How to fix end grain tearout on bowls

[Bernie Kopfer]

I'm turning some sycamore bowls and am running into small patches of tearout that I cannot seem to rid of. At times it has been so severe that I used CA glue to fill the roughness. Was then able to sand smooth. but it is the small pits that baffle me the most. So i'm wondering if a coat of sanding sealer will fill these voids so that the polyurethane will be smooth. Or should I use epoxy, or Ca glue.
The wood is not punky or soft, I think my instruments are sharp and are giving me clean cuts. So i welcome any advice or observations.

[Eugene Dixon]

YMMV. I apply a light bit of Titebond I or II to the area of the tarot. Smear it in a little if you like. Let it sit briefly to tack. As it cures, (wet) sand it with 100-120 grit paper. This will embed the sanding dust into the divot and harden the area around the tearout. The sanding action will speed the curing. Once the glue cures, you can make another light pass with tooling or move to final sanding as needed. The glue-dust mixture will blend in with the wood color. I prefer this process to avoid the staining I get with CA.

[John K Jordan]

I'm turning some sycamore bowls and am running into small patches of tearout that I cannot seem to rid of. At times it has been so severe that I used CA glue to fill the roughness. Was then able to sand smooth. but it is the small pits that baffle me the most. So i'm wondering if a coat of sanding sealer will fill these voids so that the polyurethane will be smooth. Or should I use epoxy, or Ca glue.
The wood is not punky or soft, I think my instruments are sharp and are giving me clean cuts. So i welcome any advice or observations.

Bernie,

I assume the bowl is already off the lathe so you can't work it more? My experiences is when on the lathe a good curved negative rake scraper gets rid of almost all tearout, end or side grain. (For problem cases I sometimes apply a coat of thinned sanding sealer before finishing cuts and sometimes before using the NRS.

NRS_curved.jpg scrapers_neg_rake.jpg

Any tiny bit that remains is usually easily removed with hand scrapers off the lathe. If already off the lathe, I'd try that. I use small curved or flat hand scrapers and scrape with the grain. This has removed nearly all tearout I couldn't cut away, even with razor-sharp tools, inside or out.

_scrapers_IMG_7827.jpg scraper_box_IMG_20171220_113442_765.jpg

I learned from John Lucas how to handle the occasional isolated tiny void, sometimes not even tearout but a defect in the wood - doesn't remove it but makes it disappear! He wet sands with thin CA glue. I've done this with, say, 220 grit and thin Hotstuf glue. The fine sawdust from sanding mixes with the glue and fills it the tiny pit. Since the sawdust is from the wood immediately surrounding the defect the fix is almost always undetectable. This method does have the risk of sandpaper sticking to your fingers but it's not life-threatening.

Edit: I see Eugene mentioned a similar technique using Tightbond instead of CA. I haven't tried this, but I can say that unlike applying CA directly to the wood, I get no CA staining with the wet sanding.

JKJ

[Bernie Kopfer]

This is good stuff! Will go out ant give it a try.

[Richard Coers]

Curious how you folks handle the stain from the CA and Titebond when it's time for the clear coat? I've just sharpened and taken lighter cuts to reduce the depth of the tear out, then some 80 grit for really soft grain issues.

[Dave Mount]

Hey Bernie--

What kind of cut is your finishing cut -- meaning what tool orientation? And is the tearout on the inside, the outside, or both? If wood is sound, which you say this is, I've always been able to tame tearout on the outside of a bowl using a bowl gouge in a sheer scraping orientation (not the horizontal scraping position, but one with the tool tip held diagonally upward at a steep angle and the flute facing the wood). That's not an option on the inside, though for me, it seems like the end grain tearout during shaping is usually worse on the outside than the inside. On the inside, I usually finish with a 5/8" U flute bowl gouge with a grind between a standard grind and a fingernail grind (like a fairly blunt fingernail grind), with the flute closed down pretty far. The combination of the grind and the U flute give a pretty broad curvature to the cutting edge, and rolling the flute well towards closed puts the edge at a pretty high shear angle, even though it's a regular bevel supported cut, not a shear scrape.

While you've said your tools are sharp, for any wood that's giving me trouble I will re-sharpen immediately before making my final finish cut, regardless of the tool. Sharp enough for the job at hand is user defined, but if you're fighting tearout, there's no such thing as too sharp. As is widely said, any time a cut is not going as you'd like, the first response is to sharpen. For most things I use tools right off the grinder. But if I'm struggling with a cut like this, I'll sweeten the edge with a hand held diamond hone after the grinder. For general shaping I think this is overkill, but for finishing cuts, it sometimes gives you the extra sharpness you need. I also have a small diameter diamond cone that can be used to refine the flute side of the cutting edge.

