johnsmachines

machines which I have made, am making, or intend to make, and some other stuff. If you find this site interesting, please leave a comment.

Tag: HME

Horizontal Mill Engine (HME)

The HME is our Model Engineering Club competition build for 2017.  I finished making the components and tried to get it running, unsuccesfully.

So today I took it to the GSMEE morning meeting, and Rudi, who is a retired marine engineer, and has completed his own HME, took one look at mine and said that the timing was totally up the creek.

Rudi fiddled for a few minutes, and said, “it will work now”.  A couple of other members doubted his assessment, but were not confident enough to put money on it.

Anyway, this afternoon I hooked it up to a small compressor (my air brush compressor actually), and at 10psi it started to move.  At 16psi it was ticking over quite nicely.  Then the big test, throwing it into reverse.  And hallelujah!  It reversed.

Seeing an engine working, which you have made yourself, is an immensely satisfying moment.

This one still has some finishing jobs to be completed.  Like sealing the joins against steam leaks.  And a bit more polishing.   And maybe a name plate.   And there is an annoying knock which might disappear on steam.  But if not, I might need to re-make one of the bearings.

But it goes!!   Yay!!

 

Koffiekop Modification

I have been considering this modification for some time, and today I located the aluminium heat sink-radiator material which I needed, and which I knew was somewhere in my stuff.

The Koffiekop Sirling engine requires differential temperatures between the top and bottom plates.  I wondered if installing some heat shedding plates on the top plate might increase the running time on a cup of coffee.

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The heat sink material is glued to the top plate with a heat transmitting electronic silicone glue.

Afterwards I ran a test with a cup of hot water.

The engine ran for 26 minutes!  That is an improvement of about 25% on the best previous runs.  Success!

The Horizontal Mill Engine (HME) is assembled and ready for the D valve to be timed.  This is how it looks.  I wont get to it for a couple of weeks now.

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I did squirt some compressed air into the valve chest, but minimal movement.  Not surprising, considering the position of the eccentric was just a guess.  When I get it going there will be a video.  That crankshaft pin is temporary.  It is a 3mm cap screw going through a 4mm cap screw.  go figure.

 

Another Diversion from The Triple

My model engineering club (GSMEE) has an annual competition build.  This year it is a small horizontal reversing steam engine.

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So I have taken another break from the triple to build the HME.  I have redrawn the plans to make my model 40% bigger, and also to accept metric fasteners.

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The HME blanks for the base, the cylinder block, the flywheel pillar and the flywheel.  The only stainless steel I had in my junkbox, er storage facility, had a  big hole in the middle, so I filled that with brass.

All was going well, and I spent almost a day making the piston head guide. Then finished off by making the guide rod and block.   I decided to take another thou off the guide block, and set the lathe going.

And heard an ominous bang.

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I had forgotten to remove the piston head guide from the from the piston before I restarted the lathe.  Destruction.  The lump at the bottom is another piece of brass, ready to be turned into another head guide.  I had run out of suitably sized brass, so I silver soldered a length of rod to some square section.  A day later and the new piston head guide is now made.  

At least I know from this (and other crashes), that the second part is always made much faster than the first.

And on a different subject, I recently bought on Fleabay a self centering 4 jaw chuck.

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It does not replace the independent jaw 4 jaw chuck for accurate work, but will be useful for turning small square stock.  Also, I plan to make a backing plate for it to fit into the tailstock, so it will hold taps.

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