Community challenge #14, 2019-2020 edition

Another month, another community challenge!

Lamps turned out to be a good source of inspiration, let’s see what you guys can come up with for this month’s theme.

The theme for community challenge #14 is: Gears

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Rules for this 14th challenge:

  • submit your entry in this thread:

    • the project must made on a Shapeoko or Nomad.
    • the project must include at least two working gears. Extra points if you provide a video of them moving.
    • you must include pics of the finished piece.
    • you must include the design file, so watch out for any licensed vectors you might use, that might not be shareable. Designing your own vectors is a better learning experience anyway!
    • tell us about your mistakes, tips and tricks, etc…
    • posting your project to CutRocket will get you a +2 bonus on the vote tally.
  • you can post multiple entries if you want.

  • timeline:

    • I’ll make this challenge one week longer than usual to let you look into gear design and brainstorm ideas. Deadline is set to Nov 1st, midnight PST (= ~4 weeks incl. 4 week-ends)
    • there will then be 7 days for voting.
      • voting will be open to legit community members only, and the jury reserves the right to remove votes from “outsiders”, and will also break any tie.

Here are the prizes for this challenge:

  • First place: HDZ 4.0 !

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  • Second place: 4 Tiger Claws clamps and a SuperHold kit



with Carbide3D swag as the cherry on top:

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Ready, steady, go!

11 Likes
  1. Gear Generator Online Tool. Pay to download designs. Free to design.
  2. Open Source Gear Generator Free to design and download.
  3. Woodgear.ca Gear Generator Free to design. Free to print. Pay for app to download other formats.

These may be a useful gear generation tool if you are using Create and don’t want to go full @WillAdams and construct gear geometry using booleans and the 4th dimension. :stuck_out_tongue_winking_eye:

7 Likes

There are some resources for gears at:

https://wiki.shapeoko.com/index.php/CAD#Gears

and

https://wiki.shapeoko.com/index.php/Commercial_Software#Gears

and

https://wiki.shapeoko.com/index.php/Online_resources#Gears

and also see: http://www.varmintal.net/alath.htm

and you may find some inspiration at:

http://507movements.com/

6 Likes

My guess is that we are going to see some really fabulous projects from the Giants Of Design on this one! But I should probably be cautious with the acronyms here.

Crank them out folks!
Gears

An Animated GIF :slight_smile:
Julien - What video files will be uploadable? I’ve tried a couple of formats without success?

You can’t upload video files themselves on the forum, just links. So you need to use a third-party file/video sharing site, and then just post the link to the video stored there, and it should show up as an embedded video then.

2 Likes

I figured I would play along and experiment with some of the gear generation software out there. I always wanted to try a planetary gear design, so I tried this (free) software:

Imported the generated SVG in CC,

and scaled it such that a 3mm endmill could reach into those teeth without rounding the corners too much:

Close enough, the inside of the outer gear teeth will be rounded but beyond the contact surface so that should work. The piece dimensions ended up being 220mmx220mm (~9"x9") to meet that constraint, which sounded like a reasonable size for planetary gear showpiece.

Of course I couldn’t cut the outer and inner gears as positioned in the imported SVG, so I began with the inner gears only

I did not feel like cutting wood tonight so I used a leftover acrylic panel from when I did the windows of my enclosure,

and ran the toolpaths. Single flute 3mm, 10.000RPM, 2000mm/min (78ipm), plunge rate 1500mm/min (60ipm), depth per pass 0.75mm (0.03"). I was super conservative on depth per pass to make sure I would not have chip clearing problems, since I was lazy enough to create simple contour cuts in CC (slotting…yuck) and I needed to cut down to 8mm total depth (0.3").

So far, so good.

Outer gear will have to wait until tomorrow night’s garage time.
Your turn to show us a glimpse of what you are up to!

8 Likes

@ColdCoffee - Sure hope that you’re considering entering your gear set from the Community Challenge #8 here! Such an awesome example and execution! Or your newest design of course.

3 Likes

It spins

I have no idea where this is going yet, but this is fun

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v2. Still no idea where I’m going with this, but bamboo and acrylic are my fav.

6 Likes

Whilst I write up some notes on how I thought about the design, tested cuts and fit, and then cut and made the final parts, here is a pic of the finished wooden clock. Gears a-plenty!!


Every part made on the ShapeOKO, with the spindles turned on my lathe.