A fluteless gouge is another option -- I bought one of those after seeing a video Reed Gray has on youtube. While it worked as advertised, I kind of grew away from it in favor of the U flute gouge. I like the gouge because it is able to take off a little more wood if I've got a little bit of a thick spot to take down at the same time I'm finishing, and I've found it to be good for going down around the corner and across the bottom of the bowl. I suppose another reason is that I've probably already got the U gouge in my hand for sweetening the curve, so no reason to switch tools unless I'm having a problem.

None of this is to argue against John's suggestion of negative rake scraping. Though I use NRS routinely for some applications, I generally don't use it on bowls unless I'm just having one of those days where I can't get a smooth curve with the gouge alone. I use a NRS more for smoothing ridges and valleys than for removing tearout. But that's just me, not saying it's how others should work.

I've only turned a few sycamore bowls, but I don't recall it being particularly cantankerous. But within a species the characteristics of wood can vary greatly tree to tree, so maybe you've just got a tough one there. At least sycamore is soft enough that it sands down pretty quickly if the only option is the "80-grit gouge"!

Good luck with it.

Dave

[Eugene Dixon]

I don't see staining with the Titebond. My theory is that my the time I'm through sanding, there are enough open dust pores that the finish evens out. Maybe John K has the same thing going on with the CA.

[Bernie Kopfer]

Thanks Dave for giving your experience with using sharp tools to tame tear out. This will also give me an excuse to obtain a NRS and see if it makes a difference.

[Kyle Iwamoto]

If you already have a scraper, you can just re-grind it to be a NRS, just to give it a try. If you don't like it, you just wasted a bit of your scraper instead of having to buy a new tool. But then, any excuse to buy a new tool is just that. An excuse to get a brand new tool.......
Personally, I've found that NRS in soft wood, doesn't do as well, unless you have a real nice new burr. It may take you a few tries.
I like JKJ's scraper solution. I suck at turning, so I have to sand or scrape or both......

[Dave Mount]

Relative to Kyle's "try it" comment, realize that the bevel on the top of the scraper only has to be tiny in order to try it. When you see pictures of people's NRS's, they usually have a substantial size bevel on the top, but that's only so you don't have to regrind the top very often. If you're just trying it, you can put a 1mm top bevel on, won't change the behavior. That way if you don't like it, you'll hardly lose a thing regrinding.

[John K Jordan]

Relative to Kyle's "try it" comment, realize that the bevel on the top of the scraper only has to be tiny in order to try it. When you see pictures of people's NRS's, they usually have a substantial size bevel on the top, but that's only so you don't have to regrind the top very often. If you're just trying it, you can put a 1mm top bevel on, won't change the behavior. That way if you don't like it, you'll hardly lose a thing regrinding.

That's true, any bevel is fine as long as the angle is less than 90 deg. For some of my NRS with a curve ground down one edge the reason I like the bevel the same on both sides is I can decide after sharpening whether to apply a burr to make the scraper left or right handed. For those curved scrapers I've tried several angles and like about 60-deg included angle the best.

JKJ

[Marianne Patton]

I'm turning some sycamore bowls and am running into small patches of tearout that I cannot seem to rid of. At times it has been so severe that I used CA glue to fill the roughness. Was then able to sand smooth. but it is the small pits that baffle me the most. So i'm wondering if a coat of sanding sealer will fill these voids so that the polyurethane will be smooth. Or should I use epoxy, or Ca glue.
The wood is not punky or soft, I think my instruments are sharp and are giving me clean cuts. So i welcome any advice or observations.

Since his bowl is only 8" in diameter and is already balanced, could he decrease tearout by increasing the lathe RPM? Up to 1,200 perhaps?

[Dave Mount]

I like the bevel the same on both sides is I can decide after sharpening whether to apply a burr to make the scraper left or right handed.

I hadn't thought about reversibility -- that's a slick idea! I don't use a NRS a lot, but the one I have is not ground symmetrically, it's shallower on the top. I've been meaning to experiment to see how the cut is affected by the attack angle (by this I mean the angle of the top bevel relative to the surface of the wood), but I just haven't set aside time to do it. I guess on a scraper with a turned burr, the true attack angle is determined by the shape of the burr in addition to the angle of the top bevel, but the idea is the same.

Dave

[Mike Peace]

You might be interested in this video I did on resolving grain tearout on bowls. https://youtu.be/T7U_5qaChUE

[Bernie Kopfer]

You might be interested in this video I did on resolving grain tearout on bowls. https://youtu.be/T7U_5qaChUE

Helpful, nice to find out it isn't just me or how I do things.