Finding the cut - Thompson gouge

[Aaron Craven]

A wonderful friend recently gifted my my first Thompson bowl gouge (5/8" V-shape). Wonderful tool, and I'm very impressed by it's ability to hold an edge. But I'm having a little trouble transitioning to it.

As background, I have in the past used a 5/8" Sorby gouge (a hand-me-down that was also quite nice, but was reaching it's end of life before I had a catch and broke the handle) and a Benjamin's Best 5/8" gouge that I bought as a short-term replacement until funds could support a higher-quality purchase (as a side note, I've been pretty impressed by the BB gouge -- though it doesn't hold an edge nearly as long as the Sorby and even more so the Thompson gouges).

I recreated the grind on my previous gouges on the Thompson gouge (as closely as I could anyway), but I'm having a bit of trouble finding my cut with it when doing push cuts (especially on the inside of bowls). I get a lot of vibration and my curly shavings start turning to dust (yes, this is with a freshly sharpened tool). I can switch back to the BB gouge and find my cut pretty quickly. I refuse to believe it's the quality of the tool itself, so it's either the grind or my presentation (or both). Looking at the flute on the BB gouge in comparison to the Thompson gouge, I think the flute on the Thompson is slightly more V-shaped, so that may have something to do with it, but not sure.

Any tips? I was thinking maybe I should grind the nose a little blunter (without changing the angle -- just take off a bit more material), but I hate to grind away steel needlessly if this is just a problem with presentation.

[Robert Henrickson]

Differing flute profiles can have dramatic effects on how a gouge cuts, even with the 'same' grind. I'm happier with some flute profiles than others.

[Prashun Patel]

Can you post a picture of your grind?

I wonder if you are cutting more with the tip than the side wings. I was having this problem recently. Rolling the flute to about 45 degrees reduces the risk of catching with presenting more of the wing to the wood.

If you are cutting green wood, beware with that 5/8". I find it super aggressive. It will often dig a channel on one pass which creates troughs that subsequently cause the tool to bump along instead of cut.

[Aaron Craven]

Can you post a picture of your grind?

I'll try to get some pics tonight.

In this case it was green wood, though I had a similar problem the other day on some really dry hickory. In that case, I had trouble cutting it with anything, though... dry hickory is like cutting cement :-o

What you're saying make some sense though. As usual, I did find that as I had trouble I tended to add pressure (which of course is the wrong thing to do). That would make the "troughing" you described worse.

When you say "rolling the flute", I assume you mean along the axis of the tool, correct?

[Prashun Patel]

Yes, along the axis.

[Aaron Craven]

Yes, along the axis.

Okay. Yeah, I thought I tried that, but I'll give it a go again next time I get a chance. It's not really that I couldn't find the cut at all... I would just have to hunt for it, and then I'd lose it pretty quickly. The wood (red oak) was also starting to warp on me, so I'll try with some mostly dry soft maple. I usually find it pretty easy to work with.

[Dan Forman]

Sounds like you are cutting with the tip and losing contact with the bevel, which is essentially scraping, based on the vibration and sawdust rather than shavings that you describe. Cutting with the tip in not really the problem, so much as losing the support of the bevel.

It also sounds like your grind may be close but not identical to what you are used to, which might require a different approach. Do you have a grinding jig, or do it freehand? A V flute will cut a little differently than a U flute, so you may have to just play with it a while, and find a different approach, making certain you are keeping the support of the bevel.

Dan

[Aaron Craven]

Sounds like you are cutting with the tip and losing contact with the bevel, which is essentially scraping, based on the vibration and sawdust rather than shavings that you describe. Cutting with the tip in not really the problem, so much as losing the support of the bevel.

It also sounds like your grind may be close but not identical to what you are used to, which might require a different approach. Do you have a grinding jig, or do it freehand? A V flute will cut a little differently than a U flute, so you may have to just play with it a while, and find a different approach, making certain you are keeping the support of the bevel.

