How to Replace The Gem Roller Organ Bellows Part Two

Installing The Feeder Bellows Hinge Cloth and Valves

Feeder Bellows Hinge Cloth

This is a continuation of my previous post about replacing the bellows of The Gem Roller Organ. At this point the all the bellows cloth has been removed and the wood surfaces have been sanded completely clean of previous debris.

To begin installing the feeder bellows cloth, start with the hinge cloth. The hinge cloth is cut about 1 1/2″ longer than the length of the gap (the width was about 1 3/8″). The extra material must be cut to create two tabs at each end in order to fold over the feeder bellows cloth after it’s installed (see image above). I used a piece of bellow cloth from a previous project to create the hinge, not the material from the repair kit I purchased. The repair kit cloth will work just as effectively.

Using a double-boiler I combined about two tablespoons of dry hide glue and water in a small jelly jar. Once the glue reached 160°F (I monitored the temperature with a candy thermometer in the water of the double-boiler) I went to work. A disposable craft brush was used to apply the glue both to the centered hinge gap in the wood and the area of the cloth that’s inside the gap. The hinge cloth was installed with the help of a butter knife to push the cloth to the bottom of the gap.

New leather valves were cut from the leather from the kit and installed with hide glue. Remember, only the ends of the valve leather are glued! Be sure to keep the leather tight against the wood, for an air tight seal, before moving onto something else.

I added a little surprise for someone to find in a hundred years when they’re replacing my bellows cloth. It’s a photo of Lana Wood  (Natalie’s sister) from a 1961 Playboy magazine. I made sure it was fastened good with spray mount.

The image to the right (above) is me adding shellac to the hinge cloth. As I mentioned in the previous post, shellac helps to seal up little leaks that most certainly will occur.

Installing the Feeder Bellows Cloth

Feeder Bellows Cloth

Installing the feeder bellows cloth is fairly straightforward. Use the cloth you removed as a template for cutting the new material or download the pattern I created from mine. I recommend making a template out of paper to test the fit before cutting the replacement cloth.

Working one small area at a time, I applied hide glue to both the edges of the bellows wood and the cloth. I used some push pins to hold things in place while I worked, and while the glue set. In the end I used many more pins that are in the image above. The possible leaks the pin holes create are minuscule compared the leaks they’re preventing. I used a butter knife (image above) to press the cloth against the platform wood.

One word of caution. There is a finish applied to the wood in the push rod hole on the platform (red rectangle above) where the bellows attach. The original bellows were not stuck in this area, and it was very hard to make the new cloth stick as well. I permanently attached a few tiny tacks, applied with needle nose pliers, through the cloth and into the wood to keep the bellows sealed in this area.

When the cloth is completely attached remember to glue, fold over and tack the little tabs from the hinge cloth (red circles above). Leave the pins in overnight to allow the glue to cure. Resist the temptation to “test” the bellows until you’re sure the glue is set. I also sealed all the seams with a few coats of shellac.

Installing the Reservoir Bellows Cloth

Replace the reservoir bellows cloth following the same technique used to replace the feeder bellows cloth. Start by installing the hinge cloth. The hinge cloth for the reservoir bellows does not have tabs that wrap around the sides like the feeder bellows do. Instead, the main reservoir bellows cloth has tabs wrapping around the hinge cloth. Use plenty of pins to keep the cloth in place until the glue is cured. Use a razor blade to trim any access cloth protruding over the top edge of the lid.

Assembling the Gem Roller Organ Cabinet and Push Rod

Gem Roller Organ Push Rod

Now would be a good time to inspect the reeds. With the reed block detached from the front of the cabinet gently blow on the reeds. It’s not a trumpet, you’re lips shouldn’t need to touch the block to sound each reed. I forgot to make certain all the reeds were in working order before assembling my Gem, and a few don’t sound. Reviewing some photos of my reeds, it is clear some are bent out of position. One day I’ll go back and adjust them.

Use bellows cloth, or I used black craft foam, to create a gasket for the front of the cabinet (photo above). Install the front of the cabinet and attach the mechanism. Then guide the wooden push rod from under the platform and attach it to the crank. Tighten the screw, then attach the other end of the push rod to the feeder bellows. With the push rod installed, attach the platform to the four sided base.

A note about the push rod. The original push rod on my organ withstood several attachments and detachments. During one assembly it broke (#1 in photo above). I crafted a new one out of random black walnut and it broke while being attached (#2). Next I tried a piece of Douglas fir (#3). It broke as well.

It was then I looked closely the wood grain of the original. The grain was tight and quartersawn, meaning the grain was parallel to the block (green check mark above). The red X in the image above shows bad wood grain for the push rod. The gran is bad because cracks occur with the grain.

