Author Topic: 3.5" Northumbrian Loco  (Read 2151 times)

Offline Baner

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3.5" Northumbrian Loco
« on: July 03, 2018, 03:36:21 PM »
Hi

It has been so long since I started this loco that I can't remember when I did. The original was serialised in Model Engineer beginning in 2009 so I'm guessing I begun maybe 2010. In that time there's been brief flashes of activity followed by years of idleness. I'd recently got money enough to buy some more of the castings and so set to work again.
Here's the progress so far:
Northumbrian by DAVID BANER, on Flickr

Northumbrian by DAVID BANER, on Flickr

Couple more:

Northumbrian by DAVID BANER, on Flickr

Northumbrian by DAVID BANER, on Flickr

Dave.

« Last Edit: July 05, 2018, 01:10:23 PM by Baner »

Offline Baner

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Re: 3.5" Northumbrian Loco
« Reply #1 on: July 03, 2018, 04:04:03 PM »
First little job was to finish off the front wheels. The crank pins were all that was left:

Northumbrian by DAVID BANER, on Flickr

Pretty simple parts.One end of piece of 5mm Silver steel was turned down to 4mm, the other end was turned down to 3.2mm and threaded 5BA.

Then the wheels were clamped to the mill table, orientated so that the drill would break through safely in the table slots. A piece of 8mm HSS was chucked and used to line up the axle hole with the spindle.

Northumbrian by DAVID BANER, on Flickr

The DRO was zeroed then the chuck moved 14.2mm across and the crank pin hole drilled and reamed 4mm. 

Northumbrian by DAVID BANER, on Flickr

Finally the Crank Pins were Loctited home. (The stop pins on the eccentrics were loctited at the same time.)

Northumbrian by DAVID BANER, on Flickr

The couplings will be next and after that hopefully start to tackle some castings.

Dave.
« Last Edit: July 05, 2018, 01:17:18 PM by Baner »

Offline scc

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Re: 3.5" Northumbrian Loco
« Reply #2 on: July 03, 2018, 07:40:54 PM »
 :ThumbsUp:Nice

Offline zeeprogrammer

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Re: 3.5" Northumbrian Loco
« Reply #3 on: July 03, 2018, 08:12:05 PM »
Looking great thus far and I'm looking forward to more.  :ThumbsUp:
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline Baner

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Re: 3.5" Northumbrian Loco
« Reply #4 on: July 05, 2018, 01:40:30 PM »
Thanks Terry and Zee for looking in.

The couplings are next. Enough 3/8" square stock is cut to length to make 2 couplings. It is faced off, centred and spot drilled on both sides:

Northumbrian by DAVID BANER, on Flickr

The piece is moved to the lathe and centered in the four jaw:

Northumbrian by DAVID BANER, on Flickr

It's then turned down to 4.7mm for 12.7mm and threaded 2Ba:

Northumbrian by DAVID BANER, on Flickr

The process is repeated on the other side to give this:

Northumbrian by DAVID BANER, on Flickr

Dave.

Offline b.lindsey

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Re: 3.5" Northumbrian Loco
« Reply #5 on: July 05, 2018, 01:47:15 PM »
Nice looking loco David. Looking forward to more of your progress on it.

Bill

Offline Baner

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Re: 3.5" Northumbrian Loco
« Reply #6 on: July 05, 2018, 02:18:05 PM »
Thanks for looking in Bill

Continuing with the couplings. The material is then cut in half and clamped in the mill. The threaded section is standing on parallels whilst the square is butted up against the stop which is flush to the side of the vice. The square section is indicated to idiot check the set up:

Northumbrian by DAVID BANER, on Flickr

Part is then milled to finished height and a 3mm slot drill is run through, 4 passes to depth and  2 to finish sides. Light cuts are needed to stop the part being kicked out of the vice:

Grinding vice by DAVID BANER, on Flickr

Next is to drill a hole through the forks but a drawing review showed a minor problem:

Northumbrian by DAVID BANER, on Flickr

These 2 couplings are supposed to be joined together with a pin, but as drawn, (guessing at all the missing dimensions) the hole is in the wrong place, or the slot not deep enough or the radius is wrong or a bit of everything. I decided instead to reduce the width to 1/4":

Northumbrian by DAVID BANER, on Flickr

Then drill through 1/8" at 1/8" in from the edge. I then radius the part on the disc sander. Set up here is simple: a bit of scrap sheet steel is drilled through near the edge, a bit of round stock is inserted to use as a pivot and the part is turned back and forth by hand:

Northumbrian by DAVID BANER, on Flickr

Not the most accurate solution but very quick and good enough for this part:

Northumbrian by DAVID BANER, on Flickr

Dave.
 

Offline Baner

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Re: 3.5" Northumbrian Loco
« Reply #7 on: July 10, 2018, 01:39:31 PM »
Started work on the axle pump. I thought the casting would be a bit better than it was -  getting two cylinders perpendicular doesn't seem very difficult...
Anyway, bit of eye balling got it clamped in the vice near enough, and flats were very lightly cut on the port face and chucking piece:

Northumbrian by DAVID BANER, on Flickr   

The part was flipped onto parallels and the process repeated giving two parallel references:

Northumbrian by DAVID BANER, on Flickr

Flipped on it's side and clamped on the references a third larger flat is machined perpendicular to the last, then flip again and repeat:

Northumbrian by DAVID BANER, on Flickr

This gives a place for the vice to grip well enough to machine the ports.

