Pottyengineering Horizontal Mill Engine - Imperial - Mike's 3rd Engine

[mikehinz]

It was a good day in the shop today as you'll see!

First, i managed to completely assemble the engine with everything fitting together, eventually.  I'll show 3 pix of the fully assembled engine first and then make some comments.

Pix 1


Pix 2


Pix 3


The biggest issues today turned out to be the piston valve packing being too long and the eccentric rod also being too long with it additionally being bent just a bit too much.  I trimmed off the valve packing with my belt sander being careful not to take off to much and just hacksawed off about .20" from one end fo the eccentric rod and then cleaned up the threads on the belt sander.  After those 2 mods, everything went together.

I then spent a fair bit of time getting the piston valve centered and the stroke of the valve even.  This involved repeatedly loosening the piston valve coupling and sliding it up and down until it just cleared on both ends of the stroke while looking thru inlet port with the air inlet fitting removed.  I could see the edges of the piston valve thru the port so I just made sure that they were equally visible thru the port at both ends of the stroke.  That's a poor explanation but it's pretty clear as to what's needed when looking at the operation.   

Then I adjusted the eccentric rod length via the threads on each end of the rod.  Essentially what has to be done is to make sure the piston valve moves equally on both sides of the inlet port while also not crashing into the external parts.  It turns out to be pretty tight with only about 1/32" clearance on each end of the stroke between the guide block and the piston valve packing.  But it worked and in the end was just right.  Then, based on Stew Hart's original drawing, i set the eccentric to 90 degrees lead with respect ot the crankshaft.  This is quite easy to do with the eccentric design.  I don't think that I have it perfect but it's close. 

With all that, here's the result.

<a href="https://www.youtube.com/watch?v=d2xRVH6uVUY" target="_blank">http://www.youtube.com/watch?v=d2xRVH6uVUY</a>

It runs!   What a relief!  I'm always scared that I've made some horrible fundamental mistake somewhere along the way.  It runs quite fast at around 10 psi and will easily run smoothly and slowly at around 3 or 4 psi.  I need t to rig up a better manifold and lower pressure, higher resolution gage to see where the pressure is really at, but that's a task for another day!  The video quality is also not what it should be as I just quickly shot it with my phone vs a proper camera plus I very quickly rigged it up just for test rather than for display. 

Now I need to take it all apart, polish things up and make some gaskets for the cylinder covers and the piston valve chest.  There's clearly air leaking at those joints so gaskets are required.

I will post final pix and videos when I've got it all prettied up.

All for today.

Enjoy!

Mike. 

[b.lindsey]

Congrats Mike. Nice and smooth too. Going to look even better once mounted to the wood base!!

Bill

[Admiral_dk]

You should be very happy so far 

[scc]

Excellent

[sbwhart]

Well done Mike I new you’d get a runner. There have been a lot made successfully so I know it’s a robust design.

Stew

[mikehinz]

All, thanks for your very kind comments on this engine!  I've still got a bit more to do to get into a finished state but I'm extremely happy that it runs!

Stew I have a quick question.  I was busily making gaskets for the engine today but I realized that I hadn't planned on any packing for the piston rod or the valve rod.  Do you typically use packing in those 2 location or just do without?  If you do use packing, what kind?  The traditional graphited yarn or twisted up teflon tape?  I'm just curious if I should install some.

Again thanks for all the responses and compliments!

Mike.

[sbwhart]

Hi Mike

You can use graphite packaging if it’s too thick just unravel a few strands or twisted ptfe will do I didn’t use paper gaskets just sealant

Stew

[kvom]

Great runner. 

[Craig DeShong]

Runs great.  Nice job. 

Problem is, once you put it on that spectacular base no one is gonna look at the engine !

[Tennessee Whiskey]

Excellent Mike. Smooth as silk 

Cletus

[mikehinz]

Well, at long last, the engine is finished!  In this post I'll post just a few pix of some of the final work that I did on the engine and then on the next post, I'll put the final pix and a video of it running in the final configuration. 

The final bits of work involved taking the engine completely apart and reassembling it, this time with gaskets and packing, painting the flywheel and some additional polish and cleanup on various parts. 

