So, why bother with tool control, when there is such good sanding methods available?

[Odie]

(While I was on this thought, I thought I'd move it over to another thread)



So, why bother with tool control, when there are such good sanding methods, and equipment available to the woodturner?

With all the sanding papers, discs, sanders, etc., available to us, why do turners continue to invest such time, effort and focus on mastering the cutting tools......all, in a search for the perfectly prepared surface, prior to sanding?

All the new sanding equipment, pads, discs, papers are pretty amazing stuff, and can produce a surface that is perfect in every way.....quickly and efficiently......so, it's perfectly understandable that the "newbie" would be asking himself why all that effort, because I can get a perfect surface without jumping through all those hoops........?

The answer is pretty simple, really...........and, I can remember the time when I questioned the very same things.........

Sanding is what it is.....it wears away the wood surface. There is a certain amount of skill level that minimizes the problems inherent with sanding, but skill cannot overcome its shortcomings with absolute perfection. A cutting tool doesn't have this problem. No amount of new and improved sanding tools, gadgets, or widgets has changed that. Because of the nature of sanding, combined with the natural grain patterns of wood, the sandpaper will wear away the surface of the wood at an uneven rate. It takes away wood on the long grain faster than it does on the end grain. Some woods, like Ash, have distinctly harder and softer areas between the widely spaced annular rings, and if you have tear-out on that......coarse sanding will leave a badly uneven surface. On a bowl, the same hard and soft areas are distinctly different between the long grain (softer), and end grain (harder), and excessive sanding here will produce an out-of-round condition on your bowl.

OK.........so, what's the big deal? Why does this matter?

Those who have been turning for some time, know that two planes that intersect will create a line. If either, or both of those planes aren't perfectly flat, then the intersection will vary from a line. The union of those two planes on a turning MUST be as close to a line as is possible for it to have a the greatest artistic effect, or appeal to an observer. This results in all those "oooohs, and ahhhhs" from casual observers who have no idea why they like your bowl so much.......but, they just do! 😀.....A sharp and distinct union, or corner of the intersection between the two surfaces has 10 times the positive visual effect on the observer, than a union that needed to be rounded over and minimized because of imperfect geometry.

Another little thing that looks great to the observer, is perfect detail grooves........those little grooves you make with a spear-point scraper as a final gesture in completion of a turning. If the surface they are cut into isn't as perfectly flat as you can make it, those little detail grooves will get wider and narrower around the circumference. The tool is held steady, but the turning isn't running true. In effect, it looks bad when the detail grooves have the appearance of having been cut deeper where the sanding hasn't removed as much material. The detail groove appears to be a shallower cut, where sanding has removed more material. I start to consider not doing a detail groove when the run-out is more than .010" over one revolution. I've done some that were acceptable at around .020", but here, the quality of the detail grooves are beginning to show the ill-effects of an imperfect base surface.


.....and, THAT'S WHY!...........🙂

ooc

 

[MichaelMouse]

Relatively easy answer to your groovy problem. Sand supported on the toolrest, not the work. Same thing that brought you to circularity - rotating wood against a fixed tool - will help you keep it.

 

[hockenbery]

Odie,

You are right on with "detail"

Spindle details get ruined with sanding in a hurry.
Christmas ornament finials I sand with 320 and 400. This requires a good tool finish.
Occasionally I have to use 220 in the bottom of a cove that I miss a bit and the 320 shows a tiny line.

Sanding with higher grit erodes the detail and gives a ho-hum look.


Al

 

[Odie]

Relatively easy answer to your groovy problem. Sand supported on the toolrest, not the work. Same thing that brought you to circularity - rotating wood against a fixed tool - will help you keep it.

Thanks, Al............

I figured I'd hear from you MM........😀

(BTW: MM, I checked your AAW gallery, and see you haven't added anything since 2007......are you still actively turning?)

