My N&W class A 1239 (gauge 5", 1 in 10 scale)

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GregE
Posts: 49
Joined: Mon Jan 19, 2009 10:53 pm
Location: Minneapolis

Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by GregE » Sat Nov 02, 2019 4:52 pm

Very cool to see your process.
Thanks for posting!
Greg Easter

Asteamhead
Posts: 437
Joined: Tue Jul 31, 2012 1:59 pm
Location: Germany, Duesseldorf

Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead » Mon Nov 18, 2019 3:17 pm

Hello GregE,
Please see some more of that stuff. The center part is made of several parts, which allows individual milling and drilling :idea: before beeing soldered.This makes it a great easier to drill the (hidden) valve seats. Centering is made by means of separate precise O-ring seats. Those of greater diameter are turned on the cover plates while the smaller seats are turned and inserted separately.The plan advantages as intended :D .The steps of making are shown.
Different from the usual method, stuffing boxes will be inserted into the plates from the outside :idea: .That makes assembly a lot easier!
Threads M 10 x 1 (about R 1/8) in the cover plates are used to fix mandrels, which allows precise finishing.
Necessary air chanals will be drilled after all parts are inserted and final soldering yet.

All the best
Asteamhead
Attachments
A CC pump, center piece _2175red.jpg
A CC pump, center piece. O-rings and seats for stuffing boxes are shown
A CC pump, parts of center piece_2178red.jpg
A CC pump, parts of center piece. Method of centering to be seen
A CC pump, cover plates and lanterns_2183red.jpg
A CC pump, cover plates and lanterns. Valve seats / groves are to be seen
A CC-pump, valve plate, method of making_2163red.jpg
A CC pump, method of making valve seats
A CC pump, cylinders_2171red.jpg
A CC pump, cylinders

Asteamhead
Posts: 437
Joined: Tue Jul 31, 2012 1:59 pm
Location: Germany, Duesseldorf

Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead » Mon Dec 02, 2019 2:13 pm

Hello friends of the N&W,
First intermediate part was done! Silver soldering all the fabricated parts (12) made of bronze worked out fine :D . A lot of preparation and fixing some parts was necessary however.
Small pieces of silver solder were placed inside the lanterns at several places. Some more was added carefully during the process from the outside.
Accuracy and centering wern*t affected :D
The chanals are to be drilled yet. Stuffing boxes and valves will be added finally.

Asteamhead
Attachments
A CC-AP, intermediate part, silver solderd_2209red.jpg
A CC-AP, intermediate part, now silver soldered
A CC-Ap, intermediate part_2201red.jpg
A CC-AP, intermediate part. Threads for stuffing boxes and valve caps are to be seen

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JBodenmann
Posts: 2985
Joined: Sun Oct 26, 2003 1:37 pm
Location: Tehachapi, California

Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by JBodenmann » Wed Dec 04, 2019 8:03 pm

Hello My Friends
Excellent progress on the pump. What sort of piston rings do you plan on using?
Jack

Asteamhead
Posts: 437
Joined: Tue Jul 31, 2012 1:59 pm
Location: Germany, Duesseldorf

Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead » Fri Dec 06, 2019 3:40 pm

Hello Jack,
Thank you for your interest!
For turning pistons and piston rod was one of the next steps, I made one set just today :) .
The steam (HP) piston got a set of two standard piston rings of grey iron. By the way the same size which I used with the piston valves of the A :idea:
The piston was made as small as possible (as with the prototype) to get a long stroke of 1 ".The (LP) air piston holds just one O-ring with a very slight fit inside the cylinder. This combination worked out best already with the air pump of my DB class 44 engine, which I built some 40 years ago.
Thus the air piston is a bit smaller than that of the steam cylinder. This will ensure the steam piston will stop the movement in any case :idea:
The steam piston is connected to the rod by means of a fine thread, whereas the air piston got a tapered seat, fixed by a nut.
Thus the set may be removed upwards very easily: Just the upper and lower cover plates and the (LP) air piston are to be removed before.
LP steam and HP air pistons will be arranged the same way. Yet the HP air piston will receive piston rings instead in favour to reduce friction :?: .

Asteamhead
Attachments
A CC AP, pisons in upper position_2218red.jpg
A CC AP, HP steam piston and LP air piston at upper position. Minimum distantance between air piston and intermediate section can be seen
A CC-AP, pisons_2216red.jpg
A CC AP, pistons at lower position.
A CC AP, piston rod with LP  air piston removed_2221red.jpg
A CC AP, piston rod with LP air piston removed

Asteamhead
Posts: 437
Joined: Tue Jul 31, 2012 1:59 pm
Location: Germany, Duesseldorf

Re: My N&W class A 1239 (gauge 5", 1 in 10 scale)

Post by Asteamhead » Sat Dec 28, 2019 12:05 pm

Hello friends,
Some more photos (will be the last this year).
Constructing the valve head of that minor size given by the prototype was a challange :!: . Having constructed several working pumps for my former engine even smaller than this CC pump, I'm confident all will work as intended.
Instead of a complicated cast upper cylinder cover including the valve chambers, I decided to make it of separated parts which will be silver soldered into one piece. Thus the steam chanals can be drilled much easier :D . Short pieces of tube inserted between the separate parts will stop the silver solder filling the critical small drills by accident :idea:. All parts were made of bronze in favour of safe soldering. Look, using bronze rather than brass will give you a second chance in case the solder didn't make it into each part. Just put the piece into whinegar and clean it by means of a simple ultrasonic bath and try again :D .
Diameter of the drills is 2 mm, respective 4 x 1 mm inside the valve sleeves. More about those parts will be reported next year.

Wish all of you a Happy New Year!
Asteamhead
Attachments
CC AP_2258red.jpg
CC pump with cylinder head
CC AP, main valve housing_2249red.jpg
CC pump, drilling and milling the main valve housing
CC AP, auxilary valve housing_2235red.jpg
CC pump, milling the auxilary valve housing
CC AP, exaust stem passages made as pair_2242red.jpg
CC pump, milling the exaust steam passages as pair

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