How to Replace The Gem Roller Organ Bellows Part One

Repairing the bellows of the gem organ

The Gem Roller Organ

I’ve been enchanted by The Gem Roller Organ for many years. I’ve scoured the web for every nugget of information I could about this mechanical marvel and I’ve learned just about everything there is to know. The two things that fascinate me most about The Gem Roller Organ are:

1. The bellows create a vacuum to pull air through the reeds (as opposed to pushing pressurized air through reeds, whistles or pipes).

2. The drive mechanism not only rotates the cob, but slowly offsets to the left. This increases the duration of a tune to three rotations of the cob. When the tune is complete a spring loaded release mechanism pushes the cob to the right, which resets the cob to the start of the tune. It’s amazing how much is going on in such a small mechanism! (more on that at John Wolff’s Web Museum)

Loaded with everything I’ve learned about the Gem, it was time to get one of my own! I purchased mine on Ebay for a handsome fee, even though the listing clearly stated the unit didn’t “create much sound”.  Examining the images of the Ebay listing I knew the mechanism was complete and in undamaged condition.

It was clear, however, someone tried to repair the unit by gluing the sheepskin valves on the feeder bellows completely closed! Knowing full well that there was certainly an underlying problem that caused this repair, I suspected fixing the valves would not return the unit to its original glory. Long story short, the bellows cloth and valves needed to be replaced.

Things to Consider Before Starting a Restoration

Restoring my Gem Roller Organ required about twenty hours of effort using the CONCERT ROLLER ORGAN REPAIR KIT from Roller Organ Restorations for eighty dollars. This company will restore a Gem for as little as $255. The repair kit includes an instruction sheet that, personally, I found confusing and of little use. I say this because it is assumed the reader already understands the name and function of every part and there are no illustrations. If you aren’t comfortable with working with tiny parts, hot hide glue and tight spaces with awkward bits you may want to seek the help of a professional.

The cotton based bellows cloth included in the kit functions well, but looks like neoprene and nothing like the original cloth backed black rubber of the original. I prefer the aesthetics of the original cloth and there are other downsides to the kit’s cloth which I’ll explain later. However, it’s great that someone provides a quality kit to replace the bellows and pallet valve pads in one kit.

If you decide to replace the bellows I recommend carefully disassembling the unit, storing screws and small parts small labeled Ziploc bags and record the order in which the unit was dismantled. When all the parts are clean, the original bellows material is completely removed and the wood surfaces are sanded clean the unit should be assembled in reverse order.

Hide glue is the way to go when working with bellows cloth. If you’ve never worked with hide glue before, it can be intimidating at first. It’s not as complicated as it seems and I find hide glue much easier to use than any other suggested replacement adhesive. I purchased my hide glue from Tools For Working Wood. The site has a clear explanation of the various strengths, I use 315 gram strength. While your shopping for supplies I recommend picking up some shellac flakes as well. Dissolve the shellac flakes in denatured alcohol (not rubbing alcohol) and you’re good to go.

“Good to go where,” you ask? Shellac works well for sealing up any leaks that unavoidably occur between the bellows cloth and the wood it’s attached to. A few coats around the perimeter helps keep leaks to a minimum. Shellac is not mentioned in the Organ Repair Kit Instruction Sheet, and with good reason. Shellac discolors the cotton based material, so care must be used when applying shellac. The discoloration of the cloth on the feeder bellows (under the cabinet) doesn’t matter much because it’s hidden. The shellac needs to be applied to the reservoir bellows from inside the cabinet to prevent discoloring the outside of the fabric.

Opening the case of the Gem Roller Organ

Replacing the Bellows on The Gem Roller Organ

Opening the cabinet is fairly straightforward. The feeder bellows push rod is attached to the crankshaft by the springiness of the wood and locked into place with screw #1. Loosen screw #1 enough to gently release the push rod from the crankshaft. Well done! The hard part of opening the cabinet is complete.

Now remove screws #2 and #3 to detach the crankshaft bearing from the case.  The crankshaft assembly can be removed by gently guiding it out of the bearing in the rear of the mechanism. Remove screws #4-8 in no particular order. The front panel can now be removed by sliding it forward.