Dan

That's what I'm gathering from other comments. I do think I was cutting with the tip and I know I was losing bevel contact (with the vibration I was getting, there was no way to keep it except to back up and try starting a new cut).

I'm using a Wolverine/Varigrind setup to sharpen. I actually sharpened my old gouge first to set the grind and then used that to repeat it onto the new one (including resetting the depth on the varigrind before my final passes to ensure I accounted for the change in length as I set the initial grind). That said, I know that a crucial part of the process is the amount of time you spend on the various areas, so it's very possible the grind isn't identical.

Incidentally, the BB gouge isn't really a U gouge either. It just has a less severe V than the Thompson. The difference is actually rather subtle (at least in appearance).

I'll post photos later, but mostly it sounds to me that I just need to practice. More time playing at the lathe? I think I can live with that :D

[Mark Greenbaum]

Not sure if this will help, but I grind the very bottom of the heel on my WoodRiver Gouges at a freehand 45 degrees. A mentor showed me this trick, and it helps when making that transition from wall to bottom.

[Aaron Craven]

Not sure if this will help, but I grind the very bottom of the heel on my WoodRiver Gouges at a freehand 45 degrees. A mentor showed me this trick, and it helps when making that transition from wall to bottom.

I actually just did that to try out on my older gouge. For the bowl in question, it wasn't a problem, because it had a fairly even slope, but I think this is something I will eventually be doing on my new gouge as well. It does seem to help -- especially if I do a somewhat more abrupt transition.

[John Beaver]

The flute on the Thompson gouge is generally not as deep as it is on a Sorby. This leaves more meat below the flute for strength but also leaves more length on your bevel. I would try grinding away the bottom of the gouge to shorten the bevel and see if that helps. I think Mark Greenbaum is suggesting the same thing.

[Aaron Craven]

The flute on the Thompson gouge is generally not as deep as it is on a Sorby. This leaves more meat below the flute for strength but also leaves more length on your bevel. I would try grinding away the bottom of the gouge to shorten the bevel and see if that helps. I think Mark Greenbaum is suggesting the same thing.

I liked this when I tested it on my BB gouge, so I think I probably will.

Also I do recall the problem got gradually worse as the bowl thinned, which makes me wonder if it wasn't simply a matter of the wood moving. By the time I finished sanding the piece (I decided to single-turn it and let it warp), it had already gained about a 1/4" difference between the long and short widths. Then again, the problem seemed at its worst as I neared the bottom of the bowl where the warping should be relatively small.

*sigh* Stinks to be stuck at work when I'd much rather be out in the shop. :rolleyes:

[Kyle Iwamoto]

I have several different brands of gouges, and sharpen them all on the same jig (Tormek). I find that the different brands "cut" different. I don't know why, but it's obviously due to the shape of the flute, since they all come from the same jig and have the exact same angles. It takes a couple seconds to go back and find "the cut" as you say. As mentioned, grinding off that heel does help finding that bevel and getting the gouge to cut. Try going back to the basics, run the gouge back all the way off the bevel and slowly come on to the bevel and see if that helps. I also found the Thompsin V's, they cut very different.

[Doug Ladendorf]

Good info above. For inside the bowl cuts you might also try lowering your tool rest a bit. Could be that you are just cutting a bit too high on the inside.

[Dan Forman]

If you are mainly having trouble at the bottom of the bowl, it could be that your bevel angle is too shallow to allow full support of the bevel at the bottom of the bowl, especially if the bowl is relatively deep. Some turners use different gouge for the bottom third, with a steeper bevel, and often times a traditional grind. These are generally called "bottom feeders", named after a Mike Mahoney signature gouge. Somewhere on the web is a series of drawings showing how bowl shape effects the required grind to maintain bevel contact, but I can't seem to find a link to post - maybe someone else can do that.

