1/20th Scale Burrell

[glue-itcom]

A very brief video showing the steering wheel and worm gear operating

 

[glue-itcom]

30 degree C in the workshop, but with the door and all of the windows wide open I spent some time turning the crosshead guide and then slot drilled the open sides.

At first I was worried about the size of this crosshead, but I offered the unit up to the traction engine and it looks ok. This traction engine is going to be stand-off scale as I have used quite some licence to achieve 1/20th scale.

 

[glue-itcom]

Crosshead in context with the engine - I think the guide looks ok:

Let me know your thoughts

Here's a closeup of it

 

[Peter Twissell]

Looks to be nicely in proportion with the rest of the engine.
Good work!

 

[GrahamJTaylor49]

Hi Nigel,
Looking very nice, well proportioned and still shiny. Many years ago I turned my hand to a 2" Burrell compound showman's engine. Had me in tears at times but in the end I managed to finish it. It sat in my living room gathering dust and cobwebs until in the end I sold it and bought a new Triumph 900ST. The local gun shop, who was a client of mine, got me into long rand pistol shooting so I ended up making my own long rang pistol. More toys. Shooting pistols at up to 1000 yards on Stickeldown Range at Bisley. Not bad for a pistol. Sat on a sand bag, bolt action, 12" barrel from Doug Shillen, 2oz trigger, Burris 10x scope and wildcat 460 Wetherby necked down to 30 cal. 0.1" group at 200 mtrs. Great fun until our bloody government banned the hand guns. Enough of this twaddle, I am now building a Stuart Turner Major beam engine and having great fun doing it. Will attach a few photo's as it comes along. Anyway, I am now going to go out for a ride on the current motorbike, A Yamaha Niken. Funny looking thing with 2 front wheels, goes well though.
In the mean time everyone enjoy our hobby and stay safe.
Graham T. South coast of the UK.

 

[glue-itcom]

Now onto the crankshaft. If you remember my earlier design discussions I was struggling to see a way to getting a 6mm throw and hence 12mm stroke. Well, there are a few things that help this: 1. offset of the cylinder and curvature of the firebox 2. ability to lift the bearing blocks slightly 3. two-piece crankshaft and hence single piece conrod big-end.

So here is a sketch of the crankshaft:

I assembled and silver soldered this with a single piece main shaft. That made it easy to align everything and machine surfaces. One of the last actions was to then split this main shaft and machine back to the internal web faces.

Just to prove it still splits into two and that I didn't make a mess of the silver soldering:

A little bit of cleaning and then a polish and this will be ready. And change the bolt to something more subtle!

 

[glue-itcom]

and it clears...

The crankshaft clearance is looking good all round.

 

[Peter Twissell]

Looking good, Nigel!
Next challenge will be clearance for the eccentric straps.

 

[glue-itcom]

Looking good, Nigel!
Next challenge will be clearance for the eccentric straps.

Hi Pete, Yes, I think they will be a challenge. I'm not going to split them, I think I will use grooves pin/bolt running in the groove to align. Thanks, Nigel

 

[glue-itcom]

The phosphor bronze saddle that I made is being bolted to the boiler before I silver solder it in place.

I made the bolts from PB, avoiding brass parts being permanently fitted to wet areas in the boiler based on possible dezincification.

 

[glue-itcom]

The valve chest is made from two parts:

Making the bearings out of one part meant that it was all aligned. I then removed the centre section.

The valve chest is just 22 x 20 x 7mm.

I'm thinking of making an external nut from PB to make the gland for the push rod - is that ok?

 

[glue-itcom]

The Burrell steam valve is causing me some issues. My original thought was to build it into the side of the saddle. However, that feels difficult within the space available. I think I have 3 options and thought it would be good to share these and the design to date:

 

[Peter Twissell]

Hi Nigel,
My own preference would be towards creating the valve within the saddle, perhaps even using some parts of the standard valve.
Not the easiest option, but I am one for spending several hours on a single detail.
Other opinions may vary.
Pete.

