Jointing Soundboard Material

[Viking]

Originally Posted by Tom West

Pressure on the toe of the plane to start, even pressure in the center of plate and pressure on the heel to finish.
Tom

That's roughly what I was trying for, though you articulating it that way should help me to do a better job of it I'm sure.

Originally Posted by charles Tauber

A shooting board definitely makes the task easier, as does a good quality plane - or a cheap one in which you have invested many hours to "fettle" it so that it will cut properly. A "cheap" tool isn't necessarily a bargain by the time you've spent the time necessary to fettle the thing to make it useable.

Well, given that I have more time now than money, I don't mind investing the time into a cheaper tool to bring it's abilities up to snuff.

Originally Posted by Alan Carruth

IMO, almost all of the 'affordable' planes you can find these days are rwally 'plane kits': a set of parts that can be made into a usable plane with some work.

I'd read that somewhere, now I know why they say that. Course, with having bought a harbor freight plane, I knew I'd have to expend some effort to get it to work at all decently anyway.

So I'll be spending the evening lapping the sole of my plane and the weekend trying to get a feel for jointing wood. Thanks for the feedback.

[murrmac123]

Originally Posted by jeff crisp

And if worst comes to worst there is a lot less skill in sanding the plates flat using sand paper stuck to a known flat suface. The gluing surface you're left with won't be as reliable as a nicely planed surface but might be better than a poorly jointed one.

This is one of these things which is taken for granted by all woodworkers, of whatever discipline ..." gluing planed surfaces is preferable to gluing sanded surfaces surfaces"...it's like one of the basic axioms, right ? I mean, it was one of the first things I was taught as an apprentice over 40 years ago.

Yet I cannot help but wonder whether it isn't just one of these articles of faith which has never really been subjected to scientific testing ...I am not offering this as scientific evidence, but I did once, some years ago, out of curiosity, glue up two offcuts of spruce, having sanded each edge dead straight with a few strokes of PSA 320 grit (after first planing the edge)

After the joint was dry, I planed the surface ... the joint was invisible, and the workpiece never showed any signs subsequently of wanting to separate at the glue line.

You do, of course need to have a perfectly flat and straight substrate for your abrasive to achieve this.

[jeff crisp]

Originally Posted by murrmac123

This is one of these things which is taken for granted by all woodworkers, of whatever discipline ..." gluing planed surfaces is preferable to gluing sanded surfaces surfaces"...it's like one of the basic axioms, right ? I mean, it was one of the first things I was taught as an apprentice over 40 years ago.

Yet I cannot help but wonder whether it isn't just one of these articles of faith which has never really been subjected to scientific testing ...I am not offering this as scientific evidence, but I did once, some years ago, out of curiosity, glue up two offcuts of spruce, having sanded each edge dead straight with a few strokes of PSA 320 grit (after first planing the edge)

After the joint was dry, I planed the surface ... the joint was invisible, and the workpiece never showed any signs subsequently of wanting to separate at the glue line.

You do, of course need to have a perfectly flat and straight substrate for your abrasive to achieve this.

Sorry Murray I don't really know the reasoning behind why a planed surface is supposed to bond better than a sanded one. It's what I've always been told and what I've always read as well. I seem to remember other luthiers giving a reason for it and talking about tests proving it but I just can't remember who or where. I know when you push two flat metal objects together with a machine oil slick in between it can almost feel like suction is holding them together when you try to pull them apart. I guess that anything roughly sanded is too furry (though I have heard of people purposely roughing the surface for (perceived) better contact) and anything really sanded finely may be burnishing the timber and stopping penetration of the glue being used. But I'm afraid I really don't know.

Jeff.

[Ned Milburn]

Originally Posted by jeff crisp

Sorry Murray I don't really know the reasoning behind why a planed surface is supposed to bond better than a sanded one. It's what I've always been told and what I've always read as well. I seem to remember other luthiers giving a reason for it and talking about tests proving it but I just can't remember who or where. I know when you push two flat metal objects together with a machine oil slick in between it can almost feel like suction is holding them together when you try to pull them apart. I guess that anything roughly sanded is too furry (though I have heard of people purposely roughing the surface for (perceived) better contact) and anything really sanded finely may be burnishing the timber and stopping penetration of the glue being used. But I'm afraid I really don't know.

Jeff.

Jeff and Murray,

This is an interesting issue, and I am undecided on a conclusion because I have not done extensive controlled tests. With a properly fitting glue joint, you get as much wood-to-wood contact on a molecular level as possible, with glue soaking into the wood fibres and "encasing" if you will, the wood-to-wood joint. With this being the case, it could possibly be that the planed joint (if done well & proper) could have more molecular contact than the sanded surface. This could be an argument in favour of the supposition that planed joints are stronger. On the other hand, I fairly recently made some wood-fill (thinned titebond II mixed with Indian rosewood band saw dust) to make a curved surface on a jig. This wood fill, when it dried, became hard as a rock (so hard that it wouldn't even sand well - none of the "creep" or softness of a dried blob of glue existed. So, it could be that the fibre/glue mixture yields a super tough & durable glue joint. Glue joints in certain woods, however, especially oily & non-porous hardwoods, may indeed be stronger sanded rather than planed. Whichever is the case, it is always a good idea to test glue joints if there is any doubt. That why off cuts exist, isn't it...?? ;-)

[dlowry]

Originally Posted by jeff crisp

Sorry Murray I don't really know the reasoning behind why a planed surface is supposed to bond better than a sanded one. It's what I've always been told and what I've always read as well. I seem to remember other luthiers giving a reason for it and talking about tests proving it but I just can't remember who or where. I know when you push two flat metal objects together with a machine oil slick in between it can almost feel like suction is holding them together when you try to pull them apart. I guess that anything roughly sanded is too furry (though I have heard of people purposely roughing the surface for (perceived) better contact) and anything really sanded finely may be burnishing the timber and stopping penetration of the glue being used. But I'm afraid I really don't know.

Jeff.

I'm almost finished a 9-month stint in a luthiers shop. He prepares tops and backs for jointing with a power jointer, but stresses the need to have the machine set up just so, otherwise you get similar problems - either concave or convex edges depending on the misalignment of the outfeed table with the cutter head. Even with the power jointer method, you have to understand the operation of the machine in general and the idiosynchrasies of the individual machine to get a good result, its not merely the easy alternative to hand-planing.

As for sanding vs planing, I've been taught always to roughen surfaces slightly prior to gluing to improve the grip, to the point of roughening both the top and the underside of the bridge with 80 grit prior to gluing the bridge. Each luthier has his personal preferences - whatever works for you is the best method I guess.

[Viking]

Originally Posted by HCG Canada

Jeff and Murray,

This is an interesting issue, and I am undecided on a conclusion because I have not done extensive controlled tests. With a properly fitting glue joint, you get as much wood-to-wood contact on a molecular level as possible, with glue soaking into the wood fibres and "encasing" if you will, the wood-to-wood joint. With this being the case, it could possibly be that the planed joint (if done well & proper) could have more molecular contact than the sanded surface. This could be an argument in favour of the supposition that planed joints are stronger. On the other hand, I fairly recently made some wood-fill (thinned titebond II mixed with Indian rosewood band saw dust) to make a curved surface on a jig. This wood fill, when it dried, became hard as a rock (so hard that it wouldn't even sand well - none of the "creep" or softness of a dried blob of glue existed. So, it could be that the fibre/glue mixture yields a super tough & durable glue joint. Glue joints in certain woods, however, especially oily & non-porous hardwoods, may indeed be stronger sanded rather than planed. Whichever is the case, it is always a good idea to test glue joints if there is any doubt. That why off cuts exist, isn't it...?? ;-)

Have you ever heard of cob? The building material? It's made of clay, sand and straw and is used to build all kinds of different things. When it sets and dries, I've been told it's as strong as cement. The clay and sand form the base of the material, but it's the straw that does the really hard work. When it is randomly mashed throughout the whole of the material, it binds it all together and makes it super strong when it dries. Perhaps the small fuzz left over from having sanded the edges instead of having a planed, perfectly flat gluing surface could act the same way? Making the glue far stronger than it would have been all on it's own.

