Bruised End Grain?

Re: Bruised End Grain?

Brad Vietje

>John,

Any hope of posting a photo ? I think you'll get more helpful advice if we can see the problem. Is this problem on the inside of the goblet ? I'd want to know more about the spiral you mentioned, too.

Safe Spinning,

Brad Vietje

Thetford, VT

Re: Bruised End Grain?

John Crissman

>Brad,

BTW, I am turning rock maple and my tools are pretty darn sharp.

Now, yes, the bruise is on the inside just off the center. This piece is another learning piece and I have already sanded and finished it so it is not that noticiable.

The 'bruise' is very easy to see when it happens. It resembles a little catch and there is a small separation in the end grain. The effected area is noticably not parallel to the other grain. I have sanded them down before, but I would like to correct me.

Next time it happens I will surely post a photo.

Re: Bruised End Grain?

Mark Mandell - Gone Round In Jersey

>Sounds like the low point on the bevel is rubbing. Look in the Grinds Library [Link in upper left of screen] for Russ's (and David Ellorth's) convex bevel grind for interior bowl (& goblet) work to prevent compression of the grain.

Mark

Re: Bruised End Grain?

John Lucas

>I agree with Mark. The bottom of the bevel will compress the fibers and it's very difficult if not impossible to get out. This usually happens somewhere near the bottom when you change the angle of the gouge. The best remedy is to round over the bottom of the bevel.

Re: Bruised End Grain?

John Crissman

>I appreciate the responses. i do not think that is the case in this instancee.

I was primarily using a roundnose scraper with a about a 65-55 deg bevel. I like this because it does not catch like my gouges do. Could using a scraper be my problem?

Thanks,

John

Re: Bruised End Grain?

Mark Mandell - Gone Round In Jersey

>"little bruise after going in with my scraper"

Can you describe the cutting/scraping stroke you're using?

If this blemish you're talking about occurs at the very start of your cut, you may be getting a small catch without realizing it. If you're scraping the early grain a bit before cutting harder late wood, your tool will tend to rise a bit or bounce leaving a small valley and peak, but I don't think it should be as noticeable as you describe. Tried angling your scraper edge to something of a shear-cut? Tried starting your cut "earlier" back along the sidewall and then flowing through the problem area in a single stroke?

I'm not much of a scraper-guy as I do most everything on the interior with the gouges.

Can you post a real close-up pic of the "defect?"

Mark

Scraping cuts

John Crissman

>Here is how a pic of how I cut in with the scraper. Please note that at all times the bevel is horizontal.

The black circle indicates center.

The black line indicates how I come into center. I come in from the edge just high of center line to center.

The blue line indicates how I take off a pip that is at center. I begin under the center and go over it then exit just high of center line.

The green circles are where the bruises are. They now look like hairline checks. You can see them a little beter int he next photo.

Bruise

John Crissman

>I know the clarity is not great but I think you get the picture.

Re: Scraping cuts

Mark Mandell - Gone Round In Jersey

>You using a fresh burr on your edge rather than a honed flat edge, right?

Suggest you elevate the leading edge of your scraper a tad to get more of a tangential slicing cut along your burr. Practice on "junk" wood to gain control.

Your problem seems to be not on the end grain, but when cutting across the centers of the two face grain areas. Think a shearing cut might help to sever those fibers cleanly. Tried starting at the center and moving out towards the rim so that the fibers are always support by faster-moving wood??

Again, junk-wood practice.

I think we all get some torn grain (well, ok, Ellsworth doesn't, but He's more magician than turner!), but I'll applaud your search to prevent it.

Caveat, again, I not a scraper guy, so hopefully someone else will butt in here with real hard information. in response to your pics.

Mark

Re: Scraping cuts

Brad Vietje

>Hey John,

Thanks for the photos ... It sounds like you are doing everything right, though you'll get the cleanest surface going outward from center, as in your blue line scenario.

Is the soundness of the wood the problem ? In other words, is this a common problem in your goblets -- or maybe just in this wood (or wood from this particular tree). I ask because there can be small patches of dead or rotting wood surrounded by nice, clean wood. Cherry is famous for this, and there are sometimes slightly softer patches that look a little darker, and around here (New England) it's called "Red Rot" These areas feature wood that is more decayed than the rest, so its like working with spalted wood, in that a lot more sanding is needed, and often something is needed to support the fibers. If bad enough, it renders the wood useless.

I don't know what else to suggest -- I often make goblets, but usually use a hook tool to cut the wood from center outward, except for real small ones ... maybe a true scraper god could weigh in here.

Safe Spinning,

Brad Vietje

Thetford, VT

Thanks!

John Crissman

>

Thank you!

John Crissman

>

Re: Hey John!

Mark Mandell - Gone Round In Jersey

>I'd have sent you an e-mail, but you don't post your address so . .

Please let me know if what Brad and I posted helped (solved?) your problem. I'm still learning too! Had kind of hoped that someone who uses scrapers like you do would have jumped into this thread with personal experience.

Mark

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