Crikey, I've gone grey waiting for the digital version to load and then navigate to the page. It was quicker to go upstairs and get the mag!

And the answer is… I haven't a clue!

Actually I suspect the line was originally alogned with the holes in the end of the frame, but has accidentally been shifted and recalibrated its distance – a hazard that applies to some CAD stuff, as it's possible to create dimension lines that are aligned with guides or even nothing instead of the feature they are meant to reference..

Neil

I think you will find that it's 1.093"

J

Could someone tell me the center coordinates for the r0.583 radius that is drawn hanging in space on the back of the main frames please. That or the vertical distance of the top of the buffer beam to the top of the frames.

Thanks in advance.

Martin

So if the centers are concentric that gives (1.193-0.583) = 0.61 rather than 0.625 for the buffer end.

M

Did not say the centres are concentric, you can work out the centre position of the 1.193R with trig.

The base of the triangle is the 1.189" dimension, the hypotinuse the radius of the circle 1.193, the short side is the end of the frame which works out at 0.0095" above the line of the axle box cutouts.

This is what I come out with when using the drawing dimensions in Alibre, you should be able to see the three springing points of teh arcs highlighted and notice the one for the 0.583" is above the 1.193", click to enlarge.

Though my feeling is that the 1.193" radius is wrong as it pouts the front buffer lower than it looks or the illustrator has not plotted the positions correctly which is quite possible as the junction between th etwo small curves is not exactly flowing

Edited By JasonB on 03/12/2013 18:23:55

I have asked Dick Allan to hop on and help you out.

Diane

I am delighted to have given so much amusement to you all in worling out what the back end of Derwent's main frames should look like! Martin Kyte is right, I should have given dimensions for the buffer beam (actually the drag beam) and these are 0.842" from the top line of the frame to the top of the beam and 0.470" from the bottom of the horns to the bottom of the beam. That done the exact shape of the curves is not very critical – for my own Derwent I set them out by eye! Neverthe less I am full of admiration for the display of mathematical wizardry.

While I am at it, several of you noticed the errors in positioning the water tender axle boxes (Fig 25, ME4469). Of course it is blindingly obvious the something is wrong and, no, it is not an optical illusion as one contributor wondered! This is what happened. Using Draftsight (CAD programme) when drawing in multiple objects of the same design one designs only the first and then ' copy/paste as a block/ paste as a block etc for as many as required, placing them only roughly in place. The objects are then moved into acurate positions. I did this for the pair on the righthand side of the drawing when an interruption took me away and I forgot to finish the job. Anybody building the model will find it obvious where the axle boxes have to go as they have to fit into the limited spaces in the under frame. I was surprised that the plan was redrawn for ME without this being noticed!

I will be pleased to meet any of you who may be attending the Sandown Park exhibition where I will be exhibiting a gauge 3 model of the Crampton 'Liverpool'.

Dick Allan

Brillig. Thanks.

M