 

[glue-itcom]

Hi Nigel,
My own preference would be towards creating the valve within the saddle, perhaps even using some parts of the standard valve.
Not the easiest option, but I am one for spending several hours on a single detail.
Other opinions may vary.
Pete.

Hi Pete, I do keep coming back to that approach. I may have to see if I can find some very small valve designs. Thanks, Nigel

 

[glue-itcom]

Sometimes I look at what I'm making and go back and look at some of the models my dad made in the 1980's. The comparison below with the clock and the valve chest plaque was just because I'm struggling to get the detail into the etching.

He etched, painted the numerals, cleaned the top surface and then silvered the dial. This clock is ~39mm high (bottom of feet to top of handle) and it works (it uses a wristwatch movement that he pulled apart and constructed on the back of the face).

 

[glue-itcom]

The original image I created had a jagged edge, this is an issue with powerpoint when you shrink the size right down. The best package for creating graphics that scale and keep their form is Inkscape, an upside is it's free, the downside is it takes time to learn how to use. The first one wasn't bad, but the ferric chloride was cold and I didn't leave it long enough. However, this gives you the scale of the part. The capital letters are 1.4mm high.

I warmed the ferric chloride up, I find the easiest way is to place the bottle into a bowl of hot water.

I then etched four more plaques and I think I now have a Charles Burrell nameplate.

 

[glue-itcom]

Looking in more detail at the steam valve design. The schematic looks reasonably simple. However, I've been looking at a number of references to try and improve my background knowledge of steam valve design.

My conclusions are very simple:

1. Smooth the steam flow path.
2. Can the valve reliably shut steam flow off completely?
3. Does the valve provide enough control?
4. Does the valve work at all pressures?
5. Are all parts resistant to corrosion?
6. Control rod must seal and still freely operate.

 

[glue-itcom]

In preparation for silver soldering the phosphor bronze saddle to the boiler I've been running some coupon tests.

Effectively looking at applying silver solder in different locations on the bolted sandwich of copper and phosphor bronze.

Interestingly the silver solder happily tracks (capillary action) through the joint, including through the threaded section.

The right hand side configuration appears to have given the most complete joint. I then sectioned the joints:

You can see that on the LHS the thread of the bolt has voids where silver solder has not tracked completely through all interfaces.

Left and right hand side parts are consistent through the images, although I have had to mirror some of the images to make this consistent (this doesn't affect the results).

The plan is to run some more tests, will post these as well if just to show consistency.

 

[smittman]

Hi Nigel, love your build so far. Are you going to put a sight glass on the rear of your boiler if so you could come off of it with your valve and then on to the valve box. You could still use the one coming up into your valve box straight up to the safety valve and save some precious heat loss by only running steam one way from your valve. Just a thought your build has helped lots on my build of the myfordboy traction engine. Especially making the saddle fit my boiler with a fly cutter. It saved me lots of trial and error. Thanks Dave (Smittman)

 

[glue-itcom]

Hi Nigel, love your build so far. Are you going to put a sight glass on the rear of your boiler if so you could come off of it with your valve and then on to the valve box. You could still use the one coming up into your valve box straight up to the safety valve and save some precious heat loss by only running steam one way from your valve. Just a thought your build has helped lots on my build of the myfordboy traction engine. Especially making the saddle fit my boiler with a fly cutter. It saved me lots of trial and error. Thanks Dave (Smittman)

Hi Dave,
The sight glass is not easy as the firebox is separate and so I don't have water on the rear face (the boiler extends into the firebox up to the hole in the top).

I might have to fit it into the rear panel and then pipe to the boiler, but this needs some design.

My intention is to line the firebox with a ceramic to direct the heat through the boiler and reduce losses.

Pleased this is helping with the MyfordBoy engine. Cheers, Nigel