Slow progress!

[Deleted]

Here is the latest on my US 0-8-0 switcher.
Since Christmas I have been focusing on the mind numbing mass of parts in the spring rigging.
As a bit of light relief I made the brake hanger brackets and turned the wheels. These are 'Caribou' castings and the balance weights are totally wrong so I had to machine these off. Good job really as I was supplied 2 odd castings with totally different weights!
As far as the drawings are concerned I'm still struggling with the Baker valve gear, there just doesn't seem to be any geometric data available for designing from scratch.
I've also done some basic design on the boiler which is going to be a monster by 3.5" gauge standards at 5" diameter (same as a 5" gauge 'Maid of Kent' if I remember right), bear in mind this is a 'shunter'!

[chameleonrob]

it looks good, wish mine looked as good but I favor "agricultural engineering" ie welder and big hammer. by the way that looks like an interesting spring arrangement on the rear axle.

rob

[baggo]

Hi Usra,
very nice indeed!
K N Harris wrote some quite detailed articles in ME volume 131 on the Baker gear and gave proportions etc for the various gauges. If you can't access them I can scan them and send them to you. Martin Evans book is not very helpful but does give a few pointers. If you are really struggling I may be able to help with the design,

John

[spurley]

Hi Usra

I am wondering if the 'odd' wheels you mention above are actually correct and are supposed to be for the driving axle? There would be more mass on that axle; big end, return crank etc. which would require different balancing (in full size anyway) than the coupled wheels. Might be worth a double check before you get much further? Only a thought!

Cheers

Brian

[Deleted]

John, I would be very grateful if you would scan the stuff in Model Engineer.
The Martin Evans book is pretty hopeless on Baker gear and the design for 'Caribou' is hopelessly out of scale so I would only use that as a very last resort. Part of the problem is due to the, at least, 2 different sizes of short gear frame used in the later steam period and the difficulty in finding dimensions.
As to the wheels, the 2 odd ones were completely wrong; I can only assume for some other loco as the inner edge of the balance weights were concentric with the wheel tread!
On the prototypes the balance weights on the main drivers are only slightly different to the others, top speed of these beasts was no more than 45mph and they probably spent most of their lives at under 25mph.
The prototype balance weights also extend much further above the wheel boss than those on the castings so I am into making my own weights.

[baggo]

Hi Usra,
send me an email and I'll get them off to you. I've just noticed that Tee Publishing sell a book on Baker gear by J W Harding (£5.50) which may be of interest.
John

[Deleted]

Thanks for the scans John. Haven't had time to fully digest the stuff yet but it looks really helpful.
Here is a wheel from the real thing from those who may be interested: