6″ Vertical Boiler. CNC Drilling Firetube Holes
by John
After all of the careful flange forming I was careful to not screw up the firetube perforations in the boiler end plates. At times like this it is great to have a CNC mill/drill.
The wooden form is useful as a clamping aid.
No major stuff ups (or should it be “stuffs up”?). And I am not pointing out the small ones. I was unsure in the firebox plate which side to chamfer. Will I silver solder the top side or the bottom side? Eventually I decided that I would solder between the firetubes rather than the underside. Still unsure whether that was the best decision.
The “ligaments” (the metal between the holes) must not be less than 3mm. The minimum in these plates is 3.5mm. The holes are chamfered to make the silver soldering process easier. The extra hole in the top plate is to install the bronze bush for the attachment of the wet header.
johnsmachines 
Looking good John.
CNC mill at home! Now John we’re on the edge of opulence here, but then jealousy is more of a curse.
Great to see your progress.
Tim
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Yeah. It is a bit over the top for an amateur. The mill is a 1995 industrial model which came out of a university. Converted it to run Mach3 and V Carve.
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John I think you have superior opportunities in Vic when it comes to used machinery.
I’ve looked and looked in vain in NSW so am now on the happy edge of a new 300 mm centre lathe with dro (Taiwanese).
With your approval I’ll announce the birth when it happens.
Tim
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OK. 300 between centres, or swing? BC is smallish.
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305 x 920. Hafco 960 B with dro etc.
Feels very silky.
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nice!
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Hi thanks for possting this
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