue. If you move the roughing gouge rapidly, backwards, forwards or straight, you do get rough spirals but they are gone on the next pass or the first pass with the skew or spindle gouge. BTW, I turn most spindles with the speed wide open on my lathes, over 3000 rpm. Also, I tend to use the skew for roughing the square into a cylinder and save the roughing gouges for curves (and for students). A 1-3/8" skew with a 40-deg included angle is perfect for roughing.

    JKJ

  10. #25
    Join Date
    Oct 2008
    Location
    Kapolei Hawaii
    Posts
    2,683
    You guys forgot to mention another use for a skew... A weeder....
    JKJ you have a great amount if info as many have already said. I'll toss in my $0.02. I don't think there is a "right" angle for a skew. It really depends on what you are doing. I have several skews, you can get them cheap from the bidding site. Some may have dirt on it from being used as a weeder..... I have several different skew angles and grind angles. Some are really long, i use that for cleaning off the nub on the jam chuck. Some are blunt. Use that for beads. I also encourage the use of a skew, and not be afraid of it. I'm no expert, but I practice using it. Its a good tool, and you should use it. The angles? If they seem good for you, then I think it's a good angle.They are easy to reshape and sharpen......

  11. #26
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    4,794
    Quote Originally Posted by Thomas Wilson80 View Post
    Thanks so much John. Great info and very understandable. Now I just need to get a skew and find the time to practice.
    I would love to swing by your shop, but it's a little far from Chicago (though I do have family Greeneville, TN so maybe some day....).
    Tom
    Greenville is right on the way! Not trying to twist your arm, but all shop visitors go home with some wood and if desired, a free skew and skew lesson. And you can take a llama for a walk, get stung by a bee, drive the tractor, help on the sawmill, grab some peacock feathers, shovel some manure...

    JKJ

  12. #27
    Join Date
    Jul 2017
    Location
    Northern Illinois
    Posts
    32
    Quote Originally Posted by John K Jordan View Post
    Greenville is right on the way! Not trying to twist your arm, but all shop visitors go home with some wood and if desired, a free skew and skew lesson. And you can take a llama for a walk, get stung by a bee, drive the tractor, help on the sawmill, grab some peacock feathers, shovel some manure...

    JKJ
    That would be incredible John - I'm sure you could teach me a lot. Not sure if we'll get down your way in the near future but now I have less reasons to avoid the in-laws!
    Tom

  13. #28
    I have thought that part of the spiral effect on spindles, or the bounce you get on bowls is from too much/hard bevel rubbing. I changed how I do that after seeing Ashley Harwood turn some of her finials for her sea urchin ornaments. She wasn't using her finger on the back side for a steady rest....

    robo hippy

  14. #29
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    4,794
    Quote Originally Posted by Reed Gray View Post
    I have thought that part of the spiral effect on spindles, or the bounce you get on bowls is from too much/hard bevel rubbing. I changed how I do that after seeing Ashley Harwood turn some of her finials for her sea urchin ornaments. She wasn't using her finger on the back side for a steady rest....

    robo hippy
    In one of his books Raffan mentions how to avoid too much pressure - he said if the supporting hand gets warm or hot, lighten up, you are using too much pressure on the skew.

    I use the left-hand-steady-rest method to control vibration even on squares that are not yet turned round - not nearly the problem it might seem but it does take a light touch!

    JKJ

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •