CONWAY 0-4-0 3 1/2" GAUGE LOCO

[Jo]

But speaking of journeys Julian and I are off on a bit of a trek today. I had a cheeky bid on a part built Simplex,
(a 5" gauge 0-6-0) on Ebay  and I won it 

So thats another one on the to do list 

Hey Jo I think I have caught this compulsive buying bug 

 

[Firebird]

Hi

Ok Joe enough said

Heres what todays little trip yeilded

Back to Conway. The valve chests are first centre drilled then chain drilled with a 1/4" drill then machined out with a 1/4" cutter

8 fixing holes drilled. I used the DRO to drill all the holes

Cheers

Rich

[J.L.]

Hello Rich,
As a novice,I can drop into this wonderful thread almost anywhere and learn so much .
Superb build. Your photos are self-explanatory.
John

[Firebird]

Hi

Thanks John 

More drilling and tapping of the cylinders. Once again using the DRO

The valve chest covers are a straight forward job as per the plans and again using the DRO. All the bolt holes are drilled for 3mm bolts and the 2 holes for the steam inlet are tapped 4mm

The valve chests are held in the mill vise and the edge found with an edge finder. Then using the DRO centre drill for the valve rod

In the lathe with the 4 jaw chuck centred with a spring loaded centre and DTI

Drill and ream 5/32

I have a set of transfer punches

Which accurately centre punch the opposite side

The reamer is no where near long enough to go all the way through so I have just drilled with a long series 5/32 drill. My tailstock DRO is useful for depth drilling

Finally drill and tap 3/8 x 32. The tapping size is 11/32" luckily I had an 11/32" end mill to flat bottom the hole before tapping

Now all I have to do is repeat the process on the other valve chest

Cheers

Rich

[Kim]

Nice progress, Rich.

That picture of you holding one of the cylinders really shows the size!  This is much bigger that I've been picturing!

Kim

[Firebird]

Hi

Thanks Kim 

Heres something I should have done before machining the steam chests. 

Make the slide valve rod glands.

Here the phospher bronze has been turned down to 1/2" then turned down to 3/8" and screw cut 3/8  x 32. In the rotary table to have 8 holes drilled around the edge

Part off and make another

Put the valve chest back in the 4 jaw and re align with the DTI. Screw in the gland and drill and ream. This ensures that all lines up perfectly

Turn the bosses on each end

Thats better

Cheers

Rich

[Tennessee Whiskey]

Rich, I haven’t commented much, but, I have been faithfully following your build. The work is spectacular and the photos and documentation are truly top notch. A lot of us say: “filing that away for future reference “; well if I ever have the time to pursue a loco, I’m following this build  .

Cletus

[Firebird]

Hi

Thanks Cletus 

You may have noticed on the drawing that I penciled in to drill and tap 1/4" x 32 in the end of the boss. Thats because when I drilled through with the 5/32" it touched into the centre drilled hole    so I had to make a couple of little brass plugs

While I am set up for screw cutting 32 tpi I made the piston rod glands

The slide valves are of phosphor bronze. I had to use a bit of round and machine down to 1 1/16" x 7/8"

Then lots of little milling operations with the help of DRO

Cheers

Rich

[Firebird]

Hi

A pair of slide valves

A pair of valve rods

A pair of piston rods. I have used 1/4" BSF which is 26 TPI simply because thats what I have

Moving onto the pistons. Because I have gone with cast iron cylinders the pistons also are going to be cast iron. I decided to have a practice on a bit of scrap steel first.

Turn to 1 3/16" and check for size with one of the cylinders

Cut a ring groove. I have used a small parting tool that is not quite a 1/16" wide so after the initial cut the groove has to be widened a gnats

Try a ring for fit

All looked well so I moved onto the cast iron. Firstly turn to a .010" over size

Cut 2 piston ring grooves

Drill and tap 1/4" x 26 BSF.