12 Likes

Clocks have always fascinated me, so with early lessons learned on the ShapeOKO XL, I set myself a challenge;

  1. Make a wooden clock, every single piece
  2. Make it as accurate as possible
  3. Introduce some electronics to see if more accuracy is possible

I started off with a design from Brian Law and tried cutting a few parts to see what I needed to learn, what the wood would do in practice, and to find any elements I wanted to improve. Quite a few mods and, for me at least, improvements later, I had a folder of design files that represented the clock I wanted…

Given the complex shapes and profiles, particularly on the gears, I wanted to avoid excessive hand finishing so experimented with various woods, speeds and feeds to get the best cuts I could. The next step was to cut some gears and look at the mesh and tightness, and to subtly adjust the gears and the spindle positions to achieve a free-running gear train…

Test cuts for mesh

I had to trade off backlash performance for free-running, and after reading up on historical clock makers journals, concluded that this was what they had done too. I also found that the wood flexed too much if the body was cut away for fine ‘spokes’ on the higher torque gears, so opted for more solid gears where the clock winder puts in most force.

Pulley halves from SXL

I made the winder pulley as two halves, both on the ShapeOKO, pinned and glued them to make a bobbin. This might have been easier on a lathe, but it was satisfying to work out how to make it.

Cutting the main ‘going gears’ required removal of a considerable amount of material, but wanting the stock to be as rigid as possible for cutting the tooth profiles with a 1/16" end mill, so I opted for cutting down to leave a 2mm ‘onion skin’ to hold the roughed-out gears in place whilst cutting the teeth, then running a final pass to release the gears from the stock.

Screen-grabs from VCarve showing each of the sets of gears as finally ready for cutting…

I used the ‘shaped cutter’ feature in VCarve to create a rounded-over profile to match a cutter I bought, so I could cut the clock front and back frames including rounded over edges in one session, also avoiding too much hand finishing once cut.

Spine and Small Gears

Removing so much material, learned from test cuts in MDF, showed me that I needed to cut the main frame and remove it, then clamp the now weakened stock in extra positions to complete the finer parts set out on the same piece of wood.

Both Spine and Gears Cuts

Both pieces shown laid side by side on the machine, but were cut individually (bed size on the XL). Each of these took about 6hrs cutting time to get the finish wanted, using Carbide supplied 1/4", 1/8" and 1/16" end mills, and the round-over cutter bought from a UK profile specialist.

Wanting to avoid the clock face warping, I cut 12 wedges along the same grain direction, glued and clamped them into a circle ready for flattening and cutting.

This turned out really well, and has remained as straight as a die.

A mandatory workshop picture. It’s a compact space, with the bench-top lathe just off to the right. Overnight the motorcycles wheel down the centre - those toys are precious too!!

The Workshop

My lathe then arrived, and I turned the steel and brass spindles and matched them to the hidden roller bearings (recessed into the frames). I tried to think of ways to clamp a round shaft in the ShapeOKO to cut flats every 90deg for the winder key, but couldn’t, so I held the #201 cutter in the lathe chuck and improvised an extra slider on the cross-slide for the lathe - good result.

The design of the hands I wanted involved very tight internal radii, so I ended up spending hours shaping the hour hand with a file and fine sanding paper - the minute hand design was even more intricate, but as you can see for now is a simple Perspex hand… One day I will come back to this, maybe a laser head on the ShapeOKO - so now I’ve talked myself into buying another toy :slight_smile:

The clock was built and the critical Escapement teeth polished and refined and balanced (held the gear wheel in the lathe to ensure roundness, and equal pressure from a Dremel buffing wheel held on the cross slide to ensure all 60 teeth remained the same shape).

I will add a video once I can find a suitable host location/service. It’s mesmerising and soporific…

Video link here: Video of the clock running

After a period of fine tuning, the clock holds an accuracy of about +/- 5% over the full 18hr running time, having found that the escapement arm is not equally weighted on either side despite being of identical dimensions!! I wrapped a slither of lead wire around one side and adjusted its position to get it balanced.

Then came adding the Raspberry Pi ‘Zero’ which is smaller than the frame’s width. I cut a slender frame to hold the RPiZ but allow it to be removed if needed. Designed a small interface PCB (a Pi ‘HAT’) to hook up to Opto and Inductive sensors and to run a lightweight web-server so I can time the clock accurately and capture the timing data per-second.

