LBSC's RODEAN

[manofkent]

Hello.

Rodean is well underway in 3.1/2" Gauge - working to drawings from Reeves.

I have a query on the size of the trunnion blocks.

I have carefully machined out all the grooves to fit the expansion link.
I was just about to machine the sides to 5/8" width per plan when I noticed how thin the walls would be. 
Checking the drawings I reckon the inside valve gear trunnion block should be 3/4" wide - not 5/8" as drawn.
Similar size confusion exists with the outside pair, and even the drawings specify 7/8" before (what seems to be 1/16") bushes so 3/4" would be right for this as well. 

Anyway - has anyone who has built this loco any recollection of "funny business" around the size of the trunnion blocks?

Any help gratefully received.

Many thanks

John

[jma1009]

Hi John,

I recall considerable difficulties and complications in completing the valve gear to the drawings discussed by builders of LBSC's 3.5"g SR 'Schools' design.

I have never seen one running.

I suggest you go back to basics and get a GA from from the NRM, and also brush up on the computer simulation for the valve gear in miniature.

From what I recall the problems you have described are the least of your worries.

Cheers,
Julian

[Alan]

i have always been under the illusion that LBSC almost guaranteed his locos would run 'straight out of the box'. Im sure i have read that in one of his articles somewhere.

[manofkent]

Thanks Julian and Alan.
I have many happy memories of driving a 3.1/2" schools around the track as a teenager. It was to LBSC's design, and ran well - you could load it with passengers and, provided you were careful pulling away it would cope with a good load.
I do recall it could get a bit "lumpy" if you notched it back more than about 1/4 travel. But so did a lot of locos.
At my club then there was also another schools - "Sevenoaks" again built to LBSC's design which ran well, and was steamed by some pupils of Sevenoaks school who owned it.

So I reckon at my skill level the LBSC valve gear will be "good enough for me!"...

I have worked out the inside valve gear measurements again - there is a rocking lever which attaches to the trunnion link which was not shown in the plans of the link. This takes up the 1/8" slack that concerned me. Ho hum - another part to make ..

John