Safety and Wolverine

[KEW]

I posted this on Sawmill Creek, but thought it'd be good to post here as well.

This is a spin off from the "sharpening a roughing gouge" thread. Since it is safety related, I thought it best to open its own thread.
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Quote:
Originally Posted by Mark Pruitt View Post
I sharpened a roughing gouge once with the Wolverine V-arm and met with very unpleasant results. The "short" bevel on the tool caused the wheel to want to grab it. I then used the platform and no more problems. The platform gives support where it's needed for that type of tool.
End of Quote
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I run 45 to 55 degrees on my roughing gouges, so I haven't had any problem with them.
But I did had the same problem with a scraper - I should have "thought" before I "did".
Fortunately my fingers were not under the tool when it happened. I think they could have been broken or certainly severly bruised if they were underneath.
I retired the wheel because of the divot in it.

I think a good, very conservative safety rule is to go to the platform if your bevel angle is greater than 65 degrees. Otherwise the edge of the tool can bite into the wheel and slam the tool down (which could probably do serious damage if your fingers are in the wrong place).

Just to be sure that the hazard is understood, envision sharpening a scraper at 89 degrees using the V-arm.
The tool is almost normal or perpendicular to the surface of the wheel.
If you laid your tool in this position and rotate the wheel, only very slight flex is required in the v-arm system to allow the wheel to grab the tool tip and carry it down past the center of the wheel so it drops the tool. As you decrease this angle, the v-arm system gets flexed more and the event is more violent.
Once you decrease the angle so far (as is the intended use of the wolverine), the tool is less likely to bind between the wheel and the v-pocket, and the v-arm could never flex that much if it did.

--------------------
Cheers,
Kurt

 

[hockenbery]

Kurt,

A serious hand laceration occurred using the vari-grind on a steep bevel bowl gouge. The person doing the sharpening was a very experienced teacher touching up a student's gouge.

He believed the pocket arm lock loosened allowing the pocket to slide back. With the steep bevel the tool was pulled down over the front of the wheel. His hand was pulled into the wheel.

Lots of stitches and hand surgeons to fix a severed tendon.

It was one quick nasty accident.

Happy Turning,
Al

 

[john lucas]

I noticed that Sorby is now selling a slotted tool rest that takes different jigs for sharpening things like roughing gouges, scrapers, and skews. I'm going to midify my Oneway as soon as I have time. I thought this looked like not only a safe way to do these tools but also a very good way.

 

[Steve Worcester]

... envision sharpening a scraper at 89 degrees using the V-arm.

I understand the first point, but why would you use the V arm to sharpen a

scraper​

?

 

[MichaelMouse]

Am I the only one who sharpens a roughing gouge at a constant angle? As it comes, BTW? Touch the body to the toolrest, match the bevel to the stone, and swing left or right. Are you folks sharpening your roughers in some sort of fingernail, or trying to? Sort of defeats the great advantage of the roughing gouge, where any point is equal to any other in cutting angle. Allows you to keep the handle as is all across the piece and anywhere on the edge.

 

[KenN]

I'm as confused as MM! I just got back from my studio after reading the post, trying to understand the problem. "Short Bevel"? I assume you are referring to a "spindle" roughing gouge. I could not even come close to reproducing the effect you describe - perhaps by pushing down on the gouge with quite a bit of force.....???? I prefer a gentle touch while sharpening anything. Please help me out.

 

[KEW]

I understand the first point, but why would you use the V arm to sharpen a

scraper​

?

I understand your point.

I had been sharpening a square nose scraper with the v-arm without problem. I had ground it at around a 50 degree angle (as Bill Grumbine suggests), so it worked fine in the v-arm without having to swap out the platform. My brain fart happened when I got a new scraper and didn't think about it before sharpening it at the factory ?80? degrees. It was stupid - I knew better.

 

[KEW]

MM and Ken
This is a guess, but I interpreted the roughing gouge scenario as a situation where the gouge was being sharpened at a steep angle - maybe 75 to 85 degrees.
I always use the v-arm to sharpen my roughing gouge straight across with a ~45 degree bevel which works nicely.
I do have an older CS roughing gouge which is made of ~3/16 thick steel. I suppose it would be more prone to grabbing the wheel.

Cheers,
Kurt

 

[john lucas]

I'm assuming that's what he means is sharpening a roughing gouge with a very steep grind. Some of the old turners sharpened the rough out gouge very steeply on the assumption that it would hold an edge longer.
I sharpen mine at about 45 degrees and use the V arm. I like the upper wings to be flat so I can use them like a skew so I slide the wings across the wheel and then rotate over the bottom of the U and then slide the other wing across. My gouge looks like a U from the end and from the side the wings are almost straight up.
With a grind like this I can rough out the spindle with the bottom of the gouge and then rotate it so the straight part of the U is cutting at about 45 degrees like using a skew. This allows me to clean up the wood and do some almost final shaping all with one tool. It only takes a light pass with the skew to finalize the turning.
Anyway , I got long winded. What I was going to say is if you sharpen a rough out gouge with an angle that is very blunt like 80- 85 degrees you are approaching the apex of the wheel and it could easily be pulled down tearing up the wheel and maybe your fingers.

