Friday, September 30, 2016

2016-09-29 (Th) Clockwork Theremin

A simple jigsaw was used to cut between the teeth of the 500mm gear. This gear was the one which had to be made on hardboard rather than plastic because the plastic sheets were too small. Fortunately, only two gears this size were necessary and a single sheet of the hardboard was enough for both. The material is more difficult to work with and heavier than the plastic.

Cutting between the gear teeth

The oscillating tool was used to smooth the spaces between the gear teeth. The Dremel attachment was used but it failed. The hard plastic beneath the sanding strips melted under the heat, the plate that attaches to the tool broke in two places and the rivet at the hinge became wobbly. I would not recommend this tool tip.

Area between teeth

Broken tool tip

The manual tool made from scrap wood was brought out again. This tool has worked well in the past but it is slow, tiring and uses up sandpaper quickly.

Manual sanding tool

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This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

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2016-09-17 (Sa)

Thursday, September 29, 2016

2016-09-28 (W) Clockwork Theremin SPOKED HUB

Ball bearings are often installed by placing one on each side of a hub so weight is distributed across both bearings and tension from the sides on the axle keeps them in place. If a bearing is secured in place it is possible to get away with only one bearing if the load is small enough. There are other situations of course.

While thinking about a convenient way to use 608ZZ bearings it occurred that it would be easy to print a hub with built-in shock absorbers that would allow some tension to be applied between the gears so imperfections would not cause the gears to slip as much.

A quick design was sketched which was basically a wheel with curved spokes. Not a novel idea but simple enough to create with OpenSCAD and very versatile.


Sketch of spoked wheel hub

OpenSCAD was used to create a parametric model. The parameters which a user can modify are illustrated below. Each of the changes can be made independently but some parameters can exceed the limits of other so when making changes it's important to make them one at a time unless the final dimensions have already been calculated.

For the Clockwork Theremin, a 5" (127mm) hub will be printed. This is the size of a data disc like a CD or Blu-Ray disc.

Possible changes that can be made to the parametric model

A print was made but three different sized spur gears were printed since the final gear ratio hasn't been decided. Having three choices, or more if they are printed, should give a good product with suitable speed and enough power to turn the heavy gears.

Spur gears and internal threaded gear


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All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

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2016-09-14 (W)

Wednesday, September 28, 2016

2016-09-27 (Tu) Clockwork Theremin

A Dremel contouring sander was purchased in order to smooth the valleys between the gear teeth. This area has been notoriously difficult to reach with power tools. A week ago a tooth sanding tool was created for this very purpose but a power tool solution would likely save time, work and wrist fatigue.

 Sanding attachment on oscillating tool next to gear

Only the coarse sand paper was used so some of the edges were not entirely finished. This small level of detail should not be noticeable from a distance and may wear off during use.

Close up of sanded teeth

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All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.

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2016-09-13 (Tu)

Tuesday, September 27, 2016

2016-09-26 (M) Clockwork Theremin

A couple weeks ago an enclosure for the project was designed. This enclosure would house the electronics but not the gears. This would need to have room for all the operating equipment including the distance sensors. 2' x 4' x 3/4" (609 x 1220 x 20mm) MDF was purchased although it would be possible to scale the size down slightly if the metric equivalent wasn't quite large enough.

The panel layout, linked at the bottom of each Clockwork Theremin post, was printed full size and adhered to the MDF. The design assumed the material would be exactly 24" wide so if a slightly smaller piece was used it must be scaled accordingly. Two straight cuts were made on a table saw so the cuts would be straight.

Layout printed, adhered and partially cut

The duplicate pieces were clamped together and sanded so they were close to identical. These pieces will be supported by bolts run between them so any flat surface mean to span the gap should be able to rest easily between them.

Duplicate pieces bolted and sanded

Unfortunately, bolts were not planned ahead of time so reasonable locations had to be sketched on the MDF. Holes were drilled for the cross-connecting bolts. 1/4" (6mm) bolts were decided since they should provide very rigid support. The first hole was simply drilled with a 1/4" (6mm) bit and there was significant hole blowout. For the rest of the holes, pilot holes were drilled.

Board with one blown out hole and seven pilot holes

1/4" (6mm) holes were drilled from each side of the boards and there were no more blown out holes. The long boards were cumbersome and long clamps used on the boards were unwieldy so once a couple holes were drilled bolts were used to hold the pieces together. Since the holes were drilled through boards at the same time there was no trouble putting bolts through the holes.