Course, being a guitar building virgin, I'll just go along and learn the traditional methods first.

Spent 6 hours last night lapping the sole of my plane. Almost done. Have another 2-3 hours worth of work to get the last valley out. My hands are sore this morning...

[Alan Carruth]

Back when I was working with Carleen Hutchins, she cited a study that was done by the Forest Products Lab back in WW II, on laminated airplane propellers. At that time they still used a lot of wooden props, even on military aircraft, and they'd had some problems with them coming apart, which is a drag...

What they found was that the companies that used planers to thickness the wood had no problems, while the ones that sanded laminations to thickness did.

If you've ever looked at the micro-photographs, you'll see that a good planed surface can be really clean, with all of the features of the wood structure clearly visible and no distortion or tearing. That takes a very sharp plane. Power planers and joiners, especially if they are a little dull or not set up right, can compress the surface. Too fast a feed rate can also produce a 'scalloped' surface. Since the proper thickness for the finished glue line is between .002"-.006" (iirc) scalloping could lead to improper glue line thickness: alternate areas of too thick and too thin. Anyway, a scraped surface, even though it's smooth, will be 'burnished', with the surface of the wood compressed: mashed flat, actually. This is not as good as a good planed surface, but better than you'll get in many cases by sanding.

Good sharp sandpaper does cut, rather than mash, the surface, but it doesn't stay that sharp for very long. Anything coarser than about #220 leaves scratches that are larger than the structural features of the wood: it's not really 'flat'. Finally, unless you really clean up well there will be a lot of dust lodged in and on the surface, and loose ends floating around. Even fairly good sanded surfaces can look like a plowed field under the microscope.

On the whole, assuming you can get things equally 'flat' by any of these methods, I'd have to say that a hand planed surface is the best, followed by machine planed, scraped, and then sanded, with finer sandpaper being better than coarse.

Then there's the matter of 'surface energy'. Another of those FPL studies from the War showed that wood surfaces that were glued within fifteen minutes of being worked yielded stronger joints. This is probably due to the higher 'surface energy' of the new surfaces.

Basically, when you remove material from a surface, you are breaking (weak) chemical bonds. For a time after the surface is worked there will be 'open' bond sites that are looking for something to glom onto (that's the technical term...). After a while they pick up what they need from the air or whatever, but if you can get the glue on them before that happens they will glom onto it, and produce a stronger joint.

The way to test surface energy is to spritz the surface with a light mist of water. Water is a polar molecule: the ends have slight positive and negative charges. Those open bond sites are charged too, so water will be attracted to a surface with high surface energy. In that case, it will spread out into a thin film. If the surface energy is low it beads up. If you want a precise reading of the surface energy, you can measure the angle between the edge of a drop and the surface, but that's going a bit far for our purposes. Wax has low surface energy: no open bond sites. So does fossil mammoth ivory that has not been worked recently: all the chemistry has already happened. That, I'm pretty sure, is what makes fossil ivory hard to glue. When I did an ivory bridge a while ago I checked that out. The water tended to bead up unless the surface was freshly worked. I made sure to give it a light scraping just before spreading the hot hide glue on it. So far, so good....

[John Arnold]

I don't doubt that planed is better than sanded, but you will have a hard time finding a factory guitar that does not sand their tops and backs as the final preparation before gluing the braces on.
Until the 1970's, Martin would use a toothing iron on the gluing surfaces of the rosewood backs.

[charles Tauber]

Originally Posted by Viking

Spent 6 hours last night lapping the sole of my plane. Almost done. Have another 2-3 hours worth of work to get the last valley out. My hands are sore this morning...

