The Antikythera Mechanism Episode 5 - The Input Crown Wheel Assembly

The way your parts fit so perfectly is a very sensual experience! Just wondering about the approximate time some of your more involved filing requires.

Alan Reinhart

That one is a height gauge - its on the to do list :)

Clickspring

Great video as usual Chris. What is that marking tool called, the one which glides on the marking plate and any chance of showing us how to make one on TGT?

Abdul Shalam

Hey Leo, yes its as per the original - cheers :)

Clickspring

Hey Leo, yes it would be an excellent project - I have the next few projects already mapped out, but its on the "maybe" list :)

Clickspring

Hey Ryan, yes generally that would be the case. You will notice in previous examples where I fit taper pins that I very slightly broach out the lower hole to accommodate the taper pin as you suggest. However it is not always necessary to broach out the lower hole. The pin fit that I am aiming for is quite firm, and brass is quite soft - as often as not, if the forward travel experienced by the pin during hammering is minimal, the lower hole will "give" enough so that it ends up being a superb fit with no adjustments to the lower plate necessary. Cheers mate :)

Clickspring

You use a taper broach for the steady pins and broach both parts at the same time. This would give them a continuous taper. So when you hammer in the pins to the top part, wouldn't it sit above the surface of the bottom part unless you hammered it into that part as well? The diameter of the pin at the bottom of the upper part is slightly larger than a loose fit at the joint, so there would be a gap, right?

Ryan Das

PS: Any chance I could nominate a reproduction of a Curta Calculator Type II as your next project? That’ll really push your limits to a new level, I’d bet.

Leo G.

Absolutely amazing, as always! I can see why this part was particularly challenging. Was the choice of a rectangular spigot for the drive gear a copy of the original? It seems like a square spigot similar to the main bearing would have been more logical.

Leo G.

Cheers mate :)

Clickspring

Terrific to have you watching mate :)

Clickspring

Thank you mate!

Clickspring

Geez I love watching you finish surfaces Chris... there's something hypnotic about seeing the careful sanding bear fruit.

Derek McAllan

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Great job,I've been watching since you began the clock project jusy

Another great segment, Chris!

Nathan Davey

Good suggestion mate, will add it to the TGT list :)

Clickspring

Hey Brandon, I think Paul Busby's reasoning in a comment above is pretty close to the mark - Cheers mate :)

Clickspring

Chris, completely off topic.. For us folks who want to begin machine something.. Not necessarily what to machine, but what tools you would suggest investing in? I really haven't looked into any lathes, but the Chinese stuff doesn't really look appealing (except the price).. Maybe a small video on this? Thanks for all these great videos, it helps the motivation, just like we motivate you!

Adam Ackels

Cheers mate!

Clickspring

So any idea so far as to why the vertical gear was formed in 2 parts? Could it just be the lack of round stock? Thanks for all you do!

Fantastic. I don't have any suggestions, I just love to watch it come together. Definitely cool to see how vertical cutting allowed the easier wonky tooth geometry!

Ha ha! Cheers Michael :)

Clickspring

Thank you mate :)

Clickspring

Awesome! So pleased to hear that!

Clickspring

Cheers Colin :)

Clickspring

Seriously, HOW!?!?!?!?! I watch you every time and just ask how???? You are amazing.

Cheers John, more on the way soon :)

Clickspring

Thank you very much Dean :)

Clickspring

Ha ha! Terrific to hear that mate :)

Clickspring

Apologies ahead of time for this comment, I've been watching a lot of This Old Tony videos- wouldn't it be easier to use a square drill but to make the square holes? :o) Now for the serious part- I never cease to be amazed by your videos. The production quality and the craftsmanship are amazing... and the word amazing isn't strong enough...

Michael Lloyd

Thanks for another great installment. I just finished watching it with my girlfriend, as she has become enamored with your videos as well!

Mike Michelizzi

Another great Video Chris. Thank you for showing your fixtures. Gives me more ideas on how to hold parts.

Colin Dick

beautiful work Chris. Your craftsmanship is amazing.

Dean Neumann

So I had patience today Chris. It's now 10 PM in the Great State of Texas and I just watched this video. That means I went ALL DAY LONG without even peeking. But man, what a great relaxing way to finish the day. Keep up the great work Chris.

Chris Muncy

As always Chris, the worst part about your videos is waiting for the next one.

John P

Yes certainly Dave, that would be ideal :)

Clickspring

good job Chris. For you plans...could you adjust depth by making the crown wheel a little deep initially then tune length during assembly, finally fitting the pin? Just for those of us a little less fastidious in layout ;-)

David Paterson

Thank you Alex - its certainly keeping me busy!