Offline Baner

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Re: 3.5" Northumbrian Loco
« Reply #8 on: July 10, 2018, 02:17:56 PM »
Now that I can grab the casting properly the ports are fairly simple. The port face is milled to finished height, and drilled through 3.8mm. Following that the port is drilled 5.5mm to about 8mm deep, and the top 4mm tapped 1/4" x 40:

Northumbrian by DAVID BANER, on Flickr

A stainless ball needs to seal on the lower face so a cutter is needed to form a convex surface. A simple D-bit is made for the task:

Northumbrian by DAVID BANER, on Flickr

 The through hole is then reamed. Common practice to seat the ball is to hit it with a hammer, though I've heard pressing it in is better or maybe lapping. Does anyone have any experience or suggestions?

Moving on, the part is flipped and the other port receives similar treatment.
A side port is also required for the water outlet. The part clamped on its side and a piece of 4mm silver steel is inserted through the port. An edge finder is then touched off on the side of the rod to find the port centreline.

Northumbrian by DAVID BANER, on Flickr

 The 4mm rod is then removed and the port face edge is found. The table is moved in 5mm and drilled through breaking into the port. Final operation is spot facing to provide a seat for a future bushing:

Northumbrian by DAVID BANER, on Flickr

Dave.

Offline Baner

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Re: 3.5" Northumbrian Loco
« Reply #9 on: July 10, 2018, 02:53:49 PM »
I hope I'm not posting to much detail about simple operations; I enjoy reading about set ups, so I'm tending to post about them too. That said I'd welcome any suggestions as to how I might have done things better.
Next job was the pump barrel . A center point was eye balled then a little dimple was made with a spotting drill. Then into the four jaw holding on the previous milled flats, the dimple is centered and the barrel  lightly faced and center drilled. The tailstock center was brought up for support and the outside of the barrel trued up:

Northumbrian by DAVID BANER, on Flickr

The center was swapped for the fixed steady and the barrel faced to length:

Northumbrian by DAVID BANER, on Flickr

About the time of that photo I realized I didn't have a boring bar or measuring tools small enough to finish the bore. :facepalm: So I'll have to order a reamer to finish the job. Luckily everything is only rough  turned so the part can be removed and something else done on the lathe while I wait.

Dave.

Offline zeeprogrammer

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Re: 3.5" Northumbrian Loco
« Reply #10 on: July 10, 2018, 05:25:00 PM »
I hope I'm not posting to much detail about simple operations;

Not from my standpoint. I have a lot to learn.

I did some googling about the Northumbrian but I'm not sure I'm looking at the right thing.
Do you have a photo of what you're building?
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline crueby

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Re: 3.5" Northumbrian Loco
« Reply #11 on: July 10, 2018, 06:24:48 PM »
I agree - detail on operations is great, there are so many ways to do things, I pick up new techniques all the time from builds like this!
 :popcorn:

Offline Baner

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Re: 3.5" Northumbrian Loco
« Reply #12 on: July 11, 2018, 02:26:05 PM »
Thanks Zee and Chris, I'll carry on then.

The engine is designed by Tony Weale and is supposed to be an updated version of 'Rainhill', a freelance design by LBSC based on the first successful locomotives. It's basically a boiler on wheels, Zee.
Here's a photo of Tony's engine:
Northumbrian by DAVID BANER, on Flickr

And this is one completed by Doubletop whose build log you might have seen a long time ago:

https://www.homemodelenginemachinist.com/threads/small-locomotive-boiler-me-northumbrian.14718/

Doubletop Northumbrian by DAVID BANER, on Flickr

There are a few old drawings of the actual engine floating around but the best one I've found is this:

Northumbrian3 by DAVID BANER, on Flickr

I'm hoping to add a few bits and pieces to my model based on the drawings, and tidy up a few things that aren't great like the steam plumbing and backhead, and I'm not happy with the tender at the moment either.
It's not likely to get much if any track time so it'll need to look good on a shelf.

Dave.




Offline zeeprogrammer

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Re: 3.5" Northumbrian Loco
« Reply #13 on: July 11, 2018, 02:37:20 PM »
Thanks Dave! I'm looking forward to seeing more.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Baner

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Re: 3.5" Northumbrian Loco
« Reply #14 on: July 17, 2018, 02:50:17 PM »
Some work on Pump parts:
Here's a quick drawing to help make sense of these parts:

Axle Pump by DAVID BANER, on Flickr

Part 1 is the top cap which seals the outlet and limits ball travel, an easy little job:

Northumbrian by DAVID BANER, on Flickr

Part 2 is one half of a fabricated elbow. A bit of 3/8 round stock is chucked and drilled 3.8mm at 12mm deep. Being a ball seat this is also reamed 4mm:

Northumbrian by DAVID BANER, on Flickr

It's then of to the mill and cross drilled 4mm breaking into the previous hole. Then an 8mm slot drill cuts a counter bore:

Northumbrian by DAVID BANER, on Flickr

back to the lathe and parted off:

Northumbrian by DAVID BANER, on Flickr

There are two of Part 3 which are soldered onto the inlet and outlet as per the drawing. The end 4mm is turned down to 6.35mm and tapped 1/4x40. About 3mm behind is turned to 8mm to fit in the counter bore made in the elbow. A 3mm hole is drilled through, then a parting tool is used to turn a small boss to register in the 4mm hole in the elbow. This little boss is probably not neccesary but it seemed like it would help seal if the solder didn't flow properly. Then the lot is parted off:

Northumbrian by DAVID BANER, on Flickr

Dave.
 
« Last Edit: July 17, 2018, 03:07:44 PM by Baner »