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I am thinking of getting a #7 or #8 Jointer plane from ebay.
I realised there are 2 types of sole, flat smooth and corrugated.
Which type is more suitable for joining tops and backs?
What is the advantage of either one?

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Sen CL Goh
http://senguitar.blogspot.com

The corrugations are mostly for reducing the sliding friction of planing (and also suction). For your application, it doesn't make much difference so get either one. I would get the less expensive of the two, myself, i.e., the non-corrugated one.

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

The corrugated sole helps reducing friction between wood and sole - hardly needed for jointing guitar wood i would think. I also think a nr. 8 is way too big and clumsy for what we do. I'm using a 5 jack and i think is long enough.

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Build log

I agree with Alex about the size of the plane needed to joint guitar parts. I use a #4. But I also make furniture and use a #7 for the longer joints. BTW, I have made perfect back joins with a block plane, so it's possible to avoid the expense and weight of the big plane - although it's fun to have one (or more) as part of the collection, too.

Thanks Steve, Alex for the fast replies.
It certainly feels good to have a whole set of planes
Currently, I have a block plane and a #4, so I was thinking of adding a longer plane to the collection.
But I still need to flatten the sole though and tune it up.

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Sen CL Goh
http://senguitar.blogspot.com

Here's a great forum for info handtools, especially planes.

http://www.forums.woodnet.net/ubbthreads/postlist.php?Cat=&Board=handtools

One of the eternal mysteries of woodworking, for me at least, is how a flat soled plane can cut a straight joint. Consider that a power jointer must have the outfeed table at the same height as the cutter, and the infeed table lower. If the tables are both below the cutter (what you have with a plane), the cut will be concave, often with a noticeable snipe where feed pressure is transferred to the outfeed. So why does a hand plane work?

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Howard, you raise a very interesting question.

I wonder if the power jointer bed was as short as a hand plane, the "error" caused by keeping the infeed side and outfeed sides co-planar would be the same as seen in a hand plane. I could be wrong.

My guess is that a plane doesn't give you a truly flat surface, but a progressively flatter one. You can approach flatness, but never really arrive at it. Seems a long jointer would get you closest.

There's a process in machine work by which you can approach a certain degree of flatness where the error gets closer to zero with each iteration of the process, but I can't recall if it has a name. There's something like it explained in the Accurate Table Saw book. Maybe John Hall or Todd would know?

We could say that we use planes to achieve flatness asymptotically.

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

Another thought, use of a hand plane takes a while to get the "technique" down to plane a really flat surface. The technique might correct for inaccuracies in what the tool wants to produce by virtue of the design. And by the way, a slight concavity is a good thing in a long joint, the resulting joint is tighter at the ends, which helps to keep the end from developing a separation in the joint.

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"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

If you joint your plates at close to finished thickness, they can slip into the corrugations and annoy you. You can get around that by making a ramped shooting board, jointing your plates thick enough that they won't fall into the corrugations or getting a flat soled plane.



I know what you mean, it's like magic. I do know someone who built some planes that adjusted like a power jointer- the blade WAS the sole and the part in front of the mouth went up and down to adjust the depth of cut. Pretty cool, but somehow normal planes work anyways so it probably won't catch on.

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Jordan Aceto
Ithaca, NY

Hi Howard,
With a power jointer you keep pressure on the outfeed table at all times to achieve a flat cut. With a hand plane you transfer the pressure from toe to heel as you make the cut. Until you learn to do that you don't make a flat cut. We have been doing it so long we no longer think about it.

The only thing I might use a #7 for in guitar work would be thicknessing stock. Either sole would work fine.

IIRC, they don't. I used to hang out on the hand tool list and out there the wisdom was that technique kept stuff flat. If a robot was using a plane, it would end up concave. The shorter the plane, the more concave.

p.s. I just made my best joints ever using a #4 with a shooting board.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

You know I don't have a jointer so when it came time to joint plates I just tape the two plate together then I would place the jointed edge over a straight board (of course checking to make sure that board is straight...) and use a laminate trimmer with a flush trim bit to trim the jointed edge flat, then I would use a plane with sandpaper taped on it to fine tune the joint until no lights show through. Worked pretty well for me...

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

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