Dobro repair

[Valerie Jestice]

My dad’s dobro got flipped upside down in an unlatched case. It had a terrible buzz, but it went away, so I never bothered to look at it. Yesterday it got dropped, and the buzz is way worse this time then last. The tailpiece seems to be rattling against the resonator, so I took it off, I didn’t see a problem. I took out the resonator also, and still didn’t see anything.
I started polishing the dobro, and I saw this. Could this be the issue? Or is it something else? What Is the recommended action to fix this?


I want to fix it myself, since I need the practice.

[Greg Mirken]

Step one is take the tension off it.
If the gap opens and closes when you flex the neck, the block has broken loose.

Greg Mirken

[Valerie Jestice]

Step one is take the tension off it.
If the gap opens and closes when you flex the neck, the block has broken loose.

Greg Mirken

The strings are off.
I flexed the neck, and the gap didn’t wiggle.

[Greg Mirken]

If the instrument is open, probe around with a thin blade to see if you can find something loose. There are a lot of unknowns here- was the gap there prior to the trauma? Was the instrument subjected to heat? Resonator guitars rattle. Duh. Also, banjos are out of tune.
Also, you say you need practice. Do you have some instrument repair experience? I worked for Dobro back in the seventies, and this does not look like a Dobro brand instrument, so I am handicapped in that I don't know exactly how it was put together. Post some pictures of the interior.
Is this of interest to anyone but you and me? Feel free to PM me or email me directly.

Greg Mirken

[Valerie Jestice]

If the instrument is open, probe around with a thin blade to see if you can find something loose. There are a lot of unknowns here- was the gap there prior to the trauma? Was the instrument subjected to heat? Resonator guitars rattle. Duh. Also, banjos are out of tune.
Also, you say you need practice. Do you have some instrument repair experience? I worked for Dobro back in the seventies, and this does not look like a Dobro brand instrument, so I am handicapped in that I don't know exactly how it was put together. Post some pictures of the interior.
Is this of interest to anyone but you and me? Feel free to PM me or email me directly.

Greg Mirken

I will take some pictures of the insides this evening. The dobro is a Flinthill, so it’s cheap. I think it cost $150 at a pawn shop, the gap could have been there when it was bought.

As far as experience, I haven’t done any real repair, just replacing a nut, and fixed a popped out fret. But I want to be a luthier, and being a cheap instrument, so a might as well.

Your probably the only one that knows anything about dobros.

[MikeEdgerton]

That looks like it might be just the binding. I've bought new imported instruments with the same issue. As far as looking inside, take off the cover and remove the cone and you can probably see the entire inside.

[HoGo]

That looks like it might be just the binding. I've bought new imported instruments with the same issue. As far as looking inside, take off the cover and remove the cone and you can probably see the entire inside.

Definately not just binding. The binding is still attached flush with sides, that means the block went loose from back plate and moved forward with neck when the dobro got dropped. You need to clean the surfaces and reglue the block which may be tricky with the binding in the way. I would either look for a way how to do it from inside or try to separate the binding from sides and work from there. You may need to apply some pressure on the neck to force the block back into position before clamping.
The worst case scenario is that the block split and only part of it (or even just ribs) got pulled away. That would require finding another way how to get glue inside but doable. Perhaps the neck is bolted on and can be removed to have better view of damage.

[Valerie Jestice]

Definately not just binding. The binding is still attached flush with sides, that means the block went loose from back plate and moved forward with neck when the dobro got dropped. You need to clean the surfaces and reglue the block which may be tricky with the binding in the way. I would either look for a way how to do it from inside or try to separate the binding from sides and work from there. You may need to apply some pressure on the neck to force the block back into position before clamping.
The worst case scenario is that the block split and only part of it (or even just ribs) got pulled away. That would require finding another way how to get glue inside but doable. Perhaps the neck is bolted on and can be removed to have better view of damage.

I took the resonator back out, and looked inside, nothing is broke, or creaked. It could have come from the factory that way too.
Do you think I could just glue the binding to the back, and it’d be fine?

[Valerie Jestice]

If the instrument is open, probe around with a thin blade to see if you can find something loose. There are a lot of unknowns here- was the gap there prior to the trauma? Was the instrument subjected to heat? Resonator guitars rattle. Duh. Also, banjos are out of tune.
Also, you say you need practice. Do you have some instrument repair experience? I worked for Dobro back in the seventies, and this does not look like a Dobro brand instrument, so I am handicapped in that I don't know exactly how it was put together. Post some pictures of the interior.
Is this of interest to anyone but you and me? Feel free to PM me or email me directly.

Greg Mirken

What kinda interior pictures do you want?

[MikeEdgerton]

I got two different mandolins that were made by Saga that had the same binding gap from the factory. I'm sure the wood has moved I'm just not sure it happened because of the two times it was dropped.

[HoGo]

I got two different mandolins that were made by Saga that had the same binding gap from the factory. I'm sure the wood has moved I'm just not sure it happened because of the two times it was dropped.

I wonder how is the neck attached to body. I guess it is bolted on and the heel is glued onto ribs (either with glue or by the lacquer). Or as in lower chinese end they just did a tenon of some sort. I'm pretty certain that the joint or block whatever it is failed and damage may not be easily visible from inside. I'd hav a look with mirror on long stick to see where the block meets the sides.
From the cracks in the finish you can see it's not just loose binding.

[John Morton]

Check the cone assembly One way to chase down a buzz in a resonator instrument is to remove the coverplate and string it back up with the resonator assembly exposed. Then while plucking the strings, put your ear down close to try and locate the buzz. I use the eraser end of a pencil, and press at different places on the cone, spider and saddle to see if that affects the buzz. If all this has no effect, that at least points you towards the wood structure.

