Midland Johnson 3130

[Buhar]

Hi Dave,

 

Any tips about opening the firebox area from a rolled boiler, I've only attempted this once and ended up with bends/thumb impressions in the faces of the sides, that particular kit has stopped there.  I think the brass was about 11-15 thou from memory.

[Black Country Mon]

Looks good. I put the cab roof on my 7mm quite early, after slicing two fingers on the cab side sheets.

 

Thanks, yes I keep catching the beading on the sides so I'll probably start on the cab detailing first.

 

Dave

[N15class]

Hi Dave,

 

Any tips about opening the firebox area from a rolled boiler, I've only attempted this once and ended up with bends/thumb impressions in the faces of the sides, that particular kit has stopped there.  I think the brass was about 11-15 thou from memory.

I tend to use a dowel of slightly smaller diameter than needed as the brass will spring back. I line it all up an clamp it in a vice with smooth jaws with the bottom of the firebox down. Then just roll the brass around the dowel. Better to over bend as it is easier to straighten than set up again.

[Black Country Mon]

Hi Dave,

 

Any tips about opening the firebox area from a rolled boiler, I've only attempted this once and ended up with bends/thumb impressions in the faces of the sides, that particular kit has stopped there.  I think the brass was about 11-15 thou from memory.

 

I find it can be tricky with small 4mm boilers too. I usually hold the boiler onto my x acto knife where the firebox sides start and gently try to unroll the brass. I find that after a couple of passes it starts to flatten out, then it's just a matter of using larger or smaller diameter hard objects to get the finished shape. I have a very small ball pean hammer that i also use to gently flatten small etches at the edges using a piece of flat steel as a base rather than something with give like a cutting mat. If all else fails fortunately i have a set of large GW rollers so i can roll another one if i need to. Gently gently is the key i find and not rushing into trying to get it formed in one go.

 

Dave

[Jol Wilkinson]

Hi Dave,

 

Any tips about opening the firebox area from a rolled boiler, I've only attempted this once and ended up with bends/thumb impressions in the faces of the sides, that particular kit has stopped there.  I think the brass was about 11-15 thou from memory.

I've always used flat, square nosed pliers to gently form the flat firebox sides, after soldering the boiler bottom seam.

 

Gripping the lower edge with the pliers along the boiler line and slowly "pulling" the edge out/down.starts to form the straight lower side and the reverse curve. It is then a matter of gently flattening the lower firebox sides with the pliers and tweaking to get the curve correct. This has worked with both .012" brass and .015" n/s.

 

You may be able to rescue your existing kit, using square nosed pliers to flatten the firebox lower sides. My pliers came from Eileens Emporium, but Phil at Hobby Hobbies also does them. Jewelry bits and tool suppliers like Cooksongold also have a good range.