Creating the drawing is quite straightforward. I am going to call it “Robinson 11B V0.2” to reflect that is it is a restart of an earlier drawing.
Set up some base line parameters :-
Set space units to ‘English’, type ‘absolute’, units ‘inches’, precision ‘3’ and format fractional. This ensures that the drawing will look like a GA when finished, measurements will look as presented on the original GA and the precision of ‘3’ will allow measurements down to 1/16” where it is needed.
Set grid to 1/8”, orthogonal style and lines – with major grid axis at ½” and minor grid axis at 1/8”.
The very small grid is a function of the materials we need to use, for example frames on the locomotives are normally 1 ¼” and the nearest NiSi equivalent is 1 1/8” or 15’. This allows the drawing to model the materials used accurately.
Angle style to ‘degrees’.
Layers – create as many layers as needed right at the start – I actually create 25 layers starting with
0 – base layer – default where everything goes unless it is put elsewhere such as datum line and datum measurements
GA – pictures of the NRM drawings
Frames
Frame Dimensions
Etc etc etc
Ending with
Spare1, spare 2 and spare 3
The rest of the options can be left until much later – if needed at all
Add some datum lines to layer 0 – red dashed
These make a ‘frame’ for the drawing
0,0,0 horizontally for about 500”
0,0,0 vertically for about 250”
And from the GA, we can also add lines to show boiler pitch, buffer height, platform height, frame length,
Wheel centre heights (remembering that we will be using 6’ 8” wheels).
All these are usually common to several layers and the best place is usually the default ‘0’ layer.
Import the drawing of the GA
Drawings from the NRM can be purchased on disc in which case they will come as TIFF files. Turbocad V20 can import these directly. I usually split the NRM file into two parts, top view and side view.
Set the drawing to side view, the import the side view TIFF file by selecting a spot and dragging the far corner to a large size of about 40’. Obviously this is not the correct size and it will not be aligned horizontally to any degree of accuracy.
Select the imported drawing, reset the reference point for it at exactly the point of the rail height and the rear of the buffer. Then reposition this to 0,0,0. At this point it should be seen to line up with one of the datum lines drawn earlier.
Now draw a line from 0,0,0 along the top of the rail the full length of the drawing, but do not release the mouse button. The guide numbers will show the angle of the line. Select the drawing, and rotate it by the shown amount.
Now draw a line from 0,0,0 along the measurement on the GA showing the frame length, in this case 30’ 9 ¾” and note what the length is. This will give you a scaling factor and entering this into the appropriate boxes will set the drawing to exact scale.
Now set the drawing to ‘plane’ view, i.e. from the top. Import the chassis part of the GA and repeat the alignment process but with the centre of the frame behind the buffer at 0,0,0..
If you now inspect the location of the wheel centres and other measurements you will begin to see that the original GA has stretched and not in a linear fashion. This will confuse things later!
However, it should be possible to draw circles representing the wheels at the ‘true’ positions, again on layer 0, and then add key dimensions so that they match those on the original GA.
006 Robinson 11B V0.2.jpg
Next – drawing the frames.
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Slaving away still on GCR stuff ...