Dan

[Aaron Craven]

Okay. So here are the pictures. The secondary bevel on the Benjamin's Best gouge was a recent addition, not there when I originally tried to match the grind. In taking these, though, I realized that the Thompson flute definitely doesn't go as deep as the BB flute and the wings are thicker (at least from a head-on perspective):

Top (Thompson gouge on top, Benjamin's Best gouge on bottom):
339508

Profile:
339509

Benjamin's Best head-on (note, it's a little difficult to see, but there's a secondary bevel that makes the tool look a little squatter than it actually is):
339510

Doug Thompson head-on:
339511

[robert baccus]

Are these really V flutes?? Maybe just the pic. Try a bottom feeder on bowl bottoms and your problem may disappear. Good use for the BB gouge.

[Aaron Craven]

Thanks, Dan. This particular bowl was fairly shallow with a relatively smooth curve to it, so I don't think that was the issue here, but it's something to keep in mind.

At this point, I think it was a combination of me needing to "find my groove" so-to-speak with the new gouge along with some possible wood movement due to the bowl drying as I worked it. I checked on it this evening and it has already taken on a good bit of oval shape. I do think I will put a secondary grind on the "heel" of the bevel... both to aid in transitioning on steeper bowls and to make it a little easier to maintain bevel contact.

[Aaron Craven]

Are these really V flutes?? Maybe just the pic. Try a bottom feeder on bowl bottoms and your problem may disappear. Good use for the BB gouge.

The BB gouge only comes in one form, and arrives with what I assume is a traditional grind (wings are not swept back). I of course immediately changed that to the grind you see here. I don't know if the gouge is technically a V flute or not. The Thompson packaging lists the part as a "5/8V Bowl Gouge", so I assume it's a V (though I'm not unwilling to entertain the idea that I'm wrong and it was miss-packaged).

I may eventually do just that with the BB gouge, but I don't want to change the grind I'm used to until I've become completely comfortable with the Thompson gouge. I also have a 5/8" Sorby gouge that is almost used up that needs a new handle. I haven't decided what to do with it yet.

[Prashun Patel]

I have not tried a bottom feeder gouge, but I have never had a problem cutting with a regular bowl gouge.

It may be that with a shallower flute, you need to raise or drop the handle a little vis-a-vis how you worked with the BB gouge.

I would try doing this with the lathe OFF. Present the tool with one hand and spin the bowl with the other. You'll feel when it cuts. Do this at various points along the travel, switching gouges at each position. You have a very valuable learning opportunity to see how (or if) the the depth of the flute affects the required cutting position.

Personally, I am used to a slightly steeper (acute) bevel off the nose. I can't tell you the exact angle, but mine looks steeper. I suspect I need to drop my handle more than you do.

The thicker flute on your Thompson puts the cutting point higher on the nose than your BB. I speculate that this means it requires the tool handle to be RAISED vis-a-vis the BB handle position. If you put a steeper grind, then perhaps your tool handle position could drop down lower to where your comfort zone is.

All this is speculation and I may have it backwards. But certainly don't buy a new tool; analyze your positions and grind angle and I think you'll find your sweet spot.

[Thom Sturgill]

The BB looks to me to be an elliptical flute with gently rounded sides rather than the flat sided V of the Thompson. This will change how it feels when you roll over onto the flute and requires a bit more rounding when viewed from the side (which you appear to have). Biggest difference is the amount of bevel below the flute. Rounding off the heel should help, and I would round off more than you did on the BB.

[Aaron Craven]

I have not tried a bottom feeder gouge, but I have never had a problem cutting with a regular bowl gouge.

It may be that with a shallower flute, you need to raise or drop the handle a little vis-a-vis how you worked with the BB gouge.

I would try doing this with the lathe OFF. Present the tool with one hand and spin the bowl with the other. You'll feel when it cuts. Do this at various points along the travel, switching gouges at each position. You have a very valuable learning opportunity to see how (or if) the the depth of the flute affects the required cutting position.

