PMR 7 Twin Cylinder Steam Engine

[zeeprogrammer]

Ready for assembly. Kinda sorta.

Attached is a pic of all the parts.

I haven't done the gaskets and probably won't. I don't have the proper tools to punch holes. I made a run at the material that was in the kit but it was clear I would make it worthless.

Some tubing has to be soldered between the pipe elbow and pipe 'T'. I expect I'll soft solder it.

Also need to figure out how to bend the eccentric rods.

Not too bad so far. Flubbed an eccentric hub, flubbed a valve, had to redo the pistons, busted a drill bit, and busted a center bit. One small bleeder on a knuckle. (Reamer got me when I reached in.)

Oh right. And one crapped up spindle stop. Er...make that two. 

[Jo]

  Less than three weeks from the start and he nearly has the engine finished 

Jo

[Gas_mantle]

Looking forward to seeing it running Carl 

I'd seriously think about making some gaskets they should significantly improve the performance even if you only run on air. Before I got a set of hole punches I just improvised using scribers, centre punches, scissors etc to make the holes. It's not ideal but can been done without much thought or effort 

It's worth investing in a set of hole punches, I bought some like these :-

https://www.ebay.co.uk/itm/12PC-PRECISION-HOLLOW-PUNCH-SET-3mm-19mm-LEATHER-PLASTIC-GASKET-HOLE-CUTTER/263355847973?epid=2255269250&hash=item3d513b5525:g:xP0AAOSwrhhaIQi3

They are cheap but do the job 

[zeeprogrammer]

Thanks Peter. The punches are what I need.

[b.lindsey]

A fine collection of parts Zee. Don't scrimp on the gaskets. They don't have to be perfect but they WILL help. Draw them up in CAD and cut them out or glue them to thicker stock if needed and then cut them out. Its worth the little bit of extra time in the long run.

Bill

[zeeprogrammer]

I can't fight both Peter and Bill. 

I made them from the material provided in the kit. They look like crap but are still whole.

[Jasonb]

A liquid gasket does not require any punching of holes and you also don't need to make allowance for it's thickness during construction. When I do want a gasket that is what I use but often the metal to metal is good enough for air running and more.

[zeeprogrammer]

A liquid gasket does not require any punching of holes and you also don't need to make allowance for it's thickness during construction. When I do want a gasket that is what I use but often the metal to metal is good enough for air running and more.

That's kind of what I was thinking. I was surprised how well the outboard head covers mated when I tightened down the screws. But we'll see how the inboard head covers do.

[Tennessee Whiskey]

Great family shot  . I’m betting  this is probably going to be the best retirement gift you’ve recieved so far: shop time and a runner. I’ve thought several times about buying one of those lazer printers or whatever they are; the big time scrapbookers use them. I usually use the: “grease the gasket material, stick it to the surface, and lightly tap with hammer to mark the “features” . And then again: plus 1 on what Jason said. At these pressures and temps, a fine smear of quality silly con carne (silicon sealant) will do . And don’t worry, a lot of the stuff that’s been supplied in my kits looked like crap  . Gotta go: three salami with blistered mozzarella sub, side of sautéed “baby” button mushrooms, and a Greek salad: oh yeah, my version of your hoppie. Give T that country boy wink 😉, and y’all come see us now you hear.

Cletus

[zeeprogrammer]

We've got trouble. Right here in zeepster's cribby.

Well not really. Nothing out of the ordinary. And there is one or two 'huzzahs' I let out.

Everything is pretty tight and not unexpected.

The biggest issue is the left cylinder piston won't budge. I'll break it down later and try to figure it out. My first suspicion is the packing nut. I'd forgotten to install it on the right piston and that one moves (with some coaxing). It's also possible the cross head is not square (same level) as the piston. Getting the cylinder, piston, and cross head on the same plane was my biggest fear but the right cylinder seems fine.

I need to re-thread the eccentric rods. The nuts go on part way and then bind up.

The spacers for the crosshead caps are too low or the crosshead itself is too thick. (The thickness may be the issue with the left piston.)

The crankshaft assembly spins smoothly and the connecting rods line up nicely with the crossheads.

Spinning by hand, the flyhwheel shows a slight wobble in the middle of the dome but the rims look pretty good. Certainly could be better but I'm happy.

Overall I feel things went way better than I had expected.

One thing I'm wondering about is how to run in the engine. The only thought I have is to get some kind of belt, put it on the flywheel, and drive the belt with something.
Not sure it's needed but I suspect the engine will have a tough time going until things are worn in.

[AOG]

Zee, Check the torque on the screws holding they cylinder onto the frame. If they are not evenly torqued the cylinder will cant and lock up the piston. It happened on my steam powered iPhone charger and I chased it for days before I figured out the problem.

Tony

[zeeprogrammer]

Zee, Check the torque on the screws holding they cylinder onto the frame. If they are not evenly torqued the cylinder will cant and lock up the piston. It happened on my steam powered iPhone charger and I chased it for days before I figured out the problem.

Ah! Thanks Tony. I'd forgotten but I did see that the cylinder wasn't fitting right. I'll check that first.

[crueby]

All typical issues. One of those times when you loosen screws till things move, tighten them one at a time and figure out where the tight spots are - something too high/low/thin/thick, or just out of line. Bit of filing on spacers, or adding a shim can help. Sometimes drilling a clearance hole out a size to give a cap room to shift with the piston helps, let the piston align the lower end cap then tighten the screws. Thats a common culprit, the lower cap not quite concentric, or the piston not quite concentric on the rod, or both. One of those learning things, where machining as much as possible in a setup pays off at this stage. Dont get frustrated, it will come together and you will learn a lot!

[zeeprogrammer]

Dont get frustrated, it will come together and you will learn a lot!

No frustration yet. That's for tomorrow. 

Nothing unexpected...except that it's gone far better so far than past models. 

[mklotz]

If it were me, I wouldn't try to run it in until it turns over smoothly, if a bit stiffly, by hand.

One possible way to power it for run-in would be a rubber wheel driven by an electric drill and held against the flywheel.  Those expandable rubber cylinders used to hold sanding drums spring to mind, sans sand paper of course.