How were rain-strips made?

[Guy Rixon]

Rain-strips on coaches: what kind of curve should they have? And how, on the full-sized coaches, were they positioned? I'm printing some roofs and need to commit geometry to model the rain-strips.

 

So far, I've drawn my rain-strips as segments of a circle and that looks OK, but I suspect that the reality was more subtle. A segment of a circle is right if they were laid out with a trammel, but the radius is vast --- I ended up with 200 scale feet for a short coach --- and there wouldn't be room in a typical carriage shop to trammel that. I suppose that it could be done outside, with one man holding the end of a rope trammel somewhere in the next post-code. 

 

My guess for fitting rain-strips is this: gaffer goes up onto the roof with a yardstick and chalks one mark for the centre of the strip and one for each end. Rest of the fitters heave the strip up onto the roof and screw down its centre. Then they bend down the ends to the marks and screw down those. Finally, they put in the rest of the screws to keep it flat to the roof. I think that gives a catenary curve rather than a circular arc. Of course, a rain-strip might have to be made in sections, 60-foot long timber being hard to come by, and that changes the procedure; but perhaps the strip was assembled before fitting? 

 

Anybody know for certain how it was done?

[Steamport Southport]

Presumably they would bend them like they did for ships timbers.

 

Probably doing a few hundred at a time. Like this but on a much larger and industrial scale.

 

Not a great video. but I can't find anything more apt.

 

 

Edited April 6, 2021 by Steamport Southport

[Wickham Green too]

Timber of such a small section is flexible enough to curve without steaming ...... you're probably right about screwing down the centre at a predetermined point then the ends and the rest : it's not something the carriage designer would have worried about so long as it didn't look ridiculous.

As you say, though, the timber came in sections ( but-jointed, nothing fancy ) so laying out the first section or two took a bit of intuition.

[HGR]

Once the coach design had been drawn up by the drawing office, it would be easy to determine a set of offsets for laying out a curve, for example by measuring up from the cantrail / roof edge at pre-determined points along the length of the coach. That way, the radius does not need to be measured or even known by the fitter, only a set of more manageable points that could be readily marked off directly on the surface of the roof.

 

[MikeTrice]

4 minutes ago, HGR said:

Once the coach design had been drawn up by the drawing office, it would be easy to determine a set of offsets for laying out a curve, for example by measuring up from the cantrail / roof edge at pre-determined points along the length of the coach. That way, the radius does not need to be measured or even known by the fitter, only a set of more manageable points that could be readily marked off directly on the surface of the roof.

 

That is the method used by the LNER.

[Guy Rixon]

OK, given that the strip is in segments and positioned by multiple offsets, I'll assume that a constant radius curve unless somebody knows a different figure was used. 

[Compound2632]

I'm inclined to believe that the method I've used on models is close to the method used on the prototype: fix the centre, fix the ends, then follow the natural curve. At the the very least it looks about right. But I take the point that the prototype rainstrips didn't come in packets of 60 ft lengths like my microstrip.

Edited April 6, 2021 by Compound2632

[Wickham Green too]

......... one I made earlier .................... though it looks like we were re-making it !

 

[ikcdab]

Stuff like this was pretty much done by eye by the carpenters on the day. Nothing fancy. I haven't studied rain strips in detail, but my guess is that each one is slightly different....

[Compound2632]

33 minutes ago, ikcdab said:

Stuff like this was pretty much done by eye by the carpenters on the day. Nothing fancy. I haven't studied rain strips in detail, but my guess is that each one is slightly different....

 

Skilled craftsmen doing the same job every day would produce consistent results, I'm sure.

[62613]

1 hour ago, Compound2632 said:

 

Skilled craftsmen doing the same job every day would produce consistent results, I'm sure.

That's why we need limits, fits and tolerances in manufacturing. Even if they are rather crude

[Guy Rixon]

On 07/04/2021 at 10:32, 62613 said:

That's why we need limits, fits and tolerances in manufacturing. Even if they are rather crude

Also in model making, if the model parts be made for sale.

[TheSignalEngineer]

On 07/04/2021 at 08:35, Wickham Green too said:

......... one I made earlier .................... though it looks like we were re-making it !

 

 

What was the size of the timber?

I have some to do on models at the moment.

[Wickham Green too]

Difficult to remember - that was getting on for forty years ago ! ...................... but probably in the region of 2'' x 1'' - you can probably ignore the fact that it's nothing like a rectangular section in 4mm scale & below !

