Rolling a roof

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hughesp87
Posts: 80
Joined: Tue Aug 05, 2008 8:25 pm

Rolling a roof

Postby hughesp87 » Mon Jan 13, 2020 11:49 am

Can any of you experienced carriage builders help with a question of technique for rolling a roof?

I am scratchbuilding a small boxcab diesel in P87. It has a three-arc roof profile, with tight curves down to 2.7mm radius at the gutters. The bodywork and roof have been etched in 0.3mm nickel silver, with the roof being half etched to create the beading around the edges and the lines of rivet detail. That means that the majority of the roof area is around 0.15mm thick.

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I had assumed that the initial roll should be at the larger radius (around 33mm), but creating the tighter curves at the edges would seem to be beyond the scope of the rollers.

Does anyone have any bright ideas as to how I should do these please?

Many thanks,

Geraint
Geraint Hughes
Cromford & High Peak in P4
Danish Railways in P87

best33
Posts: 27
Joined: Thu May 12, 2011 12:05 pm

Re: Rolling a roof

Postby best33 » Mon Jan 13, 2020 12:48 pm

I did the High Level Fowler Diesel last Summer which has a similar issue with a tight radius on the edge of the roof. I used a good quality vice with parallel smooth jaws and rested a piece of appropriate diameter bar on a piece of shim to bring the top of the bar flush with the top of the vice I then tightened this up. Placing the edge of the roof in the crack between the bar and the jaw of the vice I loosened the vice slightly until the edge dropped into the gap slightly. It doesn't need much, just enough to pinch it. If the jaws are truly parallel then the roof will drop the same amount all along the length of the edge. After than I used a piece of aluminium L section to pull the roof around the radius of the bar. You need to apply the load as close to the end as possible otherwise the bend will go somewhere else.

Mark Humphrys

IMG_4283.jpg

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pete_mcfarlane
Posts: 52
Joined: Wed Feb 10, 2016 4:39 pm

Re: Rolling a roof

Postby pete_mcfarlane » Mon Jan 13, 2020 2:15 pm

I've built a couple of Rustons (one from A1 and another from Judith Edge) with similar roofs and did the small radius curves using a vice and a small diameter bar (2mm drill shank, as the roofs weren't very long). The trick with the shim sounds useful, as avoids spending ages lining it all up by eye before making the bend like I did.....

hughesp87
Posts: 80
Joined: Tue Aug 05, 2008 8:25 pm

Re: Rolling a roof

Postby hughesp87 » Mon Jan 13, 2020 2:29 pm

Mark / Pete,

Many thanks for your thoughts. Can I just ask - did you roll the tight curves before the main curvature of the roof, or afterwards?

Regards,

Geraint
Geraint Hughes
Cromford & High Peak in P4
Danish Railways in P87

best33
Posts: 27
Joined: Thu May 12, 2011 12:05 pm

Re: Rolling a roof

Postby best33 » Mon Jan 13, 2020 6:04 pm

Form the large radius first.

Mark


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