Official Luthiers Forum!
http://www.luthiersforum.com/forum/

What could be holding it off?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=25449		 Page 1 of 1
Author:  ayavner [ Tue Jan 12, 2010 4:01 pm ]
Post subject:  What could be holding it off?
Hi there -

Working on the neck installation on my 14-fret OM, and have a question. Let me preface this with - I have watched John Hall's videos and spoken to him over the phone, and I am now very very close, thanks to him! But I don't want to abuse the privilege, and perhaps someone else will have this same question.

Now... I have the neck so that it is sitting in the pocket (dovetail). The Set angle is right (straight edge off fretted fingerboard is just kissing the top of the bridge), and side-to-side centering appears OK. The joint is reasonably tight, i can pop it out with a sharp rap to the heel cap.

That said, there is about 1/64-ish gap all the way around the heel-to-body surface, almost as though there is something on the inside of the joint holding it up from sitting flush. The gap is a bit much to floss-sand, I can stick the paper in all the way around with no friction. I have been using colored chalk in the pocket to get myself this close, but at this point, whatever is holding me off is so minute that I don't think I can register it with the chalk.

What can I do to either find what's holding it off, or draw the cheeks tighter to the sides?

Thanks!

Adam
Author:  Hesh [ Tue Jan 12, 2010 4:08 pm ]
Post subject:  Re: What could be holding it off?
Hi Adam!

Try this toot even though it's a bolt on the part where we floss the neck is where you are and what is holding the neck off your body is the material close to the dovetail. You wanna relieve the excess material in that area so that the flossing is effective.

Here is a pic of the area that you want to relieve even with a dovetail.

Attachment:
DSC00990.jpg


And here is a toot that if you go to the part about flossing it will be relevant to where you are now: viewtopic.php?f=10102&t=15022%22

I hope this helps
Author:  Tom West [ Tue Jan 12, 2010 4:10 pm ]
Post subject:  Re: What could be holding it off?
Have you undercut the neck so that it can go up flush against the body...?
Author:  Tom West [ Tue Jan 12, 2010 4:12 pm ]
Post subject:  Re: What could be holding it off?
Hesh beat me to in....! This is also what I meant...!
Author:  Hesh [ Tue Jan 12, 2010 4:16 pm ]
Post subject:  Re: What could be holding it off?
Great minds Tom, great minds... :lol:
Author:  ayavner [ Tue Jan 12, 2010 4:19 pm ]
Post subject:  Re: What could be holding it off?
Haha yes guys, I did undercut the neck, leaving about 1/8" or so rim all the way around. That's how i shanked my finger with the chisel a month or so ago hehe ;)

But, that is worth checking, perhaps there is a part that didn't get done. I'll check that and report back. Also, let me check that toot Hesh.

Thanks guys, I'll be back in a few!

adam
Author:  Darryl Young [ Tue Jan 12, 2010 4:29 pm ]
Post subject:  Re: What could be holding it off?
Is there a chance your tenon is bottoming out in the mortise? Not likely but possible I guess.
Author:  Fred Tellier [ Tue Jan 12, 2010 4:35 pm ]
Post subject:  Re: What could be holding it off?
Is the neck contact area of the rim flat, if it is at the normal radius the neck heel won't seat flat, take a thin feeler gauge ( thinner the better) and slip it into the gap it will go all the way to the dove tail except where it is touching and holding the heel away from the rim. That should give you the answer you need.

Fred
Author:  bluescreek [ Tue Jan 12, 2010 5:08 pm ]
Post subject:  Re: What could be holding it off?
Here is what you may have , did you flatten the area of the heel joint where it touches the body ? This area is arched and your neck heel cheek is flat . You put the neck into the block , take a pencil and scripe the heel mate on the cheeks . Take a flat sanding block and work this area till the pencil line is gone , Check that the area flattened out then recheck to see that now you are mating 2 flat surfaces .
john
Author:  ayavner [ Tue Jan 12, 2010 5:31 pm ]
Post subject:  Re: What could be holding it off?
Well, i think i am on to something, and there was also a small amount of the relief valley that needed to go deeper. It appears that the heelcap was too tight against the body, so as I went down, it wasn't allowing the rest of the face to seat.. as I sanded that back, it looks like my gap is now about 1/64" or less so I am on the right track.

Seems as I go, the joint is loosening up a bit.
Author:  ayavner [ Tue Jan 12, 2010 5:32 pm ]
Post subject:  Re: What could be holding it off?
I'll check that also, John. Thanks!
Author:  Brock Poling [ Tue Jan 12, 2010 8:21 pm ]
Post subject:  Re: What could be holding it off?
Yeah, when you can't get it to set down flat the 3 things to check are flat sides at the contact point, that the neck is relieved near the tenon, and that the heelcap isn't holding you up.
Author:  ayavner [ Tue Jan 12, 2010 8:40 pm ]
Post subject:  Re: What could be holding it off?
Think its pretty close now, I'll fine tune it some more tomorrow. Looks like all 3 things you mentioned were in play Brock, thanks so much guys!

Now, what to do about the joint being loosened now? I guess as I have floss-sanded etc, it has moved the neck minutely closer to the bridge, which i imagine brings the contact points of the dovetail apart. I don't think any more can come off the dovetail, do I need to put a shim in there somewhere?
Author:  ayavner [ Thu Jan 14, 2010 8:23 pm ]
Post subject:  Re: What could be holding it off?
Todd Stock wrote:
Chalk half the joint and see what transfers...KISS.


Did better than that, I found a charcoal artists pencil and used that.. amazing how clear it transfers, and its not all dusty like chalk. This seemed to do the trick where chalk wasn't cutting it before for some reason.

More for my bag of tricks, thanks guys!!

adam
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/