|Q & A: How do I get the endgrain to cut smoothly?|
Q: How do I get smooth endgrain?I am turning face grain solid maple and I cannot get the endgrain to cut smoothly. It always turns out rough in the two places where I cut endgrain. I sand the crap out of it and I apply my wipe-on finish and it appears dull even after five coats. I keep my tools sharp. Is there a filler you can put on the endgrain so that when you finish it, it will appear smooth all over?
~ Chuck Marsh
A: What to do when you get tearout.Tearout often happens when you're forced to turn up-hill against the grain. This happens frequently on sidegrain bowls, usually 180 degrees apart. It can also happen when turning segmented work if you're not careful in orienting the grain on all the pieces.
A freshly sharpened tool is essential as well as not forcing the cut. I find that it’s very easy to push a tool too fast through the wood. You want to go at a rate that lets the tool cut. This can be a tricky thing to learn but well worth the effort. Speed up the lathe and slow down your feed rate and you may get rid of the tearout.
Tool presentation to the wood and the sharpening angle of the tool are also important.
I’ll talk about sharpening angle first. My typical bowl gouge is ground at about 55 degrees. If I can, I’ll switch to my 40-degree bowl gouge. If that doesn’t work, then I will try my spindle gouge that I sharpen at about 35 degrees. Of course, you still need to rub the bevel for a clean cut and sometimes the 40 or 35 degree angle may be too acute. I am a big fan of the Hunter carbide tools for cleaning up torn grain. The reason is that the tool face is recessed so you get a cutting angle of about 30 degrees. The Hunter Osprey has the cutter tilted down at 30 degrees, so from the side the bevel appears to be the same as the 55-degree bowl gouge, which means it’s easy to rub the bevel inside a bowl. However, you're still cutting with that very sharp 30-degree cutting edge.
Tool presentation to the wood can also help. You want the wood to go across the blade in a slicing angle. A very rough description is that you're using the skew as a paring tool. The wood comes across the blade at 90 degrees. This is a very fast cut but usually leaves a slightly torn surface. Swing the tool handle so the wood hits the blade at a 45-degree angle and you get a very clean cut. Spindle gouges and bowl gouges work exactly the same--it’s just more complicated because of the curve. Watch how the wood comes across the cutting edge. A slicing cut will work better than a peeling cut. This can usually be accomplished by rotating the tool to change where and how the wood comes across the blade. The steeper the angle, the better the cut, usually. Really swirly wood grains or things like bird's-eye maple may not cut as cleanly with these severe angles.
Last but not least, use some sort of chemical to solidify the fibers. I use lacquer thinned about 50/50 with lacquer thinner. One or two coats usually works. It dries fast and is relatively inexpensive. For punky woods I may use five or six coats, letting it really soak in. I also use thin CA glue for smaller areas. The glue is too expensive to use on large areas but it works well. Be sure to let it dry. It’s impossible to get off your glasses or face shield. Avoid the fumes, which can really burn your eyes. That’s why I tend to use the lacquer.
I find most often on problem woods that it takes a little bit of all of these. I had a piece of green walnut that tested all of these procedures until I finally got it cut cleanly. It’s worth the effort. I’m one of those strange people who don’t mind sanding because I believe it’s what brings the wood to the next level. That being said, I despise sanding torn grain. Two tricks I’ve learned to solve that problem. First trick is to stop the lathe and sand just the torn grain area. It’s my belief that quite often these areas are mildly recessed so the sandpaper simply skips over them when you sand under power. Stop the lathe and sand just the area and it will reduce the time it takes to get rid of these marks tremendously. Second trick. Again with the lathe off, use a round cabinet scraper. It will remove tearout very quickly. It will leave a divot so you have to feather around the area with the same tool to sort of disguise the crater. It works very well and doesn’t leave the lumpy summer/winter wood that you get with sandpaper.
~ John Lucas, a retired photographer, has been working in wood for about 35 years and also dabbles in metalworking. He also enjoys modifying machines, making tools, and sharing his knowledge through written articles and videos. He has taught classes at John C. Campbell Folk School, Arrowmont, and The Appalachian Center for Crafts.
9/4/2016 » 12/29/2016
Turning 30 - AAW Annual Member Exhibition - St. Paul, MN