Yes, you are correct that supporting the sander does help, and is covered in my statement (quoted below) about skills with the sander that can improve the result. Among other things, bracing the sander is something I do regularly, but the bottom line is this.......sanding wears the wood away, and you can make the pressure lighter between the sandpaper and the wood, but you cannot eliminate the basic principle of how sanding works.......it takes pressure between the sanding surface and the surface of the wood. If you use no pressure, there will be no sanding. Since pressure is a necessary element, the long grain will necessarily be removed at a faster rate than the end grain.

There is a certain amount of skill level that minimizes the problems inherent with sanding, but skill cannot overcome its shortcomings with absolute perfection.

Since most new turners are "in progress", and haven't learned advanced tool control as yet, his surfaces will require more sanding. The solution for many newer turners (as it was for me some thirty years ago), is to simply cut those detail grooves deeper. By cutting the detail grooves deeper, it won't be quite so apparent that the wood surface the groove was cut into was not very flat. It is my belief that a very small delicate looking detail groove is much more refined, and artistic looking, than a deeply cut groove. I guess that's part of my woodturning philosophy now, as it has evolved.

I'm adding some photo examples of detail grooves and intersecting planes. My intent is for small delicate looking detail grooves and nice crisp sharp edges between intersecting planes. (I call them planes, for lack of a better way to describe what I'm talking about.....the "planes" are actually curved around the bowl. Maybe two intersecting surfaces would be a better way to describe it.)

It is much more difficult to maintain a crisp sharp edge at the intersection between two surfaces that intersect at an obtuse angle, than either a right angle, or acute angle. For this to work well in all three cases, the two planes need to be as flat as possible, so as to create the crisp corner at the intersection, all the way around. All the photos have examples of intersecting surfaces, but the last two show examples of obtuse angles.

I know this might be a bit difficult to comprehend for a "newbie", but just keep this information in the back of your mind, because it all will make perfect sense if your progress is continually sustained. Some turners progress to a certain point and stop advancing. I suppose there are a variety of reasons why there is no further progress, but you will need to keep turning continuously and keep an open mind about new concepts......whether they be from your own discovery, or by input from others.

ooc

 

[john lucas]

Odie I agree. When I need super fine details I do my very best to cut the surface clean with cutting tools. I think 220 is the coursest you can use and still keep fine detail. Anything courser removes too much wood. I have pointed edges on some of my finials that will almost cut you. It's matter of pride and even thought the customer may or may not notice, I do.
On Bowls with line details like you show I often sand first and then do the lines. They are cleaner looking and if I do them properly they don't need sanding to the shadow line created from the edge is very clean.
I know you've been touting scraper use but on finials with fine details you can't use a scraper and I can get a cleaner surface off the cutting tool. Especially the bottoms of V cuts and inbetween Beads. Sandpaper almost always degrades those areas because it makes a slightly rounded joint instead of the crisp cut line that is left by the toe of a skew.

 

[MichaelMouse]

Sure, OD. If you don't want to cut deeper with your gouge or scraper, you just stop pressing, right? Same thing with the supported sander. Keep it where it is until there's no more dust coming away.

It's especially helpful to use a supported sander when you have delignified portions in spalted pieces. If you press, they'll dish. If you let them sand themselves, they don't.

 

[Odie]

Odie I agree. When I need super fine details I do my very best to cut the surface clean with cutting tools. I think 220 is the coursest you can use and still keep fine detail. Anything courser removes too much wood. I have pointed edges on some of my finials that will almost cut you. It's matter of pride and even thought the customer may or may not notice, I do.
On Bowls with line details like you show I often sand first and then do the lines. They are cleaner looking and if I do them properly they don't need sanding to the shadow line created from the edge is very clean.
I know you've been touting scraper use but on finials with fine details you can't use a scraper and I can get a cleaner surface off the cutting tool. Especially the bottoms of V cuts and inbetween Beads. Sandpaper almost always degrades those areas because it makes a slightly rounded joint instead of the crisp cut line that is left by the toe of a skew.

