Bass Bridge Repair/Replacement

[Terry Farrell]

Cracked bass bridge on 1920s Gulbranson upright - glue failure also. Took strings off today and bridge and apron fell off. Made new bridge and apron this evening and glued them together. My question is this: Can I glue & screw the apron to the soundboard AND re-install the bass strings AND bring them up to pitch in one sitting? Would four wood screw through the back of the soundboard into the apron adequately stabilize the bridge/apron assembly enough before the glue (Titebond II or III) completely dries?

Thanks!

Terry Farrell

[Paul McCloud]

Hi, Terry:
Well, my guess is that if it doesn't hold, you may have to do it over. If it holds, but the glue joint isn't tight, you may not be able to see it. Then, you'll have to take it apart again, clean off the glue and start over. IF you can get the screws out, that is. I'll bet those screws are hard to get to, since they're probably behind the posts, right?
All good things come to those who wait.
Can't hurt to wait, unless you can't.
Paul McCloud
San Diego

[Euphonious Thumpe]

Use bolts and then plug with dowels, if unsure. Thumpe

---

From: Paul McCloud <pava...@gmail.com>;
To: <pian...@googlegroups.com>;
Subject: Re: [ptech] Bass Bridge Repair/Replacement
Sent: Tue, Apr 30, 2013 2:15:54 AM

[Ron Nossaman]

On 4/29/2013 8:51 PM, Terry Farrell wrote:
> Cracked bass bridge on 1920s Gulbranson upright - glue failure also.
> Took strings off today and bridge and apron fell off. Made new bridge
> and apron this evening and glued them together. My question is this:
> Can I glue & screw the apron to the soundboard AND re-install the
> bass strings AND bring them up to pitch in one sitting?

I did it that way every time.

>Would four
> wood screw through the back of the soundboard into the apron
> adequately stabilize the bridge/apron assembly enough before the
> glue (Titebond II or III) completely dries?

Beats me. I always used Titebond original. For that, yes.
Ron N

[Joseph Garrett]

Terry,
TSK! The original bridge/apron were glued on with hide glue. Titbond, etc.
is not compatible with hide glue, even tho both are water based. I'd use
Cold Hide glue and let it set for at least 24 hours before putting the
strings back on. My reason is the cantilever, it will have a tipping force
that will cause the glue joint to fail if it's not set properly. That's my
take on that one.
Best,
Joe

Joe Garrett, R.P.T.
Captain of the Tool Police
Squares R I
http://gpianoworks.com/


> [Original Message]

> From: Terry Farrell <mfar...@tampabay.rr.com>
> To: <pian...@googlegroups.com>

> Date: 4/29/2013 6:51:05 PM

> Subject: [ptech] Bass Bridge Repair/Replacement
>

> Cracked bass bridge on 1920s Gulbranson upright - glue failure also. Took
strings off today and bridge and apron fell off. Made new bridge and apron
this evening and glued them together. My question is this: Can I glue &
screw the apron to the soundboard AND re-install the bass strings AND bring

them up to pitch in one sitting? Would four wood screw through the back of

the soundboard into the apron adequately stabilize the bridge/apron
assembly enough before the glue (Titebond II or III) completely dries?
>

> Thanks!
>
> Terry Farrell

[David Love]

If he's made a new bridge and apron then why is the compatibility of hide
glue and titebond an issue? Even if it were I presume he would be cleaning
off all the old glue before he glued it back down to the soundboard. This
is not unlike what happens on the inner rim of a piano when a new soundboard
goes in. The old board was glued down with hide glue and so you clean it
all off and use something else. No problem with compatibility there.

Personally, I wouldn't use cold hide glue. I don't think it's reliable for
this kind of stress joint. However, I would feel more comfortable if the
glue joint were allowed to dry 12 - 24 hours (Titebond), though it probably
isn't absolutely necessary with everything screwed down. Still, a real pain
if you jump the gun a bit and the joint fails

David Love
www.davidlovepianos.com

[Joseph Garrett]

David,
It's difficult to get all of the glue out of the wood or even off of the
surface of a soft wood like spruce, so there remains the incompatability
issue.
I"ve been using cold hide glue for forty years without a failure.
If used properly it is a good glue albeit slightly less strong than regular
hot hide glue, but not so's you'd notice imo.
Your example doesn"t wash as it's the opposite of what is being done..
i.e. gluing new maple to soundboard contaminated with hide glue as opposed
to a new soundboard being glued to maple slightly impregnated with hide
glue. Besides, there is no sheer in the soundboard gluing and there is in a
cantilever bridge. That's how I see it. No matter what glue it needs to
have sufficient set up time else it's doomed to possible failure imo.

Best,
Joe

Joe Garrett, R.P.T.
Captain of the Tool Police
Squares R I
http://gpianoworks.com/


> [Original Message]

> From: David Love <davidlo...@comcast.net>
> To: <pian...@googlegroups.com>
> Date: 4/29/2013 11:47:07 PM

[Brian Trout]

(I made bold and underlined the part that stuck out to me.)

That's really one of the more critical elements of this whole thing, and that is, how long the glue would actually have to set up before pressure was brought to bear upon the joint.

I've not used Titebond II or III but like Ron, have used the original Titebond glue.  I don't know what the manufacturer suggests for set up times but I am aware that if I glue up a joint, clamp it (in this case secure it with screws) and let it sit for even 15 to 20 minutes, I can't get the joint apart again without major damage to wood in most cases. 

I don't know how fast you work, Terry, but I can see how you might have sufficient time for that glue joint to sit for a while before much pressure gets put on it.

