Skew almost killed me.. - Woodworking Talk - Woodworkers Forum
 
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post #1 of 15 Old 02-06-2016, 12:06 AM Thread Starter
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Question Skew almost killed me..

Hey again everybody, sorry I've been blowing up the forum lately. I've been playing with my lathe much more.

Anyways, I had a "catch from hell" this week with a 1" skew. The chisel started skating back toward me and as I pulled it away I hear a loud "CLINK" from the tool rest. I looked over myself and found a deep puncture wound on my left pinky, right beside a joint. What was strange is that it didn't bleed at all. I've had smaller cuts from carving tools that bled like crazy.

So, damage done, I looked into why it happened. I sharpened the skew using a Veritas skew registration honing jig on a Trend diamond plate and some Shapton stones, then stropped it a bit (goin' all out with Christmas gifts!). After using it for some time and doing lots of peeling cuts, I touched it up, free hand, on my bench sander with 1000 grit. I notice now that if I lay the chisel on a piece of wood between centers, the skew can't cut the piece unless the bevel heel is raised away from it... I'm pretty sure I messed it up free-handing it on the belt sander. Haven't had catches or problems before.

I found an article online explaining the same thing:

"When you hone, be careful to keep the bevel flat against the stone to avoid producing a convex curve right at the cutting edge. This rounding of the edge has a big effect.
With a rounded edge, the tool will not cut when the bevel is flat on the wood, or nearly so, because the actual edge is above the surface. To get it to cut, you have to rotate the tool more than normal, which brings the heel of the bevel well off the surface. This makes the tool harder to control and will likely give a much rougher cut. Further, because of the extra rotation, a runback is much more likely to occur."


I'm pretty certain this is the case. Anyways, are there any "training wheel" type of skews that lessen the chances of catches? Maybe a different grind when using a skew predominantly for planing cuts?

I'm also looking into chainmail gloves, lol.
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post #2 of 15 Old 02-06-2016, 02:52 AM
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Hey, we demand pictures of the problem! I sliced halfway into my pinky with a table saw, and my first thought before the doc stitched me up was "crap, I need to get a picture to show everybody"!

At any rate, sounds like you know about what caused the problem, although I'll admit I've never heard that before. Makes sense though. As far as slightly safer skews go, I wanna say I've heard that oval skews are supposed to be safer from catches, although I can't image that would help with your particular case

I would poo-poo the idea of the gloves though. For one, chainmail doesn't hold up well against stabbing, its more there to stop slashes (think a slash with a saber vs a stab with a rapier). For two, I think a stab would be vastly preferable to the gloves catching on the work and dragging your hand round and round

I need cheaper hobby
etsy.com/shop/projectepicfail
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post #3 of 15 Old 02-06-2016, 09:11 AM Thread Starter
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Quote:
Originally Posted by epicfail48 View Post
Hey, we demand pictures of the problem! I sliced halfway into my pinky with a table saw, and my first thought before the doc stitched me up was "crap, I need to get a picture to show everybody"!

At any rate, sounds like you know about what caused the problem, although I'll admit I've never heard that before. Makes sense though. As far as slightly safer skews go, I wanna say I've heard that oval skews are supposed to be safer from catches, although I can't image that would help with your particular case

I would poo-poo the idea of the gloves though. For one, chainmail doesn't hold up well against stabbing, its more there to stop slashes (think a slash with a saber vs a stab with a rapier). For two, I think a stab would be vastly preferable to the gloves catching on the work and dragging your hand round and round
Here's some soft-core gore for ya' then!

Good point about the gloves. I do sometimes wear leather gloves when doing roughing work where bark and chips are shooting every which way, but I'm on high alert to make sure my hands are behind the rest and away from the chuck. I also use gloves when hollowing. I have had a spinning piece get loose from the chuck while hollowing, escape a steady rest, bounce off of my hand, and land across the room. No injuries from that though. So I'll wear gloves, and try not to hollow a 15" long piece above 2,000rpm...

