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Practice Joining Top - Does this look OK?
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=16430		 Page 1 of 1
Author:  Glenn LaSalle [ Sun Mar 16, 2008 5:31 pm ]
Post subject:  Practice Joining Top - Does this look OK?
Hi,

As I build my 1st guitar, I am trying to practice as I go along. I have a defective top that I am practicing joining. I am hoilding the top towards a light.
Attachment:
Practice Joining.jpg

Does this joint look tight enough? I joined using a shooting board and a very sharp Record #5.

Thx!

Glenn
Author:  sharp_custom [ Sun Mar 16, 2008 5:36 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
Hi Glen, A good test is to hold the joint up to a light. If you can see light through the joint, it's no good. If no light is visible through the joint, it's good to go.

Hope that helps.

Edit: Looks like you may be doing that in the photo. It looks good but, that's the real test.
Author:  jmanter [ Sun Mar 16, 2008 5:37 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
I like to hold it against the window and look for sunlight through it. Just work the points that are making contact until the gaps close. Looks like you're on the right track. It also seems to help if you join up a bit thick, then thickness afterwards.
Author:  Hesh [ Sun Mar 16, 2008 6:19 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
I do what Jmanter does, shoot with a record #5, place in a window and line up the bottom edge, and then move my head back and forth checking for sunlight passing through any spot on the joint. I always have some gaps and then I resort to a level that I have placing "clean" 120 grit on it, if you use the same paper that you used for a back, head stock, etc you may get a visible line in the joint, and I hit the high areas only on both halves with a few swipes. I check and repeat as necessary.

I like to joint at .140 - .145ish and then thickness after the plats are glued.

BTW I just received one of Tracy's (Luthier Suppliers) new jointing jigs and I am excited to try it on the next opportunity.
Author:  Mitch Cain [ Sun Mar 16, 2008 6:38 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
When I was at John Osthoff's shop last weekend, I saw that he used a modified "light box" similar to what a photographer would use to preview slides. His had each side covered and the middle was clear, allowing light through an opening about 2" wide. There was a bright light inside the box, and after he jointed and used a jig similar to what Hesh described above, he placed the top on the light box to perform the candling - worked great!

For those that don't have windows or natural light in their shops...
Author:  Hesh [ Sun Mar 16, 2008 6:40 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
Mitch/John great tip on the light box - so for I have been limited to jointing only during day light........ [:Y:]
Author:  James Orr [ Sun Mar 16, 2008 7:10 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
I like using the window, too. It's helpful because it gives you something to press the boards against to help ensure that everything is lining up alright. And I also use a #5 with a very sharp iron. It took a bit of practice, but last night I jointed a redwood top and rosewood back in roughly ten minutes.

Something Todd mentioned that helped me out quite a bit was to keep the pressure on the toe for the first 2/3rds of the pass, then put it on the heel for that last 3rd.

After that, I use the tape method Hesh created a tutorial for in order to glue them together with hide glue. I'm amazed at how easy it's getting to create good joints with this routine.
Author:  Glenn LaSalle [ Sun Mar 16, 2008 7:40 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
Thanks guys!!

It looks like I actually have this there - holding up to a bright light, I dont see any light coming through. Following is a detailed close-up - you can see the light coming thru the defect in the right side:
Attachment:
P1010702.jpg

I may try to join this and see what happens.

Thanks!

Glenn
Author:  James Orr [ Sun Mar 16, 2008 8:00 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
Good work, Glenn. Congrats!
Author:  Hesh [ Sun Mar 16, 2008 8:26 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
Looks great to me too! [:Y:] [clap] [clap] [clap]
Author:  Glenn LaSalle [ Sun Mar 16, 2008 9:41 pm ]
Post subject:  Re: Practice Joining Top - Does this look OK?
One more question. At what thickness do you usually join the tops? The practice top I have started at .260 and is now .180. I was going to join at this thickness (I just have to smooth out a bit, as I am doing this using a plane.

The "real" top I have is a lutz top from Shane. It is ~ .250". Should I take the thickness down or can I join at this thickness?

Thanks again!

Glenn
Author:  Todd Mylet [ Mon Mar 17, 2008 12:49 am ]
Post subject:  Re: Practice Joining Top - Does this look OK?
It's really hard to tell from a picture if the joint is tight or not. When I'm candling, using my windows, I have to closely inspect up and down the joint moving my head slightly side to side as I go to try to see light coming through any gaps. If I'm looking from just slightly the wrong angle, I might be unable to see a gap that I could see if a moved just an inch or so to the side. That why a picture is inconclusive. I would suggest inspecting closely for light shining through gaps. If there are gaps, even slight ones, the candling trick should be fairly conclusive if you look carefully. It can sometimes be frustrating trying to get rid of those gaps, but if you're patient and believe in yourself, you can certainly do it.

I think your idea of using a test board is wise.
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