Official Luthiers Forum!

I just thought you could discuss it on the forum instead of siphoning people off to your blog.

I'm in the 'different' camp, rather than better or worse. This reminds me a bit of HHG vs Titebond vs fish glue, hot pipe vs heating blanket. outside mold vs 'free style'
and many others. Each side has valid reasons for what they believe and what works best for them. It's the end result that counts. If your way is working for you, why change ? If it isn't, make a change somewhere.

Every Sunday I post something on TLB.com that hopefully, informs, amuses, or inspires instrument makers both amateur and pro. Over the last year some "big" names have contributed. One of the main reasons why so many respected makers have been so willing to contribute is in part due to the fact that TLB.com is a blog and not a forum. They get to say what they think on an subject with out having to put up with defending their point of view. Readers don't get the opportunity to respond directly, which is just as well as it's not unknown for folk to be very rude - which is quite possibly one of the commonest reasons many professional makers don't contribute to forums. I think one of the guys here ran a survey a year or two back which said as much.

So, in order to give folk the opportunity to discuss whatever TLB was about that week, every Sunday I post up on this forum (and often a couple of other forums) a link to the latest post.

TLB gets some views, but then it's Lance who gets the traffic straight back as many gifted and enthusiastic makers on this forum get to discuss the post. Right here, on luthiersforum.com. I benefit too - by getting clues from the responses for future topics to write about.

That seems like a pretty good deal for everyone.

If you don't like it, if you feel you're getting a raw deal, that's fine: when you see a post with my name attached, just give it a miss, because the likelihood is that it will contain a link to the latest post over on TLB.

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nigel

http://www.theluthierblog.com

I thickness sand to 120 and finish sand to 220 for a nitro or cat urethane finish. Works for me. For an oil finish which I have used on necks I pretty much polish the wood to at least 600 or more. I agree that if you only go to 220 with TruOil you'll see scratches.

Planing looks cool, I admire folks with the chops to get a ready for finish surface with a plane and scraper. My old joints require powered assistance! I hear you on dust though. So do my sinuses. I enjoy your blog.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I had a look in the book - couldn't find it - but that doesn't mean it's not in there!

I've written about this subject a few times and talk about it in my design courses. The story goes like this:

Part of my process is to take a top half panel, reduce it to maximum uniform thickness (say 4.00mm) then tap it to derive its elastic constants (Young's modulus etc.) so as to then calculate how thick to leave the panel. When I did the initial work on this approach, years back, I tested it all out by taking a lot of abrasively planed tops (wide belt sander) measuring them up to derive Young's modulus etc. and then went on to make guitars out of some of them. The panels got re-tested after I'd taken to them with a plane and they always came out with a higher figure for Young's modulus. At first, I thought that there was some unaccounted for thickness dependency either in the equations or in the nature of the way the wood behaved. I tested more panels planed to the initial uniform thickness (rather than sanded) and found it all worked out OK. What the problem was is that sanded wood has a "mashed" surface and the "mashing" (depending on the grit size) can run close to 0.5mm deep, which is a lot, each side of a 3 or 4mm panel. In bending, it is the surface of the wood that takes most of the stress, but mashed wood, with short discontinuous fibers is incapable of supporting this stress (discontinuous fibers are one reason why wood is less stiff cross grain than long grain). So the surface layers add thickness and mass to the panel, but no effective stiffness and then there's the cube rule. So sanded wood measures up as having a lower Young's modulus than planed wood. This is unfortunate if you then go on to use that inaccurate Young's modulus number to calculate a final target thickness for the panel!

If the panel ultimately gets fine sanded, thus removing the majority of the surface damage from heavy grit abrasive planing, you get back to measuring much the same stiffness as you do with planed wood of the same thickness. However, I've seen a good number of guitars where the the inner side of the top panel looks like it came straight off a 60 grit wide belt sander, so those tops are carrying a layer of material on the inside which adds little but mass to the structure.

I hadn't seen the paper that Nigel pointed to before, so thanks for that.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Could well be I saw it online in discussion somewhere...

Thanks, I'll give it a miss

Yep



New isn't better, but 1984 is neither. Carleen Hutchins, on the other hand...

Exactly.

Ditto on the comment by meddlingfool. My skill at hand planes is a serious drawback for me. Don't think I would be making too many guitars without my drum sander. Guess I really need a remedial class in planing, but I'm content for now.

