The Fair Organ Preservation Society Discussion Forum

Organ Repair...
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Author:  Dave Stubbs [ Mon Nov 16, 2009 12:59 pm ]
Post subject:  Organ Repair...

Welcome to the Organ Building and Technical section of the FOPS Forum.

I will 'get the ball rolling' with an item about an organ repair I carried out recently.

I operate the ex-Stuart Marti-Bowler 31 keyless Dean organ that now belongs to George Houghton.

I noticed that some of the notes weren't playing, so I examined the pneumatics and found that the leather on the pallet motors had deteriorated quite substantially:

File comment: At least 6 pallet motors had completely deteriorated - note the tear in the leather!
organ_repair_1.jpg [ 24.23 KiB | Viewed 21792 times ]

So the first job was to remove the motor board:

File comment: I hope that I can remember where all those tubes go - and yes, I know about the Duck tape, it's sealing a crack in the primary action modules perspex cover!
organ_repair_3.jpg [ 43.09 KiB | Viewed 21792 times ]

Then I gave the board to organ repairer Sid Reeves for re-leathering, who made it look like new!

File comment: Great job Sid!
organ_repair_6.jpg [ 30.04 KiB | Viewed 21781 times ]

Then I had to reassemble all that plumbing!

File comment: The pallet motor board, now reconnected to the primary action module, phew!
organ_repair_4.jpg [ 40.51 KiB | Viewed 21792 times ]

Then I had to do some juggling with the air feeds so that I could operate the primary action with the windchest cover removed, to set the pallet spring tension (taking into account that once the windchest air pressure is restored, there will be some extra force on the pallets).

File comment: Testing the action. Note the 'inflated' motor pushing a pallet.
organ_repair_5.jpg [ 50.55 KiB | Viewed 21792 times ]

Then it was over to the primary pneumatics for some adjustments using a repeating note:

File comment: The primary action module with the bleed screw at the top and the exhaust adjustment at the bottom
organ_repair_7.jpg [ 31.68 KiB | Viewed 21792 times ]

And after all that the organ is playing very well and I now know a lot more about the mechanics of a keyless system!

Author:  George Houghton [ Thu Nov 19, 2009 11:18 am ]
Post subject:  Re: Organ Repair...

I look forward to hearing the Organ after the repair that all the notes are playing again. :music2:
Glad you managed to put everything back in the right place. :clap2:

George :grinder:

Author:  Richard Ellis [ Tue Nov 24, 2009 1:39 pm ]
Post subject:  Re: Organ Repair...

Thin Kangaroo skin is extremely effective for pneumatics. It's toughness yet suppleness is why it is used for ballet shoes.

Richard Ellis, Australia

Author:  Dave Stubbs [ Tue Nov 24, 2009 1:48 pm ]
Post subject:  Re: Organ Repair...

Hi Richard.

I have heard of many animals providing pneumatic leather, but that is definately a new one...well, in the UK at least. Maybe you can start a new trend for organ builders! :lol2:

Author:  Arthur Nichols [ Sun Nov 29, 2009 8:36 am ]
Post subject:  Re: Organ Repair...

Hi Dave
It would be interesting to analyse the reason for the failure of the pouch motors.
You mention deterioration of the leather,looking at your photographs there are some things which in my view would speed up failure of the motors. Having said that how many years has the organ been running satisfactorily?
1. The diameter of the motor recess could be enlarged to give more leather in the flexing area.
2. The edges of the motor recess could be chamfered to avoid a sharp edge around which the leather presently folds.
3.The tear damage looks to be caused by over stretching the leather. the distance that the pallette is allowed to travel could be restricted to prevent this, the leather will still fully extend under the influence of the air pressure but with more leather between the motor recess and the glued on pad, stress on the leather could be reduced.
I am not writing this to be critical of any builder but to draw attention to these considerations which could be done when new pouch chests are made.
Looking again at your photographs it looks like there is a plastic nut on the threaded wire which is probably set to act as a stop. Again from the photographs the distance the pallette opens, could this be reduced by adjustment of the aforementioned plastic nut preventing overstretching of the leather and enabling a faster action by reducing the distance the pallette travels. I also observe that the glue on the leather may be holding the leather a little into the recess, care needs to be taken as to how much glue is around the edge of the recess, when building my motors I use a ring which I place over the edge of the recess and blow into the pouch to extend the leather to prevent it being glued over the edge into the recess, a further point glue either the hot melt or PVA will cool or dry brittle which will be very abrasive on the leather.
I hope these comments might encourage some discussion.

Arthur Nichols

Author:  Dave Stubbs [ Sun Nov 29, 2009 11:55 am ]
Post subject:  Re: Organ Repair...

Hi Arthur.

Thanks for your comments.

The organ (a Dean) was built, according to a bit of research, in 1982. I am not an organ builder, but I felt that as I was the operator of the instrument, it was necessary to understand how to do some essential maintenance and basic adjustments.

Your comments about the plastic stop nut postition is interesting, as that is one item I have not adjusted, so I will lower them to reduce the pallet travel and hopefully the leather will last longer and maybe, as you say, it will make the action a bit faster.

I took the organ out yesterday for its first booking since the repair and apart from one or two minor celesting issues, the organ sounded better that it has for a long time...but considering how many pallet motors were damaged, it had to sound better!

When the motor board was repaired, I had wondered about the amount of leather between the pad and the edge of the recess, but as I am an electronics engineer on a crash course in mechanical organ repairs, I had to bow the the expert knowledge of Sid Reeves on that one!

Good to know there is an expert on line for future enquiries!

Thanks again

Author:  Stuart Dobbs [ Sun Nov 11, 2012 9:40 am ]
Post subject:  Re: Organ Repair...

Having worked on numerous mechanical organs i have noticed that the Tan Split Skivers deteriorate faster than the normal white split Skivers. It is said that it is part of the tanning process in the tan coloured splits that causes this but have never confirmed this with anyone

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