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#2274104 - 05/11/14 04:23 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Dan Cravens Offline
Full Member

Registered: 05/05/14
Posts: 26
Loc: Central Texas
Should the cantilever be made of quarter sawn hard rock maple? And how would you implement the saw lines?
_________________________
1st time reconditioning 1923 Gulbransen, http://imgur.com/a/Zmvka

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#2274278 - 05/11/14 09:37 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Gene Nelson Offline
1000 Post Club Member

Registered: 09/10/04
Posts: 1510
Loc: Old Hangtown California
Thinking about the load direction I would flat saw the apron.
How was the original oriented?
What species of wood was the original?
Why not just copy the original?

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#2274853 - 05/12/14 02:06 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7901
Loc: France
Originally Posted By: Dan Cravens
Should the cantilever be made of quarter sawn hard rock maple? And how would you implement the saw lines?


the saw lines are for suppleness on small pianos, that may have some soundboard curvature ( spherical soundboard) and that use a 2 parts cantilever, not 3 as in your case.

the saw lines are located between the ribs.

When on the bridge itself they go up to half the height of the bridge.

if your base is in a soft wood this is probably not necessary.
but not a problem to make some.

Soft woods save weight on the bridge so sometime they are employed.

The minimum space between pins on the bridge is 8 mm.





Edited by Olek (05/12/14 02:14 PM)
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2274871 - 05/12/14 02:23 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Olek]
Dan Cravens Offline
Full Member

Registered: 05/05/14
Posts: 26
Loc: Central Texas
I took the apron and bass bridge to a wood specialty shop today. They said both were made of the same type of maple, though couldn't say if it was hard rock maple. I did try indenting it with my fingernail and wasn't able to leave much of a mark. Orientation meaning how the grain runs? The wood grain on the apron runs parallel to the 4 cracks, so it's running vertical. I thought the grain for the bridge ran horizontal or the length, but need to lightly sand it due to the varnish to be certain.

I wrote the measurements in inches on the back of the apron and included a picture if that is helpful at all.

[img]http://imgur.com/a/Zmvka#fplUA78[/img]

When you say a "3 parts" cantilever what do you mean. Does that include the spacer and the bridge? The apron originally was a single piece before it cracked. Are the ribs the notches or indentations from the bass strings?


Edited by Dan Cravens (05/12/14 02:24 PM)
_________________________
1st time reconditioning 1923 Gulbransen, http://imgur.com/a/Zmvka

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#2274937 - 05/12/14 04:17 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7901
Loc: France
hello, the ribs are under the soundboard.see how is the bridge located vs them.

I am not sure the cracks are so much a problem, due to the way the brige works, may be shimming them or open them more woul pe OK (?)

But it can be fun to make a new part indeed.

The wood does not look as a very hard wood to me it may have hardened in time. (I am not a specialist in woods )

The cantilever that Fenner proposed was done with only the bridge and a support , no intermediate part, the curved shape allow to gain some lenght for the strings, locate the brige foot a little farther, but really not much ( 20 mm) and it is an exemple for a small piano.
Anyway if saw lines where to be done that would be in the bottom part of the spacer it is too difficult and I think that in the underpart of the bridge it is not so much useful in your case.

Cannot be bad anyway.

Regards
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2274954 - 05/12/14 04:37 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Olek]
Dan Cravens Offline
Full Member

Registered: 05/05/14
Posts: 26
Loc: Central Texas
Originally Posted By: Gene Nelson
Thinking about the load direction I would flat saw the apron.
How was the original oriented?
What species of wood was the original?
Why not just copy the original?


I sanded the ends in order to see the grain better. Looks like you are correct about the original apron being flat sawn and the bridge is quarter sawn.

http://imgur.com/a/Zmvka#OjMEQJw
http://imgur.com/a/Zmvka#LmWKhMu

At wood craft an older gentleman there said it was maple, he didn't say hard or soft. I will just copy the original orientation. Thank you very much!

The video below helped me to understand flat vs. quarter sawn.

http://www.youtube.com/watch?v=sVBsA1KbfY8


Edited by Dan Cravens (05/12/14 08:02 PM)
_________________________
1st time reconditioning 1923 Gulbransen, http://imgur.com/a/Zmvka

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#2322164 - 08/31/14 08:53 AM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Dan Cravens Offline
Full Member

Registered: 05/05/14
Posts: 26
Loc: Central Texas
It's been awhile since I've updated this thread. Building the new bridge was a slow process as I was dependent on someone else's help. Plus my friend likes to work very slowly and methodical, but we finally have an exact replica of the old bridge! At least to the point where the dimensions, pin placement and angles all match. Reblitz says to burnish it with a mixture of alcohol and graphite? I've searched online and gather it means to rub something smooth, but could anyone please elaborate?