Personally, I am used to a slightly steeper (acute) bevel off the nose. I can't tell you the exact angle, but mine looks steeper. I suspect I need to drop my handle more than you do.

The thicker flute on your Thompson puts the cutting point higher on the nose than your BB. I speculate that this means it requires the tool handle to be RAISED vis-a-vis the BB handle position. If you put a steeper grind, then perhaps your tool handle position could drop down lower to where your comfort zone is.

All this is speculation and I may have it backwards. But certainly don't buy a new tool; analyze your positions and grind angle and I think you'll find your sweet spot.

Thanks, Prashun. I'll give that a try.

I definitely won't be buying a new tool. Despite some initial difficulties, it didn't take me long to realize that I'm going to love this tool. I just need to figure out how to use it.

[Aaron Craven]

The BB looks to me to be an elliptical flute with gently rounded sides rather than the flat sided V of the Thompson. This will change how it feels when you roll over onto the flute and requires a bit more rounding when viewed from the side (which you appear to have). Biggest difference is the amount of bevel below the flute. Rounding off the heel should help, and I would round off more than you did on the BB.

Thanks, Thom. I almost certainly will, though I'm hesitant to make any major changes until after I fully understand what's wrong with my tool presentation (I just need to get out to the shop and do some practicing).

[Steve Schlumpf]

Aaron - just my opinion - but based on your photos, I would say that the nose angle is OK but that you would find it a lot easier to use if you removed 1/2 of the bevel. Using a bevel that wide is going to cause issues when hollowing a bowl. Think of it as trying to force a straight line around the inside of a circle. It can be done but not without a lot of force because the leading edge and the lagging edge will both be digging in.

[Aaron Craven]

To all who have offered their advice, a very heartfelt thank you. I'm itching to get out and try some of your suggestions.

By thinking through all this (especially Prashun's suggestion of dropping the tool handle), I had a sudden "Eureka!" thought that probably would probably have been obvious to all of you... I kept varying my presentation, but I set my tool rest at roughly the same height I usually do and left it there. I can only drop the handle as far as the tool rest will let me... as I near the center of the bowl, the handle is very nearly horizontal. So I'm thinking I need to drop the tool rest a little.

The suggestions regarding removing the heel of the bevel are also good, and I'm almost certainly going to do this. For the bowl in question, I don't think this was an issue simply because the transition was gradual enough. That said, it may be making it harder for me to find the cut simply because I'm used to something a bit more shortened.

[Aaron Craven]

Aaron - just my opinion - but based on your photos, I would say that the nose angle is OK but that you would find it a lot easier to use if you removed 1/2 of the bevel. Using a bevel that wide is going to cause issues when hollowing a bowl. Think of it as trying to force a straight line around the inside of a circle. It can be done but not without a lot of force because the leading edge and the lagging edge will both be digging in.

Thanks Steve. I'll give it a try, but probably not quite 1/2 to begin with. Actually, I'll probably make that change first on the BB gouge and if it works well for me there, I'll do it on the Thompson gouge. The BB gouge is cheap enough that I don't mind grinding away lots of steel to experiment with different grinds.

[Steve Schlumpf]

Aaron, there are a number of threads on this forum that deal with gouges and the various grinds. Everyone has their favorite based on what works for them. Here is a link to an old thread about how I had my go-to gouge at the time (Thompson 5/8" V) set up. Grind (http://www.sawmillcreek.org/showthread.php?176579-Questions-for-Misters-Schlumpf-and-Keeton&highlight=gouge)

My go-to gouge is now a D-way 5/8" and while I still use swept back wings, they are not quite as long as shown in the old thread.