A Look Inside the Reservoir Bellows

Bellows Springs, Push Rod, Reed Block
We’re finally getting a view of things my internet searches failed to reveal! The top half of the image is the inside of the reservoir bellows. The springs hold the bellows open against the vacuum created by the feeder bellows below. When the vacuum compresses the reservoir too much the lid touches the relief valve push rod which opens a valve on the underside of the cabinet, temporarily allowing air into the reservoir to reduce the vacuum.

The lower half of the image shows the reed block attached to the front panel. The reed block can be detached and gently cleaned. To do so,  remove the two remaining screws on the front panel to the left and right of the palette valves. A word of caution: In my haste to attach the reed block after cleaning, I mistakenly attached it upside down.  The resulting music was not very good.

Remove The Gem Roller Organ Reservoir Bellows

Remove Reservoir Bellows Gem Roller Organ
Using a heat gun (top left) to remove the bellows cloth.

Notice the little tabs on the large, three-sided bellows cloth that wrap around to the front at the corners and cover the “hinge cloth” across the front of the unit. These tabs are important to include with the replacement cloth.

I started the process of removing the reservoir bellows cloth by gently poking, prodding and cutting at the tabs with and x-acto blade and small dental hook/pick. This process worked well where the glue was compromised. However, the bellows cloth was stuck extremely well on the corners and a few other areas. That’s when I got out the heat gun.

With the heat gun on a low setting the flow of hot air was swept side to side on the areas that were stuck solid. To my surprise just as the temperature of the wood got almost too hot to touch, the bellows cloth easily peeled away from the lid and cabinet.

Be careful with the heat gun. Too much heat will ruin the finish of the wood cabinet! A heat gun, after all, is a great tool for doing exactly that, removing paint and finish. Those uncomfortable using a heat gun should start with a hair dryer with low heat.

Remove the two valve leather strips as well.

Accessing the Feeder Bellows

Gem Organ Feeder Bellows

Accessing the feeder bellows of The Gem Roller Organ was something that had me stumped. After a brief study of the construction of the cabinet I believed the feeder bellows were simply glued to the underside of the platform. “Perhaps a sharp downward drop would knock the bellows loose?” was the general theme of my thinking.

This is NOT the reality, so please don’t try it! The bellows do not disconnect from the underside of the platform, the platform disconnects from the sides of the cabinet. The image above has four red circles highlighting the screws to be removed to accomplish this. I suppose these screws were invisible to me because the construction of the unit was not as I originally expected.

Removing the Feeder Bellows Cloth

Building on the experience you’ve gained by removing the reservoir bellows cloth, removing the feeder bellows cloth is mostly an easy task. Start by removing  the spring and the three tacks to remove the relief valve (already removed in image). Next remove the two screws on the wooden feeder bar and remove the bar (a little heat should loosen the glue.  Remove the eight feeder bellows tacks (four on each side), I used needle-nosed pliers for the task.

Removing the Feeder BellowsNotice the tacks are binding  down tabs connected to the hinge cloth. This tab configuration is opposite of the reservoir cloth. Remember, the tabs on the reservoir cloth cover the hinge cloth, the tabs on the feeder bellows stem from the hinge cloth and cover the side of each feeder bellows. This must be replicated with the replacement cloth.

I removed the bellows cloth using heat, x-acto blade and small dental hook/pick. The hinge cloth is the most problematic to remove. I ended up using a rotary tool with tiny diamond burrs like these. The hinge cloth and glue need to be completely removed down to the wood! It took me two hours to remove the hinge cloth down to the wood.

The two valve leather strips should be removed as well.

Make sure all of the old bellows cloth and glue is removed on all surfaces! I will admit I used this Sanding Disc Kit quite a bit to accomplish the task. Don’t be fooled, these little sanding discs are hungry little buggers! A careful and gentle touch is all that’s required, slow and steady wins the race. A little side note about the sanding discs, I use them all the time on countless things. I’ve owned the set for more than ten years and I still have most of the discs. They last forever before they need to be replaced.

My next post How to Replace The Gem Roller Organ Bellows Part Two coming soon. I will provide downloadable patterns for the replacement bellows cloth. And yes, I’ll share the experience of replacing the bellows cloth and reassembly. If I’m feeling ambitious a video performance will be included as well!

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