Ok back for some more, I rang PPD today as I'd not heard anything and they are usually very prompt after receiving the files, anyway, it was in the queue so no worries.
However, this layering was concerning me and I'd taken the file to work and opened it up at lunchtime, disaster, the layers had not saved, well they probably had but it seems Autocad can have some funny turns when loading up a large image with layers ( my guess) as reloading caused the error areas to go away.....and new ones appear
clearly something was amiss.
Whilst fudging around I noted about 40 rivets missing off the RH frame skin
so a quick call to PPD to delete the file was in order, ironically they didn't as I had a mail when I got home saying they were ready to go if I contacted them with payment and delivery address
not to worry I will make sure verbally tomorrow they have the revised file before they proceed, minor FUBAR averted !
So, back to the layers, it'd been a while since I'd done any multi layered work and had forgotten some basic principles, that's not to say what I'd done wouldn't have worked, just that there was an increased window of opportunity for Captain cock up and his merry crew to make an entrance.
First off an image of an area that will hopefully try to explain what was wrong, and the better way of achieving the same result.
This is the front LH overlay with rivet and raised detail, we are going to focus on the front bogie wheel arch as it has all three layers, I.E. a front etch, a rear etch and solid. Everything in red will be etched from the front, everything in blue will etch from the rear, everything in black remains the full thickness. I know there are some here who already know this, so apologies for the egg sucking exercise.
To achieve these areas we flood fill or in Autocad terms, hatch these areas, before we start the whole art work is just a bunch of outlines.
Now when we hatch we have to select the areas we have to fill and the areas we do not want to fill, being as most of this part is half etch red then the easy way is to just hatch it all except the bits that are etched all the way through, slots for the cylinders etc.
The dotted areas being the boundaries required for the hatching, this gives us this result
All of the frames are now red, except the areas where there are holes all the way through, from this point we now add the extra layers on top, black and blue...those that know what they are doing will already know we're on the road to doom and frustration! Note in the above, when we highlight (it turns hatched) the red area it obliterates the black and blue areas, this is not good. In the first image, no hatching was selected so we had nice solid colours.
So adding the black areas in next
Again note it obliterates the blue guidelines, but is a layer above the red.
Finally we add the blue
This does not cover anything as it's the last layer.
Now, if we take a close look at that last blue half etch rivet under the cursor in the last image, we now have three layers under here, blue, black and red and here's where Autocad sometimes has a fit, sometimes it will render the red above the black, so that lozenge bracket becomes red, or it will render the black above the blue and you get no half etch behind, Autocad knows there are layers there but fails to render them very well on occasion. Even if you try and send the blue dots to the top or the red layer to the bottom, it will revert back or worse still do something else somewhere else, you end up playing wackamole around the etch, fix one layer error and another pops up.
So how do we do it properly, well we stop being lazy and hatching the largest area possible, we hatch exactly the area we want.
Which now gives us this
The red only covers the red areas, it does not cover any black or blue, the same applies to the black
it does not cover the blue.
If we now go back to our rivet from before, it still has three layers like before, but only the blue layer is filled, so if the red of black layer decides to jump about it will have no effect as in both of those layers there is a hole which cannot ever cover the blue. The same applies to the red and black layers, simples
Back to the first image
Some notes for those that might be interested, the small black clips for the mudguards can be seen, these have half etch rivets from the rear, as does the brackets for the sand box, upper right and the slidebar bracket up there as well. Up front is a strip plate for the smokebox footplate to rest on. At the bottom rear of the front arch is the lozenge bearing fitting for the cylinder drain cock activation rod which runs right across the engine.
The large oval hole is for the combination lever, larger on this side as the short lever is deeper than the longer one on the other side (which has a smaller opening), above and forward of that is the lifting hole. There are five vertical slots, the first two are for the outside cylinder faces and this area is also covered by the large cylinder flange plate, with corresponding slots in it too. To the rear of these are the two slots for the sand box fixing and finally the outside slide bar bracket slot.
The rest of the large black dots are full depth heads (as opposed to domed rivet heads) used to fasten the various stays, front to rear, the combination lever stay, then lower down the bogie pivot stay followed by the inside cylinder mounting bolts (many covered by the sand box....but I know they are there
) and finally, far right we have the double row that holds the front brake cylinder stay. All of these stays are on the etch sheet.
Below the frame is one side of the cruciform stay O-12818-D, no drawings exist of this stay but the GA's that do show what few parts are visible show it to be close to the A3 and A4, whilst this part is accurate there are no front or rear views so best practice is used, although the W1 looks like the A4 the frames are very different in many areas, some parts are common right through the LNER range, like the front combination lever stay, but others are unique. The slots are for the horizontal and vertical plates to slide through, these also go right through the inner frames and the + effect will strengthen the frames in this area and increase the chance of it all being straight and square, longitudinally and vertically. The large boss is the rear of the intermediate driver brake hanger, there being a corresponding cut out in the vertical part of the stay.
Finally we have the two bogie mud guards with flanges for the brackets, these appear not to be riveted to the mudguards but welded, certainly on A3 and A4 and the one image that shows this in any sort of detail on the W1 shows it follows suit.
Enjoy.