New Turner, first attempt (questions)

[alex grams]

So I got the lathe cabinet made up (will post pictures later) and had a small maple bowl blank I wanted to start on.

The roughing out went well, though at first I had some issues with the roughing and got frustrated, trying to figure out what was going on. Finally the sharpening jig arrived in the mail, and as expected what a difference a decent sharpening makes...

Onto the questions:
-I can sharpen the roughing/skew/scrapers fine, but the bowl gouges tend to heat up very quickly and burn on the grinder (woodcraft medium speed 120 grit wheel). Is there any trick on sharpening the small gouges? No matter how light I tried to sharpen them, they seemed to keep burning some on the points.

-When I was using the scraper to smooth out the bowl, I kept getting some mild tear-out, and a high pitch squeal on parts of the bowl. I got the scraper edge well sharpened, but still had the issue. Is this a technique problem, or something else? It only seemed to happen on the top of the bowl (furthest from the chuck). Whereas the base of the bowl scraped fine without the noise.

Hmm, I am sure there will be more questions as my learning/experimenting progresses.
Thanks in advance.

[John Keeton]

Alex, glad you are off to a good start!! The "burning" of the tools will minimize as you get more experience sharpening and realizing that you need to take off only a very, very little bit of metal. Besides, the HSS is not harmed by the discoloration.

Using a scraper is not something I do often, but I suspect you are getting harmonic vibration from being out close to the rim. A couple of things might help, in addition to having a very good burr on the scraper - hold the scraper at a 45* angle to the surface (rolled up on its side) and place your hand on the back side of the bowl to offset the pressure and deaden vibrations.

[alex grams]

John,
Do you do most of your finish cutting with your bowl gouges? What is the last tool you use to get the best finish before you need to use any sandpaper.?

And welcome back. My lathe cabinet turned out great, but now I just need to learn how to use my tools to their full potential.

I need to do some more reading (I also have the Richard Raffan bowl turning DVD on order), but technique wise I found it easier to see what I was doing by putting the lathe in reverse and scraping on the back (far) side of the bowl. I have the 46-460, so can't flip the headstock, but in the normal (fwd) spin direction, you can't really scrape the inside of a bowl on its inside/blindside.

[John Keeton]

Alex, I try for a finish cut that will permit me to go to 150 grit or better. And, I rarely do bowls, so the techniques are different - with hollow forms there is no inside scraping.

Really, one would have to be there with you to provide specific help, but the rare times I do scrap, I do so from the back side of the lathe with the lathe running forward. If you have a "closed form" bowl (one where the rim returns back toward the center of the bowl, scraping is very difficult and problematic - you can end up with an horrendous catch if not careful.

One thing you might try (if you have swept back wings on your gouge) is to lay the gouge down horizontally, with the flute at just about 90* to the surface, and back drag the inside - pulling toward the rim. This is, in effect, a negative scraping situation, and as long as you do not permit contact with the upper wing, it can provide a reasonably good surface.

[Prashun Patel]

Alex-
What are you using to sharpen yr bowl gouge? Also, my instinct is that you are using a spindle roughing gouge on yr bowl blank for roughing. Is that correct? I wouldn't do that on larger blanks; stick to a bowl gouge.

Are you running yr grinder at it's slowest speed?

Also, are you getting any bouncing on the wheel, or is it pretty balanced?

[alex grams]

Thanks John. This was just kind of a shallow coin/key bowl, nothing significant. I have a larger piece of 8/4 maple I may make into a platter/tray style next.

My gouges are all standard, nothing swept back.

Live and learn!

I did make some mallet handles from osage orange. That is a very unforgiving wood.

[Prashun Patel]

Ok, let's see a pic of your bowl gouge grind. If yr like me, you'll have the most success with a good fingernail grind

[alex grams]

I'll grab some pics this evening when I am home of the cabinet/grind/bowl.

[Reed Gray]

The coloring of your gouges as you sharpen is mostly due to having a heavy hand, rather than a light one. You should just need to lightly touch the gouge to the wheel. Having the wheel clean and dressed helps. If you want fancy wheels, the CBN wheels from D Way Tools are the best ones out there, but are about $180 each. They also run cooler than standard grinding wheels.

Any scraping cut on a bowl will leave some tear out. The fibers tend to tear out before they can be cut out. I never use a scraper, flat on the tool rest any where near the rim on a bowl that has most of the inside cut out. It starts the wall vibrating, and it can vibrate enough to cause the bowl to blow up. Use a shear cut, with the scraper on its edge, and make very light pull cuts. It will take several passes to remove a tool mark. I do consider the scraper the most effective tool for roughing, or getting the bulk of the stuff out of the way.

Some days the gouge works perfectly, and and some days not. On the not days, I will use the scraper in a shear cut mode to touch things up so I don't have to sand as much.

I do have a couple of short clips up on You Tube under the name of robo hippy, and show some gouge use, and some scraper use.

robo hippy

[Primvs Aebvtivs]

I'm glad it's not just me that gets the squealing on the bowls... (Sorry Alex, I'm new to this too!) The vibration reply makes sense - will try the shear scraping method next time I'm in the shop.

[Rick Markham]

+1 on Reed's videos! Especially the video where he turns a bowl with just scrapers, probably the best demonstration of scraper techniques I have personally seen.

I generally turn my bowls just using a bowl gouge. I didn't have a scraper for a long time.

The most important thing before making finishing cuts (IMHO) is taking the time to sharpen the tool you plan on using to finish with before you start It will make taking a finishing cut much easier, controllable, and you will have less tear out. No matter what method you use.

[Dennis Ford]

The vibration issue can also be addressed by doing the inside in stages; do an area near the rim first to final thickness, then do a little deeper to final thickness. Once the first couple of sections are blended together; do not go back to the rim area. If the bowl is thin, this is the only way I have been able to completly avoid the vibration problem.