Jan Ridders coffee cup hot air engine

[brickyParticipant @bricky]

[brickyParticipant @bricky]

I have been trying to make it work and remade parts and had to reseal the diplacer after the first failed attempt.I decided that I would bed the plastic ring on beds of mastic and it has sealed a treat.I found that the the engine would still not turn over but was making an attempt.I decided to leave it overnight and rebalance the flywheel.when I tried to spin it over it wouldn't budge.when I pulled the displacer piston rod up whith some force I found the piston rod was rusting I think.Does mastic cause this on steel and if so will a phospher bronze rod run OK in a phospher bronze bearing.And I thought this engine was going to be easy.

Frank

[Anthony KnightsParticipant @anthonyknights16741]

Some types of sealant emit acetic acid when curing. That may be what has happened to you.

Regards Anthony

[Andrew EntwistleParticipant @andrewentwistle]

Hi Frank,

I got mine to work with a graphite piston in the honed bore of a glass test tube, but I'm sure other pairs will work if clearances are optimised. There needs to be practically no friction for the engine to work as there are only milliwatts of power available. If you look from 1:34 of this video I made about my Jan Ridders engine you can see how free the piston needs to be.

Testing a low temperature difference hot air engine

Andrew.

[SillyOldDufferModerator @sillyoldduffer]

Posted by bricky on 19/11/2020 16:37:31:

… I decided to leave it overnight and rebalance the flywheel.when I tried to spin it over it wouldn't budge.when I pulled the displacer piston rod up whith some force I found the piston rod was rusting… .And I thought this engine was going to be easy.

Frank

Snap!

Have a look at this thread from 2016 where I hit the same problem.

From memory I think I decided it wasn't acetic acid from the sealant because it happened with a safe type too. I fixed it by using a graphite piston.

I found the engine difficult to get running at first, but it does go and is reliable thereafter. The secret is to minimise friction by turning it over many many times by hand to remove all trace of stiffness. Clock oil helped – 3in1 is too thick. I also had to replace the el-cheapo ball-bearings with expensive ones. More details in the thread.

It formed the basis of a MEW Article describing a low power dynamometer. Efficiency and power output are both tiny.

Don't give up.

Dave

[brickyParticipant @bricky]

Thanks for the advice given and I will continue to get it going, but it is doing my traps in.

Frank

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