# Rhombic stirling... any one seen this?



## jwcnc1911 (Apr 14, 2013)

While I have spent a couple hours digging up internet hooha I haven't found an actual model excluding a YouTube video or two.  None of the ones I found actual models of have prints.  Actually the only prints I've been able to find are here:

http://www.modelengineeringwebsite.com/Rhomboid_drive_hot_air_engine.html

It looks like this:














Has any one seen a working model this engine?  Better yet, has any one built one of these?  Better even yet, does any one have prints for a known working model of this type?

I don't know why but I'm really drawn to this unique design.  I've built a couple IC engines, and countless steam engines if you count all the little wobblers so I'd like to add a Stirling to that list.  I want to do this design or a LTD design.  If any one knows where I can find such prints I'd be very grateful !


----------



## RLWP (Apr 14, 2013)

There was a rhombic drive engine built by someone called Ross in the Model Engineer magazine in the eighties (I think)

He was building 'serious' engines with largish power outputs

Richard


----------



## jwcnc1911 (Apr 14, 2013)

I'd like to find another set of prints... this thing is huge relatively speaking.  Watching these in videos... it appears as though the pitch of the gears could be changed as long as the swing of the rods remained the same and provided smooth motion.


----------



## windy (Apr 14, 2013)

I have a book Advanced engine tecnology by Heinz Heisler that has a brief description of it but no dimensions.

Paul


----------



## deverett (Apr 14, 2013)

Julius de Waal is a Dutchman (or possibly Belgian) now living in New Zealand.  He has produced several different engine designs which have been published on the ModelEngineering site.  Other designs by him appear on the Dutch model engineer site catalogue
http://www.modelbouwers.nl/pdf/Catalogus stoom.pdf

Some of his designs have been built by members of this forum, so the chances are pretty good that this design will work.

Dave
The Emerald Isle


----------



## Hopper (Apr 14, 2013)

The Stirling Engine Manual, Volume 2 by James G Rizzo has plans in it for a vertical Rhombic Drive Stirling engine that could easily be adapted to this style, using Rizzo's dimensions for the critical linkages etc for the rhombic drive. 

Check your PM box, I might be able to help you out with some further info.


----------



## PlumberMike (Apr 15, 2013)

I can see why you are drawn to it. That looks like s really interesting machine.

 Mike


----------



## gg89220 (Apr 15, 2013)

bonjour
j'ai realisé un stirling rhombic on peut le voir tourner dans la section video
http://www.homemodelenginemachinist.com/video/moteur-stirling-9.html 

View attachment Stirling Beta - Rhombic drive.pdf


----------



## jwcnc1911 (Apr 15, 2013)

Fantastic!  

Thank you very much!

After seeing that I'm even more interested!  I believe I'll have a go at both of them.  The bigger one will take some time to gather material.


----------



## jwcnc1911 (Apr 19, 2013)

I've decided to do both of these engines but I have one problem... the glass tubes.  Where can I find these glass tubes, internet searching only yields tubing open on both ends.  None of the test tubes I find are the correct size.  Along this line of thought, what material would be suitable to substitute here?  I've never done a stirling so I don't know how forgiving the design is.  Any advice would be appreciated.


----------



## fcheslop (Apr 19, 2013)

Hi have a look on ebay that's the place most of the ones Iv used came from
Do you realise the gears on the first design are not a standard DP or Module its not a problem if you cut your own
Stainless steel is very good for the hot end
The fits on any Sterling need to be good and the build up should have no tight spots as they don't develop a lot of power in the small sizes
For a first Sterling build  a more conventional one maybe be better option but I don't  how much experience you have.
Good luck
best wishes
frazer


----------



## Hopper (Apr 19, 2013)

Very thin walled stainless steel can be used for the displacer and displacer cylinder. Thin wall tube with an end plug silver-soldered in is a common way.


----------



## gunna (Apr 21, 2013)

This one was in Model Engineer, Sept 30, 2005. The displacer cylinder and displacer are of thin-wall stainless. These came from some of those el-cheapo solar garden lights, I was lucky enough to find a couple of sizes that ran nicely inside one another with about the right clearance. The power cylinder and piston are cast iron. The gears are from a very old, and dead, cordless drill, and make a dreadful racket as they are only pressed steel not machined. All the ball bearings came from old computer fans.

Ian.


----------



## jwcnc1911 (Apr 27, 2013)

gunna, do you have video?


----------

