Supporting > Boilers
Calbourne - 5" gauge boiler
vtsteam:
It's an eye opener seeing that hole saw work on that round copper sheet and do such a nice job of it. :ThumbsUp: :popcorn: :cheers:
Kim:
--- Quote from: vtsteam on January 29, 2023, 03:31:19 AM ---It's an eye opener seeing that hole saw work on that round copper sheet and do such a nice job of it. :ThumbsUp: :popcorn: :cheers:
--- End quote ---
Yes, that's interesting for sure!
Was the copper tube half hard or fully annealed? Seems like it would be harder to do the hole saw if it was annealed. Just curious.
Kim
springcrocus:
--- Quote from: Kim on January 29, 2023, 06:17:17 AM ---
--- Quote from: vtsteam on January 29, 2023, 03:31:19 AM ---It's an eye opener seeing that hole saw work on that round copper sheet and do such a nice job of it. :ThumbsUp: :popcorn: :cheers:
--- End quote ---
Yes, that's interesting for sure!
Was the copper tube half hard or fully annealed? Seems like it would be harder to do the hole saw if it was annealed. Just curious.
Kim
--- End quote ---
This had not been annealed, just as delivered from the supplier. I used the same method on my first boiler and that one was annealed but no problem either. I expect the barrel shape is self-supporting.
Regards, Steve
springcrocus:
The outer wrapper had a centreline scribed at the half-way point and was simply folded around the barrel, followed by bending back to form the waist and creating a nice fit around the backhead. Then it was on to the throatplate.
This was the most difficult part to make because of the reversed double flanges and I cut the raw material a good one inch bigger all round than the suggested starting size. I also cut a packing piece for the front of the wrapper, clamped the backhead to the bench and temporarily assembled things to get a feel for the finished shape and size. The offcut of tube was used to mark where the barrel reaches to.
Learning from my experience with the Britannia boiler, I decided to get the side flanges fully-formed first and a piece of MDF was made into a former. I could have cut down the backhead former and used that but it was just as easy to make a new one. No pictures here, it was just simple folded-over sides. The former for the barrel flange was a little more complicated and a piece of oak kitchen worktop was used to make this, squared-up all round and milling out the middle to support the side flanges. The top was shaped using a 110mm hole saw.
The first former was cut down to act as an internal support but allow the flange to be formed and the throatplate was placed in the former and the flaring at the top beaten into place. Some of the waste area was marked for removal and was cut out with the Abrafile before I started to form the barrel flange.
I found early on that the sides of the former would need support and a large clamp was used with the rest just held in a bench vice. I don't have any special hammers for copper-forming and a one-foot length of 1.1/2" diameter stainless steel was used instead because of the concave form.
Between the many annealings, I kept returning to the mill to remove excess material because the further I went, the harder it got to keep the shape. This is the point that I decided to call a halt to the bashing and bring all the flange widths to size although the picture was taken after thinning the top wings.
So this is a trial assembly to see how well things fit and it's not too bad. The circular shape wasn't perfect, however so I decided to skim a little off the inside using a flycutter.
I don't have any left-hand tools for the boring head so set up a right-hand one and ran the mill in reverse. This promply unscrewed the head from the mandrel so I had drill and tap a hole in the side to accomodate a locking grub screw. After that, I milled the diameter to a near-perfect fit. Once again, the former acted as a support for the soft copper and the opportunity was taken to scribe a centre-line through the workpiece.
A pair of fixing holes were drilled in the barrel flange and this was then rested on the barrel using a large vee-block to get everything in line and upright. The holes were transferred through to the barrel and a pair of 6BA holes tapped to take some bronze screws at soldering time. Another centreline was scribed on the underside of the barrel, diametrically opposite the top one. This enabled accurate alignment of the throatplate.
Another fixing was made to hold the wrapper to the barrel and the assembly held together with clamps. I can now mark out a few more fixings knowing everything is square and correctly aligned. I won't make any fixings for the backhead yet, though, because things like the firehole ring and the foundation ring will determine the final position of that.
Regards, Steve
Admiral_dk:
Great looking parts so far :ThumbsUp: but I bet that the moment you noticed the Boring Head starting to unscrew was a heart stopping one :o
Will follow with interest :cheers: :popcorn:
Per
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