Here's a few pictures prior to routing the edges that show transferring the pinhole positions and how the angle for the pinhole were drilled. Not only was the table for the drill press placed at a 45' angle, but the bridge was then placed at a 45'.

http://i.imgur.com/7xos1g4.jpg
http://i.imgur.com/1di9i3X.jpg


Edited by Dan Cravens (08/31/14 08:54 AM)
_________________________
1st time reconditioning 1923 Gulbransen, http://imgur.com/a/Zmvka

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#2322172 - 08/31/14 09:06 AM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Ed A. Hall Offline
Full Member

Registered: 08/23/01
Posts: 265
Nice job. You can buy it in a small jar and it's called Acheson DAG. That said, it's not needed. It's very messy stuff IMO. Some of the high end pianos don't use it. I would just spray a thin coat of nitrocellulose lacquer or better yet conversion varnish and call it good.

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#2322385 - 08/31/14 08:18 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Dan Cravens Offline
Full Member

Registered: 05/05/14
Posts: 26
Loc: Central Texas
Thanks Ed. I also came across this which talks about using alcohol and molybdenum disulfide powder. I have some from building kid's pinewood derby cars.

http://www.graflex.org/speed-graphic/lubricants.html
_________________________
1st time reconditioning 1923 Gulbransen, http://imgur.com/a/Zmvka

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#2322547 - 09/01/14 07:44 AM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Ed A. Hall Offline
Full Member

Registered: 08/23/01
Posts: 265
if you are concerned about the new bridge matching the others, you can also use black lacquer. It's a lot less messy than graphite.

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#2322551 - 09/01/14 08:04 AM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Dan Cravens Offline
Full Member

Registered: 05/05/14
Posts: 26
Loc: Central Texas
I'm not concerned about the appearance matching. I was under the assumption (maybe falsely) that the graphite or DAG served a purpose such as allowing the strings to move or vibrate.
_________________________
1st time reconditioning 1923 Gulbransen, http://imgur.com/a/Zmvka

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#2322681 - 09/01/14 02:03 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Gadzar Offline
1000 Post Club Member

Registered: 12/15/06
Posts: 1813
Loc: Mexico City
Originally Posted By: Dan Cravens
Originally Posted By: Gene Nelson
Thinking about the load direction I would flat saw the apron.
How was the original oriented?
What species of wood was the original?
Why not just copy the original?


I sanded the ends in order to see the grain better. Looks like you are correct about the original apron being flat sawn and the bridge is quarter sawn.

http://imgur.com/a/Zmvka#OjMEQJw
http://imgur.com/a/Zmvka#LmWKhMu

At wood craft an older gentleman there said it was maple, he didn't say hard or soft. I will just copy the original orientation. Thank you very much!

The video below helped me to understand flat vs. quarter sawn.

http://www.youtube.com/watch?v=sVBsA1KbfY8


Nice video. Finally I understad what quarter and flat saw mean.

Though I do not yet know when and why to use one or the other.



Edited by Gadzar (09/01/14 02:04 PM)
_________________________
Rafael Melo
Piano Technician
rafaelmelo@afinacionpianos.com.mx

Serving Mexico City and suburbs.

http://www.afinacionpianos.com.mx

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#2322773 - 09/01/14 05:43 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7901
Loc: France
Originally Posted By: Dan Cravens
I'm not concerned about the appearance matching. I was under the assumption (maybe falsely) that the graphite or DAG served a purpose such as allowing the strings to move or vibrate.
.


slip better, probably - tentative to have less than the 6-8% tension difference (retained by friction between the pins and on the surface) between front and back of the bridge, as all the tension that do not transit thru will make the bridge tilt, or try to, forcing then on the ribs and assembly.

I was said that Bechtein used a fixture to hold the tall bass bridge while pulling the bass strings at pitch.e
Now due to the curved shape of that bridge this may be only helping for some models, the curve stabilizes the bridge.

protect against corrosion at woo/steel contact . Some have no graphite but are certainly rubbed with something paraffin may be. (Gaveau, possibly only steatite, but something clearly is on/in the surface)

The wood can be hardened by heating, I believe it had been done sometime for the surface of the bridge.

Anyway burnishing the wood before or after graphite is better.



T



Edited by Olek (09/01/14 06:25 PM)
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2323071 - 09/02/14 10:36 AM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Olek]
Dan Cravens Offline
Full Member

Registered: 05/05/14
Posts: 26
Loc: Central Texas
I did burnish the bass bridge using alcohol and graphite. It was a little messy, but I was working outside and am more concerned with the bridges function over appearance.

http://i.imgur.com/hXqqy47.jpg

I was hoping to get it installed yesterday but instead helped my son with the brakes and fuel system of his project car. I should get it done this week, but aren't in a hurry.

Isn't the purpose of using quarter sawn for a piece like the bridge done for stability?
_________________________
1st time reconditioning 1923 Gulbransen, http://imgur.com/a/Zmvka

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#2323146 - 09/02/14 01:59 PM Re: Reconditioning 1923 Gulbransen Player, Replacing a Bridge [Re: Dan Cravens]
Ed A. Hall Offline
Full Member

Registered: 08/23/01
Posts: 265
[quote=Dan Cravens]
Isn't the purpose of using quarter sawn for a piece like the bridge done for stability?[/quote]

To better resist cracking.

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