 

[KEW]

if you sharpen a rough out gouge with an angle that is very blunt like 80- 85 degrees you are approaching the apex of the wheel and it could easily be pulled down tearing up the wheel and maybe your fingers.

Well phrased. That was the caution I was trying to give.
Regardless of the tool, If the angle gets blunt you are taking a risk using the v-arm.

 

[Bernie Weishapl]

I agree with MM. I use the platform at a 20 degree angle to sharpen all my scrapers. I would not think of doing it freehand or with the V arm. I also don't understand about the spindle roughing gouge problem. I sharpen mine all the time with the V arm at a 45 to 50 degree angle and I don't think I could make what you are saying is happening if I tried.

 

[Gordon Seto]

I sharpen mine all the time with the V arm at a 45 to 50 degree angle and I don't think I could make what you are saying is happening if I tried.

The key is because you have the proper angle of 45~50º. (I personally use 40º)

Imagine if the V-arm is extended further out for the blunt angle, the contact point on the wheel drops and the tool almost forms a straight line with the center of the wheel. That is when the safety issue comes in.

Gordon

 

[gsieracki]

I can see how it would happen on a very blunt angle. I don't have that angle on any of my gouges and use both the V arm and the wolverine jig. As far as scrapers are concerned, just the rest to lay it on. I also try to use as light a touch as possible. I never really liked grinding so I find the jigs very practical for myself.

Gerry

 

[waltben]

I'm also kind of at a loss to understand exactly why anyone would use the adjustable fingernail bowl gouge tool to try sharpening anything else - especially a scraper! This sounds more like misuse (or abuse!) of a tool and there's no doubt it would cause serious trouble. Oneway's instructions tell you to sharpen scrapers and spindle roughing gouges on the platform.

 

[KEW]

I'm also kind of at a loss to understand exactly why anyone would use the adjustable fingernail bowl gouge tool to try sharpening anything else - especially a scraper!

The v-arm is the bar that slides under the wheel and has the v pocket on it. Nobody has talked at all about using the vari-grind jig to sharpen roughing gouges or scrapers to my knowledge.

Cheers,
Kurt

 

[Gordon Seto]

I'm also kind of at a loss to understand exactly why anyone would use the adjustable fingernail bowl gouge tool to try sharpening anything else - especially a scraper! This sounds more like misuse (or abuse!) of a tool and there's no doubt it would cause serious trouble. Oneway's instructions tell you to sharpen scrapers and spindle roughing gouges on the platform.

This could happen on a blunt angle bowl gouge with traditional grind for the inside of deep bowl. Grinding a bowl gouge is within the guide line from the instruction.
The kind of small gouge that Jimmy Clewes used in his 2nd DVD series; Jimmy grind it free hand.

BTW, I just re-watch the video on using the jig:
http://www.oneway.on.ca/multi-media/wolverine_videos.htm
Kevin was using the V-arm for grinding the traditional bowl gouge and SRG; but the front angles were 45º.

Gordon

 

[Captain Eddie]

Woodturners, there are professional turners out there selling scrapers which look like flat versions of your spindle gouge. They are easily sharpened using a type of fingernail jig. Because of the edge profile, if the jig slips, or it doesn't fit properly, the tool can jump into the wheel. I have one and will photograph it soon. I also made a jig to fit my Blackhawk sharpening system to hold this scraper flat and eliminate most of the chance of slipping. This scraper is awesome for spindle work, small detail work, etc.

 

[hockenbery]

I can see how it would happen on a very blunt angle. I don't have that angle on any of my gouges and use both the V arm and the wolverine jig. As far as scrapers are concerned, just the rest to lay it on. I also try to use as light a touch as possible. I never really liked grinding so I find the jigs very practical for myself.

Gerry

Gerry,
the accident I mentioned occurred using the veri-grind on a bowl gouge with 80 degree front bevel. The 80deg. angle allows riding the bevel to bottom of some bowls.

the vee-arm apparently slipped back a bit. With the tool low on the wheel it was pulled down below the the wheel and a hand injury occurred.


-Al

 

[waltben]

The v-arm is the bar that slides under the wheel and has the v pocket on it. Nobody has talked at all about using the vari-grind jig to sharpen roughing gouges or scrapers to my knowledge.

There's two arms that come with a Wolverine. Again, if one reads the instructions, there shouldn't be a problem using this device. Al later said that

"the accident I mentioned occurred using the veri-grind on a bowl gouge with 80 degree front bevel. The 80deg. angle allows riding the bevel to bottom of some bowls.

the vee-arm apparently slipped back a bit. With the tool low on the wheel it was pulled down below the the wheel and a hand injury occurred."

If you don't follow the instructions completely with any tool, you're inviting disaster.