Maybe I can put a little plastic cover on the tip of the skew while using it to do planing cuts. Might help after I get the bevels flat again.
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post #4 of 15 Old 02-06-2016, 11:22 AM
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Sounds like you lost the bevel support, got a skate, and then got a catch (point into the wood).
When you free handed it you probably added a micro bevel or rounded it as the article stated.
Question, why did you go back to the sander, even at 1000 grit? It may not be right but I treat mine as a bench tool in that it only gets re-honed.
An oval skew may help but IMHO they are too light weight and more difficult to sharpen. I also tried a curved cutting edge and prefer just a straight edge. I found the curved edge harder to see the short point when rolling beads and much harder to hone.
I could link to a couple of good videos on why skates/catches happen with the skew. Since you "Haven't had catches or problems before" it seems you already know what caused this one and how to correct it.


I do wear gloves often but they are skin tight and very thin (aviator gloves) and the fingers are cut off at the middle joint.

They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety. Benjamin Franklin

Last edited by NCPaladin; 02-06-2016 at 11:39 AM.
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post #5 of 15 Old 02-06-2016, 12:45 PM
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I've seen a similar geometry with some wood carving tools. Your quote in Post1 is most revealing. Thank you.

To begin with, paint the bevel with black felt marker so you can follow the sharpening process.
I have a geologist's 10X magnifier to inspect the bevel & edge.
Time and time again, I can see a fine, fine ribbon of marker ink, right along the edge.
That tells me right away that I should use a slightly steeper process to get that
OR, I simply haven't taken off enough metal.
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post #6 of 15 Old 02-06-2016, 02:25 PM
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Quote:
Originally Posted by NCPaladin View Post
Question, why did you go back to the sander, even at 1000 grit? It may not be right but I treat mine as a bench tool in that it only gets re-honed.
It was too late to edit the above. I think "sander" threw me. In essence my honing plate is about the same grit so I can understand going back to 1000 to touch it up.

They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety. Benjamin Franklin
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post #7 of 15 Old 02-06-2016, 03:44 PM
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You Probably came off the bevel or let the cut get too far up on the cutting edge. You should always be cutting on the lower half of the cutting edge. You probably have a mico bevel from sharpening free hand but there's nothing wrong with that. Don't worry about not touching the bottom of the bevel when honing. I do try to touch the bottom just to keep my angles consistent but it's not important.
I have turned with skews that have a convex edge and it still works just fine. Here are a few of my skew videos that will hopefully show you something.
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post #8 of 15 Old 02-06-2016, 03:53 PM
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So, what you are trying to say is you got skewered.
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post #9 of 15 Old 02-07-2016, 01:17 AM
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Glad all is well now. I wanted to post this valuable video I found on YouTube. It really helped me understand catches with skew chisels and also found out how to better hollow out my bowls based on what he teaches.