Thanks for bringing up a few points, and allowing me to make some clarifications, John.......

It is important to leave no room for misinterpretation, since some new turners will be reading it........

All reference to my using scrapers for finish work are for bowl turning as the grain pattern alternates between long grain and end grain as you turn. As with most turners, I never use a scraper for finish turning of spindle work......

Also, all my detail grooves are done after completely finish sanding. I normally stop finish sanding at 400, sometimes 600.....and then cut the detail grooves.

Using 600g paper, I do a quick swipe on intersecting planes to take off the sharp edge from the corner. It still has that crisp corner look to it.

I normally use 600g paper to clean up detail grooves, and feather the edges there, as well.

ooc

 

[Odie]

Sure, OD. If you don't want to cut deeper with your gouge or scraper, you just stop pressing, right? Same thing with the supported sander. Keep it where it is until there's no more dust coming away.

It's especially helpful to use a supported sander when you have delignified portions in spalted pieces. If you press, they'll dish. If you let them sand themselves, they don't.

It is against my better judgement to argue a point with you, MM......but, for the sake of those listening in, I suppose I probably should give a response to the content of your post, so those who are still learning aren't misinformed.......

In theory, you are correct that it is possible for sanding to actually true, or maintain trueness of a surface.......but, the problem is practicality. If it were practical, then the basic belief nearly all advanced turners have about the value of getting a tool finish that requires the minimum of sanding, is all a bunch of hogwash......and unnecessary. The only way your assertions can work, is to have a non-flexing, very stiff backing pad holding the sandpaper, or disc.....or to use such a small amount of pressure that the disc doesn't flex, as it's designed to do. Either way, it's a very time consuming process that isn't practical, as well as near impossible to do while negotiating more difficult and complex shapes........and I can say that because I've been there, and done that.

Our sanding backing pads are designed to conform to the surface it's presented to, and it's best to start the sanding process at the finest grit that is possible. We strive for a surface requiring the minimum of sanding for the specific reason of maintaining the most geometrically true surface possible AFTER the sanding stage is brought to completion. (Best to start with a good foundation, rather than to rely on fixing the foundation......horse sense..!) The coarser the grit one needs to start the sanding process, the more difficult it will be to maintain a surface that will promote successful refinements and artistic appeal.......these are things that include, among other things, consistently true small and delicate detail grooves, and intersection of planes that result in a fine crisp line, or corner......

........ Looking over your photo gallery, doesn't give one a sense that these things are particularly meaningful to you, but to others....they are extremely important to our woodturning goals.

MM's gallery:
http://www.aawforum.org/photopost/showgallery.php?ppuser=1022&cat=500

If you have done any turning since 2007, you haven't shown us any examples. Of those you do show, there are a couple bowls with detail grooves that are cut very deep, and very few intersections of surfaces that result in a crisp corner. For someone who posts here nearly every day, maybe you ought to post some current pictures.....just so the rest of us have some sort of reference point as to how we can apply what you say, to some visual evidence of what you do.



ooc

 

[robo hippy]

For me, it is easier to do most of the finish work by cutting first, then sanding last. Sanding is painfully boring, and the less time I spend on it the better.

I can not leave my sander supported on a stable rest because all of my bowls are warped. I have not noticed that there is any run out created by sanding, but again, impossible to tell from my warped bowls. The only time I could see that being critical would be if I was turning less than 1/8 inch thick, and when I do that, it is warped, and because of movement differences, there will be wall thickness variations. Most of the time, it is not observable unless you take out your calipers.

robo hippy

 

[MichaelMouse]

I can not leave my sander supported on a stable rest because all of my bowls are warped. I have not noticed that there is any run out created by sanding, but again, impossible to tell from my warped bowls. The only time I could see that being critical would be if I was turning less than 1/8 inch thick, and when I do that, it is warped, and because of movement differences, there will be wall thickness variations. Most of the time, it is not observable unless you take out your calipers.