Planing is easy. Just kind of push the thing and it will cut. Hardly an art to it. The harder bit is the sharpening and the set up of unfettled Planes. Not so easy for a beginner who knows nothing about Planes. Much easier if you buy the more expensive 'ready to go' Planes, which just leaves sharpening the blade, setting the chipbreaker and setting the depth of cut. Bit of lateral adjustment too. Nothing difficult about any of it really.

I think real time videos hand planning versus a few passes through a drum sander will illustrate how easy each process really is. I truly respect you guys that have the time, energy and tool maintenance time and funds to perform hand thickness operations for top and back plates. Even after having expert training and use of very high quality planes -- (life is too short) I made exactly one guitar with hand thicknessed plates -- before I built my next guitar, I built a drum sander. Just my $.02

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Ken Cierp

http://www.kennethmichaelguitars.com/

It's nowhere near as bad as some make out, although seriously hard woods are going to make life more difficult. Hand planing is never going to match drum sanding in terms of speed but it doesn't have to take all day to thickness Back. Sides and Top. In fact the Soundboard is incredibly easy and fast.
The 'trick' is to have two or three prepared Planes. I use a wooden Plane to remove the bulk. It's not a scrub Plane but the idea is to take thick(ish) shavings with a gently cambered blade, often working across the grain. The blade has to be incredibly sharp, otherwise it will just blow out the wood. I also have a metal Jack Plane prepared. It's only when I have the last 1 mm or less that I switch to a finely set smoothing Plane. The smoother does very little 'work'. It's the other two planes that really remove the great bulk of material.
I also have a workboard that saves me from clamping the boards. I don't have to continually clamp and unclamp, itself a bit of a time saver.

I'd say it takes close to an hour for me to do a top, back, and sides in the 10-20. My feed rate is around 3, and I take shallow passes. I haven't planed a set yet, but I'd like to on the next guitar. Smoothing five 5x24" boards of maple to laminate for my Moxon vise project took about the same amount of time.

Yeah, we have a 10-20 Jet for bindings -- I agree not something I'd recommend for sizing B&S&T sets.

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Ken Cierp

http://www.kennethmichaelguitars.com/

The 10-20 is fine for sizing back, sides and top. Just slow

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Steve Smith
"Music is what feelings sound like"

I've been watching this thread for a while now and wanting to weigh-in.

Sure we all know that a planed surface has less damage to the wood cells and less debris left over from the process using abrasives. One does not have to be Einstein either.... to surmise that deep scratches will have an impact to varying degrees being more serious with thinner plates on the stiffness of the material.

But come on..... really?????

What's missing here is the "specific" processes that are being compared as applied to Lutherie or more specifically when deflection measurements are taken, how they are taken and if the heavy lifting from the abrasives are over yet.

Or in other words I pop a top in the easy bake oven (Performax 10-20 Plus) and since it's a top I'm using 120 grit (YMMV...). When I approach target thickness I pop the top in the deflection testing set-up and see what I have. I know in advance that this is not going to be my final thickness because I have to finish sand and when you are like me and try to keep up with Lance for how clean the inside of the box will be finish sanding can be more involved.....

Anyway when all is said and done I've skim sanded with the EBO, ROS sanded to 220 to keep up with Lance, and if there are any scratches to weaken my plates I'm not seeing them. My top is now at near final thickness (I finish sand again prior to finishing...), the deflection numbers that I want are there, I've never touched a plane except to shoot the joint, and someone wants to tell me that my decision to not use a plane for all thicknessing will make my guitar sound, play, or look inferior?

Hooey!

From some of the posts above I can also see that not everyone envisions thickness sanders the same way either. Folks who have wide belt sanders with 60 grit on them may indeed have some nasty, deep scratches if they take deflection measurements prior to further sanding the surfaces. For those of us with the hobbyist types of sanders that choke if we try to hog off more than .003 - .005" at once the level and depth of our scratches will not be nearly so severe.

If on the other hand what's really happening here, and no I am not off my meds at present... is the old "I'm better than you because I struggle with only hand tools" argument then this entire thread and some of the directions that it has taken are much more understandable to me and I'll add a waste of time.

