A princess in the making

[darrene]

I've just picked up my first Princess Marina - a rolling chassis a friend found in a box of Dinky cars!
I was interested because I've heard it's a decent, basic design that's a very willing runner.

This one is definitely on the agricultural end of the engineering spectrum (that's not to say my skills would be any better ) it seems pretty 'vintage' and came with free dust and cobwebs.

Every nut, bolt and screw I've found to date has been loose. It's getting stripped, cleaned and reassembled. Although the tolerances aren't the closest, everything moves quite nicely and smoothly.
I think I can see why they're said to be pretty pokey - the steam chests look enormous given its size; bigger than the Britannia and Hall.

The lubricator eccentric is 'interesting' and I can only assume was because it was put on after the axle was assembled...

The water pump eccentrics by comparison retain the traditional collar approach, in which I've been replacing the huge slot-headed screws for some proper grub screws.

The hornblocks are ridiculously deep and will require some attention I think.

I had a poke inside the valve chests and noted the gaskets needed replacing. I am pretty sure they were just brown paper templates. They're very thin and fragile and I haven't come across gasket material like this before. Does anybody recognise it as actual gasket material?

Edit: I've just educated myself as to the use of oiled brown paper as steam gaskets. Every day's a school day (for me at least!)

As several owners seem to note, the tolerances between the main rod and crosshead slides is really minimal. One side seemed to start bind slightly on the bottom of the rod at back dead centre. This was solved by a tiny amount of filing of the hanger which allowed the lower guide to be dropped a fraction.

More pictures to come as I slowly reconstruct it.

I'm on the lookout for parts if anyone has any - there's a posting in the Buy/Sell/Exchange section

[darrene]

The steam chests are off - both held on by four of seven possible bolts. I've taken them off ostensibly to check and clean but wanted to chase the threads for the mounting bolts too, as a couple didn't nip up completely.

I was expecting them to be 2BA since that seemed to be the head size, however the TPI count of the bolts I removed didn't match the tap...interesting

The micrometer is telling me they're probably ME bolts; 3/16-40 to be precise. Slightly annoying as I dont have any ME taps. They're available though and don't cost the earth.

Of more concern is sourcing the remaining ME bolts, since my machining hasn't reached the dizzy heights of thread cutting yet.

I shall need to track down some unless by some miracle there is a very close match with something else

Darren

[don9f]

Hi, ME threads do use the Whitworth threadform but the pitch of a 3/16” Whitworth screw is 24tpi, a lot coarser than 40tpi. Could you obtain a 3/16” x 40 split die and make some bespoke screws? No real need to screwcut them.

Cheers Don

[norfolkandgood]

May 21, 2021 20:12:49 GMT don9f said:

Hi, ME threads do use the Whitworth threadform but the pitch of a 3/16” Whitworth screw is 24tpi, a lot coarser than 40tpi. Could you obtain a 3/16” x 40 split die and make some bespoke screws? No real need to screwcut them.

Cheers Don

You've answered a question I was going to ask with regard to Whit Form (WF) on M.E. taps and dies.
Guy

[darrene]

Cheers Don!
I thought I'd read they were based on the Whitworth thread but had indeed, struggled to find anything as fine as 40tpi.

I've followed your advice and picked up a die to go with the tap - I can turn down some hex stock and use that to make some up.

Thanks again!
Darren