Bamboo Dowel Supplier & Oxidized Wood

SLivinghouse · #1 10-17-2010, 11:48 PM

Hi,
I have a dumpster bass rescue project (abandoned school Czech plywood) that I'm going to start next month and am learning as much as I can before I begin (I've got the Traeger book and do wood working as hobby.)
The biggest problem is a neck break at the pegbox about an inch and a half under the nut (broken so the top of the scroll has pivoted forward toward the bridge). I'm thinking about removing the fingerboard and installing bamboo dowels as suggested in a previous post, but cannot find them anywhere online. Any suggestions? Also the break is relatively clean but the maple looks a little brown and oxidized. Am I correct in assuming I need to remove the oxidized wood for the glue to adhere? I'm considering both the high gram hide or T-88 (and yes, I have read the glue holy wars and don't want to touch off another)

Thanks for the suggestions in advance!

Steve

moles · #2 10-18-2010, 02:29 AM

No opinion on the pros and cons of bamboo (IIRC there was some slight controversy in that post) - but you may want to Google "Chopsticks".

Cody Sisk · #3 10-18-2010, 05:53 AM

Ya, my presented method isn't really "traditional" but I've found it to work very well for my rental stock and school instruments.

I found my bamboo in different sizes at an asian grocery store (yes, chopsticks..) The biggest I could find was a little more than 10mm in diameter. The idea is that with the bamboo, you use several smaller dowels rather than one big one..

robobass · #4 10-18-2010, 06:12 AM

Why bamboo? I understand using dowels for positioning, but why not use standard hardwoods? Bamboo is very fibrous - techically not a wood - so expect a learning curve when trying to shape it with standard woodworking tools.

Jake deVilliers · #5 10-18-2010, 10:14 AM

Quote:

Originally Posted by robobass

Why bamboo? I understand using dowels for positioning, but why not use standard hardwoods? Bamboo is very fibrous - techically not a wood - so expect a learning curve when trying to shape it with standard woodworking tools.

+1 What he said - maple dowel for your maple neck...

Cody Sisk · #6 10-18-2010, 02:15 PM

Doweling a neck repair will weaken the heel no matter how it's repaired. I've been trying out ways to keep my rental stock in one piece longer. The theory is that several small bamboo reinforcements vs. one big hardwood dowel would be a stronger fix. Bamboo is strong lengthwise but very flexible and forgiving across the grain. Take a maple dowel the same diameter as a bamboo dowel and see how far they will bend before breaking. The string tension will eventually work a hardwood dowel loose from the glue and/or the brittle dowel will snap and the repair will fail. However if you combine bamboo and T-88 epoxy, it will be more like trying to break a really green branch fresh off a tree. I've proven it to take more punishment. Having a rental pool full of clumsy beginner kids really helps the R&D!!

Jake deVilliers · #7 10-18-2010, 02:52 PM

Quote:

Originally Posted by DallasStrings

Doweling a neck repair will weaken the heel no matter how it's repaired. I've been trying out ways to keep my rental stock in one piece longer. The theory is that several small bamboo reinforcements vs. one big hardwood dowel would be a stronger fix. Bamboo is strong lengthwise but very flexible and forgiving across the grain. Take a maple dowel the same diameter as a bamboo dowel and see how far they will bend before breaking. The string tension will eventually work a hardwood dowel loose from the glue and/or the brittle dowel will snap and the repair will fail. However if you combine bamboo and T-88 epoxy, it will be more like trying to break a really green branch fresh off a tree. I've proven it to take more punishment. Having a rental pool full of clumsy beginner kids really helps the R&D!!

I don't think so Tim. If bendy was better you'd be replacing all those brittle necks with bamboo or maybe rubber...

SLivinghouse · #8 10-18-2010, 03:53 PM

Thanks for the replies so far, so what about dealing withe the oxidized wood? I have no idea how long ago it was broken.
Thanks,
Steve

Cody Sisk · #9 10-18-2010, 03:57 PM

Quote:

Originally Posted by Jake deVilliers

I don't think so Tim. If bendy was better you'd be replacing all those brittle necks with bamboo or maybe rubber...

C'mon Jake! You have to realize that the neck joint, being under varying tension from strings and seasonal movement, with a hardwood dowel reinforcement will weaken over time.

Besides, the epoxy is the main defense and the bamboo is an afterthought.

Your comments here are the equivalent of a heckling Yankee fan in Dallas..

robobass · #10 10-18-2010, 03:59 PM

Sorry, I didn't read thoroughly and thought you were only talking about a fingerboard remount. Still, I see no advantage to bamboo. I repair scroll breaks with hide glue and wood screws. Unconventional, and I haven't done hundreds, but none have come loose so far -knock on wood! My theory is that good positioning and strong clamping pressure are key, both of which are easy to achieve with screws. Also, epoxy creeps, hide glue doesn't. I bet a lot of real luthiers do this, but then later remove the screws and replace them with maple dowels. If you are doing such repairs with epoxy, then perhaps you would want cross-grain flexibility in the dowels. Not for me, though.

robobass · #11 10-18-2010, 04:30 PM

Quote:

Originally Posted by SLivinghouse

Thanks for the replies so far, so what about dealing withe the oxidized wood? I have no idea how long ago it was broken.
Thanks,
Steve

Too bad Arnold doesn't seem to be around lately. He would be the person to ask. My guess is that oxidation would be less of an issue than how well the pieces still fit together. Hide glue works best when you can squeeze almost all of it out in clamping. Old breaks which were left untreated are not likely to join seamlessly, so this will make things difficult. On the other hand, there is almost nothing you can't do with some hide glue and a well thought out clamping arrangement. Also, the beauty of hide glue is that you can mess up once or twice and still save the project. Not so with epoxy!

**Matthew Tucker** · #12 10-18-2010, 07:31 PM

FWIW Cody I'm with you here ... I think bamboo would be very good for pinning repairs and especially where price is a factor. Bamboo is very stable and strong and probably glues better than CF rod, which is the other non-traditional option. It is also easier to work with. I wouldn't be worried about the flexing of the bamboo, since it's only there to anchor the maple pieces together firmly. I'd be more concerned about the shear strength at the crack, and as we know bamboo performs very well in this regard.

SLivinghouse · #13 10-20-2010, 12:05 AM

Thanks all for your suggestions. I think I'm going to go with the bamboo and a medium/ high gram strength hide glue. The reversability of the hide glue is a big plus over the epoxy for me since I don't have the experience. I'll do some dry runs to determine clamping and practice with hide glue on scrap and small repairs first.
Thanks again,
Steve

**Matthew Tucker** · #14 10-21-2010, 06:46 PM

if the dowel fit is good you don't need much glue at all ... but u need to allow for excess glue to squeeze out, and work quickly because it will cool very quickly inside the hole.

And don't count on the reversibility of the hide glue in the dowel holes though ...if you do need to redo the dowel, you'll probably end up drilling it out!

powerbass · #15 10-22-2010, 07:19 AM

Another method that is extremely strong is to use epoxy and threaded rod, a technique called "potting". It is essentially the same process as dowelling except that you drill a slightly larger hole than the threaded rod (can be a small bolt with the head cut off). Then use epoxy which grips onto the threads, the slightly larger hole allows wiggle room for the parts to fit as opposed to the tighter tolerances of a wood dowel. This technique may not sit well with hide glue purists but it produces an extremely strong joint in an otherwise weak area