If you look in some of the clock pictures you can see the RpiZ hiding towards the bottom, with just the sensor wires and LEDs visible.

This showed me through Fourier Analysis of the per-second timing data that the Escapement wheel was the main source of the timing errors being seen, coming from roundness error and unequal friction on the teeth - so I sacrificed my ‘made entirely from wood’ ideal and re-made the Escapement wheel and paddles in Perspex, with a view to perhaps using Brass if this wasn’t good enough.

Hands and Escapement

Immediately the timing improved to about 2%. Now using the inductive sensor driven backwards to give a magnetic pulse (a tiny neodymium magnet is hidden in the pendulum shaft), I can add a tiny amount of energy to the pendulum to slow down the swing (too little energy results in the escapement paddles letting go of the wheel without a good swing happening on the pendulum, resulting in the swing losing travel and speeding up). With this, and some experimentation, I now see about 0.5% timing. The RPi sensors don’t “touch” the clock per-se, they all sit in recesses or slender ‘fences’ that hold them in place. The old and the new working together but still a wooden clock at the heart of it.

But of course, there’s always the next thing to see if I can improve…

I wasn’t sure what sort of capability or accuracy to expect from the ShapeOKO XL when I bought it (March this year), but it has proven to be an immensely capable machine, accurate - and given countless hours of productive fun using it.

During this project, I ran in to a number of ‘learning opportunities’… I hadn’t tensioned the left and right X-axis belts the same, and ended up with some dimensional errors until I realised… Carbide support were great (and this forum) for helping work through that. I had a special ‘opportunity’ when I noticed the Z-axis belt was starting to fail, so I read up various threads on here and opted for a steel cored belt and an in-line clamp rather than the cut belt original design (Vince Fab idea, I think). Realising that the belts are somewhat a consumable is the lesson in all this, so I have a spool of 9mm steel belted GT2 equivalent ready for when X and Y need attention. Oh, and sharp cutters. I tried a down spiral cutter for the Perspex, run with a very high feed rate to ensure good chip clearance and to avoid melting the local surface.

I have been given permission by the original, raw drawings designer to post JPGs of his drawings that were the starting point for this clock. There was a huge amount of fiddling with nuances of the design to please my eye, gap gear distances and refine teeth cutting. Reading engineering drawings and drawing the parts suitable for CNC work was a lot of this early work, only a few vectors were usable just ‘imported’. JPGs follow to give a flavour;



It’s all a country mile away from my work life in electronics and high speed video systems, but thoroughly enriching for the effort spent learning how it, and the wood really works…

19 Likes

Wow. just wow. @MikeG was right, that is one fabulous project!

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It was certainly challenging, educational, fun and - importantly - gave me something to focus on during the infernal Covid-19 lock down in the UK…

I can’t work out how to embed ‘a click to run’ image of the video, just a link out to Youtube. Any ideas?

Just pasting the link to the Youtube video should work
EDIT: I edited your post, it should show up as a playable image now

1 Like

I thought about doing a clock, but sadly, didn’t peruse this due to a lack of time… I’m glad I didn’t because you would have totally outdone me :rofl:

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Maybe a clock would help with that?
:wink:

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@AndyC - Awesome project and certainly a dream of mine to tackle one day. I hope that you’ll be able to share the design files with us here and that they aren’t an originally paid design. Thank you for sharing this!

1 Like

A bit of tidying the files and merging a few that became separate during the making, but I will post what I can (size limits apply too, so will need to find somewhere for the larger files). Note that many of these files use Vectric macro-variables to control cut depths and start depths etc, so look out for them
Clock Face 32 Segments 2x4 Rev-1b.zip (41.4 KB)
Clock Face 32 Itself Gears Rev-1m.zip (3.4 MB) Hands and Paddles Rev-1n.zip (178.0 KB)
First Gears 32 VAR Rev-1e.zip (1.6 MB)

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Good lord. That is so impressive! From the allusion to Covid lock down… can I ask how long this took you? Or did you do this since the contest was announced? Trying to decide how depressed/in awe I should be at the output, as this is just blowing my mind!

1 Like

That’s excellent.

Did you know that the engineers at Seiko settled on a similar method when they made the “Spring Drive” movement? The spring runs the mechanism which generates power to run the quartz crystal which uses electromagnets to brake the mechanism down to target speed.

4 Likes