http://youtu.be/jOvF5f1phhY
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post #10 of 15 Old 02-07-2016, 08:29 AM
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At the very beginning of the video the catch with the skew is pretty common. You can see him getting the cut higher on the cutting edge until it pulls the skew into the wood. The easier catch is when turning a bead. as you rotate the tool over the bead it is so easy to come off the bevel and get what I call a run back. kind of a catch but pretty predictable which direction the skew will go. That's why I developed the skew practice video showing turning barrels, then balls, then beads. It teaches you to roll the tool just enough but not too much. sure you'll get some catches when doing this but it's a piece of 2x4 scrap so who cares. Nick Cook who is a skew expert once said, all skews have a certain number of catches and you simply have to use them up. couldn't be said better.
Nick and I both love our oval skews. Most of the hype over an oval skew not being good is simply that. They can be harder to sharpen depending on how you hold them to sharpen. But I don't have any more chatter with that tool than I do my thicker Thompson tool. I've turned a 54" long cylinder that went from 16" down to 6" and cleaned up the last pass with the Oval skew. I've used it so much I'm just more comfortable with it. That's what I learned when I had the 17 tools in the types of skew video. It's not the tool shaft or the bevel grind or the angle of the grind that makes it a good skew. It's the one you practice with the most. That's the one that will work for you.
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post #11 of 15 Old 02-08-2016, 09:27 PM Thread Starter
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I resharpened the skew. The original angle was about 44 degrees total. I set my Veritas skew registration guide to give each side 20 (total of 40) and ended up with a 35 degree total. Maybe that happens when I sharpen it too long. I came up with a simple way to use the belt sander to speed up the process (see photos). The block of wood is the same height as the sand paper on the platform. After taking off some metal there, I hone it on a diamond plate for a few minutes. I tested it on the lathe and, yea, a lot more of the bevel was against the wood than before and no accidents today.. whoop whoop.
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post #12 of 15 Old 02-08-2016, 09:55 PM Thread Starter
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Quote:
Originally Posted by saculnhoj View Post
You Probably came off the bevel or let the cut get too far up on the cutting edge. You should always be cutting on the lower half of the cutting edge. You probably have a mico bevel from sharpening free hand but there's nothing wrong with that. Don't worry about not touching the bottom of the bevel when honing. I do try to touch the bottom just to keep my angles consistent but it's not important.
I have turned with skews that have a convex edge and it still works just fine. Here are a few of my skew videos that will hopefully show you something.
Thanks for the videos! Can you show different ways to use the bedan? I have one and love using it for tenons and rough shaping.
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post #13 of 15 Old 02-09-2016, 07:58 AM
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A skew only needs to be sharp. How flat the bevel is doesn't matter. Or for that matter even what shape the bevel is doesn't matter. When you practice with it you learn to use what ever it is. the belt sander is great for sharpening although I usually go through a diamond hone protocol to really get it sharp. The skew requires more subtle movement of the hands when guiding it around the workpiece and I think that's where most people get a catch. For example when I haven't been turning in a while I always have trouble cutting the bottom side of a bead. That rolling of the blade is just so critical. After I turn a few I get that very smooth subtle adjustment of the edge back and don't have any problems. You are obviously working to learn to use the skew and consequently you are learning how your grind works. Personally I like a 35 to 45 degree grind on my skews. I tried 25 and it's just challenging to use.
The bedan is used just like a skew but the edge is shorter and usually straight. Jean-Francois Escuelon is who I learned to use the bedan. He used it flat side down most of the time instead of bevel down. If you can find a video online of him turning you will probably see it. I have one. Rarely use it but it was part of my skew testing.
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post #14 of 15 Old 02-09-2016, 05:45 PM
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Another thing you may want to check is the spindle height of your lathe. Most folks like it about elbow height, I like it about and inch and half higher. Dave Hout (an instructor) talked about tall folks having problems on a "normal" lathe. When put on 4X4's the problems almost disappeared. The low height caused them to lose the fine tool control you have when your elbow sorta forms a V instead of an L.


Hout also brought up the situation like John described where most of the catches/skates on beads happen in the bottom third. "The skew requires more subtle movement of the hands when guiding it around the workpiece and I think that's where most people get a catch. For example when I haven't been turning in a while I always have trouble cutting the bottom side of a bead."
Difficult to explain but if I can get my son to video tape (and post it) I will; very simple corrective action when you see it.

They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety. Benjamin Franklin
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post #15 of 15 Old 02-10-2016, 02:48 AM
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Quote:
Originally Posted by NCPaladin View Post
[SIZE=3]..... Dave Hout (an instructor) talked about tall folks having problems on a "normal" lathe......

........ The skew requires more subtle movement of the hands when guiding it around the workpiece and I think that's where most people get a catch. For example when I haven't been turning in a while I always have trouble cutting the bottom side of a bead....
Of course, getting a Robust or a Oneway is another very nice way to solve the spindle height issue.

When I first started turning, I practiced until I was pretty good with the skew. I also took a class with Nick Cook which helped a great deal. Then I said to myself that I have gotten that hurdle out of the way and stuck the skew in a drawer and mostly forgot about it except when I used it to shear scrape or cut a dovetail tenon. Then one day I needed to make a spindle and I discovered that I was. Getting run backs like a beginner. That made me mad so I said to myself that I'll show that @$%#*! Skew who's boss, so I started getting even worse run backs. So maybe I need to treat Boss Skew with more respect and practice more.

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