[MikeEdgerton]

And it has been dropped at least twice. Everything should be very visible inside. One thing about the way that instrument is built, nothing should be hard to see. I'm pretty sure there won't be a whole lot of solid woods involved either.

[Greg Mirken]

I was thinking some shots of the neck attachment from the inside might help. If you can't find any gaps or cracks to force glue into, I don't think there's much you can do.
There's no guarantee that the gap is related to the rattle, or that it even opened due to the drop(s). My approach, if I found a gap of some sort, would be to force glue into it and clamp the neck to close up the gap. For reference, the plane of the fingerboard should be parallel to the top, if this is built like a typical squareneck Dobro. If the neck angle is OK and you can't force the gap closed, just move on and look elsewhere for the rattle.
With the guitar assembled you can press on each leg of the spider with a screwdriver to tell where the buzz originates. Disassemble the spider and cone and see if all the legs touch if you set the spider on a flat surface. If it's aluminum you can bend the legs. We would grind them on a big disc sander, but you could use coarse sandpaper on a flat surface. Reassemble the spider and cone and tighten the screw just enough to hold it solidly. Any tighter and it just crushes and distorts the cone.
The tailpiece [or the string balls, for that matter] can also buzz against the coverplate- a piece of rubber or leather under the tailpiece can help that.
Good luck!

[Valerie Jestice]

I put the cone back in, left off the cover plate, and stung it up. There isn’t any buzz when I play the open strings, but there is a little bit when I use the slide. The gap has increased though, before I could close the gap when I press hard enough, but now I can’t close it.

[pops1]

You might want to check using a thin feeler gauge inside. I think the block is coming unglued from the back, and possibly part of the sides.

[Valerie Jestice]

There isn’t any bolts holding the neck on, should I take the neck off, then maybe I could get a better look?

[pops1]

If the neck is not bolted on, it is not easy to remove. You may have to attach a feeler gauge to a dowel to reach in thru the holes in the well inside to see if the block is coming loose. See if there is a gap at the bottom between the block and the back. It may not be visible with no tension from strings, but the feeler gauge should slide in if it is loose. You could clamp the body to a bench and lift up on the neck (CAREFULLY) to simulate string tension and see if there is any movement also.

[Valerie Jestice]

If the neck is not bolted on, it is not easy to remove. You may have to attach a feeler gauge to a dowel to reach in thru the holes in the well inside to see if the block is coming loose. See if there is a gap at the bottom between the block and the back. It may not be visible with no tension from strings, but the feeler gauge should slide in if it is loose. You could clamp the body to a bench and lift up on the neck (CAREFULLY) to simulate string tension and see if there is any movement also.

I clamped the dobro to a bench, and did just what you said. There is a gap between the block and the back. Now what?

[pops1]

Well you will have to glue it. First since only hot hide glue will stick to itself you will need to clean as much old glue as you can. Since we don't know what glue was used, but definitely not HHG, you will have to decide on a glue to use. Before you glue anything figure out how you are going to clamp it and practice clamping so it is quick and easy. Now dry clamp (no glue) and use your feeler gauge to see that you have closed the gap with clamping. GLUE WILL NOT FILL GAPS. You will most likely have to use the feeler gauge to spread glue into the gap, choose a glue that will give you enough time to get glue in there. Since this is an inexpensive instrument and you won't be able to really do a good job cleaning old glue I would use epoxy for the repair. I don't like using epoxy, but there are times when it may be the best choice. Since you don't have much experience or access this may be the glue of choice, it will give you a little time to work, and will bond to old glue better than wood glues.

[Valerie Jestice]

Well you will have to glue it. First since only hot hide glue will stick to itself you will need to clean as much old glue as you can. Since we don't know what glue was used, but definitely not HHG, you will have to decide on a glue to use. Before you glue anything figure out how you are going to clamp it and practice clamping so it is quick and easy. Now dry clamp (no glue) and use your feeler gauge to see that you have closed the gap with clamping. GLUE WILL NOT FILL GAPS. You will most likely have to use the feeler gauge to spread glue into the gap, choose a glue that will give you enough time to get glue in there. Since this is an inexpensive instrument and you won't be able to really do a good job cleaning old glue I would use epoxy for the repair. I don't like using epoxy, but there are times when it may be the best choice. Since you don't have much experience or access this may be the glue of choice, it will give you a little time to work, and will bond to old glue better than wood glues.

So I will have to take the top off?

[pops1]

No you will have to use something like the feeler gauge on a stick to get in there and spread glue. First make sure you can clamp it. Next without glue figure out how you will get glue into the crack between the block and the back. Now practice until you can do it quickly and cleanly.

[MikeEdgerton]

I'd be tempted to do a little alligator dentistry on that and just put a screw through the neck into the block while I was gluing it.

[pops1]

While I am prone to not putting screws in for lack of a proper repair, I would agree with Mike on this. Hesitant to suggest it, but agree it might be easier. If you decide to put a screw in the back I would put two and a spacer between them to act like a big washer, but rectangle. Maybe a piece of aluminum heavy enough to support the screws, but not so heavy as to stick out much.

[Valerie Jestice]

While I am prone to not putting screws in for lack of a proper repair, I would agree with Mike on this. Hesitant to suggest it, but agree it might be easier. If you decide to put a screw in the back I would put two and a spacer between them to act like a big washer, but rectangle. Maybe a piece of aluminum heavy enough to support the screws, but not so heavy as to stick out much.

I already glued it. There was no way I could put glue in from the inside, because a tone bar was planted right in the way. Daddy insisted that I remove some of the binding from under the neck, I’m glad I did! There was pieces of wood wedged in between the block and the back, keeping it separated, the block didn’t even appear to be glued in the first place! My brother mixed up 15 min. epoxy, and used that.

I hope this is the cause of the buzzing.