3D Printing Clock Parts

[Mike Dempsey]

View attachment 3D Printing.pdf
I wrote this article on 3D printing and was going to have it printed in the bulletin, but decided to have it put on the message board. If you have any questions about the article, let me know.
Mike Dempsey

 

[R. Croswell]

Sixty or seventy years ago the idea of radios without vacuum tubes, color TV, flat screens, and phones without wires seemed just as unlikely as "printing" clock parts.

RC

 

[Dick C]

Mike,

I would like to thank you for posting the article here as well as your research.

I understand the using the printer for prototyping is a great tool; however, I wonder if one were to print a replacement gear for a wooden wheel clock, would it stand up to the wear or should it only be seen as a prototype?

Dick

 

[bangster]

Cain't get it to open. What am I doing wrong?...

Nevvermind. Soon as I posted that, it opened.

 

[bruce linde]

wow. Just wow. That is very cool… Thanks for posting

 

[Dan K]

Mike, have you had anything printed in metal yet? I want to send a STL to Shapeways and see how a metal 3D printed part looks. I picked up a 3D printer last Fall and have been experimenting with it as well. BTW, Fusion360 is a good CAD tool and they offer free trials if you qualify.

 

[Mike Dempsey]

Dan,
Yes I have had parts printed in metal. I have a guy in Chicago that I use. The metal printers are very expensive but have also dropped in price over the last year. The quality of the metal parts is still crude as far as clock parts. You have to do a lot of filling and sanding on them to have them work. If you are printing something bigger, they work very well. It just the smaller stuff that is a problem. I can send some pictures if you like.

 

[David S]

Mike if you have pictures of metal parts can you include them in this thread. I think it would enhance the subject.

David

 

[Mike Dempsey]

David, here are some images of 3D metal printing. I thought I had a picture of the verge that I had him print, but I can't find it. The cost of having the verge printed was very expensive. When done, it needed a lot of polishing to get it to work correctly. I have been making verges for years, and all the work I put into the printed metal one, I could have made it from scratch easier. All that being said, the metal printing technology has changed since last year, so I will give it another try.

Hope this helps,
Mike

 

[cuckooqueen]

View attachment 309438
I wrote this article on 3D printing and was going to have it printed in the bulletin, but decided to have it put on the message board. If you have any questions about the article, let me know.
Mike Dempsey

Hello, Mike!

Thank you so much for sharing your article and projects with 3D printing. I am new to clock repair and do it as a hobby right now. I just discussed ideas for 3D printing parts for my clock with my boyfriend, but had no idea if it would work, or if anyone had tried it yet. This is amazing and should really be utilized for antique restorations. I was deciding between other casting mold methods or 3D printing and this really helped.

Best,

Jacey

 

[Dave Diel]

Would it be possible to make a plastic verge and attach metal slippers with epoxy?

 

[THTanner]

If you use the corn based 3D printing material it is quite inexpensive. It also melts at a fairly low temperature. You can 3D print your part in the corn starch medium, then coat it with plaster of paris like they do with lost wax casting. Drill or cut in the ports to pour in the liquid metal and the vent holes and the corn starch melts quickly as it is displaced by the metal. Let it cool slowly in an oven as with lost wax casting, break off the plaster of paris and do the finish filing and polishing. This works better with thinner parts, but with practice you can cast fairly complicated parts and get a good metal casting without voids.

If the finished part needs small holes or cut out it is best to drill or cut them in after the casting rather than trying to 3D print the holes and small cut out. Those tend to not hold the plaster of paris very well during the hot metal casting step and you often end up with a partial hole which is harder to finish than doing a compete drilling after the cast has cooled and been separated from the plaster.

 

[Mike Dempsey]

Dave,
I have designed and printed many verges for clocks. I have one that is my own clock that I printed out of nylon. The clock is a 30 day Seth Thomas clock. It has been running for over a year with no sign of ware on the pallet faces. That all being said, I would never leave a plastic verge in any clock. I believe that all parts of a clock movement should be kept as original as possible. When I do design and print a verge for a clock, I "prove" the concept of the design of the part in the clock, and when I'm satisfied that the part is made correctly, I remove it off the arbor, and glue the plastic verge to a piece of tool steal, and saw it out.