I didn't take any pix of the painting of the flywheel, as it was pretty boring, but I'll give the details.   I washed the flywheel with mineral spirits, dried it off and sprayed 2 light coats of Rustoleum filler primer.  Then I let it dry for 10 or 15 minutes and sprayed it with 2 coats of Rustoleum Hunter Green Satin.  I'd bought several cans of various shades of green paint and my wife chose the Hunter Green color as the best for the engine.  Who am I to argue with her!   I masked of the rim, but to make a fine demarc line between the paint and the polished area I reinstalled a piece of 5/16" drill rod and chucked it up in the lathe and then lightly sanded it and then used a bit of grey Scotch Brite on it.  I think it came out OK and more importantly, my wife likes it!

I also didn't take any pix of polishing but that mostly involved sandpaper stuck down to a granite plate with 3M 45 adhesive and lots of rubbing.  I tried to touch up the crosshead slide bars to make them as polished as possible and various other bits just to improve the appearance.  At the end of the day, I ended up with about .004" clearance between the crosshead slide bars and the rails.  It operates very smoothly with no binding that I can detect.

Finally some pix of how I made the gaskets.  Since I had drawn the engine up in CAD, I made fresh prints of any parts at 1;1 scale and printed them.  I had some .010" teflon sheet that I used as I wanted the gaskets to be quite thin.   The first pix shows the spray adhesive that I used along with the teflon gasket material.  I sourced it from McMaster-Carr.  The 3M 45 spray adhesive is fairly low strength so you can peel things apart if you spray it on lightly and only one one part. 


Once the print was sprayed and dried for a minute or 2, I cut out a small piece of the teflon and stuck it on top of the print.


Here's a pix of the 4 gaskets I needed 1/2 way thru the process.  I just used a scissors, leather punch, and a craft knife to cut and punch out along the lines on the print.  Its actually very easy to do and quite accurate.


And the 4 gaskets finished.


A single pix of working on one of the walnut bases.  I was going to use threaded inserts, but my brother told me that there's no need to, just thread the wood directly as it's very hard.  I transfer punched the required locations, drilled thru for 100% threads and shown here is tapping one of the holes 10-32 with a hand-held tap guide.  My brother was right.  The threads in the wood are plenty strong for the purpose. 


And this rather oily looking pix shows graphite packing being installed in the piston valve rod guide.  I was amazed that the local hardware store actually HAD some graphite packing in stock!  For both this and the piston rod guide, I unraveled a bit of the packing material, wound it around each stem and pushed it in place with a small screwdriver while liberally oiling it.  After I assembled everything I moved the rods by hand for a bit and kept applying oil and slowly tightened the packing.  It worked out well with almost no air bypassing when the engine runs.


So this concludes the final details on making/assembling the engine.  Next up, the pix of the finished engine and a video of it running!

Enjoy!

Mike

[mikehinz]

And the long awaited (at least by me!) final photos of the engine!! 

First up are 2 pix of the three engines that I've build so far, all assembled on the walnut wood bases that my brother made for me.

Family pix 1


Family pix 2


And now 7 pix of the finished engine:

Pix 1


Pix 2


Pix 3


Pix 4


Pix 5


Pix 6


Pix 7


And last but not least, a video of the engine running.  This is with about 5 to 7 psi of air applied.

<a href="https://www.youtube.com/watch?v=hJ3J8GHIhyg" target="_blank">http://www.youtube.com/watch?v=hJ3J8GHIhyg</a>

It runs well and very smoothly with very little vibration at this speed.  I do like the scale model fasteners and the brass accents on the engine.  What does everyone thing about the color of the flywheel? 

I did learn a LOT during the build of this engine.  Prior to this, I'd never made an eccentric assembly, nor had I done any cylinder lapping, nor had I drill/tapped any small holes of size 2-56.  So, I'm rather pleased about all that and it make me confident enough to start on the next challenge!

So this is it for this engine, enjoy!

Mike

[10KPete]

Sweet!! A beautiful engine that runs beautifully, Mike. An excellent job.
It's been fun following this build and I hope your next engine is more so!

 

Pete

[crueby]

Excellent job on the engine Mike!!


I like the dark green on the flywheel, the darker colors look great against shiny metal.


 

[Admiral_dk]

Chris and Pete has already mentioned the important details - so I will just tell you to enjoy the great result