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Greetings OLFers,

I have begun my 4th instrument, and have come to realize that practice is not making perfect for me where jointing is concerned. I have had similar difficulties each time I've tried it....I try to apply extra pressure to the "high" spots, taking care not to sand the "low" ones and find myself getting farther away from a true joint.
My setup is as follows:
I have a flat 3/4" MDF surface which is shellaced. I clamp a Fat Max level with 120 grit adhesive sandpaper (3M) to it and slide the taped plates on their sides back and forth with small movements. I check it every 10 - 20 passes and when I find a high spot I try to press that point harder into the sanding surface.
I have also tried jointing with a jointing plane clamped to the same board, but my skills with the plane are just developing and maybe I don't have it set up optimally (though I'm pretty sure the blade is sharpened properly).
I don't have access to a jointer, and really want to be able to master this manually. I don't mind spending significant time doing it, but I want the joint to be getting better with effort and not worse.
I'd love to hear about your experiences with manual jointing of plates.

Thanks, Beth

Hi Beth,

Try clamping the wood in place and taking long swipes in one direction with sandpaper on a 4 foot level. Start and stop with the wood in full contact with the sandpaper.

Steve

Thanks Steve. After reading your response, I remembered that I had once tried that technique, but was using the 2' level (the longest I have). Maybe I should invest in the 4' one.

Beth, if you have a hand plane, that would be the tool of choice IMO. Joint both pieces at the same time using a shooting board. You shouldn't have to fight the plane, it'll eventually follow the sole of plane if you can guide it along with even pressure. The beginning and end will probably be the hardest for you, just be ultra aware of what you doing and you should get it. It'll take some practice but it's a skill worth having.
How do you know if your levels are straight enough to join on? It's a level, not a straight edge. I'm sure it's pretty straight, but not like a straight edge, I know other people do this too.

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Jim Watts
http://jameswattsguitars.com

Same problem here... keep planing, and it shaves along the curve instead of flattening it. Last couple plates, I wrapped sandpaper on the plane and ran it back and forth, focusing a little more on the center and checking until it's nice and tight. First 60 grit to get close, then 100, and I might have done a bit with 220 as well, can't remember. Then take one final micro shaving with the blade to smooth the surface. Same result as a fully planed joint, but much easier and less width lost in the flattening process. Also works on curly woods that like to tear when planed. Using the sanded joint directly would probably be fine, but on such a small glue area, I want it as smooth as possible for maximum surface contact.

Jim gives you good advise. Most levels are not true enough for trueing plates for jointing. And the cheaper ones can bend if you put too much pressure on them. If you have a good sturdy aluminum/magnesium level(2ft should be long enough), you can true it by attaching sandpaper to a true plate, like a cast iron table saw top or a flat piece of granite. Otherwise, stick with the hand plane.

Chuck

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I'd use the factory edge of the MDF. Lay it on top of the wood with just a hair of the wood you are joining proud of that edge, Clamp them together, take a template pattern bit in a hand held router, and rout me a straight edge on that sucker, letting the bearing on the pattern bit ride the edge of the MDF. But i build electrics. One day I'll build an acoustic, and that's how I'll joint the top and back.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

So, a hand plane instead of a jointing plane? Let's say your plates don't have too much gap anywhere....how many passes (broad range) do you usually need to take to complete the joint? One of the problems with a lack of experience is not knowing if things are going as expected or if you're spinning your wheels

Mike, I like that idea...I guess I have seen a jointing jig that facilitates that using a table router, but I could do your idea with a laminate trimmer too. Then you could fine sand the joint to give the smooth gluing surface. Huh!

Beth:
I use 80 grit stuck on 1/2" thick glass (glass end-table top) and it seems to work for me. Remember that the whole surface should be in contact with the sandpaper for the whole stroke.

Bob

Thanks all! Todd, I really enjoy your videos. I will learn to "fly" the plane

I use a plane and finish with the level. A plane with an accurate shooting board is a one step process, but apparently my level is straight. To use the plane just scrub the center area of the plate until your plane won't take a shaving, then widen the area until again you can't get a shaving, repeat full length. At this point you have a perfect edge with minor convexity the full length. A few strokes with the level and the joint is perfect.

There's another recent discussion on this topic viewtopic.php?f=10101&t=31356
It's worth a look...
IMHO learning to use the plane is the way to go; it does include learning to sharpen- really sharpen
regards
pvg

I dont hand joint, but I agree that a level is NOT a straight edge, and surprisingly can vary a large amount (in guitar making terms) over their lengths, have bows in them, or other random stuff. The factory edge of MDF is just as bad probably, but at least it's cutable, and will shape along with your plates. Good luck, you have far more patience than I do...I'm a router guy.