 

[Mike Dempsey]

I now print in metal on my printer. I print in stainless steal. copper, brass, and bronze. The metal is 70% metal powder, 24% plastic. This is the formula for printing in most standard 3D printers. If you are reproducing case parts or finials this stuff is great. After printing, I use steal wool to remove the external plastic and then use a buffing machine to polish the metal material. I have reproduced many brass finals for clocks using this method. Works and looks great. If you would like more information on these materials, go to ColorFabb or read this review ( http://3dprint.com/32271/colorfabb-brassfill-filament/ ). It will not give you the strength of a solid piece of metal but if your looking to do something that is not under stress, this stuff works great. I also print case moldings that are missing in wood.
Mike

 

[THTanner]

Very good write up = thanks. The colleges and libraries around here give free access to 3D printers but you have to supply your own medium and right now none of the free machines work the harder metal mix medium.

When you say you print wood - what is the actual material? Is it a mix of wood dust and plastic similar to the metal mixes?

I now print in metal on my printer. I print in stainless steal. copper, brass, and bronze. The metal is 70% metal powder, 24% plastic. This is the formula for printing in most standard 3D printers. If you are reproducing case parts or finials this stuff is great. After printing, I use steal wool to remove the external plastic and then use a buffing machine to polish the metal material. I have reproduced many brass finals for clocks using this method. Works and looks great. If you would like more information on these materials, go to ColorFabb or read this review ( http://3dprint.com/32271/colorfabb-brassfill-filament/ ). It will not give you the strength of a solid piece of metal but if your looking to do something that is not under stress, this stuff works great. I also print case moldings that are missing in wood.
Mike

 

[john e]

Mike,

I would like to thank you for posting the article here as well as your research.

I understand the using the printer for prototyping is a great tool; however, I wonder if one were to print a replacement gear for a wooden wheel clock, would it stand up to the wear or should it only be seen as a prototype?

Dick

Actually, I would use the printed gear as the template fixture for a pin router table. I believe that as long as the router bit is sharp, you would not require excessive pressure against the template to hold it in place.



hmmm. A nice little dremel mounted in a table, a set of little router bits, and a light duty overhanging pin arm. A mini version of what I'm using now, although I'm using .250 thick aluminum for my templates.

And, prior to doing the wood, the printed gear would be great as a test piece in the clock itself..

John

 

[Mike Dempsey]

Yes, it is a mixture similar to the metal. I use coconut wood. Its easy to sand and takes stain very well. It is the choice for moldings. For more strength, I use bamboo wood. Its very hard. I have printed many wooden clock wheels and pinions for wood works clocks. They print perfectly and run great in a clock.

 

[bangster]

How do you provide a pattern to a 3d printer?

 

[Mike Dempsey]

Well,
If I'm reproducing a case part I use a 3D scanner. The scanner will make a 3D image that I import into the computer, and then send it to the printer. If I'm designing a part, I use AutoCAD Inventor which is a 3D drawing software.

 

[R. Croswell]

Well,
If I'm reproducing a case part I use a 3D scanner. The scanner will make a 3D image that I import into the computer, and then send it to the printer. If I'm designing a part, I use AutoCAD Inventor which is a 3D drawing software.

All of this is very interesting but sounds quite expensive. Can you suggest a 'ball park' investment for everything one would need (hardware, scanners, printer, software, supplies etc.) to be able to go from a broken wooden pinion to a finished printed part ready to go into a clock?

RC

 

[Mike Dempsey]

RC,
Your asking a very difficult question. It really depends on what your trying to do. I will try to answer it the best I can, the easiest part first. The cost of 3D printers are coming down in price dramatically over the past year. You can buy one for as little as $100.00. I would suggest something in the $300.00 range. All the printers come with all the software you need to print almost anything a clock repair person would need. The wooden filament is about $50.00 a spool. Lots of parts can be made off of one spool. I have printed about 25 parts on my spool and it still is over half full. Now the hard part of the question. You don't need a scanner to 3D print. It helps to reproduce a part if it has a lot of detail. I do own a scanner, but hardly use it. To make a pinion or wheel, I draw them out on the computer and then send them to the printer. Scanning would be a waste of time. It is much easier to just draw it. I use AutoCAD Inventor to draw my parts. This is a very expensive program and I would suggest not using it because of the expense. If you search on the internet, you will find many free drawing programs. I like Tinkercad. Its free, easy to use, and will do just about anything you need. This is the program that many of the grade schools use to teach 3D printing. So to sum it up, you could do what you want for about $400.00.

 

[steve323]

Very interesting post. Thanks for collecting the data and posting it.

I have also been doing some experiments with 3D printers for clock gears. The first experiment was for the tooth size in PLA on a Prusa MK3 printer. I tried pitches ranging from 10DP to 40DP, before settling on 20DP as a good size for an FDM printer. Finer pitches are possible, but some of the teeth had a tendency to curl away from the print bed. 20DP printed very reliably. An SLA (resin) printer should easily be able to print 40DP gears.