A scrounged around my stockpile of wood scraps and found a suitable piece of black walnut. The resulting push rod (#4) installed with easy success.

Replacing the Valve Pads

Replacing the valve pads was an easy task. I used a dental hook to remove the old pads, they basically fell off. I used Q-Tips soaked with denatured alcohol to clean the metal surface. My patience was wearing thin so I decided to use CA glue (super glue) to fasten the new pads. Nothing stressful or unpredictable to report about the process.

The Gem Roller Organ Performance

With The Gem Roller Organ fully assembled (and somewhat adjusted) it was time for its first performance! I put on one of the cobs that shipped with the organ and started cranking. Strong and clear music filled the room. As I mentioned earlier, some of the reeds aren’t adjusted, so they sound weak or not at all. Regardless, the melody was clear and very familiar.

After sharing this video with my parents they immediately knew the name of the song, “Nearer, My God, to Thee”. My parents also knew this as the song the band played as the Titanic sunk.


I hope you’ve found my posts about The Gem Roller Organ helpful. I know it’s far from comprehensive, but it’s a lot more information than what’s on the internet. If you’d like me to post other specific information, or if you’ve found any errors in the text please let me know. I had a fun time restoring my Gem Roller Organ. If you decide to restore a Gem on your own, take your time, don’t rush or set any deadlines. It’s a slow process that’s best suited for deliberate and careful work.

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!

Walking Wooden Poodle Automata / Karakuri Machine

jchismar Poodle Dog Automata Karakuri

Yesterday was my super-sweet standard poodle Fleur’s thirteenth birthday. To commemorate the occasion I dug in and built an automata in her likeness. Loosely defined, an automata (or Japanese karakuri) is mechanism that imitates the movement of a living creature. This project has been on my to-do list for several years and I thought it was about time I gave it a go.

The mechanism is based on a popular design that’s been around for a while. In the early 2000’s Theo Jansen, either refined or invented the linkage for his very popular wind-powered walking machines. Each part of of Jansen’s mechanism is carefully specified, elegant and mind-boggling in it’s function. Me? Well, I just sort of guesstimated the dimensions and ran with it.

jchismar Poodle Dog Automata Karakuri

I first made templates out of cardboard of each part. Each template was transferred to 1/8″ plywood and cut out using a scroll saw. The holes for the pivots were made with the drill press. I then used 1/8″ wooden dowels to assemble the mechanism.

Assembly was tricky at times because I didn’t have an assembly schematic. I just went with the flow. I made sure the dowels were plenty long to allow me to put the puzzle together on the fly. Once everything was in place the excess was trimmed from each dowel.

All in all I’m pretty impressed with the complete mechanism. This was the first, but certainly not the last machine of this style I build. I already have tweaks I’d like to try to give this girl a little more life. Watch the machine in action in the video below.

How to Design and Make Automata or Whirligig Gears Using the Power of Geometry

“…Chemistry is not an exact science” ~Mario Andrada

jchismar How To Make Wood Gears

In this post I will do my very best to simplify the process of designing and making gears from wood and other materials. The process to build a simple Spur Gear and Pinwheel Gear will be explained.

Thanks to my background in 3d animation I have a rudimentary understanding of geometry and mathematics. I would love to be a math magician but like many people I get lost with anything beyond algebra. Thank goodness for the internet and calculators!

jchismar N-Gon Automata GearAs my math magician friend Charlie reminded me, “To get the teeth to mesh, the spacing BETWEEN the teeth need to be the SAME on all gears.” With this in mind, using the n-gon is ideal to design a gear, the spacing between each vertex is uniform. Simply stated, an n-gon is a polygon with “n” amount of edges. The image to the left is of an eight sided n-gon. The n-gon has two radius measurements: circumcircle (rc)and incircle (ri). If you need a refresher, the radius is the distance from the center to the outer edge of the n-gon, the diameter is the complete distance from side to side (through the center). Vertices are the angular points where each edge meets (the white “edge” arrows point to vertices).

When designing gears we will focus mostly on the circumcircle radius (rc), the vertices are positioned along this radius.  The vertices will become the teeth of our gears.  If the desire is to use a gear to turn another gear uniformly each gear will be identical resulting with a 1:1 ratio. To use a drive gear to rotate a second gear at half speed the second gear needs twice as many teeth as the drive gear, a 2:1 ratio.

Below I have included a calculator to do all the hard stuff for us.

Say you want to make a pair of gears with a 2:1 ratio, the drive gear turning twice for each turn of the second. You also want the drive gear to have a 1″ radius (2″ diameter). You also want the teeth to be separated by 0.5″. This is easily accomplished with the use of the above calculator. The calculator’s default settings are Edge Length (a): 0.5 and Number of Vertices (n): 8 resulting with radius (rc)  of 0.6535. This radius is just over half of what we desire. We can’t change the Edge Length because in this example we want the tooth spacing to be .5″. Instead, increase the Number of vertices to 12. Now radius (rc) is 0.9664 just under the 1″ radius we were looking for. Perfect!