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http://www.sixgunguitars.com

Far be it from me to disagree, but I have several levels and they are all dead flat on the edge. They are metal ones, not plastic ones, though. Some of my best joins have been using the edge of a level with sandpaper on it. Even now, if I have trouble getting it right with the plane in a few strokes, I'll use the level, then take a couple of passes with the plane to get a good clean face on the plate, though I think a sanded joint is just as strong.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I see people mentioning levels. but what about those pieces of small aluminum beams that you see at hardware stores? could a sander belt be glued to one of those?

a nice aluminum level is around $30 and an aluminum beam (same thing?) is around $10-15.

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"...you have to get over your strict adherence to your largely imagined notion of absolute perfection..."

I just picked up a 3 foot by 6 inch by 1/4 inch pane of tempered glass at a salvage store for $2. My thought is that it should be level for these sort of operations.

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http://www.Harvestmoonguitars.com

I'm in the "long shooting plane" camp myself. I use a Record no. 7 jointer plane and shooting board. One important trick I learned as an apprentice cabinetmaker - at the beginning of the stroke, concentrate your force on the front of the plane, then as the plane progresses through the cut, shift the force to the rear of the plane. This prevents cutting too much from the start and finish of the stroke. With a sharp plane iron ("if it isn't sharp enough to shave with, it isn't sharp enough to plane lumber with...", another chestnut from my apprentice days), I can get a tight fit in about four to six strokes (starting from a tablesawn rip cut). For spruce, this produces a great joint, but for back sets in woods like cocobolo, the sandpaper method is better, since the glue joint in cocobolo benefits from the sandpaper scratches. That's my $0.02!

I'm in the "long shooting plane" camp myself. I use a Record no. 7 jointer plane and shooting board. One important trick I learned as an apprentice cabinetmaker - at the beginning of the stroke, concentrate your force on the front of the plane, then as the plane progresses through the cut, shift the force to the rear of the plane. This prevents cutting too much from the start and finish of the stroke. With a sharp plane iron ("if it isn't sharp enough to shave with, it isn't sharp enough to plane lumber with...", another chestnut from my apprentice days), I can get a tight fit in about four to six strokes (starting from a tablesawn rip cut). For spruce, this produces a great joint, but for back sets in woods like cocobolo, the sandpaper method is better, since the glue joint in cocobolo benefits from the sandpaper scratches. That's my $0.02!

I went shopping for a level at lowe's yesterday and the only ones they had, had ridges in them, or a hole in the side, to view the bubbly thing. so i bought a piece of mdf for $7 and had them rip it for me, too. i applied sandpaper and screwed the small strip to the factory edge. i joined tops and backs over the weekend and it worked like a dream. i get it close with my plane and make a few swipes on the shooting board.

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"...you have to get over your strict adherence to your largely imagined notion of absolute perfection..."

Waddy: Dead flat is a tall order. First of all,compared to what...? In order to insure the level is close to being flat you need three of them to check against each other. If you use two and they appear to be flat,you may have one that is concave and another that is equally convex. They fit together perfectly but neither is flat. With three levels you can check to see if they all fit perfectly ie they are flat or you will see discrepancies when all the levels are cross checked against each other. Most folks are not aware of this unless they have had some sort of machinist or mechanical fitting training.
Tom

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A person who has never made a mistake has never made anything!!!

I'll put it this way, I check things against each other, also against my "precision" straight edge, and against my ground granite counter top section, which I've found is really flat. Maybe "dead" was a poor choice of words.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Waddy : We could go on for a while discussing this I'm sure but I'll just ask you a couple of questions. How do you know your precision straight edge is in fact straight..? How have you checked you ground counter section to ensure it is flat...? Just trying to point out to the crowd that it is easy to fall into a trap with measurement facts.
Tom

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A person who has never made a mistake has never made anything!!!

I am very curious why no one has mentioned using a jointer? You can pick them up used for less than the price of a good plane and it really makes quick work of jointing a top or back.

Try a homebrew try plane about 18-20 in long , they are also inexpensive on e bay about a stanley number 6 plane . Properly sharpened and with some practice , it will pay dividends in the long run. Sandpapered levels , work, but planes IMHO leave a much smoother gluing surface, and besides you will be proud you did it, once you master the skills needed to flatten of backs , tops or sides , a very useful skill,