I attached a picture of my first 3D printed clock. It runs 4 days with 8 pounds of weight. Total print time for all of the components was around 75 hours.

Steve

 

[bangster]

Cool beans, Steve!

 

[kinsler33]

But suppose you're trying to replace an impossible sort of part in an existing clock, like the worm gears in a Sessions electric movement? These are tiny, with fine threads and fine teeth, and were originally molded of nylon directly onto brass arbors, if I have that right. Is there any hope of making these in the 3D printer?

M Kinsler

 

[etmb61]

I like the concept of 3d printing. My problem with it is I doubt you can achieve the same mechanical properties for any given item that come close to those created by more appropriate manufacturing processes. So can you 3d print a worm gear? Probably. Will it perform the same over time as a gear molded as a monolithic part? Most likely not. The process to mold the gear was designed to get the most out of the material used to make the part, and the material was selected as part of the design of the end item where it was installed. 3d printing? Not so much.

You are limited by the properties of the filament material you feed into the printer. You basically have a computer controlled hot glue gun.

Rapid prototyping? Yes! Proof of concept? Yes! Manufacturing an end item for direct use? Not so much.

My thoughts,
Eric

 

[steve323]

Yes, it is like a computer controlled hot glue gun with a very fine nozzle. This doesn't seem much different than injection molding where molten plastic is pushed into a mold.

I think that the technology will eventually be capable of producing low volume replacement parts. There will always be some mechanical limitations. A nylon worm gear molded directly around a brass shaft is not possible on a 3D printer. It could be done on a 4D printer where the shaft is rotated as the nylon gets added. I don't know if these types of printers exist yet. CNC routers with a 4th axis are relatively common. Another option for this very specific task is to press or glue the nylon part onto the shaft.

Another side note is that 3D printing may have the ability to make parts that are not possible for injection molding. Single piece hollow parts is one example. Of course, it will likely always be a low volume niche.

Steve

 

[kinsler33]

There's more than hot glue, though. Powdered metal can be made into a filament by using a plastic binder. Iron/nickel alloys, for example, have been molded into parts for many years, and the same trick works in additive technologies. The catch is that you have to heat the completed part in a furnace such that it reaches a temperature just short of the melting point. This burns away the binder and sinters the powder granules together. When it cools down the result is as strong as a part machined from the solid.

M Kinsler

 

[THTanner]

If you really want to go with more traditional metals, but want the quicker manufacturing of 3D printing, consider the corn starch medium to 3D print the part. After carefully finishing that, treat it like lost wax casting, cover it with plaster of paris and proceed with a brass or bronze casting. The corn starch melts right out of the casting and you get a real brass or bronze part. It will require finishing, but this might work better from some parts that are not that easy to make from stock on a lathe.

 

[kinsler33]

I wonder if anyone has solved the Sessions electric clock movement problem. The motor coil opens up, and the plastic primary gears strip. (Those are the plastic worm and wheel that reduce the speed of the rotor.)

Mark Kinsler

 

[zedric]

These guys can print you a jet engine out of metal if you want, so I don't think the technology is the problem any more, just the cost to achieve it. Although for a one off it will probably cost less that buying the tooling necessary to mould plastic gears.

Amaero - World class additive manufacturing specialists

 

[kinsler33]

What also fascinates me is the technology used to make the tiny gears in quartz clock movements (and, I suppose, those plastic-geared platform movements that Kieninger insists on.)

Mark Kinsler

 

[etmb61]

These guys can print you a jet engine out of metal if you want, so I don't think the technology is the problem any more, just the cost to achieve it. Although for a one off it will probably cost less that buying the tooling necessary to mould plastic gears.

Amaero - World class additive manufacturing specialists

Thanks for that! I guess I don't spend enough time researching all the latest manufacturing systems. You've excited my inner geek!

Eric

 

[THTanner]

Thanks for that! I guess I don't spend enough time researching all the latest manufacturing systems. You've excited my inner geek!

Eric

As you research the newest printing you will likely see 4D printing now too. The fourth D has to do with shape shifting materials that are printed in one shape and then change shape as the material hardens or cures. These are mostly used in the medical field for printing body parts and tissue, but I have also seen them for printing manifolds.

 

[Klaas]

View attachment 309438
I wrote this article on 3D printing and was going to have it printed in the bulletin, but decided to have it put on the message board. If you have any questions about the article, let me know.
Mike Dempsey

Hi Mike,
Are the STL files available?