[Compound2632]

For Midland arc-roof carriages, I'm using 0.010" x 0.020" microstrip, thin edge downwards. They're not drawn in, let alone dimensioned, on most of the drawings I've seen - a standard item taken for granted. I think the ones on LNWR arc roof carriages are taller.

[TheSignalEngineer]

33 minutes ago, Wickham Green too said:

Difficult to remember - that was getting on for forty years ago ! ...................... but probably in the region of 2'' x 1'' - you can probably ignore the fact that it's nothing like a rectangular section in 4mm scale & below !

Thanks, that was about what I thought it would be. I can't find anything with actual details but I tried Evergreen 10x20 and 20x40 but neither looked right so I will source some 15x30 to try.

[Steamport Southport]

Not great for the bendy bits, but this stuff is a godsend.

 

https://www.wizardmodels.ltd/shop/wagons/c20/

[tomparryharry]

It might have been steamed, fixed to the centre, and then affixed at either end. Depending on the wood (ash? ) it will follow through the natural curve. If it's a short length, then it's fixed at the joint, and re-fixed at where the rain strip should have finished, and re-fixed. 

 

If it's wood, then 1"x 3/4" batten. 

[Ian Kirk]

I believe that the specification for LNER coaches was 3 inch square timber planed half round on top. This would then be screwed to the roof and allowed to adopt a curve as has been suggested over a 60 ft length I think that this would happen easily. (try lifting say an 8ft length of 1/4 dowel by the middle. It will curve naturally.)  In my O gauge kits I supply specially long lengths of Slaters rod. This once cemented in place, if the cementing and painting can be made to fill the slight undercut gives I think a good representation of a square section with the top planed half round.  

 

best wishes,

 

Ian

[Enterprisingwestern]

On 09/04/2021 at 11:46, TheSignalEngineer said:

What was the size of the timber?

I have some to do on models at the moment.

 

On 09/04/2021 at 12:31, Compound2632 said:

For Midland arc-roof carriages, I'm using 0.010" x 0.020" microstrip, thin edge downwards. They're not drawn in, let alone dimensioned, on most of the drawings I've seen - a standard item taken for granted. I think the ones on LNWR arc roof carriages are taller.

 

Rightly or wrongly, I use 020" x 010" for ventilated van roofs laid wide side down, a spot of Tamiya extra thin in the (marked out) centre of the strip and roof, and when dry pull the ends rounds and affix.

Maybe coach rainstrip was of heavier section due to there being a bigger surface run off area?

 

Mike.

[Bulleidnutter]

On a recent 12":1' overhaul at Kidderminster. We re canvased GWR 9055 and refitted the 2 lines of rain strips. Even though it has pretty decent sized gutters. 

Each rain strip was roughly 8ft in length. Their shape was roughly trapezoid but with the higher edge squared off. We measured then off the gutter before being taken off but when it came to refitting a drawing was provided which confirmed our measurements. Plus we used many photos to get a good idea of where they are.

 

[Enterprisingwestern]

46 minutes ago, Bulleidnutter said:

On a recent 12":1' overhaul at Kidderminster. We re canvased GWR 9055 and refitted the 2 lines of rain strips. Even though it has pretty decent sized gutters. 

Each rain strip was roughly 8ft in length. Their shape was roughly trapezoid but with the higher edge squared off. We measured then off the gutter before being taken off but when it came to refitting a drawing was provided which confirmed our measurements. Plus we used many photos to get a good idea of where they are.

 

 

, and their cross section was?

 

Mike.

[MikeTrice]

12 hours ago, Ian Kirk said:

I believe that the specification for LNER coaches was 3 inch square timber planed half round on top. This would then be screwed to the roof and allowed to adopt a curve as has been suggested over a 60 ft length I think that this would happen easily. (try lifting say an 8ft length of 1/4 dowel by the middle. It will curve naturally.)  In my O gauge kits I supply specially long lengths of Slaters rod. This once cemented in place, if the cementing and painting can be made to fill the slight undercut gives I think a good representation of a square section with the top planed half round.  

 

best wishes,

 

Ian

 

I think your dimensions are a bit out. LNER cross section below:

 

[Nick Holliday]

The LBSCR used rectangular timbers, 1¼" high x 1" wide.

[Bulleidnutter]

5 hours ago, Enterprisingwestern said:

 

, and their cross section was?

 

Mike.

Take an isoceles trapezoid and square off one side. I couldnt tell you the size of them without being at work and climbing on the roof.