The 2:1 ratio requires the second gear to have twice as many teeth. This doesn’t mean twice the teeth makes the gear twice as large. Let’s see. In the calculator change the Number of Vertices to 16, doubling the amount of the drive gear. Radius (rc) is 1.9162.

This is important! When I started designing gears I was under the impression that to double the ratio, the radius simply needed to be doubled. This is NOT the case (thanks Charlie)! Let’s examine our calculated radius values:

  • 12 vertices Drive Gear (rc): 0.9664
  • 24 vertices Second Gear (rc): 1.9162

That’s double, right? No. It’s not double. By doubling the drive gear radius (rc), 2 x 0.9664 the product is 1.9328, a difference of 0.0166. Doesn’t seem like a huge deal, but a .0166 error can, in fact, impede the smooth operation of the gears. To emphasize this point let’s examine a more extreme 10:1 ratio example.

  • 12 vertices Drive Gear (rc): 0.9664
  • 120 vertices Second Gear (rc): 9.5552

Multiplying the 12 vertices Drive Gear (rc): 0.9664 by 10 (0.9664 x 10) results with a product of  9.664. That’s 0.1088, or a tenth of an inch, larger than calculated (rc) value.

Making Spur Gears

Right about now you’re probably thinking, “Hey John. I thought you were going to show me how to make gears, not bore me to death with math.” Well, you’re in for a treat, let make some gears! We’ll start by making a pair of spur gears: one 1:1 and another 1:2. A spur gear is a gearwheel with teeth projecting parallel to the wheel’s axis, this is the sort of gear everyone is familiar with. For this example we’ll be making wood gears. You’ll need paper, wood, glue, drill (or drill press), saw, an accurate caliper gauge and a quality pencil compass.  If you don’t own these instruments you can find them at any hardware store – or you can be like me and score vintage beauties at flea markets and estate sales. Cheap tools may work, Harbor Freight – cough, cough, but I often find cheap tools more frustrating than productive.

jchismar How to Make Wooden Gears 01
Step 1

Step 1: Layout the Gear

Laying out the gear is the most important task of making your own gears. I own a few sets of old drafting tools I picked up estate sales for a few dollars. The compasses in these sets are fantastic quality and several of them have an adjustment lock. I use several compasses, and once their settings are perfect, I don’t change a thing until every gear is marked on on wood.

First, calibrate the compasses by drawing on paper. To layout the drive gear use a pencil to draw a small dot on paper, this is the center of the first gear. Set your caliper gauge set (rc): 0.9664 (or as close to this value as the gauge allows) match the pencil compass to this value. Place the compass needle on the pencil center mark and draw the circle. Reference your caliper gauge from the center of the circle to ensure the drawn circle is correct.

Set the caliper gauge to the Edge Length (a): 0.5 and adjust a second pencil compass (preferably locking) to match. Using the circle as reference, draw ticks across the circle (rc) at .5 intervals. When you’ve gone all the way around the circumference your last tick should match the first tick exactly. Refer to the Step 1 image to see my terrible first result (red circle). If it’s not perfect, something went amiss in your settings. You’ll need to start again. This requires patience and practice. The width of the pencil line complicates creating accurate marks. You’ll need to get a feel for the process.

Once you’re comfortable laying out the gear, layout the pattern for each gear on the wood you’re using. This also may require a few tries. Working on this example required about two hours to layout eleven gears from start to finish.

jchismar How To Make Wood Gears 02
Steps 2 & 3

Step 2: Cut Out the Gear

Now you’ll need to cut the round gear from the block of wood. Generally I use the band saw or jigsaw for the task. You can use whatever works best for you: hand jigsaw, Dremel, router, etc. Cut to the outside of the radius (rc) line you created with the compass. Try not to remove the line! Once the gear is roughed out, use a disc sander to shape the circle precisely to the line (bottom left Steps 2 &3 image).

Step 3: Drill a Hole

I generally use 1/8″ wire to mount the gear to the project. The wire serves as the shaft for the gear to rotate about. I use an 1/8″ drill bit in my drill press for the task. Drill an appropriate sized hole centered on the depression you make with an awl. This is the middle of the gear.

After the gear is complete I use a small round file to enlarge the hole to make it rotate more easily on the wire shaft. But that’s the last step!

jchismar How To Make Wooden Gears
Step 4:

Step 4: Add the Teeth

This is where personal preference, practice and experience comes into play. For this example I will be using poplar that I’ve planed to .125″ thickness. The strip of .125″ poplar is ripped on the table saw to .75″ width. Individual teeth are crosscut from the strip to a .75″ length. Each tooth is .125″ x .75″ x .75″.

