Thoughts on sanding

SNIP

I take the gouge to the grinder and make the last pass with a freshened edge for purely economic reasons. A thousand sharpenings versus the time and the paper to run a coarser grit makes it seem a bargain.

Haven't found a wood that didn't improve with a _cut_ made with a sharp gouge. Bunch of them get torn or picked out with a scraper.

Thanks Darrell, Thoughts from actual experience are usually good ones.

George, you just knew someone would have to ask about very light shear-scraping as the last cut before sanding. Your opinion? Darrell's too.

Turn to Safety, Arch Fortiter

Arch I think a light shear scrape before sanding is a great technique. I use it all the time, especially since I made a set of shear scrapers after watching a John Jordan video on hollow turning. For $2.00 they are some of my used tools.

Thanks, Darrell... I printed this in 14 point bold to go on the wall over the lathe...

mac

Please remove splinters before emailing

After watching a Clay Foster demo, I tried using various shaped cabinet scrapers (Lee Valley) for pre-sanding shear- scraping. I like them.

Now back to topic, "Darrell's thoughts on sanding". Serendipity is often good, but after taking time to offer one's thoughts, it can be disconcerting when the thread wanders far OT or dissolves into ? humor. I plead guilty on both counts. :)

Turn to Safety, Arch Fortiter

Nope, but since you asked, I'm not sure what shear scraping is. I own no videos and only one turning book. I picture it as a scraper on edge to scrape a narrower face, based on comments here and elsewhere. As a practice, I don't use scrapers unless I have to.

I find from reading here and working with other turners that they are prone to gouge techniques like overextending from the rest and getting chatter as they either turn the end of the gouge upward to pick up endgrain or pressing into the side of the piece and getting out of circular as they follow the gouges they make into the long grain and bounce up into short. For these folks, a scraper is a way to get it back to round, because they (finally) have a closer rest, or heavier section to reduce chatter, and they're referencing to the rest, allowing the piece to bring the proud wood to the edge. A broad contact surface perpendicular to the rotation will still tear and pull, however.

My gouge selection and technique is different. I use broadly curved forged or spindle gouges placed as close as possible to the work for best control and rolled up on edge with the lower edge leading into the work slightly to provide a bevel guide. This is the guide which I told you about which is mostly parallel to rotation, not perpendicular. I may broaden or narrow the cut by diminishing or increasing the angle into the work, because the dual curve of the gouge ensures both that the exit is cut, not scraped, and that the work cannot climb over the end of the gouge as it often does with narrow bowl gouges.

This allows me to take out modest ridging left by less-than-smooth angular changes on rough cuts as well. So you see I'm getting the broader bridging of a scraper with the clean severing possible with a gouge - and no catches, because I give no leverage and guide the bevel. I like to run rim to button in one continuous motion.

I suppose where the form of the curve has an extremely small radius - where I can't get a good reference with the bevel on a broad gouge, I might be shear scraping. It does, however, generally give a surface inferior to a smaller flat-section gouge cutting in that section alone. You don't have to have a "scraper" to scrape, after all. Any edge will do.

I like the last couple of passes inside to produce tightly twisted continuous shavings with the outside of the shaving smooth. I then make my first pass with the supported disk basically 90 degrees to the remaining gouge ridging.

When is a scraper not a scraper? When it is a shear scraper. A shear scraper cuts with a slightly rolled burr along its edge and is presented at 45* to the angular rotation of the wood. In effect it becomes a gouge with extremely small radius and little back pressure allowing an extrememly fine cut with little or no tear. A gouge can be angled to produce the same cut and this sounds similar to what George is doing albeit at a tangent to the angular rotation. It should give a very fine cut in most situations. I am of the opinion that the wood will produce its own situation wheI least expect it :-)

To continue our thoughts on _sanding. :)

I occasionally cut-shear-scrape-rip-tear- and worse using a shallow 1" gouge with the bevel ground on the flute. The wings upside down on the toolrest and the cut a little high up on the blank with the toolrest close up. Stable and the edge is automatically angled for (excuse the expression) shear-scraping. The cutting point is narrow as the two convex curves touch. Your further thoughts? George, You might be a shear scraper if...... :)

Turn to Safety, Arch Fortiter

Sounds like Joaz's (Python) in-cannel method. He claims good results. No turned burrs, but, as I said, any edge can scrape.

Like a lot of "tips" along the way, this one answers a problem I don't have. I'd rather cut across the fibers than scrape.

BTW, as of this morning I too am the owner, though not yet the possessor, of a (used) Nova 3000. Have to wait for my wife to go to a conference in March and pick it up at her sister's. Gives slower start and greater swing than Ol' Blue, but I'm not likely to pass him along any time soon. Hope to turn some of the larger pieces of wood on him that I've got lying outside frozen right now.

Router Workshop's over, and I've got some display shelves to finish. Almost a shame, speaking of sanding, to have to sand them after running the plane over the surfaces, but the routed edges need work, so in the interest of consistency, everything will get two grits prior to shellac.

toolrest

results. No

possessor, of

No one has yet mentioned a very important part of final cuts and shear scraping. For best results, always go with the grain.

When hand sanding, especially at the beginning when using coarse sand paper, I find that by applying a small amount of wax ( paste, briwax or bees) to the wood, that the sanding goes much faster, and much less dust is created. I use this technique when hollowing end grain when making boxes. I haven't made any bowls, nor have I tried it with power sanding.

Dan Using wax when sanding, especially on the lower grits, can certainly speed things up. Sometimes I apply it to the wood in areas of torn grain, sometimes to the paper itself. It can be a help in both power and hand sanding. I suspect that any paste wax would be fine, however I use a mix of beeswax, mineral oil, and vegetable oil, the same wax I use as a finish in some cases. Remmeber that using a wax in the higher grits may interfere with some finishes.

that was a gritty comment, Arch..

mac

Please remove splinters before emailing

Thanks, Darrell. But I have a dumb question.

Aren't you contradicting yourself?

You say slow is better. But a belt sander works well because it's fast??

Perhaps if you elaborate?

Bruce the belt sander works "well" because it so fast that the 80 grit does not get a chance to work as 80 grit. The tips of the grit are all that get a chance to touch the wood, not the sides, so the paper does not have a chance to remove as much wood as it ought. We use a coarse grit to remove the necessary damaged wood and leave the good. A belt sander moves too quickly, generates too much heat, and leaves a case hardened surface. It is good for removing wood quickly but should be started with a lower number grit than usual.

Okay. But you said that slower was better on a lathe. So does speed help or hurt a belt sander? And if it helps, why doesn't it help on the lathe?

It seems to me that the type of paper makes a big difference as well. Perhaps it is more important than speed?

I use a faceplace-sanding disk, and used a disk cut from the belt of a floor sander. That worked much better than more typical sanding paper. That's because the disk lasted longer, and didn't clog up as much.

Torn fibers pack between the grains and heat/burnish the surface because they aren't ejected as they are created. That's why rotary power sanders work so much better than holding a piece of paper against your bowl as it rotates - they can unload themselves to a much greater degree. But take a hint from the directions on your Random Orbit Sander - don't press.