[Aaron Craven]

Aaron, there are a number of threads on this forum that deal with gouges and the various grinds. Everyone has their favorite based on what works for them. Here is a link to an old thread about how I had my go-to gouge at the time (Thompson 5/8" V) set up. Grind (http://www.sawmillcreek.org/showthread.php?176579-Questions-for-Misters-Schlumpf-and-Keeton&highlight=gouge)

My go-to gouge is now a D-way 5/8" and while I still use swept back wings, they are not quite as long as shown in the old thread.

Those were some seriously long wings! Can your gouge fly?

Thanks for the link. Definitely helpful.

[John K Jordan]

I actually just did that to try out on my older gouge. For the bowl in question, it wasn't a problem, because it had a fairly even slope, but I think this is something I will eventually be doing on my new gouge as well. It does seem to help -- especially if I do a somewhat more abrupt transition.

Chris Ramsey from Kentucky, visited our club and turned a couple of cowboy hats. I always grind away the heel of the bevel on both spindle and bowl gouges, rounding the heel and sometimes polishing it to keep it from contacting and burnishing a mark in the wood. Chris, however, takes that a step further, he rounds nearly all of the bevel leaving only about a thin 1/16" wide "cutting" bevel along the edge.

I took a photo with my phone and although it is a horrible photo, I think you can see the grind:

339564

I tried this with one of my bowl gouges and sure enough, it worked very well. With a bevel angle like this you can cut nicely in the very bottom of the bowl.

Chris sharpened entirely by hand with no jig. He probably has more experience at this than most of us. I have no idea how many hats he has turned but it is hundreds.

JKJ

[robert baccus]

You can fight it or smile while cutting in the bottom. Take a cheap BB 1/2" bowl gouge (or whatever) and grind a 70 deg. bevel on it and call it a bottom feeder. Been using one for 20 years and its also good for other cuts. Great finishing tool and unbeatable for platters. It simply allows you to ride the whole bevel for control while cutting long curls. Allows the handle to be held at almost 90 deg. to the cut surface.

[Prashun Patel]

I ground back the heel of my 5/8" bowl gouge and I have to say the results are pleasantly surprising. The cut is definitely smoother as I go down the inside of the bowl. My transitions are almost never abrupt down there, but with a fat heel, I realize now that I have been coming in a little aggressively nose-in all these years. Last night I rounded over the heel more aggressively, and I find it much easier to cut down now.

[Aaron Craven]

You can fight it or smile while cutting in the bottom. Take a cheap BB 1/2" bowl gouge (or whatever) and grind a 70 deg. bevel on it and call it a bottom feeder. Been using one for 20 years and its also good for other cuts. Great finishing tool and unbeatable for platters. It simply allows you to ride the whole bevel for control while cutting long curls. Allows the handle to be held at almost 90 deg. to the cut surface.

I do think becoming a bottom feeder is in my BB gouge's future. It's a 5/8" gouge though.

[Reed Gray]

Only comment I have on the pictures of the grinds is that the noses are a bit square instead of a smooth round. This can make it feel funny when cutting especially if you roll your gouges more on the side. If you have a mentor in the area, that would most likely solve it instantly. Experiment at slow speeds till you get comfortable.

robo hippy

[Aaron Craven]

...If you have a mentor in the area, that would most likely solve it instantly...

I do! He's the one that gave me the gouge! If I continue to have issues, I'll most certainly pay him a visit.

The grind is a little sloppy, though the pictures make it look worse than it actually is. I'll continue to improve on it.

Thanks! By the way, I really enjoy your videos.

[robert baccus]

A 5/8" bowl gouge will work ok and don't be afraid to go to a 75-78 deg bevel to find your preference. Try grinding it on a disc or belt sander and just rotate the whole tool and the wings will have clearance. I have also done this on a spindle gouge but like the bowl gouge better--both work. A 1" spindle roughing gouge sharpened to the same bevel makes a great gouge for the outsides of vases and bowls--even a finish cut. BUT only when ground to a 70-80 deg bevel. This is dangerous with the factory 45 deg bevel. With the flat bevel it is just about impossible to get a catch--great for new turners.