I know you said that you currently have more time than money, but just to put your $20 plane into perspective, at even $20 per hour, you've just added about $200 to the price of you plane.

Then you can fettle the iron and chip breaker, adding more hours for that. All said And done, the $20 plane isn't so cheap. It'll end up costing about the same as a well-made plane, but it is still - more often than not - poor quality steel that no amount of Fettling will improve.

A newer technique for the back of the iron is to bevel the back near the cutting edge. This saves time in not having to flatten the back of the iron for the first3/8" or so. David charlesworth has written on the method.

[Ned Milburn]

Originally Posted by charles Tauber

I know you said that you currently have more time than money, but just to put your $20 plane into perspective, at even $20 per hour, you've just added about $200 to the price of you plane.

Then you can fettle the iron and chip breaker, adding more hours for that. All said And done, the $20 plane isn't so cheap. It'll end up costing about the same as a well-made plane, but it is still - more often than not - poor quality steel that no amount of Fettling will improve.

A newer technique for the back of the iron is to bevel the back near the cutting edge. This saves time in not having to flatten the back of the iron for the first3/8" or so. David charlesworth has written on the method.

Also, more expensive planes have better and more accurate adjustment hardware (usually).

Interesting point about the technique you mentioned about bevelling only a portion of the back edge. Useful idea! Thanks for sharing.

[murrmac123]

Originally Posted by Viking

Spent 6 hours last night lapping the sole of my plane. Almost done. Have another 2-3 hours worth of work to get the last valley out. My hands are sore this morning...

My heart goes out to you ... (seriously)

Back in the day, I too used to spend hours lapping my plane soles and chisel backs .

Nowadays, as the fortunate owner of a 5' x 3' granite surface plate, I simply cut a 5' length off of a roll of 36 grit aluminum oxide cloth backed abrasive, 4" wide, and clamp it to the plate at both ends. With the plane iron in position (but retracted) it never takes longer than 5 minutes max (and usually only about two or three) , to get rid of all the hills and valleys even on planes up to a #8. The resultant flat (but extremely rough) surface is then lapped on successive PSA grits of 60g, 80g and 120g. The whole process never takes longer than 15 minutes, even for a #8.

120g is as fine as you need to go on a cast iron sole IMO, but of course you could go as fine as you like. The important thing is to start off with a really coarse grit on a dead flat surface.

[Viking]

Originally Posted by charles Tauber

I know you said that you currently have more time than money, but just to put your $20 plane into perspective, at even $20 per hour, you've just added about $200 to the price of you plane.

Then you can fettle the iron and chip breaker, adding more hours for that. All said And done, the $20 plane isn't so cheap. It'll end up costing about the same as a well-made plane, but it is still - more often than not - poor quality steel that no amount of Fettling will improve.

A newer technique for the back of the iron is to bevel the back near the cutting edge. This saves time in not having to flatten the back of the iron for the first3/8" or so. David charlesworth has written on the method.

It's a 15 dollar plane, not a 20 dollar one. Actually, the harbor freight pack I bought it in came with a second, smaller block plane, which really is a piece of junk. So I suppose this would technically be more like a 10-12 dollar plane.

Yes, I can do the math and I know how much time and energy I will have put into the plane and what that is worth in terms of the time value of money. The fact remains that I HAVE more time than money right now and no desire to get a second part time job. So while it sounds cool to say that I will have added 200 dollars to the price of the plane, I really haven't because I wasn't going to use those 6 hours last night to earn actual money if I had not been working on my plane.

So I play with my tools. It's a heck of a lot more fun than working a second job. I sat up late last night watching the Walking Dead and pushing my plane back and forth across the sand paper I had clamped to a 40LB block of flattened granite I got for 6 bucks at the local used building supply store.

I already lapped and sharpened the iron though, so that is done. Though even that is something that will have to be redone periodically. That's how I was able to get .0025 full blade width shavings with the thing.

