Vacformed roofs

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JackBlack
Posts: 117
Joined: Tue Jul 22, 2008 1:25 pm

Vacformed roofs

Postby JackBlack » Fri Oct 25, 2019 5:00 pm

Is it roofs or rooves? Anyway I was wondering if anyone knew of a supplier for vacformed coach roofs like those supplied with the old Mallard kits. I find them really nice to work with and preferable to the brass or aluminium roofs that come with the later Blacksmith versions, or the Comet coach kits. I've been looking around the usual suppliers but to no avail.

Thanks, Nick

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PeteT
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Joined: Tue Jan 11, 2011 9:53 pm

Re: Vacformed roofs

Postby PeteT » Fri Oct 25, 2019 7:25 pm

Not exactly a direct answer, but Ralph Robertson (on here with his Alpha Mill topic among other things) has done several LMS coach building demos & has built himself a jig for clamping & forming a plasticard roof in the oven.

I keep displacing my round tuit to have a similar go myself, and he then builds in some bracing to form a solid roof structure rather than just bonding the plasticard to the body sides/ends - but the concept & method look good to me.

The extruded roof could be used to help form the curve of the jig. If memory serves the oven is only set to 50 degrees or so.

Rdunning
Posts: 18
Joined: Tue Oct 21, 2008 8:38 pm

Re: Vacformed roofs

Postby Rdunning » Sat Oct 26, 2019 12:07 pm

Roxey Mouldings coach kits come with vac-formed roofs although their website doesn't list them as available separately. It might be worth contacting Dave Hammersley to ask if he could supply you, if you haven't already tried them.

Richard

ralphrobertson
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Joined: Wed Nov 27, 2013 3:57 pm

Re: Vacformed roofs

Postby ralphrobertson » Sat Oct 26, 2019 5:31 pm

PeteT is quite right, I did demonstrate a method once at Scaleforum about 3 years ago. I cannot claim any originality to this - I was taught how to do it by Dick Petter who has been using it for years on his extensive fleet of LMS coaches.

The prime reason for me using this method was because of the mis-match between the Comet aluminium extrusion once it is thinned out to a more acceptable thickness and their etched coach ends which just don't fit the revised profile. Their extrusion isn't a correct profile for an LMS coach roof anyway and Dick had addressed this problem years ago. An extrusion that is no longer available matched the LMS profile correctly and this was made by 247 Developments. The method I am about to document uses this, 247 Developments LMS profile.

The first thing that needs making is a form tool. This is made up of bits of wood, an aluminium roof extrusion and some steel strip. The photo below shows the tool.

20170911_143219(0)_resized.jpg


20thou plastic sheet is cut into a rectangle and wedged under the metal strips and the screws are tightened once the plastic wraps over the aluminium extrusion snugly. It is not easy to do this, the plastic is not very pliable, but it is possible - it is probably easier to do if the plastic is warmed but I have never needed to do that. Once the plastic is wedged in place the form tool is placed in an oven at 100 degrees for 10 minutes. Once it is cooled it is removed from the form tool and you are left with a plastic roof to the profile of the aluminium extrusion.

20190905_135251_resized.jpg


Once you have the roof a base is glued in place and the sides trimmed off. I use di-Limonene as an adhesive as it seems to give a bit of time to adjust things and it also seems to give a better bond. A central spine of Evergreen 6mm x 2mm strip is glued down the centre of the base first and some profiled ends are also fitted prior to the roof being bonded onto the base with the spine and ends. I never glue the formed roof to the central spine only to the ends and the base.

20190905_135203_resized.jpg
Sample of roof showing before trimming


20190905_135227_resized.jpg
Sample after trimming


20170911_143324_resized.jpg
Roof made up to attach to coach


20170911_143643_resized.jpg
Coach showing Palatine underframe, Comet coach sides and my own correct profile coach ends matched to roof shape, 3D printed coach seats and a plastic coach roof made as described.


DSCN0772a.jpg
Coach roof for LMS suburban.


Hope this encourages you to make some yourself, it can be done.

Ralph

ralphrobertson
Posts: 157
Joined: Wed Nov 27, 2013 3:57 pm

Re: Vacformed roofs

Postby ralphrobertson » Sun Oct 27, 2019 10:19 am

I forgot to mention that if you do this using an extrusion you need to file off the lip that protrudes over the side of the coach. Also it might work with 15thou plastic but I haven't tried it.

Ralph

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JackBlack
Posts: 117
Joined: Tue Jul 22, 2008 1:25 pm

Re: Vacformed roofs

Postby JackBlack » Mon Oct 28, 2019 5:08 pm

Thanks for the replies and thanks Ralph for that very details post on how to them myself. I'd rather not have to do this if I can help it, especially as the Mallard vacform roofs have a small shoulder to them that I think would be difficult to reproduce using this process (although the brass roofs later supplied by Blacksmiths didn't have this).

I will start by contacting Roxey Mouldings. Maybe that will work.

Thanks, Nick

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JackBlack
Posts: 117
Joined: Tue Jul 22, 2008 1:25 pm

Re: Vacformed roofs

Postby JackBlack » Fri Nov 01, 2019 7:10 pm

I've been having a look around at vacforming machines, as you do, but Ralph's post got me thinking...

And I found this, on eBay: Vacuum-Forming-Machine - £64.99!

And the accompanying youtube video it looks quite straight-forward to use: .

And with a working area of 11" square, that should fit a 70' coach roof right?


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