Cut and drilled boards

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All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.

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2016-09-13 (Tu)

Monday, September 26, 2016

2016-09-25 (Su) Clockwork Theremin

Experimenting with the miniature version of the theremin made it quite clear that driving a large gear directly from the motor was a poor choice. This was supposed to be a 200mm gear but that would likely prove unworkable.

An internal ring gear [convenient list of gear types] was the easiest choice since it could be hidden under the 200mm gear. This type of gear uses teeth on the inside of a cylinder and can be driven by a regular spur gear from the inside. Rather than research the intricacies of this gear, an existing model was found on Thingiverse by Jag. His planetary gear reducer was downloaded and the OpenSCAD files were modified to produce an isolated internal ring gear.

Model of internal ring gear

Before printing, the model was changed from the one shown above to one with mounting holes and a solid bottom. The purpose of the solid back was so that the small gear would not catch on the spokes. The mounting holes were placed beyond the rim of the gear so no screws would be inside because that could also cause the gears to snag.



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All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.

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2016-09-13 (Tu)

Sunday, September 25, 2016

2016-09-24 (Sa) Clockwork Theremin

I'm no illustrator. When I draw it is usually limited to technical drawings. Someone more experienced in this field probably wouldn't have made a whole day out of this animation.

One of the things I fail to do at the beginning of a project is to show what I hope to accomplish by the end. I have a grand idea in my mind with details and approaches but when I get to these journals I only share the details and document the procedure. This way the overall goal isn't shown until the end. That's not a good way to communicate an idea. This should journal have happened on the first day rather than a couple weeks into the project.

I've described that there will be large gears moving according to distance sensors but this is significant because the gears do two things. Functionally, they move a couple of potentiometers on a frequency generator. Theatrically, they move according to the movements of the performer. Hopefully, the gears will turn quickly enough that it will appear as if the performer has strings attached to her or his hands. This is exciting to me. The comically large gears will be right out in front of the performer and in plain view

Enough background
----------

Basic shapes were sketched on graph paper. Transparency between sheets of paper was useful as a dark sketch of the gears was made then transferred to the pages above it. The left and right side were both sketched to act as templates but only the right side was used.

Flipping through the sketches

Sketches were scanned and imported to GIMP. GIMP has been used several other times in this blog and it was used exclusively for this animation. Images were brought in, isolated, and scaled. The round gears were drawn twice and to show motion they were toggled between the two drawings. This was not meant to act as an accurate representation of interlocking teeth or gear movement proportions. The whole process took hours and was undoubtedly a matter of inexperience with graphic editing.

Animation showing the operation of the Clockwork Theremin

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All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

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2016-09-12 (M)

Saturday, September 24, 2016

2016-09-23 (F) 2 Cyborgs and a Microphone EPISODE 10


Episode ten was edited. There was some debate about using different intro and outro music as well as the idea of playing a music track softly in the background. Each of these was tried but neither of them seemed appropriate. That may have been because Tim and I were so used to the old music that 0music track four just became part of the show.

Track six of 0music replaced the music but it didn't sound right. We also tried using track seven as the background music and it was looped very quietly. Neither sounded right.

Please head over to the show page and listen to the latest installment if you haven't already subscribed through another source.

I'm on the left, Tim's on the right


Ad spot for 2 Cyborgs and a Microphone

The rest of the posts for this project have been arranged by date.

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This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim claim property or assets based on their post.

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2016-09-15 (Th)

Friday, September 23, 2016

2016-09-22 (Th) 2 Cyborgs and a Microphone


Episode ten was supposed to be about interfaces but at the last minute I asked Tim to split the episode into two parts, input then outputs. So we recorded a full show about input devices. It turns out this wasn't easy to define but in my mind I see the division. I'll try to clarify a bit here. Input devices are ones which provide information to a processor.

An output device presents information to a user.

Example: Cyborg Distance Sensor. An ultrasonic distance sensor acts as the input by collecting information about the nearest object. Processing happens in the middle to translate data. A solenoid acts as the output by stimulating an internal magnet.

A large chunk of the episode was devoted to talking about MIT's DuoSkin which you can read up on here before listening to it in the show. This link also has the information necessary to make your own functional temporary tattoos.

Me - Left. Tim - Right


Ad spot for 2 Cyborgs and a Microphone

The rest of the posts for this project have been arranged by date.