Then drill with a letter D drill which is a few thou under a 1/4" for a depth of 1/4". The piston rod is held in a collet in the tail stock and turning the chuck by hand is screwed in tight into the piston. The 1/4" piston rod pulling in tight into the letter D drilled portion. This ensures the piston rod and piston are in line

Part off

Try a piston ring

The piston rod will next be held in a collet in the head stock and the piston turned to a finish

Cheers

Rich

[zeeprogrammer]

As a novice,I can drop into this wonderful thread almost anywhere and learn so much .

Ditto.

Rich's threads was one of the first I came across when I joined the forum. Always enjoyable.
Always hoping for a peek out his windows too. 

[Firebird]

Hi

Thanks Carl 

With both pistons and rods assembled its in the lathe in a collet to finish to size

<a href="https://www.youtube.com/watch?v=0Awmhihs55U" target="_blank">http://www.youtube.com/watch?v=0Awmhihs55U</a>

A thou at a time until a nice fit is obtained

To help with fitting the pistons into their cylinders I turned up a bit of steel tube

Fit a pair of piston rings

Liberally coat in oil and fit the piston into its guide. Then hold the guide into the cylinder and push the piston in

<a href="https://www.youtube.com/watch?v=ycxjKZu-e40" target="_blank">http://www.youtube.com/watch?v=ycxjKZu-e40</a>

The slide valves each need a nut. 3/8" square stainless steel is called for so in the mill to square off a bit of 5/8" round stainless steel bar

Drill, ream and tap as per the plans ecept that I have used 3/16" unf for the grub screw as I had some stainless ones

Cheers

Rich

[zeeprogrammer]

How did that steel tube guide help in getting the piston in. Keeps it straight and lined up?
How was that different than getting it into the steel tube?
Thanks.

[Firebird]

Hi Carl

Each end of the cylinder has a recess of 1 1/4" machined into it to locate the cylinder covers. The piston ring enters this first making it difficult to squeeze the ring into the 1 3/16" bore. The steel tube has a bore of 1 3/16" the same as the cylinder and the first bit of the tube outer is turned down to 1 1/4" which sits in the recess. By keeping pressure on the tube the piston can be pushed through the tube and straight into the bore.

Cheers

Rich

[Firebird]

Hi

The expansion links and die blocks are next on my agenda

You will see from the drawing that the expansion links (and the die blocks which are not shown) have a radius of 4 9/16"
a diameter of over 10". I have a 4" rotary table and a home made 7" rotary table but clearly the are no where near big enough. 10" rotary tables are way beyond my budget although I have had the need to machine large arcs/curves on other projects. On those I have managed to cobble something together but its been far from satisfactory. I have had an idea in mind for some time so now was the time to put the idea into practice by making an 11" rotary table.

Its basically a car brake disc, nicely machined on all surfaces. A bit of 10mm thick steel plate with another steel disc an exact fit in the centre of the disc bolted to it. the disc revolves around the steel disc. Another large disc this time of 1/4" thick brass fits inside the disc and bolts down with springs on the bolts to provide pressure while still leaving the disc free enough to turn

The brass disc is centre drilled which allows me to centre it in the mill

<a href="https://www.youtube.com/watch?v=zCeSvCy-9Pk" target="_blank">http://www.youtube.com/watch?v=zCeSvCy-9Pk</a>

A circular piece of 20mm thick MDF is fitted on top with 4 counter sunk 6mm socket head screws. The MDF is sacrificial and will be replaced whenever neccacery. I printed out a 360° protractor, I had to print on 2 sheets of paper and join in the middle as a guide. The table is hand operated by a piece of steel bar inserted into the disc vents. An adjustable stop from a piece of angle iron and a bar bolted to the underside of the disc with 2 6mm bolts.  2 bolts are fitted into the slot in the angle iron as adjustable stops

Total cost, well next to nothing. The disc I got from work (one of those things that had been lieing around for ages) and the rest came out of the things that will come in handy one day box.

Cheers

Rich

[zeeprogrammer]

Nice one. That's something to remember.