Chris's Marion 91 Steam Shovel

[crueby]

Once again a long read to catch up  Excellent as ever  It may also prompt me to replace the old, and probably dimming, fluorescent tubes in my workshop with new LED ones.

Thanks Roger!

I was really surprised with how the LED shoplights brightened up the place, with lights in the same place as the old ones. There are lots of choices out there for the shoplights, need to pay close attention to the output lumens and color temperature (5K color temp works well for shop). My model shop uses a series of track lights plus a few task lights on goosenecks, they are all par20 LED bulbs now, very nice and they run a lot cooler than the older incandescents and halogens. The wood shop is mostly 4' shop lights with some track lights.

[crueby]

This morning the elves, um, I mean 'I', got started on the valve sliders. These are a double-decker D-valve, with the two outer chambers connected with a drilled passage. The chambers are pretty small - one is .044 wide, the others are .131 wide, so milling them all around would be pretty tough. So, decided to drill the corners with a nbr 58 drill first (spot drilled before drilling to prevent skating)

The end chambers are deeper than the center one, to connect in with the cross passage. Then, hogged out the larger chamber centers with a plunge cut with a 1/8" end mill:

and drilled the cross passage to connect the end chambers:

That left the edges to clean up and take out to final dimension. I could have used the dental bur in the mill, but I can do the same thing quicker with the high speed air handpiece, takes a light touch but the cuts are quick. The first pass was with a .025" diameter carbide bur, then smoothed things with a diamond coated taper bit:


Last steps are to cut the openings on the top for the valve rod and adjusting nut, and cut/trim them off the longer bar and to length. Finally the valve face will be lapped on a diamond plate. After that, can start on the slider for the throttle (center) position, which looks like a standard d-valve with one chamber.

Also, been talking with the head of the historical society, looks at this point like I'll be able to get in to take pictures of the model with the real machine in late August. Also, they are holding a kids day out at the shovel and I'll be talking at that on how the machine works and what it was used for - should be fun!

[crueby]

Today the slots for the valve rods and adjusting nuts were cut in

and then started the process of fitting the finely floating ajusting nuts, with filing, fettling, fussing till a fine floating fit was functional. Goal was to get the adjusting nuts to be a easy slide fit without any slop front to back, allowing the slider to move vertically to maintain a steam tight fit on the valve face. So far, the two cylinder sliders are fit to a satisfactory level.


Next need to make the slider for the throttle valve in the center, that one is a normal looking d-valve, just with longer ends to cover the tapered slot in the valve face. As the taper gets uncovered, more steam is let into the passage, while the exhaust from the other passage is directed to the output pipe. Note that on the two cylinders, the sliders never uncover the ports like in a normal d-valve, they just redirect the steam between different pairs of ports.

[ozzie46]

 fitting the finely floating ajusting nuts, with filing, fettling, fussing till a fine floating fit was functional
Say that fast 10 times.

Still following. Looks great

Ron

[cnr6400]

I'm filled with fine feelings looking over your fettling on the freakin' valves and floating fripperies.......

Tomorrow's subject - use of the letter H in alliteration.....   

[crueby]

 

[crueby]

The throttle valve slider is made and fitted, filed, fettled, etc, everything but flocked.  This morning got a start on the (hopefully) final assembly of the steering engine. The top and bottom cylinder gaskets were made from the paper gasket stock, like the other engines, and the cylinder all bolted up. After lunch will get a start on the steam chest gaskets. After that its a matter of getting the valve rods bolted to the levers and timed, and with luck get a test on compressed air. The connections at the levers may need some extra work, on the larger ones the holes in the ends of the levers needed to be elongated to give the shoulder bolts a slot to ride in, due to the arc of the lever ends pulling the valve rods up and down. Will see if I have enough of that filed in yet, or if it needs a bit more. Weather, time, and tide permitting, should have this running this week!

[cnr6400]

Enjoy finessing the fine fitment of the levers with the files, generating filing fragments. Don't flagellate yourself if the features fail to function immediately..... (oh boy I'm out of F's - time to go to Word Mart) 

[crueby]

Well, one big step forward - steering engine is all assembled with the gaskets, all moves smoothly:

 

Then, a step or two backwards!     Wired on a air tube to the input pipe from the compressor, and found two problems:

• There is a leak (big one) in the gasket between the cylinder and the crosshead guide, causing a big leak out the base of the right cylinder when it is driving forwards. Quite a lot coming out there, must be a tear or blob in the gasket there. Of course it HAS to be at the farthest in gasket, requiring removal of the most parts.
• The throttle valve slider is binding on the valve rod, and is not seating properly, causing a leak of pressure out the exhaust pipe direct from the steam chest. This one should be easy to fix with some filing on the inside edges of the slot the rod runs in.

Neither is a big deal, but they do require taking the cylinder back off the crosshead, and also the steam chest off the cylinder - lots of fiddly screws and nuts. It also looks like the paper gaskets are seeping out the side of the steam chest cover slightly, through the paper - was a little worried about that during assembly, since the distance from the outside to the screw holes and such are so small. I think I will be better off going with either a solid gasket material (have some thin viton and silicone sheet) or maybe switching to a RTV type gasket goop. This engine is quite small, so the width of the faces being squeezed in the joints is quite small. Good thing is that all the moving parts appear to be sliding nice and smoothly, no sticking points anywhere.

Hmmm.... I THINK I grabbed the correct gasket roll from the stock, have to check that, have a couple of different paper gasket materials. Oh, and don't suggest using paper bag stock, have tried that in the past, and the stuff the stores around here use is quite porous down the center - air whistles through from cut edge to cut edge. I have some rolls of gasket stock made for use on cars that works well, just may have grabbed the wrong one. If so, need to toss that one roll, have had problems in the past with it but for some reason kept it. PackRatItis!

So, good place to stop for the day, and pick it up fresh again tomorrow - it wants to run, just needs to hold in its pressure and push cylinders rather than blowing the elves off the tabletop! 

[JC54]

Have you supplied the elves with parachutes? Just in case, got to keep an eye on Elf and safety. Great build. JC

[crueby]

Have you supplied the elves with parachutes? Just in case, got to keep an eye on Elf and safety. Great build. JC

Elf and....  Ooohhh, you have been hanging out with CNR. And Zee. And Thomas... And, well, the rest of us!      Good one!

[crueby]

Yup, grabbed the wrong roll of gasket paper, throwing that one out... 

[steamboatmodel]

Yup, grabbed the wrong roll of gasket paper, throwing that one out...

Don't throw it out, BURN IT.
If you just throw it out those little scoundrels' will fish it out and resell it on Elf-Bay.
Then six months later they will resell it back to you.
Gerald.

[crueby]

Yup, grabbed the wrong roll of gasket paper, throwing that one out...

Don't throw it out, BURN IT.
If you just throw it out those little scoundrels' will fish it out and resell it on Elf-Bay.
Then six months later they will resell it back to you.
Gerald.

Those little swarfheads! I think I have bought it 3 times...   

[cnr6400]

There's that gigantic penny again!

Sorry to hear about the gasket tribulations. You didn't buy the "light" type of gasket paper did you? That kind has all the reclaimed CO2 from light beer built into the centre, so it leaks. (so I'm told, anyway)

Permatex or GE silicone are your friends. 

I second the motion about burning the bad material to prevent elf resale shenanigans. While you're at it, maybe burn the waterskis and ski boat from their recent birdbath exploits.....