Clickspring

Thank you Al, much appreciated :)

Clickspring

Hey Dean, the driving rectangle dimensions are a direct copy of the original artefact - the question then becomes, why did the maker do it? At this stage, I'm not sure - correction of a filing error perhaps? (ie shooting for a square, but ended up correcting to a rectangle)

Clickspring

Hey Matthew, yes there is much scan evidence of the use of soft solder throughout the device. It raises some really interesting questions that I'll cover in one of the next fragment videos :)

Clickspring

Hey Stephen, a possibility for sure :)

Clickspring

Once again, beautiful work; clearly and concisely presented.

Al McKague

Why did you use a rectangular boss to drive the crown wheel instead of a square as on the other end of the shaft?

Dean Thompson

Hey Paul - I didn't until reading one of your suggestions. There is another feature in the mechanism that points to a very sophisticated and sound turning technology (the calendar ring inset groove) so I think it would have been possible to simply recess a solid blank using the tech of the day. As to why it was done the way it was, I like your other suggestions, all potential candidates, but specifically the idea of "messed up teeth" - Its clear that the crown wheel teeth will be prone to damage if the device experiences a bearing siezure anywhere (ie if forced by the user, the teeth will be easily deformed) So the ability to remove and replace the teeth whilst maintaining the center driving rectangle would definitely be a plus. It would preserve the filed rectangle (not a trivial bit of work to locate on the central axis), and allow repeated "re-toothing" - Great suggestion mate, thank you :)

Clickspring

Hey Travis, grinding away the waste stock to form the arc took about 5 minutes, and then about another 30 minutes to tidy up the perimeter with files and paper. Cheers mate :)

Clickspring

The pole lathe seems much older than the 1800's, I'm not sure though how well it'll work on metals though

Roel Jordans

Thank you John, much appreciated :)

Clickspring

Cheers mate :)

Clickspring

Cheers Ruben!

Clickspring

In this video you use solder twice. Would the original designer have had access to solder?

Matthew Dillard

Just speculation on the crown wheel. It could have been easier at the time to divide and file the teeth into the outer band while it was just a sheet then wrap the support wheel. Any tooth deformation could have been addressed with some finish filing.

You mention the turning limitations of the ancient greeks. Are you going to cover what methods they used for turning concentric parts? My reading tells me that lathes weren't really invented until the 1800's, so I'm curious how they could make such parts.

Ryan Das

Another great video Chris. Love the longer length. Did you have any revelations in making the crown wheel as to why it was made that way and not out of a single piece? Could it be that they just didn't have stock that size or a lack of ability to machine away that much material. Could the hard way have been the easy way for that time period? Another thought. Could it have been done that way to make sure less material would be wasted if the teeth got messed up, maybe to just save on brass. You would "only" have to remove the outer ring and remake but the inner block of brass would be saved OR was it made from one solid piece to start with. Messed up somehow and rather than throw out the whole lot the outer teeth were turned away and the metal added back in the method you showed. Make you think. I look forward to the next.

Paul Busby

Around 12:40 when you are trimming that bracket with the arced top side, about how long does it take to grind it down on the belt and then do the finish filing? I want to get an appreciation of how long those little parts are actually taking to create, because you make it look so easy, but also cut out a lot of the repetitive work from the videos (which we appreciate!). Thanks for everything.

Fantastic episode, can see why it took so long as there's an awful lot to it. The level of precision you achieve through ingenuity and craftsmanship is fantastic. I follow a number of CNC channels as it feeds directly into my own work, but it disheartens me when I see them not achieve polished results despite having so many advanced tools at their disposal. I think your episodes really highlight the importance of being thorough and very methodical.

Alex Banks

Beautiful work as always.

John Creasey

A 20 minute video?! I must be in heaven

Awesome Chris!!

Ruben vd Merwe

Thank you Ray :)

Clickspring

With each episode, I keep thinking, this can't get any better, and with each episode, I am continually proven wrong. Just stunning.

Ray White

Thank you mate :)

Clickspring

So pleased to hear that Scott :)

Clickspring

Thanks Nick :)

Clickspring

Cheers Bill!

Clickspring

I was thinking you were just showing us how they did the crown gear the hard way and then you did the hard way too. Even the raw formed ring was nearly perfect. Continuously impressed Chris ;)

Jess Neal

Superb work, Chris! A great way to spend my Sunday evening.

Scott Clausen

Great job the crown wheel looks like it's made from one piece of brass incredible and again a very informative video Chris.

Nick Oates

Wow! As always, incredible craftsmanship! And I learned a lot as well. Thank you so very much for sharing!

Bill Yester

:)

Clickspring

Woohoo!

Aidan Jeffes