Stevens Model Dockyard Engine

[Michael S.]

Then it's an easy fix.
I'm always amazed at what a small amount of play in the bearing causes a knock.

Michael

[crueby]

Great detective work, and not stopping at the first thing found is good, there are often several things stacked up!

[Chipmaster]

New bronze sleeve 5/16 od x 1/4" id fitted to the crosshead.

IMG_5111 by Andy, on Flickr

IMG_5112 by Andy, on Flickr

Followed by a new stainless steel piston rod 5/16 diameter with 1/4" BSF thread at each end.

IMG_5099 by Andy, on Flickr

IMG_5100 (2) by Andy, on Flickr

IMG_5120 by Andy, on Flickr

A new pin was fitted to the cross head and the engine turns over very smoothly at this stage

Flickr video
IMG_5113 by Andy, on Flickr

The excess thread might permit fitting a slim locknut if there's sufficient clearance under the cylinder cover.

 IMG_5125 by Andy, on Flickr

Next step will be replacement of the rusty valve rod.

IMG_5121 by Andy, on Flickr

Andy

[Chipmaster]

At each end of the cylinder there was evidence of a plugged hole, ex cylinder drain cocks I presume but it looks like the thickness of flange at the end of the cylinder has been reduced, what happened to this bitza - weird.

 IMG_5177 by Andy, on Flickr
IMG_5180 by Andy, on Flickr

Buffed up.

IMG_5185 by Andy, on Flickr

The gland for the valve rod had an M10 x 1 pitch, I reckon the 1/4" bore male end union from the hydraulic brakes of a car had been used and the female part had been soldered onto the valve chest.

IMG_5211 by Andy, on Flickr

As it was very worn I bought an M10 x 1 male brake blanking plug then drilled and reamed it to 1/4".
IMG_5227 by Andy, on Flickr


IMG_5228 by Andy, on Flickr

Here it is on a new stainless valve rod complete with a new half of the pivot.

IMG_5229 by Andy, on Flickr

Reassembled with brass dome nuts and given a whiff of compressed air.

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

Buffed up it's looking better but there are still several issues to be corrected. The bent crankshaft is pretty bad and may have to be replaced if careful hammer blows don't straighten it. A new valve chest will be required because bodged/oversized holes around some of the studs have left almost no surfaces for the cover's gasket to seal against so it's leaking air at quite a rate.
It would be a bad idea to steam it with such a leak.

Andy


 

[Michael S.]

Hello Andy,
very nice old steam engine.
Maybe you can straighten your crankshaft on the lathe. I bend the end of the crankshaft in the right direction with my hand and check with the dial indicator. I wouldn't use the hammer.

Michael

[Jasonb]

It's certainly looking and running better than it wa sin your first post.

As to the crank, you know the saying " if in doubt, get the Stilsons out" 

[Chipmaster]

After no posts on the Stevens Model Dockyard restoration (SMD) for exactly two years.

This is how it looked and ran two years ago.

P1100184 (2) by Andy, on Flickr
P1100185 (3) by Andy, on Flickr
P1100186 (2) by Andy, on Flickr

Flickr video.....

Stevens Model Dockyard engine improved running by Andy, on Flickr

The flywheel was a mess and a loose fit on the bent crankshaft, The keyway on the crankshaft had been butchered by grub screws, the valve chest leaked where screw holes had broken through the edges. There was a lot to be done but I was more interested in other projects.

Earlier this year 2024 I bushed the hub of the flywheel, cleaned it up and painted it. The flywheel is probably a bronze casting and looks good and I broached a 1/8" keyway in the new hub.

 IMG_0472 by Andy, on Flickr

IMG_0473 by Andy, on Flickr

A new crankshaft was next, here are the webs being sawn to length.

IMG_7831 by Andy, on Flickr

Compared with the old crank.

IMG_7843 by Andy, on Flickr

Silver soldered

IMG_7847 by Andy, on Flickr

That was it until a couple of days ago when I hacked a new valve chest from a piece of 1/2" thick brass. I used transfer punches to replicate the irregularly space holes.

IMG_E0452 by Andy, on Flickr

The slide valve.

IMG_0456 by Andy, on Flickr

New crank and old valve chest.

IMG_0461 by Andy, on Flickr

The new valve chest and cover in position.

IMG_0458 by Andy, on Flickr

Andy

[Michael S.]

A very successful restoration of the individual parts. Some things need to be renewed from time to time.

Michael

[Admiral_dk]

Great looking recovery 

Per           

[Chipmaster]

Some more work and additions to the valve chest.

IMG_0481 by Andy, on Flickr

IMG_0487 by Andy, on Flickr

IMG_0489 by Andy, on Flickr

With what I believe to be the original Stevens Model Dockyard valve.

IMG_0492 by Andy, on Flickr

I need to make a longer valve rod which will extend into the guide on the top of the valve chest and make it all steam tight.

Andy

[Jasonb]

Its looking tidier.

First time I have seen that pinned method of locating the valve nut.

[Roger B]

Nicely done   

Did you see any distortion after silver soldering the crankshaft?

[Chipmaster]

Hi Jason, I agree it is unusual. I think it was an  improvisation to press the slide valve against the port face.....

Stevens Model Dockyard Steam Engine by Andy, on Flickr

The pins are there to retain a pair of small bronze springs,

Stevens Model Dockyard Steam Engine by Andy, on Flickr

A view of the underside of the slide valve,

Stevens Model Dockyard Steam Engine by Andy, on Flickr

Assembled.

Stevens Model Dockyard Steam Engine by Andy, on Flickr

Many parts of this engine are probably indicative of someone assembling it who didn't have the tools we are fortunate to have.

House decorating is interfering with my model engineering activities at the moment.

Andy

[crueby]

Ahhh!  Interesting! Thanks for the detail pictures of the springs/pins!

[Chipmaster]

Hi Roger, you asked whether I saw any distortion after silver soldering the crankshaft?

Thankfully none at all. In recent years I have fabricated at least seven crankshafts using silver solder and they were all successful.
However, I did have failures with silver soldered crankshafts when I was new to model engineering thirty years ago. Of course I may be lucky and / or have much better equipment.

Andy