Lots of ways to do lots of things Lutherie.... The debates for control of the idea of Lutherie purity will never end either. As for me I'm not buying any notion that using edge tools over abrasives makes it a given that the instrument that did not have edge tools used to build it is inferior in any way.

Don't get me wrong I too admire the folks who prefer edge tools and the lower levels of dust is attractive as well. But no one has an exclusive nor will they ever on one method being superior to any other method nor can someone discern if an instrument was built with edge tools over abrasives by listening to it. If anyone disagrees on the last point you must have better meds than I do....

Not to bum anyone out but my interest was never woodworking and although I have developed a bit of woodworking interest it's to the extent that it serves my Lutherie chops. I could care less if one planes, sands, wishes, imagines, hallucinates, what ever... just so what ever you do makes you happy, is safe, and likely legal as well although not a biggie for me either...

It's the judgmental aspects of these useless debates that will never sit well with me so hooey again..... Please note smiley faces....

Guitars are tools for musicians..... please tell me how using only edge tools makes this statement any more or any less true?

Only a beginner here but I love my 10 20 plus sander. Thought it might be a bit of a toy by its size if not its price but it's a solid bit of kit. Been using 120 grit which is slow but hey, with me everything is slow. . .

I'm right there with ya Mike and like my 10 - 20 as well. They are well made and mine has had a lot of use. Good stuff!

A consideration that I always bring up in discussions when evaluating thickness sanders is that even though the 10 - 20 is a double pass sander the level of dust collection required ($$$) is less too. If I were building only to make my living I might want a bigger sander but think that I could live with the 10 - 20 just fine too.

So you are not concerned that using a sander will make your guitars suck? Me either......

The 10-20 is a cool machine we've had it a long time (when it first became Jet rather than Performax), bought it for binding and finger-board work. paid just over $400 they are a bit more now. My only issue is with the elevator screw stripping out the aluminum housing happened twice first time under warranty -- second time I made an auxiliary lift plate that is bolted to the housing -- I will say that original lift screw is some kind of bastard thread, we were never able to match it with the appropriate tap???

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Ken Cierp

http://www.kennethmichaelguitars.com/

Planing can be done by machine also. The small cutterheads and close proximity of the rollers on portable planers, when used with sharp blades, can make a finely finished surface at the thicknesses used for lutherie. And they can do it quicker than a thickness sander, and with much less dust.

I thought my 13" planer did a pretty nice job with fresh blades --- until I had a thin piece of the figured Black Walnut explode and shoot shrapnel that was bouncing off the walls -- glad I was standing off to the side. Truth is I knew better, never again.

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Ken Cierp

http://www.kennethmichaelguitars.com/

"I thought my 13" planer did a pretty nice job with fresh blades --- until I had a thin piece of the figured Black Walnut explode and shoot shrapnel that was bouncing off the walls -- glad I was standing off to the side. Truth is I knew better, never again."

Figured woods can be problematic- probably one of the best arguments for owning a thickness sander. "Fresh blades" are sometimes different than sharp blades, but even sharp blades may not always give the best results when dealing with end grain figured wood (crotch, curly, birdseyes, etc.). Attaching them to a carrier board can sometimes eliminate catastrophic failures.

Spruce is much more tractable.

Isn't the soundboard all we're talking about in terms of increased stiffness by planing instead of sanding? A planer should be fine on that.

Figured or super-hard back side woods should definitely be thicknessed by a sander if possible, or hand plane/scraper if not.

Here's an interesting thought... a thickness sander with proper dust collection may in fact be less dusty than hand planes. Sure most of the wood becomes chips, but it's by no means a dust free process. And you spend more time in the cloud. I always wear a mask for thicknessing.

Over the years every so often we see a post from someone who thought like we all must have thought at one time or another and that is "hey, that Lowes planer is half the price of a thickness sander...." So they buy it, take it home, stick a top in there and then post on the OLF that at some point the thing exploded into a million pieces..... Then someone comes along and suggests a backer board and using adhesives to tape the plate to the backer board. Invariably when all is said and done someone else comes along, gets irritated, and simply proclaims that thickness planers are not suitable for thicnknessing plates for guitar building because our plates are too thin. Lots of these threads in the archives I suspect.

I personally wondered about planers too once I saw what the price of entry was to thickness sanders. It's understandable but lots of folks have had Ken's experience and were not able to make a planer work for what we do.