Jan Ridders recently updated his plans for a vertical flame eater engine that he originally made in 2003 as a birthday present for his son Marc. He made a number of improvements and redrew the plans using a CAD program. Jan says this engine is “more forceful and noisy” than his Stirling engine models.
This is just one of about two dozen beautiful engines Jan has designed. You can see them all by visiting his web site, which is in both English and Dutch (look for the buttons to change the language). Jan gives his plans away for free, although he will accept a donation if you’d like to make one. You just have to send him an email telling him which plans you would like. You can contact him via his web site.
Begin by turning the shoulder the CDs will fit on.
Here’s how I made the hub for Jan Ridders’ New Simpler LTD Stirling Engine. I started with a piece of 1.25-inch diameter aluminum and turned down a shoulder to fit the CDs that are used for the flywheel. This part has only two critical dimensions and this is one of them. The CDs need to fit well so the flywheel will have a minimal amount of runout. The other critical dimension is the center hole. It needs to be drilled or reamed so it will fit well on the crankshaft and the hub won’t wobble when it turns. I recommend drilling the hole to fit a crankshaft made from 3/32-inch drill rod (more about this in my next post).
It is also important to cut a square shoulder so the disks will fit tight against it. I use indexable carbide inserts and they have a very small cutting radius. So I was able to cheat and cut just a little deeper into the corner of the shoulder so the radius left by the insert would be a little below the surface. The radius ground on HSS bits is usually bigger so they might require you to clean up the corner with a parting or grooving tool, or a pointed bit. If you don’t know what I mean then see the bottom of this page where they show and explain how to turn a shoulder.
The next step was to turn down the diameter that will be drilled and tapped later for the set screw used to hold the hub on the crankshaft. I also faced it down to the correct length and center drilled it.
Here's how the CDs will fit on the hub. They are used as a flywheel.
The hub is parted off.
The flange (is that the correct term?) is too thick and the parting tool left it convex-shaped. So I flipped it around to face it down to the correct thickness. You can't see it, but I wrapped a piece of aluminum tape around the part in the chuck so it wouldn't get marred by the jaws.
Usual Disclaimer: I’m not the most experienced machinist and there is almost always more than one way to do something. Please leave a comment if you can teach us all a better or different way of making this part.
I was going to build his Coffee Cup Stirling but I have started building this one instead because it will take a lot less time. I have not been able to spend much time in my workshop lately, which is typical during the warm weather months, and I would like start a project I can finish within a reasonable amount of time.
I know I get a lot of visitors looking for information about Jan’s Stirling engines, so I am posting this with the hope that someone will find it useful. I usually hate studying plans to determine what materials and tooling I’ll need to buy. I’m always worried I’m going to miss something and the project will grind to a halt while I place an order and pay a huge shipping fee for just one item. I’m not too fond of ordering stuff either.
Fortunately, I already have almost everything I will need. I just have to buy the graphite, a glass tube for the power piston cylinder and a suitable plastic tube for the displacement cylinder. I did some checking last week and I think the glass and graphite will be easy to obtain. Finding a 4-inch clear plastic tube has been a problem. You really can’t make the top and bottom plates until you know dimensions of your tube.
Jan’s plans are in Metric units and I’m in the US, so I am going to have to convert them to English units. I have not built this engine yet, so consider the fractional English sizes I listed to be just suggestions for now. Stayed tuned because I’ll start posting some construction photos and notes soon.
32 mm [1.26 ~ 1-1/4-inch] round – CD kernal (Hub) – Sheet 6
Material to make two 112 mm [4.41-inch] diameter disks for the top and bottom plates of the displacement cylinder. One needs to be 5 mm [.20-inch] thick and the other 8 mm [.31-inch] thick.
You have a couple of options here. One is to start with a couple of disks cut from a 112 mm or bigger round bar. This could be very expensive if you have to buy a length of it.
A cheaper alternative is to make them out of a flat plate by following Bogstandard’s excellent tutorial. You also have some choices if you do it this way. You can buy your aluminum plates in the two thicknesses you’ll need or use the same thickness for both cylinder plates, which should look and work fine. You can also mill the metal down to the thicknesses you’ll need.
I am a big fan and admirer of Jan Ridders. He is a talented and prolific designer of Stirling, flame-eater and internal combustion engines that are both beautiful to look at and fascinating to watch operate. Jan generously shares his plans for free and you can also frequently find him answering questions on the Yahoo Barstockengine discussion group, a group that I highly recommend if are interesting in building one of Jan’s designs or some other engine that doesn’t require castings.
I have not built one of his engines yet, but I have been gathering the materials needed to build his Coffee Cup Stirling and I have made some practice parts. That engine, like most of Jan’s designs, has some features that almost make it a work of art, like the spoked flywheel, the finned power cylinder and the connecting rods with decorative holes. It also uses bearings and a lot of brass. These features require extra time and skill to make and they increase the cost of the materials and effort needed to obtain them.
Jan just designed a new easier-to-build version of that engine. Instead of a spoked flywheel it uses two CDs mounted on an easy-to-make hub. Balancing the engine should be easier because a small weight is added to the flywheel instead of drilling small holes in it and slowly enlarging them as needed. Silicon sealant is used to attach the top and bottom plates of the displacer cylinder instead of six machined brass spacers that need to be tapped and then used with screws that are countersunk. The new engine also does not use any ball bearings. Instead it uses “point bearings” that do not look hard to make.
A glass tube is used for the power cylinder and the piston is made of graphite. Graphite is also used to make bearings for the crankshaft. I am sure that Jan chose these materials to minimize friction, which is absolutely critical when building a low temperature differential Stirling engine. I was initially concerned that it might be difficult to obtain them in the right sizes and then fabricate the parts, but it doesn’t look like that is going to be a problem. I easily found numerous sources on the Internet and learned that it is apparently not that hard to cut a piece of glass tubing to length, even if it is made of borosilicate or Pyrex. Using glass is also an inexpensive way to make a cylinder. The working cylinder for the Coffee Cup Stirling is made from a piece of 30mm (1.2-inch) diameter brass, which could be costly to buy.
I would say that the biggest obstacle to building one of Jan’s LTD Stirlings might be finding an affordable large-diameter transparent tube for making the displacement cylinder. That is what has been holding up construction of my engine because you need to know the dimensions of the tube in order to make the top and bottom cylinder plates. Jan suggests looking for a suitable piece of packaging to use. I did find a wholesale-club size package of Slim-Jim snacks that was almost the perfect size but I am reluctant to use it because it looks cheap and would detract from the appearance of the engine. I know others have had the same problem and there was a recent discussion about it on the Barstockengine group. I plan to pass along some of the suggestions that were made at another time.
The plans are written in Dutch and English. The units are metric but I don’t think you are going to have any problems converting them to English units and using standard size metal stock if that is your preference.
Jan usually asks that you to send him an email request if you would like a set of his plans but he has kindly given me permission to make them available for download here (PDF, 2.9 MB). As I said, Jan gives his plans away for free, but I do know that he’ll accept a small donation via PayPal “only if you are very satisfied and feel called upon.”