new way to shear cut?

[curtis rosche]

well i was playing around last night with a couple peices of apple trying to figure out the best way for me to make the cleanest cut, after what happened on thursday i will probably not shear cut with a scraper on an angle for a long time. so i was playing around with my bowl gouge, and found that for shear cutting on the outside, you can take the bowl gouge and turn it upside down, and use the "wings" to shear cut. is this new or is this just something that has been around? i was able to use it this way to make several peices that are now see through.

[Jim Becker]

Shear cutting with a bowl gouge, particularly those with an "Irish" type grind is standard practice. David Ellsworth teaches it and it's one of the primary drivers for his gouge grind. Bill Grumbine, who was a student of David, teaches the same. There are many others, too.

I would not necessarily advocate turning the gouge over, however. Having a grind that you can easily move from cutting at the tip to shear cutting with the side grind makes for more flexibility and probably more safety. You shift not just the cutting location on the grind, but also the orientation of the tool. For shear cutting and finishing work, the tool is typically held at a 45º angle from vertical and up to about 45º off horizontal...resulting in very light, fluffy shavings.

[curtis rosche]

jim, can you post a picture of what you mean? i am lost.

[Wally Dickerman]

Shear scraping with a side ground gouge, either bowl or spindle, is done with the flute facing the wood, very lightly scraping with the lower cutting edge and with the upper cutting edge very close to the wood. The tool handle shold be down or level but not up. Cutting very lightly with the grain this is very effective in cleaning up endgrain tearout etc. in preparation for sanding.

There is a possible danger when doing this....if the upper cutting edge gets too far from the wood you now have an unsupported cutting edge and it will dig in.

Wally

[Bernie Weishapl]

Curtis you need to get Bill Grumbines DVD Turned Bowls Made Easy. He shows several ways to do the shear cut. I would not use a shear cut with both edges. I do it like Wally said. One edge on the wood and the other lifted just slightly off the wood. You will get a better cut. Instead of laying your gouge horizontal turn the handle down so it is a a 45 deg angle to the tool rest.

[Leo Van Der Loo]

Nothing new Curtis, Peter Child in his "Craftsman Woodturner" book from early 1970 already mentioned the cutting with all parts of the gouge, as he said "totally upside-down", though he was using the then brand new bowl-gouges and they still used a close to square across grind, something we still use on the spindle roughing gouges.
I use the cutting with the wing often when taking a cut from the edge of a bowl down the outside wall with a conventional ground gouge, works for me.

[Steve Schlumpf]

Curtis - maybe it is not something new to the rest of us - but it sure is fun when you get to the point in your turnings that you start 'discovering' these things!

Have fun with it - and make sure no more bowls to the face!

[Dewey Torres]

For this who want to see a video of this:

Click on the bowl gouge technique video once the page loads. He does a shear cut with the bowl gouge and shows how to do it after the bowl is shaped.

http://www.woodmagazine.com/woodvision/?lid=1339217302

It's about 5minutes into the video in case you are short on time.

[Wally Dickerman]

Not a bad demo. I don't know anybody who grinds their gouge at 80 degrees. That's almost flat. Ellsworth grinds at 60 degrees. I do too.

If he had been rubbing the bevel with his pull cut he wouldn't have had tearout. He was going with the grain with what looked like Doug Fir. Not the easiest to turn.

It would drive me nuts to turn at the slow RPM's he appeared to be using. Looked like 500 to 700 RPM. For a bowl that size I would be turning at 1600 to 1800. Faster, smoother, easier IMO.

Wally

[Steve Schlumpf]

Wally - I agree with everything you just said! I actually stopped the video less than halfway through as it was painful to watch everything progress at such a slow pace! I do not turn my bowls any where close to the speed you listed but find 800-1000 rpm comfortable - with my skill level. I can only assume that as my skill level increases - so will the speed at which I can turn comfortably.

Also agree with you on the grind of the demonstrator's gouge. I have mine ground at 60* - or close to it and find it does everything that I ask.

[Bob Vavricka]

Dewey,
Thanks for the link. I actually liked the slow speed because it gave me a clearer understanding of the cut process. I'm sure for experienced turners it was painfully slow, but for me it was fine.
Bob V.