You could sand supported if you liked. Only the wet piece, of course, still round from your gouge or scraper, which was, of course, supported. Sanding does not cause runout. Didn't in 1912 and doesn't in 2012. You can, however, go a bit oval with riding either the bevel or the gravel, because, as you mention, thinner stock will move away when pressed, and face grain will abrade faster than end.

My wet stuff gets a 120/150 depending on grit at hand. I use stearated paper, you use a glycerine soak, as I recall. I blast with air to drive out unbound water and get a bit of superficial surface drying to prolong the time between paper cleanings, and recommend it, not because it takes a day off the dry time, but because it saves paper.

There are also flex disks available in the power-lock style. They follow irregularities and tight curves without having to press. Not as aggressive as the hard backs, but you still don't want to "ride" them if you're looking to use a surface finish which might accentuate surface deviation.

http://i35.photobucket.com/albums/d160/GoodOnesGone/Flex-Edge-2.jpg

Once they're dry, it's lap sanding, where, in my experience, the flex still puts the least strain on the worker.

 

[robo hippy]

Well, actually, even though I turn very fast (rpm and time wise) the wood has already moved, so I can't have a stationary sander. I am playing around with an articulated arm for resting my arms on when sanding. I do agree that there is no run out created by sanding unless you are doing some thing really wrong, or if there is run out, it could not be seen by eye, and would have to have a micrometer put on it.

robo hippy

 

[Odie]

Well, actually, even though I turn very fast (rpm and time wise) the wood has already moved, so I can't have a stationary sander. I am playing around with an articulated arm for resting my arms on when sanding. I do agree that there is no run out created by sanding unless you are doing some thing really wrong, or if there is run out, it could not be seen by eye, and would have to have a micrometer put on it.

robo hippy

Hi Robo Hippy........

I don't know if you caught the following partial quote from my previous post, but a micrometer is close to what a turner will need to use, in order to have detail grooves that look good to the eye.......

Another little thing that looks great to the observer, is perfect detail grooves........those little grooves you make with a spear-point scraper as a final gesture in completion of a turning. If the surface they are cut into isn't as perfectly flat as you can make it, those little detail grooves will get wider and narrower around the circumference. The tool is held steady, but the turning isn't running true. In effect, it looks bad when the detail grooves have the appearance of having been cut deeper where the sanding hasn't removed as much material. The detail groove appears to be a shallower cut, where sanding has removed more material. I start to consider not doing a detail groove when the run-out is more than .010" over one revolution. I've done some that were acceptable at around .020", but here, the quality of the detail grooves are beginning to show the ill-effects of an imperfect base surface.

I tried to stress that absolute perfection isn't necessary, but a near perfect base is definitely necessary for detail grooves to have a pleasing look to the observer's eye......otherwise, unless the grooves are cut deeply (which doesn't have the refined look of small and narrow, shallow, well proportioned grooves), the grooves will have an obvious look of being flawed.

What I use to test the surface, is a machinist's dial indicator and magnetic base. As stated, around .010" run-out is the point where a decision has to be made on either not doing the grooves, or going deeper than I'd prefer to go. Anything under .010", and the detail grooves will look nice and consistent for the entire circumference. Anything over .020", and I usually just forgo the grooves altogether. The detail grooves are a plus, from my point of view......but, not having them is much better than detail grooves that look poorly executed.

Here's a little tip for cleanly cutting detail grooves: It depends on the wood, as sometimes you can plunge a spear point scraper straight into the wood, but there are woods, and specific examples of some woods that won't cooperate in getting a nice cleanly cut detail groove. Usually the harder and denser the wood, the more difficult.......but, this isn't necessarily always the case. On the other end of the spectrum, very soft and punky spalted woods are usually a nightmare for getting nice detail grooves. I normally do a shallow test cut first, and if that looks good, proceed as normal. If I can't get a cleanly cut groove, there is a technique of alternating the sides of the tool.....bit by bit.....one side, then the other. Usually this will get the desired result on otherwise very difficult wood.......

ooc