First time here?

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This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim claim property or assets based on their post.

This blog, including pictures and text, is copyright to Brian McEvoy.


2016-08-25 (Th)

Thursday, September 22, 2016

2016-09-21 (W) Clockwork Theremin

H-Bridges have never been used in any project on this site but their concept was clearly explained and they are a logically designed tool. A small one was attached to a small 3.3V motor and an Arduino UNO. An Arduino Micro Pro was selected for this project but the UNO is notoriously simple to connect and the model on hand already had header terminals attached so no soldering was necessary.

Motor - H-Bridge - UNO

Programming was not difficult. A PWM signal was applied to one pin or the other and the motor ran one direction or another at the desired speed. The gearing scheme was too much for the small motor to handle and the tolerances of the gears were insufficient for appreciable movement. A video was taken showing a gear glued to the motor axle and turning another gear mounted with a sewing pin.

The program activates the gear at maximum power in order to overcome inertia then ramps the speed (duty cycle) down to slow the motor. Code is freely available through codebender.cc



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All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.

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2016-09-11 (Su)

Wednesday, September 21, 2016

2016-09-20 (Tu) Clockwork Theremin

The second largest diameter gears were 500mm plus the teeth and would not fit on the plastic sheets. The largest diameter gears only fit because they were printed with half the teeth. 1/4" (6mm) hardboard was purchased to make these gears. Hardboard could have been used for the whole project but it is more difficult to work with and heavier. Low inertia will be important for these gears which only have a small motor to drive them.

Gears were adhered to the wood the same as plastic, using Super77 spray adhesive. They were then clamped to a table with a long steel bar to distribute the pressure. A jigsaw was used to cut out the teeth as before.

Jigsaw and clamp used to cut gear teeth

When all the teeth were cut from the 500mm gear a picture was taken with my left hand as a size reference. Cutting hardboard was slower and more difficult than cutting plastic but it smelled better. The plastic was softer and less prone to flaking plus the friction of the saw blade was enough to slowly cut with the sides and back of the blade so tighter turns could be made.

Large gear cut from hardboard

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All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.

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2016-09-10 (Sa)

Tuesday, September 20, 2016

2016-09-19 (M) Clockwork Theremin

A different jigsaw was used which didn't cause debilitating hand cramping. The last time gears were cut by hand 72 teeth were cut and hand fatigue persisted for hours. This time 167 teeth were cut, with the same blade, and there was minimal hand fatigue. The difference was a saw which required a momentary switch to be held compared to a sliding switch which maintained contact.

Gears and 167 teeth

Considerable scrap was generated during the process. Large pieces of plastic were saved if they could be made into small gears but a lot was thrown away if it was damaged or small. The repeated tooth cutting left a lot of plastic tabs strewn on the floor below the cutting area.

Below the cutting area after cutting gears

A special tool was made to aid in the tooth sanding. This device was modeled like a handsaw, with a large handle, and a cutting edge at the bottom, or top depending on orientation. Just like the blank wooden slate used earlier this has a 1/2" (12mm) piece of wood with sandpaper clamped to the side. Adding a handle should reduce hand fatigue. Scrap wood chosen for this tool was 1/4" (6mm) thick so it had to be doubled up, but only one side was doubled so the remaining side could become a thinner sanding tool for more precise work. The wood was glued together and clamped to dry.

Tooth sanding tool

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This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.

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2016-09-09 (F)

Monday, September 19, 2016

2016-09-18 (Su) Clockwork Theremin

A model was designed which would flush mount the common ultrasonic distance sensor HC-SR04. This sensor has been used in previous projects such as the Cyborg Distance Sensor and subsequent distance sensors. The model used the previously tested footprint but that was also edited. Previously, the model would always include a cutout for the crystal, the elongated circle, but this was moved to a variable which will ignore the crystal if set high. By requiring the variable to be set high this ensure that any previously written code will not falter by using the updated model.

The second advantage to being able to toggle the crystal cutout was that the surface plate, the flat cube, could be given transducer holes with the same footprint. The ultrasonic screw holes, the holes in the cylinders, were already able to be toggled in the code.

It can't be seen in the model below but the large holes in the cylinder go all the way through and allow the sensors to be exposed but the transducers are flush with the surface. This was done to reduce damage when other people are allow to play with the Clockwork Theremin.

