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Dowel problem with neck joint
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Author:  Donald V [ Sat Jul 31, 2010 12:42 pm ]
Post subject:  Dowel problem with neck joint
I am working on #4 now. The first three have had butt joint bolt on necks with the inserts threaded into the end grain. No problems with any of them so far but I like the idea of putting in a vertical dowel so the insert goes into vertical grain for a little extra peace of mind. I tried this a couple weeks back and failed miserably. As I am preparing to try again if anyone has suggestions I would greatly appreciate it. My steps previously were:

1. Drill 5/8" hole from bottom of heel through the top of the neck with edge of the hole approximately 3/16" from "face" of the butt joint.
2. Check fit of 5/8" oak dowel. It was tight so I lightly sanded the dowel with paper in hand until I had a smooth fit. Not too tight, but not loose enough to rattle in the hole. (looking back, I could not have evenly sanded the dowel using my hand, but it seemed like a good idea at the time.)
3. Thin coat of Titebond 1 on the dowel.
4. Start the dowel in. Mid way through it gets stuck. No problem, light tap with rubber mallet. Now it's more stuck.
5. Can't get it back out, can't get it through, I start to think I can actually hear the glue setting and making it worse.......panic.
6. More hammer, more panic, bad things happen and now that neck is no longer usable.

I know the panic part made the problem worse and is not typically part of my working method, but I'm sure there is something I'm missing prior to the panic step. Any suggestions? All help will be greatly appreciated!

Donald
Author:  Kathy Matsushita [ Sat Jul 31, 2010 1:02 pm ]
Post subject:  Re: Dowel problem with neck joint
Did you drill the hole all the way through? If so, just put another dowel in from the other end, to fill up the empty space. (This time make it thinner — the glue will take up the extra space around the dowel.)
Author:  woody b [ Sat Jul 31, 2010 1:29 pm ]
Post subject:  Re: Dowel problem with neck joint
If I'm understanding correctly the neck is no longer usable, so you'll be using a different neck. If so, here's what I do. It may be helpful, and may not, but it works for me. I use poplar dowels. I don't know if this matters, but they're cheaper than oak. I also use 1/2" instead of 5/8". This is probably what will help. I use a hacksaw to cut 3 grooves longways in the dowel. (maybe 1/32" deep or so) This helps keep them from sticking. I use hot hide glue. I don't think it matters, or makes any difference reguarding the dowell sticking, but thought I'd note that for accuracy. I use 1/4" hanger bolts instead inserts. I also use a dowell through the heel with dovetail necks, but I put in farther away from the tenon into the actual heel. It may not be necessary with either attachment. It can't hurt, and it isn't much trouble.
Author:  JohnAbercrombie [ Sat Jul 31, 2010 2:23 pm ]
Post subject:  Re: Dowel problem with neck joint
woody b wrote:
I use a hacksaw to cut 3 grooves longways in the dowel. (maybe 1/32" deep or so) This helps keep them from sticking.

[:Y:] [:Y:]

Without an 'escape route' (either a thru-hole or grooves) you are trying to push a piston into a cylinder. The glue provides the seal.
Water-based glues make the wood swell, adding to the problem of 'too tight'.

If you are going to use an undersize dowel (sanded smaller), epoxy is a better glue choice as it is gap-filling.

Cheers
John
Author:  Robert Renick [ Sat Jul 31, 2010 2:57 pm ]
Post subject:  Re: Dowel problem with neck joint
As a young door builder, I lost one that way, started clamping ad it just froze, cranked on the clamps till they bent, switched from dowels to splines after that. The commercial dowels are off, both in shape and dimension, they are oval from the process of making them, which is usually moulder with a top and bottom cut. So the measure to check has to be all around. They do require clearance, perhaps some one has a good number, but it should slide in easily with a smidge of wiggle. When the glue hits the wood, there is some expansion, especially on the endgrain of the heel, I would guess that .010-.015 oversized hole would be about right. Also, there needs to be an escape for the glue, or it can blow out the side of the joint, a saw kerf works. I used to do a shallow cut on the TS. Epoxy would be a good choice, as great gap filling and won't swell the wood. Sorry about the neck.
Rob
Author:  Link Van Cleave [ Sat Jul 31, 2010 5:31 pm ]
Post subject:  Re: Dowel problem with neck joint
Your problem was twofold.
Not enough glue and nowhere for the extra glue to go. Seemingly at odds with each other. You need the extra glue to lube the operation.
On a blind hole as has been mentioned you need a grove or two lengthwise on the dowel. The other thing is to wet out all the surfaces with glue and then put plenty of glue on the dowel and on the beginning of the hole. You need to use more glue than would be necessary. The extra glue will lubricate and let things slide home before grabbing. You get lots of squeeze out and a little messy but that is the way to do it. Try it on a test hole.
Too little glue on the dowel or in the hole will about guarantee things will grab before you are in far enough. If fact it is always a good idea to do a test first to get the feel for things. Also all you would have had to do is cut the dowel off flush and re drill. I guess you know that now. gaah
How hard are you cranking down on the neck where you aren't confident in the inserts ? If the threads in the wood end grain are epoxy or ca enhanced what is the pull out strength ? You might do a test with that to either bolster your confidence in your present method or firmly commit you to the dowel reinforcement.
Link
Author:  es guitars [ Sat Jul 31, 2010 5:39 pm ]
Post subject:  Re: Dowel problem with neck joint
if the hole is not drilled all the way through drill a small relief hole all the way through to let air and glue escape.


brent
Author:  DennisK [ Sat Jul 31, 2010 8:49 pm ]
Post subject:  Re: Dowel problem with neck joint
Did that neck actually break, or is the presence of the dowel the only reason it's unusable? You could probably just drill it back out. The open part of the hole on the other side should make it easy to align the drill bit precisely. Or just put in another dowel from the other side, as Kathy suggests (but make sure there's a way for the glue to squeeze out!)

The suggestions of extra glue to lubricate or epoxy sound good to me.

Another option on future necks would be to skip the dowel and use barrel bolts rather than inserts: http://www.cumpiano.com/Home/Articles/Special%20interest/headblock.html. That's what I'm doing, including the vertical grain rosewood reinforcement plates on the sides of the tenon.
Author:  Donald V [ Sun Aug 01, 2010 10:29 am ]
Post subject:  Re: Dowel problem with neck joint
Thanks to all for your suggestions. I believe Kathy's suggestion would have worked if I had not tried so hard to get the dowel all the way seated the first time. I could have stopped and salvaged it, but my pushing lead to splitting, broken glue joints, etc making it unusable. That neck will hang on the wall as a reminder.
It was drilled all the way through so both air and glue had an escape route. From the suggestions made here I am going to make the following changes:

1. Test pieces first, then the real thing (if I'd done this the first time I wouldn't be here now!)
2. Couple grooves in the dowel
3. Swap to epoxy vs. titebond
4. Heavier application of the glue to act as lubricant.

Thanks again to everyone with a suggestion here. All of them made me think a little.
Author:  Donald V [ Sun Aug 01, 2010 4:15 pm ]
Post subject:  Re: Dowel problem with neck joint
Done and successful! bliss It was 5 times as easy the second time as it was difficult the first. I appreciate all the suggestions. Have fun makin' sawdust!
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