[curtis rosche]

i played with different cuts today, today was interesting. i broke my lathe twice and fixed it twice. then go to turning some of the locust that got cut down this summer. for being really wet still, it only comes off as dust. i made 2 peices of locust that you can see the light through, they almost look like a peice of norfolk island pine

[Leo Van Der Loo]

Hé Curtis you know the rule,.........No Pictures, it didn't happen :( :D

[Dewey Torres]

Not a bad demo. I don't know anybody who grinds their gouge at 80 degrees. That's almost flat. Ellsworth grinds at 60 degrees. I do too.

If he had been rubbing the bevel with his pull cut he wouldn't have had tearout. He was going with the grain with what looked like Doug Fir. Not the easiest to turn.

It would drive me nuts to turn at the slow RPM's he appeared to be using. Looked like 500 to 700 RPM. For a bowl that size I would be turning at 1600 to 1800. Faster, smoother, easier IMO.

Wally


Wally and Steve,
It was interesting to hear you both agree on this. As a newbie I gather info as I can and it is g great to hear different points of view.


Even in the Grumbine video he often does a cut at what I call “professional speed” and then slows it down for the Newbies which calls for my title in the above thread.
I am not sure if you guys realize it or not but if I went to your shop and watched you turn I would learn a lot but I would learn even more at slower speeds because my mind is still developing the knowledge needed for proper bevel riding, grain control, which tool to use, techniques, among various other sorts of (could I do that or this or ....) types of things.
Same would happen if I invited someone who just built their first step stool over for a double bevel marquetry demo. Chances are they would get lost if I worked at full speed the entire time.
To you PROs I am sure some of the videos I have seem slow but to me they are so fast I often have to rewind.

Steve,
I agree that the comfort speed is the right speed.

Wally,
Man that seems awful fast but you are talking to someone who has been turning for a month.

I don’t want this to be taken wrong. Steve has helped me learn to turn more than any video or Creeker. He and Wally are both just way better then me.

[curtis rosche]

what do you want pictures of, the lathe of the locust?

[Jim Becker]

Curtis, it's important that you are "Cutting" to avoid the "dust" problem with any wood, including very hard species like locust. That means rubbing the bevel, even in a shearing cut like I originally mention. Wally also talks about this in one of his posts above, too.

This is one of the things I inherently have against the term "scraping" because that activity, if done correctly, is actually cutting. A properly prepared and used "scraper" will also provide nice, fine, curly shavings. If one is getting "dust", something is not right, either with the tool or the technique.

[curtis rosche]

i got shavings when doing face grain, but end grain only make shaving with a parting tool that was angled to "rub the bevel" i will try again and see if i get better results once i get a grinder and can sharpen my tools.

[robert hainstock]

what do you want pictures of, the lathe of the locust?

Yes Curtis, pictures of the lathe and the wood:)
Bob

[Wally Dickerman]

Dewey, you're right, turning at 1600 is too fast for a beginner. In my classes for beginning bowl turning I have students start at 1200. The wood we use is soft maple, 6 to 7 in. in dia. and 3 in. thick, so it works easily. Before the students start turning I demo a few things. Tool and hand position, rubbing the bevel with a gouge, cutting with the grain vs. against the grain, and cutting at various speeds.

I've been teaching for a lot of years and I've found that students have better tool control, better cutting, with better results at 1200 than at lower speeds. If they've never turned at slower speeds, 1200 seems comfortable for them.

I suggest that you mount a small blank, 4 or 5 inches and try cutting at various speeds. In a very short time you'll find that as you ramp it up cutting does become easier and the results are better. You won't be forcing the tool. It should feel as though it's just floating through the cut.

Wally

[Gordon Thompson]

So after reading this thread, and watching the videos (thanks!!) - i was doing alot of practicing today. my question is why on certain areas would my gouge bounce? It seemed that certain areas the cut was smooth, but certain areas my gouge would bounce or chatter alot?

[Dewey Torres]

Yep I just roughed my first set of bowls today ans noticed the same thing. What the heck, I just pressed on with it.