Rotating view of model

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All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.

This blog, including pictures and text, is copyright to Brian McEvoy.

2016-09-09 (F)

Sunday, September 18, 2016

2016-09-17 (Sa) Clockwork Theremin

Yesterday's panel layout made it clear there would be one part difficult to produce out of plastic. The piece had a couple chamfers but it was otherwise blank. Rather than leave the panel blank a model was sketch to take the place and provide the S symbol which has been used in the past.

Sketch of plate

OpenSCAD was used to make a model of the plate which included the chamfers, symbol, screw holes and was hollowed out so it wouldn't waste plastic. All the modeling was done from scratch aside from the symbol.

Rotating view of model

A print was made of the panel. It was done with the flat side up even though this was illogical from the standpoint of conserving plastic. Given the theatrical and educational nature of this project it was more important to show that this panel was a 3D printed piece so the exposed part was printed as the top which always has the distinctive look of a part made on a 3D printer.

Print of panel

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This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.

All information in this blog, or linked by this blog, are not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property or similar, is the responsibility of those involved in the replication.

All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.

Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.

This blog, including pictures and text, is copyright to Brian McEvoy.

2016-09-09 (F)

Saturday, September 17, 2016

2016-09-16 (F) Weekly Summary

Naturally, another episode of Two Cyborgs and a Microphone was published. This episode was about tDCS units which was great because I've built a few. The first was a fixed 2mA device and the second was adjustable from 0 to 2mA. I mentioned these in the show but the links are right there for your convenience. As I mention in the show, there was a little mishap when I used the tDCS units, due to my own error, so I'm a little gunshy.

Show page on Twin Cities Plus

Tim is the handsome one on the right

For the Clockwork Theremin, pseudo code and Arduino code were written. The code, at this point, was only 150 lines long and it was spaced generously so it would be safe to say it was a simple program. It was never intended to be complex, in fact, one of the virtues of this project was the simplicity while outwardly it appeared busy.


Construction of the gears was started. The two smallest sizes printed on paper in actual size then meticulously cut out. This was slow work that was best done with mindless television going. The printed pieces were taken to the hackspace where the backs were sprayed with 3M Super77 adhesive. The glue was allowed to set then the paper was applied to 1/4" plastic sheets. A dangerous old bandsaw was used to cut out the gear teeth. Only rough cuts were made.

This saw has probably claimed a few fingers

After the initial work with the bandsaw, sandpaper was used to smooth the edges. In the picture below it is easy to see the rough cut between the teeth on the left compared to the smooth edges between the teeth on the right. Straight edges were maintained by wrapping a piece of sandpaper over some scrap wood and using a sawing motion to remove the unwanted plastic.

Gear with finished edges on the right

After the technique was refined on the small gears the largest ones were printed in real size. They can be seen below with the smallest diameter and the largest diameter, banana for scale.

Largest gear, smallest gear, banana

All the work going into the gears made it clear that they would not be done quickly. Since 3D models already existed, spokes and everything, they were printed. The idea was to make a miniature version that would make a cute gift for my young cousin and allow some experimentation with the code while full-size gears were being produced.

Stacked gears

The small gears were mounted on a wooden plank and a hole was drilled underneath the driven gear. A small electric motor was mounted in the hole. The final and largest gear will eventually have to be mounted to a potentiometer to get servo feedback.

3D printed gears arranged to spin

Another important component of the project was a sine wave frequency generator. Inexpensive version were sold as "learn to solder" kits so one was ordered from Amazon. It was a surprise to see how well made the PCB was when it arrived. The kit was assembled by my girlfriend as way to start teaching soldering. She did remarkably well and made very neat work.

Learning to solder

While playing around with the 3D printed gears it became apparent that the smallest gear didn't mesh well. It had six teeth but its diameter didn't warrant so few teeth. Another couple versions were produced with the same diameter, one had seven teeth and one had eight teeth. Four of each size were printed on paper.

The old six-tooth gear next to its seven and eight toothed prints

Cutting out each tooth on paper was laborious and boring. It was also obvious that the power tools would not be slowed down if they had to cut paper as well so gears were cut out of paper by simply cutting out the outer circumference. Many of the large gears were roughly cut out of plastic. The second largest gear, over 500mm in diameter, would not fit on the plastic sheets. The largest gear, over 600mm in diameter, only fit because it was designed as a half gear.

Roughly cut gears in a big stack





 

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