And as I've said before, I think there is something to be said for doing things the hard way, at least once. One can learn a tremendous amount from the activity. When I'm done with this, I'll never again have any questions in my mind about how one laps a plane sole and laps and sharpens a blade. It's how I learn best. Jumping in and using my hands.

As HCG said though, the only thing I will end up not liking much about this plane are it's lower quality controls. But, if you snug the blade down enough before trying to use the adjusting nob, it does it's job.

[murrmac123]

Originally Posted by HCG Canada

Interesting point about the technique you mentioned about bevelling only a portion of the back edge. Useful idea! Thanks for sharing.

Bryan Burns, noted Californian luthier, was, AFAIK , the originator of this concept, predating David Charlesworth by years, and he has produced a very illuminating treatise on how to apply the idea not only to handplanes, but to jointer and planer blades as well.

In addition, he has designed an extremely clever honing system, which I am proud to use, after 40 years of believing that freehand sharpening was the only way to go.

[Viking]

Originally Posted by murrmac123

My heart goes out to you ... (seriously)

Back in the day, I too used to spend hours lapping my plane soles and chisel backs .

Nowadays, as the fortunate owner of a 5' x 3' granite surface plate, I simply cut a 5' length off of a roll of 36 grit aluminum oxide cloth backed abrasive, 4" wide, and clamp it to the plate at both ends. With the plane iron in position (but retracted) it never takes longer than 5 minutes max (and usually only about two or three) , to get rid of all the hills and valleys even on planes up to a #8. The resultant flat (but extremely rough) surface is then lapped on successive PSA grits of 60g, 80g and 120g. The whole process never takes longer than 15 minutes, even for a #8.

120g is as fine as you need to go on a cast iron sole IMO, but of course you could go as fine as you like. The important thing is to start off with a really coarse grit on a dead flat surface.

Hmmm. I've got the granite surface. Not quite as big as yours but it will still suffice I think. It's over 2 feet long by about 10 inches wide. Picked it up yesterday at a store in town we've got run by Habitat for Humanity. It's called the "Restore". They take donations of used building supplies and have a yard full of stone counter top cast offs. Out there because of some defect or another. Usually it cracked in the wrong spot or the guy cutting it made a mistake. But they are super flat.

Have you got a link for the abrasive cloth you are using? I'm using aluminum oxide paper (60 grit), but it looses it's cutting edge pretty quick which is part of what made the process so long last night. Does yours last longer because you are using such a long length of it?

[charles Tauber]

Originally Posted by murrmac123

Bryan Burns, noted Californian luthier, was, AFAIK , the originator of this concept, predating David Charlesworth by years, and he has produced a very illuminating treatise on how to apply the idea not only to handplanes, but to jointer and planer blades as well.

In addition, he has designed an extremely clever honing system, which I am proud to use, after 40 years of believing that freehand sharpening was the only way to go.

Thanks for the introduction to Brian Burns' method.

Sharpening is like religion in that there are numerous approaches, each with its own true believers, and ive changed "religions" numerous times over the years as technology has changed. Clearly, Brian Burns has considerable knowledge and expertise that he has applied to create a viable sharpening method. However, a lot of new sharpening related products have been introduced since he created his system in 1995. Are they improvements? Depends on your beliefs and preferences.

While not having been at is long as he has, I, too, started out with oil stones and Arkansas stones,followed by water stones, DMT diamond stones, Tormek, and , most recently, Lee Valley's power sharpener. I've also tried many honing guides. And, I've been taught a number of different systems for sharpening, with and without honing guides.

One method that I was taught was free-hand sharpening with water stones. i didn't encounter the issue of stone gouging that prompted him to develop his guide system. lastly, in some woodworking applications, one does not want a back bevel on chisels. Possibly, Charlesworth's method is less finicky and requires less jigging. Regardless, I don't use back bevels on tools, but understand it can reduce the back-flattening process that is a lot of work.