Designing coach sides and ends.

A couple for the collective.

1. If a coach side has turnunder do you allow extra material to cope with the curve when drawing the side as a flat drawing?

2. If a coach body has turnunder on both the sides and ends what curve does the corner join describe when the ends and sides are flattened out?

I’m trying to learn 2d and haven’t even looked at 3d cad hence the question.

I guess the answer in 4mm and below is probably 2 strokes of a 6 cut file and forget about it but what about the larger scales such as G3?

Ralph
 

michael mott

Western Thunderer
Ralph a great question, from a simple 2D drawing perspective if you are drawing full size it probably amounts to a fractions of an inch (old school imperial) but at a model size probably hard to see without an electron microscope. just my perspective on things and on G3 very tiny I think perhaps 3 strokes with a 4 cut file.
I have been known to bend the rules a bit so take my thoughts with a grain of salt.

Michael
 

Mike W

Western Thunderer
My ears pricked up when I read "G3" - nice to see you here Ralph. As others have said, for the turnunder forget it - the etching process isn't that accurate. Same for matching the curve on the end to that on the side. I don't think you are a GWR man so am guessing this might be GER ... in Gauge 3 ... getting quite excited now .... ! I have some castings fro 4-wheeled carriages that might suit, depending what you are doing.

Mike
 

geoff_nicholls

Western Thunderer
I think I just added 0.5mm, when I tried it in G3. If you're using CAD it may give you the length of the arc and therefore the extra to be added. I'm pretty sure it does in Turbocad
 
Graham - it’s a pleasure, didn’t say tumblehome once - blast just did!

Micheal and Geoff - many thanks, I’ll try measuring the side with the turnunder and see how much difference it makes. Then get my big file out.

Mike - well done Sherlock I may well be knocking on your door…..

Regards
Ralph
 

ianlbsc

Western Thunderer
There is always the sort of thing I saw Malcom Mitchell doing years ago when designing the 7mm firebox. He drew them on cardboard, cut them out, assembled them and then undid them and measured the parts. Surely this could be done with an end profile and roll the end profile against a rule to get the correct length of the side?
Cheers, Ian
 
There is always the sort of thing I saw Malcom Mitchell doing years ago when designing the 7mm firebox. He drew them on cardboard, cut them out, assembled them and then undid them and measured the parts. Surely this could be done with an end profile and roll the end profile against a rule to get the correct length of the side?
Cheers, Ian
I did think of planing a short length of side and end to make a corner and then take a profile from that. After thinking about the extra length from the turnunder and the shape made by a side and end with turnunder I also wondered about a side with turnunder meeting a bow or angled end as in GNR or LNER coaches. With all the CAD expertise on WT I was worried that planing a dummy side might come across as using flint tools and sharpened mammoth tusk as it were! Ralph
 

Daddyman

Western Thunderer
There is always the sort of thing I saw Malcom Mitchell doing years ago when designing the 7mm firebox. He drew them on cardboard, cut them out, assembled them and then undid them and measured the parts. Surely this could be done with an end profile and roll the end profile against a rule to get the correct length of the side?
Cheers, Ian
Or stick a bit of masking tape on the end profile, cut it to length while attached to the end, take it off and put it on a piece of glass (say), and then measure it.
 

Phil O

Western Thunderer
I would suggest, just adding the thickness of the material to the depth of the side. You may have to file it down a fraction.
 

Richard Gawler

Western Thunderer
I have an unbuilt brass kit for a coach with a turnunder. The sides (and end profiles) are pretty much vertical from the waist upwards, and the turnunder is below this.

Well, I have had a go at measuring the vertical height of the ends and the heights of the sides in their flat state and both measure so close to 45 mm I think they are the same. The vernier wants to tell me the sides are 0.2 mm shorten than the ends, which doesn't seem right, so I think they are "the same height". This is for 7mm scale.

Edit - I forgot to say, this is a Connoisseur kit and they seem to go together well.
 
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