Building a Boiler for a 3 1/2" Gauge Locomotive

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shoey51:
Sorry bout the leg pull mate ::)
your doing some realy great work there :D :thumbup:

sbwhart:
No Problem shoey you can't beat a bit of leg pull :)

Quick up date.

John has kindly given me a loan of some imperial step drills:- Thanks John

But I found a problem in using them three of the holes are right up against the flange and the drill will catch it.

So I ground a 3/8 drill up as suggested by Rob :thumbup: but it cut too 0.020" over size but I found a 23/64 drill among my stash, most of these drill I inherited from my Dad and its a weard and wonderful collection, but don't knock it you can't beat weard . :nrocks: . So I ground that up and it gave a hole that cleaned up nicely with a 3/8 hand reamer.

Hand a practice with the scrap tube plate, I used a drop of milk as a cutting fluid as suggested by John:- Semi skimmed worked ok

And this is the result.

The bit of sheet is 0.5 mm thick

Top Job

I then drilled 3mm pilot holes in the former using the mill DRO this is the set up.

And made a stubby centre pop out of a bit of 3mm silver steel (drill rod)

And marked the position of the holes in the new boiler tube.

I decided not to drill the tubes just yet as I wont to ask the boiler inspector a couple of questions, I'm a bit concerned with the closeness of some of the tubes to the flange, the drill will just kiss the flange, and I was wondering if a should slightly reposition these holes.

So I'll get on with something else.

Stew

madjackghengis:

--- Quote from: P.J on April 27, 2010, 03:33:23 PM ---
--- Quote from: sbwhart on April 27, 2010, 02:33:46 PM ---
Stew

Who knows that "drilling soft copper can me tricky" :bang:

--- End quote ---

Not sure it's possible given the shape of the plate you'r drilling... But you can try
clamping the copper plate between two thicker pieces (1/4") of aluminium and drilling through all 3.
This usualy results in a perfectly round hole with nice crisp edges when working with soft or thin materials.. allthough marking out and making sure the hole ends up where it's ment can be a bit of a pain..

Maybe it's possible to turn a 1/4 plate with an OD fitting the ID of the copper cap, mark out on the alu plate and clamp the whole contraption to a second alu plate, drill the holes and Bobs your uncle? :)

Keep up the good work :clap:

/PJ

--- End quote ---
Stew, if you've got a bunch of holes to drill in copper, such as a tube plate or the like, you can take a drill bit, and use a stone to make the cutting lips of the bit parallel with the centerline of the bit, essentially giving it zero or negative rake, and it will drill far better. Milk is a good cutting solution especially with modified drill bits, for copper. The same is true about bits drilling into any copper alloy, doing this will keep the bit from jumping in full depth, and half way off the mark when you just "touch off", especially good for aluminum bronze which has broken my heart many times, as I sat there and stared at the remnants of the drill bit remaining in the hole, and the shank still in the chuck. mad jack

shoey51:
Jack I have heard of that solution myself but have never tried it.
keep up the great work Stew :thumbup:

madjackghengis:
Stew, I use copper plate to back up steel which needs welding together, but has a large gap between pieces, the weld doesn't stick to the copper, it sinks the heat too fast, and it allows a second pass, will full power, from the second side, knowing your first weld has full integrity. Getting the blocks and pieces of copper to fit where they need to go usually means cutting and drilling. I used to have a set of drills just for copper and such alloys, but I don't do as much of that work any more, so I experience the joys of breakage more often.
You can take an actual dull drill bit, lay the cutting edge on a stone with the bit parallel to the table, and just cut about thirty thousandths of a flat, and then flip the drill, and match the flat, keeping the point centered, and it will cut well. Urine is supposed to work well as a cutting fluid too, but I haven't ever considered trying it, my machines might think bad thoughts of me. I will repeat, I have seldom seen such fine hammer work, few people have the patience to take the time and do it right and try to muscle it to the end, that last piece you show looks almost like it went through a die, just that little wiggle in the edge gives away the hand work. I'm really looking forward to see this build run, you are a smith, by any good judge. :jaw: :jaw: :clap: mad jack

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