Can some one please let me know where to buy a sheet of 0.005" PTFE from?

Thank you

Mansel

Always worth checking that you don't have a simple leakpath between portface and steam chest/cover . Most common causes are surface(s) not flat , raised burrs and deep scratches .

Not usually nescessary on little engines but workmen erecting full size engines often took great care to make mating surfaces flat on flat – sometimes even to the point of sraping them in .

I've always used Hylomar Blue (or SQ32M) for steam joints and never had a problem, rarely use a gasket.

Just apply sparingly to both surfaces of the joint, allow to become tacky and assemble.

As the joint is incredibly thin there is no problem with disassembly.

Lofty

Lasers are ace for doing gaskets

That hole in the centre of the ventruri support is 1mm and the hole near the edge is 1/2mm.

These are for vacuum valves and you cannot use any typle of sealant because of contamination.

Hi Mansel ,

The design of Mollyette seems to have varied a bit over the years but on mine the lubricator attaches by means of a little two bolt flange to front end of valve chest . Awkward to attach after cylinders are in frames so pre-fixing advised .

Mollyette would benefit from some upgrading – in particular by the fitting of proper sprung drop out axleboxes .

Regarding grooves for O rings there are proper design rules but on an engine like Mollyette with little power to spare I would use a bit of trial and error so as to get the O ring sealing but sliding easily in bore at same time . Try groove width of 1.25 times O ring diameter for starters and progressively make groove deeper until O ring is only just nipped between piston and bore .

Regards ,

MikeW

Edited By MICHAEL WILLIAMS on 24/07/2013 10:16:15

Loctite plastic gasket works quite well at ordinary steam temperatures .

Perhaps don't forget that many model and full size engines have been sealed successfully for many years without using any gaskets at all – just properly fitted parts and sometimes with a smear of red lead or putty thinned with oil .

MikeW

Hi Michael

Thank you for your very helpful posting. The Mollyette drawing is not good. If possible can you please explain the steam pipe fittings from the lubricator to the steam chest.

Mansel

Hi Mansel ,

I've put a sketch showing arrangement of lubricator and steam feed in your pm's .

Union connection shown may have to be angled slightly to clear axle .

Last part of steam passageway into oil tank is specified as being a ' fine hole ' – might be better to contrive a simple needle valve instead .

Mollyette is a tricky engine to get to run properly but very pleasing when you do .

Ask any further questions you wish .

Regards ,

Michael Williams .

Edited By MICHAEL WILLIAMS on 26/07/2013 23:10:50