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Re-creating a bowl gouge profile

R

Randy Heinemann

Joined
Jul 19, 2017
Messages
492
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Location
Roscoe, Illinois
I have sharpened my bowl gouges on a Tormek since buying them. They came sharpened with the Ellsworth profile so I matched that as closely as I could with my Tormek gouge jig. It's worked extremely well, but I noticed that there is a more pronounced rounded section of the gouge edge near the tip. I remember reading or watching a video awhile back that indicated, if that occurs after many sharpening, the edge profile should be made more flat around the curve. Is the way to kind of start over to just flatten the gouge edge and then proceed with normal sharpening to get the correct edge back? Probably not a clear explanation but I enclosed pictures. Hope that helps. Maybe the profile is already correct, but it looks like it's a bit more curved than it was when I got the gouges about 2 years ago.unnamed.jpgunnamed1.jpg
 
Just spend more time on the wheel where you want less steel. You can do it all at once to return to the grind you want, or just a little at a time with each sharpening (my preference, wastes less steel)
 
Randy Heinemann said:
I have sharpened my bowl gouges on a Tormek since buying them. They came sharpened with the Ellsworth profile so I matched that as closely as I could with my Tormek gouge jig. It's worked extremely well, but I noticed that there is a more pronounced rounded section of the gouge edge near the tip. I remember reading or watching a video awhile back that indicated, if that occurs after many sharpening, the edge profile should be made more flat around the curve. Is the way to kind of start over to just flatten the gouge edge and then proceed with normal sharpening to get the correct edge back? Probably not a clear explanation but I enclosed pictures. Hope that helps. Maybe the profile is already correct, but it looks like it's a bit more curved than it was when I got the gouges about 2 years ago.View attachment 50083View attachment 50084
Click to expand...
Looks perfectly fine and useable to me. You mention the tip but your photos don't show the tip. However, I would definitely grind a relief on the bottom of your bevel to remove that hard edge.
 
I meant the curve near the tip, which seems like it should be straighter (or maybe was when I got the gouge). Don't get me wrong, the way it is ground does work, but I was just making sure the shape was the way it should be. Based on the Tormek instructions and YouTube videos I've seen by Nick Agar and other Tormek representatives, I feel I've been following the Tormek steps.
 
I refer to this aspect of sharpening BG’s as “sharpen to taste”. Anything from a straight flat line to one with even more convex curve is perfectly fine - different people will have preference for a certain shape.

Mine look pretty similar to what you show - a slight convex curve. I find it is easier for me to keep it slightly convex to ensure I dont go concave along the line over many sharpening. And yes, I find the edge will change shape a bit over time and sharpenings and I have to correct it every so often.

As mentioned, relieve the heel line.

I use a Griz wet wheel. The things are slow. Before I knew what a Hanns Michelsen grind was I started using it to reduce wet wheel sharpening time. I got the tormek BG-100 tool arm which allows using the jigs with a bench grinder. The bevel is relieved (and the heel, a 3rd tertiary bevel) on the bench grinder, leaving only a thin bevel (up to ~1/8”) to sharpen on the wet wheel. The primary bevel will start at < 1/16” and when it grows to >~1/8”, I take the tool back to the bench grinder. I do this for both bowl and spindle gouges.
 
Doug Freeman said:
I refer to this aspect of sharpening BG’s as “sharpen to taste”. Anything from a straight flat line to one with even more convex curve is perfectly fine - different people will have preference for a certain shape.

Mine look pretty similar to what you show - a slight convex curve. I find it is easier for me to keep it slightly convex to ensure I dont go concave along the line over many sharpening. And yes, I find the edge will change shape a bit over time and sharpenings and I have to correct it every so often.

As mentioned, relieve the heel line.

I use a Griz wet wheel. The things are slow. Before I knew what a Hanns Michelsen grind was I started using it to reduce wet wheel sharpening time. I got the tormek BG-100 tool arm which allows using the jigs with a bench grinder. The bevel is relieved (and the heel, a 3rd tertiary bevel) on the bench grinder, leaving only a thin bevel (up to ~1/8”) to sharpen on the wet wheel. The primary bevel will start at < 1/16” and when it grows to >~1/8”, I take the tool back to the bench grinder. I do this for both bowl and spindle gouges.
Click to expand...
Can you post a picture of your gouges?
 
The thing is, I'm still experimenting to some degree. Since I've only been turning for about 5 years, and larger pieces and hollow forms, the last 2 years, I'm not sure what the effect of changing the grind, even a little, is. The grind on my Crown Pro-PM gouges is the same on my 2- 1/2", 3/8", and 1/4" tools. For example, I have not, to this point, ground some steel off the heel, which I understand improves the inside surface of a bowl. I might try that with one of the 1/2" gouges. For sheer (or shear) scraping, which helps me improve surfaces with tearout, I want to make sure that the grind allows the best result from that.

Last, the settings I use on my Tormek result in a 60 degree angle. Would a 55 degree angle make a significant difference in gouge performance, either inside or outside of bowls? Recently I've seen a video by Nick Agar indicating that 55 degrees might be a better choice, especially for inside the bowl.
 
I had the same issue with my tormek clone using the tormek jig. It’s just a matter of grinding more on the sides. For me, it seems to work better less convex
 
One of the main differences with the swept back grinds that I see are that some like straight wings, some like a slight arc to their wings. I don't think there is much real difference in them. I don't use one any more though.... With the 40/40 grind, on the Thompson gouges, most tend to have more of a straight wing, due to the V shaped flute. If it cuts well, then it works. If you want a straighter wing, just spend a little more time on that part with the jig rolled over on its side.

robo hippy
 
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