I’ve constructed a miter bar jig for the table saw to hold the gear while cutting a dado for each tooth around the the gear. The dado I cut is .25″ deep and .125″ wide.  With the table saw jig I am able to center the vertex ticks drawn in Step 1 spaced at .5″ around the gear. I center the tick to the blade, cut the dado. The gear is rotated to center the next tick and the next dado is cut. This process continues until each required dado is cut.

I squirt out a puddle of wood glue on a scrap. I dip the point of a wood skewer (the grocery store kind) into the glue and spread glue into a gear dado. Then, using the skewer, add a little glue to the end of a tooth square. It is important to insert the tooth square into the dado so the wood grain is perpendicular to the dado. If the tooth is attached with the grain parallel to the dado you run the risk of the tooth breaking with the grain.

Continue this process until you’ve completed the gear.

Step 5: You’ve Made a Spur Gear!

Congratulations on making your first gear! Repeat these steps for the second gear (keeping in mind the second gear is larger: 24 vertices Second Gear (rc): 1.9162).

Making Pinwheel Gears

Let’s say your project requires the drive shaft to power another element or shaft at a ninety degree angle. Enter the Pinwheel Gear. You’ll need wood, drill (or drill press), saw, an accurate caliper gauge and a quality pencil compass.

jchismar How To Make a Wood Pinwheel Gear
Step 1: Layout the Pinwheel Gear

Step 1: Layout the Gear

The layout for differential gears is the same as spur gears above. Use an awl to mark center. Then draw the circle with radius (rc) using a compass. Use the compass again to draw evenly spaced vertex ticks around the circle. Because we’ll be using nails as the teeth on these gears we’ll need to draw another larger circle outside radius (rc). In this case radius (rc) is 0.9664, I generally add an eighth of an inch (0.125) resulting with a radius of 1.0914.

Step 2: Cut Out the Gear

Cut the gear to the outside of the largest circle. Then sand precisely to the line.

Step 3: Drill a Hole

This is exactly at Step 3 for the spur gears. I drill a 0.125″ hole centered on the awl mark.

jchismar How To Make Wood Pinwheel Gear
Step 4

Step 4: Add the Teeth

I use the drill press to create an appropriately sized pilot hole at each vertex cross tick. The pilot hole should not be completely through the gear, only as deep as the nail will be driven into the wood. Here, I’m using three penny nails. Start the nail in partway then place a scrap of wood against the nail as a depth gauge. Then hammer the nail until you’re hammering the wood scrap. Continue adding nails in this fashion until your pinwheel gear is complete.

Step 5: You’ve Made a Pinwheel Gear!

You’re an expert gear maker now. Let your imagination run wild! I’d love to see the mechanical creations you’ve built.

A Note About Gears

I started the post with a quote that originated from the 2016 Rio Summer Olympics, “…Chemistry is not an exact science…” This was an Olympics official’s response to questions pertaining to why the pool smelled rotten and the water was green. I’m here to say Chemistry is and exact science. What does this have to do with making gears? Well, making gears is an exact science also. This post, however, is the groundwork to understand how to construct gears, not exact science.

Earlier I posted about building a Pegasus whirligig kit. Assembling the kit was a fun distraction, but I honestly didn’t learn much from the task. I’m a tinkerer. I enjoy spending time considering how to make things, and how things work. I find little satisfaction in following a detailed design – robots do that. I like to build the plane while it’s in the air, as they say. It’s fun to start something, and troubleshoot and modify along the way. This is how I gain a full understanding of the project. I often build many test projects before I tackle the actual build.

Creating mechanical machines is challenging. There is a lot of trial and error involved for the novice (myself included). There is more to designing precision gears than I’ve mentioned in the post. I’ll be honest, I don’t understand most of the technical mumbo jumbo, big words like dedendum, addendum, clearance and working depth versus whole depth. If things don’t work – that’s normal. It’s an entertaining learning experience. I personally find as much enjoyment in the flops as in the successes. When the project is complete, the challenge is over – and that can be a bummer.

Making gears using this method will require trial and error. The space between the gear positions will be an issue. The heads of the nails and the lack of a taper on the ends of the spur gear will likely cause these gears to jam. Consider using a metal cutting wheel to cut the heads off the nails – and taper the metal end. Also consider sanding a taper on each tooth before assembling the spur gear.

For those makers that want a detailed, guaranteed plan you can visit to design and print precise gears. This post will get you started making functioning gears. Please take what you learned here, build on it and make it your own. There’s more than one way to make a gear.

I am planning a follow up post regarding making wooden gears. There will be more information and project ideas to be found in the follow up post. In the meantime, be creative and have fun.