Another thing that no one really talked about (that I read, I could have missed it) is just how much downbearing is on this bass bridge?  I've seen quite a few of them where there was pretty much zip.  A larger downbearing would cause more stress on the joint than a practically non-existent one.  And if the thing is screwed securely to the soundboard, it's really not goin' anywhere.

Just a couple o' thoughts from a has-been...  :-)


Brian

[William Monroe]

I agree with Joe that Cold Hide glue is not something to be concerned about.  Based upon a couple of strength tests (one recently in Fine Woodworking) and upon my own experience, I have no reason to believe Cold Hide would fail before any other glue.  I've used Cold Hide in all manner of applications, including soundboard installation.  As with all glues, it should be reasonably fresh, though even a lack of fresh hide glue doesn't guarantee failure.  Out of curiosity, I have used a bottle of Cold Hide glue that has been on my shelf for over 8 years in a few non-critical projects and have had no issues of failure.

As to compatibility, I would disagree.  There may be some residue, but not enough for concern.  If the wood is prepped reasonably and there is a reasonable amount of exposed wood, there will be plenty for the glue to bond with and there should be no issues.   

William R. Monroe

On Tue, Apr 30, 2013 at 2:15 AM, Joseph Garrett <joega...@earthlink.net> wrote:

David,
It's difficult to get all of the glue out of the wood or even off of the
surface of a soft wood like spruce, so there remains the incompatability
issue.
I"ve been using cold hide glue for forty years without a failure.

 

SNIP

[Terry Farrell]

> My reason is the cantilever, it will have a tipping force

Yes, and hence, precisely the reason for my question.

> that will cause the glue joint to fail if it's not set properly.

Yeah, but my question is whether four well-set wood screws through the back of the soundboard into the apron would hold it in place while the glue dried (and with tension on the strings).

I think Ron answered me - as he has done it that way successfully.

Terry Farrell

[Terry Farrell]

On Apr 30, 2013, at 2:47 AM, David Love wrote:

> If he's made a new bridge and apron then why is the compatibility of hide
> glue and titebond an issue? Even if it were I presume he would be cleaning
> off all the old glue before he glued it back down to the soundboard. This
> is not unlike what happens on the inner rim of a piano when a new soundboard
> goes in. The old board was glued down with hide glue and so you clean it
> all off and use something else. No problem with compatibility there.

Zzzzzactly.......

> Personally, I wouldn't use cold hide glue. I don't think it's reliable for
> this kind of stress joint.

I suspect it would work just fine as many pianos were successfully made this way in the past. However, as long as it is just as easy to use Titebond, I'll be going that route.

> However, I would feel more comfortable if the
> glue joint were allowed to dry 12 - 24 hours (Titebond), though it probably
> isn't absolutely necessary with everything screwed down. Still, a real pain
> if you jump the gun a bit and the joint fails

Yeah, and the reason I asked. Ron says he has done it that way many times with success. (Or did Ron simply say that he has done it that way many times????? ;-))

Terry Farrell

[Terry Farrell]

On Apr 30, 2013, at 3:15 AM, Joseph Garrett wrote:

> David,
> It's difficult to get all of the glue out of the wood or even off of the
> surface of a soft wood like spruce, so there remains the incompatability
> issue.

First of all there is pretty much no glue there to begin with - the darn thing fell right off. Secondly, I'll be using an emerging technology called sandpaper - you simply rub back and forth with pressure and it removes the surface - they even have come out with various grits!

;-)

Terry Farrell

[Terry Farrell]

> I suspect it would work just fine as many pianos were successfully made this way in the past.

Oops! Before (I Hope!) anyone jumps on me, I was thinking HOT hide glue. My bad for saying pianos have been made of cold hide glue.

:-(

Terry Farrell

[David Love]

Sandpaper? Wow, I'd patent that--and there's, well, so much beach.

David Love
www.davidlovepianos.com


-----Original Message-----
From: pian...@googlegroups.com [mailto:pian...@googlegroups.com] On

Behalf Of Terry Farrell
Sent: Tuesday, April 30, 2013 7:57 AM
To: pian...@googlegroups.com
Subject: Re: [ptech] Bass Bridge Repair/Replacement

Terry Farrell=

[Ron Nossaman]

On 4/30/2013 9:51 AM, Terry Farrell wrote:
>
>> My reason is the cantilever, it will have a tipping force
>
> Yes, and hence, precisely the reason for my question.
>
>> that will cause the glue joint to fail if it's not set properly.
>
> Yeah, but my question is whether four well-set wood screws through
> the back of the soundboard into the apron would hold it in place
> while the glue dried (and with tension on the strings).
>
> I think Ron answered me - as he has done it that way successfully.

More than that, I've never done it any other way. I'll never understand
why techs have such faith in glue, which in this case wasn't there to
keep the bridge from falling to the bottom of the piano when the string
tension was let down, and such doubt about screws, which in this case
probably would still be holding the original joint together well enough
that you'd have had to break it to get the bridge loose.
Ron N

[Isaac OLEG]

What is that glue ? I never heard of bridges glued with PVC glues (or aliphatic resins) 

[Ron Nossaman]

On 4/30/2013 8:05 PM, Isaac OLEG wrote:
> What is that glue ? I never heard of bridges glued with PVC glues (or
> aliphatic resins)

Please make some minimal attempt to look up and verify before posting
what you heard. Google Titebond and do some reading. It's a PVA,
aliphatic resin and works quite well.
Ron N