Agnes.... 1/16 Scale Pollit & Wigzell Tandem Compound Condensing Engine.

[pgp001]

Cheers Jason, just what I was looking for.

I do like the idea of machining both parts in one go like that.

Phil

[pgp001]

Some more slight progress in the last few days.

The cylinder sleeve has emerged from a lump of cast iron.



I like mounting parts on mandrels using Loctite 601





The column has now gained some side webs, and tested for a trial fit with the cylinder sleeve.



Here is the embryo cylinder end cover being spot drilled for the stud holes using the DRO's PCD function.



The steam chest and its cover also came from a spare chunk of cast iron, here being sliced up with a solid carbide saw.





After finishing to size it too was spot drilled for the stud holes, in this case they are 12BA.



Then the outer face was pocketed out 0.010" deep.



The faces were then polished on very fine emery to remove all machining marks, and the pocket was roughed up a bit with a Burgess engraving tool.
The photo has not really shown it at its best on this one.



Phil

[pgp001]

OK, a few more bits to cross off the list.

Steam chest.









And its valve rod gland made using the method suggested by Jason. To give an idea of scale those threads are 1.2mm diameter.











Phil

[pgp001]

Next was a session of stud making on my Pultra 1770, I had to spend a while setting up all the capstan tooling but it works a treat.





The blued steel cladding will be held onto the cylinder using M1.2 screws, as I did not fancy breaking a tap in the cylinder at this point I made some threaded brass inserts to press in instead, these are only 2mm diameter and were made on the little Boley watchmakers lathe.



The piston rod gland was made using the same method as the valve rod gland.



Then the crosshead was made using a bit of gunmetal. This part is only 5/16" diameter.



Here it is on a makeshift 3/32" mandrel having the last cuts on the outer faces.







And the cylinder assembly so far.





Phil

[Jasonb]

Comming together nicely Phil, good to see the gland making method worked OK for you.

J

[Roger B]

Very nice work  I like the small turret lathe for stud making     

[Rivergypsy]

Nice work!

By the way, how do you plan to blue the cladding for this - rust or chemical? I only ask as i'm reading up on bluing the cladding for my compound.

[pgp001]

Re the bluing of the cladding.

I have not 100% decided yet, but a friend has recently blued some parts for a regulator clock using bluing salts which are heated until they melt and then dipping the parts in.
Unless someone has a better suggestion I think I will try that method on the cladding. The one on the barring engine is tiny, but there is also quite a bit of complicated cladding on the main engine cylinders.

Phil

[pgp001]

Connecting rod next I think.

The main problem when parts get so small is how to hold them without causing any damage, I like to machine as much as possible whilst the component is still part of the raw material.



Here the sides are being machined using a back stop to prevent any flexing.







Then once it has been parted off, the 1.2mm diameter bolt holes can be added by holding it in a watchmakers vice.



This gives an indication of just how small it is, there is even a bronze bush for the 3/32" little end pin.



Phil

[Rivergypsy]

Very nice - well done!

Good luck on the bluing too, and thanks for the info.

Dave

[pgp001]

I don't want to sound too smug (well maybe just a little bit) 

My little barring engine did better than I could have expected at the Bradford Model engineering exhibition today, I got one trophy for best "unfinished model", and another for best "general engineering" exhibit.

The entries are all voted for by the other members and not by judges. It makes it all worthwhile when your work is appreciated by others.

I didn't realise that I had accidentally moved the mode dial on my camera, and it has put star bursts on it for me as well. 

Phil

[Gas_mantle]

Congrats Phil, a well deserved award for a couple of fine exhibits 

[crueby]

Nice!

[Dave Otto]

Congrats Phil, that's beautiful!
Very nice work.


Dave

[b.lindsey]

Beautiful Phil, and well deserved recognition too.

Bill