Newbie Bowl Problems

[Chris Jenkins]

I'm pretty new too turning. I've been playing around with some blanks made of "Free Wood." I've turned about 3 of these blanks and I keep getting this horrible tearout in the end grain. I turned a bowl at a friends house using freshly sawn maple and had no problems. I don't know if this is due to the fact the maple was freshly sawn vs that of the blanks I have (sawn down about 6 months ago) or if it is my tool presentation.

Is it me? Is it the wood? Any suggestions? This bowl pic is sanded from 50 - 150.

77052

[Jim Becker]

Sharp tools are absolutely necessary to cut cleanly. Technique is also important and one of the reasons that many folks learn to use a shearing cut for final finishing with a side-grind bowl gouge, such as the Ellsworth gouge. It really tames the fuzzies as that end grain goes by twice on each revolution on a faceplate oriented turning...

And you shouldn't have to start your finishing with a 50 grit gouge... ;) ...if you get the technique down. Practice, practice, practice. And get some mentoring from videos or live people. Watching someone else do it really helps drive home what you need to do yourself.

[Dennis Peacock]

Chris,

Freshly cut wood (wet wood) always cuts easier and cleaner than drier wood. Unfortunately, tearout is going to happen from time to time and in some woods...it happens all the time. ;)
Very sharp tools and lite cuts go a long way to reducing tearout and there are only 2 ways that I've learned to clean it up:

1. Cutting from the rim of the bowl towards the foot of the bowl. Again lite pass here.
2. Cut using a "shear scrape" type cut with a 3/8" or 1/2" bowl gouge with a freshly sharpened edge on it. It's easier to "show" this than to explain it in words. I just don't have a pic of it at the moment. But let's try this: hold the angle of the cutting edge at about 45º and lightly skim the area while rubbing the bevel. This will produce very light shavings when done properly. This cut needs to be practiced before you jump on a really nice piece of wood. DAMHIKT!!! :D

[Dean Thomas]

Jim said it right. If you read any of the posts on this forum about problems in turning, the first suggestion made or question asked is about the sharpness of the tools. John Jordan's first answer to EVERYthing is "Sharpen!" :D

Most tearout is caused by scraping across some portion of end grain. Think of wood as a bundle of straws. When a tool that is not cutting touches some marginal cells/straws, it grabs those cells and unceremoniously yanks them out of the bundle. Unlike straws, the wood cells & fibers do not close ranks. They just leave pits!

Bowl gouges that are wildly sharp and scrapers that have their burrs intact are your main weapons against tearout. A "wire burr" does not last long. Seconds for HSS tools, maybe minutes for vanadium steel tools like Doug Thompson's tools, but not long enough to finish very much, or at least reliably IMO. Maybe a pass or two on a larger bowl.

The other contributor to tearout is the wood itself. Some species are prone to it, some are prone after over-drying. Some wood gets punky in places as it dries. It's a moisture thing. Moisture removal has to be done a la Baby Bear--juuuuuuuuuuuust right.

[Chris Jenkins]

I currently use a 120 grit AL Oxide wheel and Wolverine Jig to sharpen my Sorby 1/2" Bowl gouge using an Elsworth grind. I usually sharpen to roughout the blank, then I sharpen again once I turn the inside.

I know I shouldn't be using the "50-grit gouge," but I did in this case to see if I could sand down and down to get to something fresh, but never did. Which is why I think it was not just me, but the wood grain as well.

Dennis, I am fimiliar with the Shear Scrape, I have the Bill Grumbine video and watched not too long ago again. Maybe I don't have the technique down just yet, but I know when I do it I can get little fine curlies where it is picking off high spots.

[Jude Kingery]

Chris, it indeed might be the wood; I've turned a lot of bowls and twice have had problems with Mulberry. You might try a different wood and evaluate it that way, sounds like your tools are sharp, you know the presentation you want, and sometimes the chunk of wood simply won't cooperate. I'm prone to saying (about myself) must be user-error and sometimes, it's actually not. Best to you, Jude

[Gordon Seto]

Some sanding sealer or lubricant prior to the finish cut may get you different results. It is easier to sand out the tool marks than tear out and chattering.

Gordon