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2mmFS Boiler Fittings Without A Lathe

Ian Smith

Entry posted by Ian Smith

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A little more progress with the Metro Tank. I have now made some of the boiler fittings (Dome and Safety Valve cover). Unfortunately, I do not possess or have access to a lathe so these have been turned up in an electric drill using needle files.

 

To produce the parts, I used an electric drill, a vice (big enough to hold the drill), various needle files, wet and dry emery paper, and a vernier caliper.

 

The material used is 1/4" round bar, chosen because the widest point on the Dome (the larger of the two parts) was about 1/4" diameter in 2mm scale.

 

I mounted the electric drill in a vice and made sure that it was stable and wouldn't move. A short length of brass bar (about 2") was mounted in the chuck and the whole piece blackened with a permanent marker - this allowed me to mark the top and bottom of the part to be turned up (I also marked the extent of the narrowed portions so that I didn't take off too much material).

 

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The drill mounted in the vice, the turning of the dome is well underway.

 

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Illustration of how I held the file so that if it snagged in anyway there was no danger of the handle of the file from going into my hand or wrist. You should also ensure that you have no loose fitting clothes or hair that could get caught in the spinning drill too!!!

 

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After the parts have been turned to shape, they were separated from the bar, then the flat bottom of the parts were filed and sanded to shape so that they would sit comfortably on the eventual boiler - to complete this, a piece of emery was wrapped around a boiler diameter sized piece of brass tube and the base of the part rubbed back and forth until a satisfactory fit was achieved.

 

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The parts were offered up to a piece of boiler sized tube on a regular basis to ensure that they would sit vertical and snuggly.

 

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The completed parts along with the mandatory coin to illustrate the finished articles (the top hat shaped piece will eventually form the vacuum cylinder below one of Richard Brummitt's GWR Siphon kits.

 

Ian

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Mikkel
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Many thanks for posting this, Ian. I've always been slightly mystified when people said they did these things without a lathe. Now I get it. Great illustrations and well described, and the results look like something I'd pay a lot of money for :-)

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scanman

And I've just spent £600 on a lathe...!

 

Well done Richard - very neat. I like the 'Metro's as well, so I'm follwing this closely. I'll prbably be in line for one of Richard Brummitt's tho, by the time I've finished everything else I want to do!

 

Regs

 

Ian

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richbrummitt

And I've just spent £600 on a lathe...!Well done Richard - very neat.

I think you mean Ian :wink_mini:

I like the 'Metro's as well, so I'm follwing this closely. I'll probably be in line for one of Richard Brummitt's

I've to finish it first, and I'm not the only person working on one. Mine will be a large 'metro' whereas I know the other, when it appears, will be small.

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mmagliaro

Brilliant trick of sanding the bottom of the dome over a piece of tubing like that.  I have just turned two brass domes of my own, and rough-filed the bottoms, but I have been puzzling over how I would get that bottom curvature to at least be close to my boiler radius.  Great idea.

 

Incidentally, turning model parts in a hand drill works well for a lot of things, including even turning down wheel flanges.  It's not as accurate as a lathe, of course.  But in my experience, we really don't need that level of precision in our models.  A decent electric drill turns true on its axis,

and we aren't putting a lot of cutting pressure on it.  The normal issues that one addresses with a lathe such as run-out and spindle deflection really don't matter as much as you might think for situations like this.

 

After all, a dome turned within .005" would look perfect to our eyes,

while a machinist would probably think that .005" of error would be

"terrible" on a lathe.

 

Thank you for the post.  It is a real help.

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