The Sun & Planet Oscillator 'Jasper'

[BenPeake]

Welcome to the build of Jasper, a double-acting oscillating steam engine incorporating a sun & planet gear. I'm aiming to share the highlights of this build rather than a comprehensive build thread, as I simply forget to take enough photos for the latter. To begin, here is a brief clip of the 3D model I've drawn up in Fusion 360, along with an illustration by Albert Jahandier from a book published in 1876, which I've used as inspiration for the build. Thanks for watching.

 

[deeferdog]

Looks good Ben, are you working from available plans or are you drawing them? For some reason I am not able to play the video. I would love to know a bit more about the engine and I will look forward to watching your progress. Do you work in metric or imperial? Cheers, Peter

 

[BenPeake]

Hi Peter

Thanks for pointing out the YouTube problem. I’ve fixed it up now, so you can see the model. I’ve drawn the plans up in Fusion 360 and I generally work in metric, although it ends up being a bit of both because materials are sometimes only available in imperial sizes where I live. Thanks for checking in!

 

[vederstein]

Is there some advantage to the Sun-Planet setup other than being neat to watch?

 

[BenPeake]

Is there some advantage to the Sun-Planet setup other than being neat to watch?

There is an advantage - you can decide how many times you want the flywheel to rotate for each full cycle of the engine. If both the sun and planet gears have the same number of teeth the flywheel will spin twice for each cycle of the engine. I've utilised a sun and planet ratio of 27:23 which will cause the flywheel to spin approximately 1.7 times per cycle. The practical benefit is that the flywheel will store 1.7 times the energy that it would have if it were driven by a standard crank. Subsequently, you could use a lighter flywheel to achieve the same result as an engine with a crank.

Of course, if you had the same number of teeth on each gear, then each tooth would always engage with the same tooth on the other gear every time, which is not ideal because it can promote uneven wear of the gears. In this design, The ratio I chose also means that each tooth will mate with each tooth on the other gear an equal number of times during its life, promoting even wear on each tooth. I did this by making sure the number of teeth on each gear do not share a common prime factor.

Interestingly, the sun & planet gear was invented by Boulton & Watt's chief engineer, William Murdoch, to avoid using a crank which had been patented by someone else. Thanks for your interest!

 

[johnmcc69]

That's pretty interesting, I'm looking forward to your build of it.

Nice job!

John

 

[BenPeake]

After finishing the 3D model of the engine shown in the video in the first post, the cast components minus the flywheel are rearranged into a 3D model for a mould. This is processed into gcode and the two halves of the mould are cut from steel on the CNC mill. The moulds are prepared and then poured using a process called gravity die casting. I use this method of casting because it utilises a permanent mould, is relatively safe and makes accurate, high resolution parts. The master casting is then separated into the individual castings ready for processing. I'm happy to answer any questions about this process if people are interested in a bit more detail.

The 3D model of half of the mould.

The two halves of the mould and the master casting. Notice the the steel moulds are oxidised to provide a barrier between the casting and the mould to prevent bonding. The final moulds are slightly different to the 3D model as I had to make adjustments on the fly to get the best possible results.

A close up of the top platform.

 

[john_reese]

Have you considered selling casting kits with drawings? I would be interested in building one of these.

 

[johnmcc69]

I'd like to hear more about your casting & mold design process.

Nice work!

John

 

[propclock]

Beautiful castings! I would be very interested in the complete process details.
Looks like you could go into production.
How do you go from fusion 360 to G code? Is that part of it's capabilities?
Thanks for sharing.

 

[BenPeake]

Have you considered selling casting kits with drawings? I would be interested in building one of these.

I have considered this though I'm not quite there yet and I also am mindful not to break the forum rules about commercial use by saying too much. The time will come!

Beautiful castings! I would be very interested in the complete process details.
Looks like you could go into production.
How do you go from fusion 360 to G code? Is that part of it's capabilities?
Thanks for sharing.

I'm thinking it might be best to make a separate thread for the casting process. I am yet to cast the flywheel, so when I get to that point I'll take care to document the process so I can share my method.

 

[LorenOtto]

Welcome to the build of Jasper, a double-acting oscillating steam engine incorporating a sun & planet gear. I'm aiming to share the highlights of this build rather than a comprehensive build thread, as I simply forget to take enough photos for the latter. To begin, here is a brief clip of the 3D model I've drawn up in Fusion 360, along with an illustration by Albert Jahandier from a book published in 1876, which I've used as inspiration for the build. Thanks for watching.

Very interesting engine. I will be observing and will learn.

 

[JimDobson]

Fantastic castings.

 

[kadora]

I am amazed with castings quality and also very interested in your casting process thread.
Thank you.

 

[charmseza]

After finishing the 3D model of the engine shown in the video in the first post, the cast components minus the flywheel are rearranged into a 3D model for a mould. This is processed into gcode and the two halves of the mould are cut from steel on the CNC mill. The moulds are prepared and then poured using a process called gravity die casting. I use this method of casting because it utilises a permanent mould, is relatively safe and makes accurate, high resolution parts. The master casting is then separated into the individual castings ready for processing. I'm happy to answer any questions about this process if people are interested in a bit more detail.

The 3D model of half of the mould.

The two halves of the mould and the master casting. Notice the the steel moulds are oxidised to provide a barrier between the casting and the mould to prevent bonding. The final moulds are slightly different to the 3D model as I had to make adjustments on the fly to get the best possible results.

A close up of the top platform.

Loving that mould, bro!! Parts are looking great, and the lines are clean. Not like sand casting. I love it!

What material is the mold made of? Did u use a releasing agent on the mould??

 

[BenPeake]

Thanks bro! The mould is made from mild steel. It's not the ideal material for making this sort of mould, but it's the easiest to get. Ideally you'd use casting iron (which is different from cast iron). They use it in commercial die casting, but I have no idea how to get it as a home operator. If anyone does know, I'd be interested!!

I use a dusting of talc as a releasing agent and periodically I'll touch up difficult parts of the mould with a graphite pencil. Graphite works a treat because it make a thin barrier that is slippery, but is slow to apply manually. Perhaps graphite blasting could be a solution to this, but I haven't tried it yet.

Sorry I've been inactive on this thread, but I will be back! I'm single dadding at the moment and have little free time!!

 

[Richard Carlstedt]

Ben, Is the material you used for casting A 356 Aluminum ?
Beautiful looking Engine and your graphic work is superb !
Good description of the Planetary /Flywheel math relationships.
Rich