GJChurchward

Ron It seems a shame I have not been following the thread on a daily basis for the past week or so, because I could have said sooner that those castellated decorations look ideal candidates for 3d printing. I've been mulling the problems I will face when I get round to doing the old Great Western Hotel which used to stand over Birmingham Snow Hill. It was a brick building with stone facing, and covered in classical decoration. Pretty much every window has a pediment, and I was a little daunted by the prospect of building them in plastic sheet. If I use 3d printing, they will be solid, accurate, but especially consistent. Where 6 or 7 adjacent windows are meant to be identical, it only needs a small variation in one to make it stand out. Andy

Ron, Excellent work as always! The 'extrusion' you speak about is presumably a lamination of various strips of plastic to build up the cross-section, and I've had some difficulties with this procedure in the past. I'd like to know how you cut it into the required short lengths without distorting the joints. I've found that an edged blade acts as a wedge, pushing the top lamination apart before the second, and so on, but a toothed blade (piercing saw), followed by filing or abrasive paper (midnight raids into SWMBO's endless supply of nailboards), tends to push plastic swarf between the laminations (unless I was liberal with the solvent in order to avoid unbonded areas, with other problems ensuing from that). Andy

Ron, I just love how you post drawings at 22:30, then photos of the first four cut beams at 22:46. Rather quicker progress than I could hope to achieve! Andy

Nine days since your last post, Ron. Does this mean you don't have something reasonable to show? I can't believe that - unless SWMBO's feet have been nailed to the floor. Hope everything is OK...?

Does this mean you are no longer allowed to drink the local canned lager?

Somehow, this post has conjured up an image of mighty cathedrals and abbeys in impossibly intricate detail.

There's plenty of potential in it for a failed print. You wouldn't want to be 90% through printing this and then have a big nondescript blob of plastic appear. It might be a good idea to use 3D printing for some sub-assemblies though. The transverse beams, for example.

I do hope it's not tempting fate to suggest that it's over 4 days since we heard anything, and after your recent healthscare I hope all is OK, Ron? Andy

It's been quite a while since I last visited this thread, but having just returned, I can see some very attractive 45 ton cranes. Am I going to be able to get my hands on one of these? Is it something you will make publicly available on one of the 3D printing web services? Great work! Andy

Best wishes for a speedy return to full health, Ron. Andy

Ron, How does imprecision arise at corners where lines in different layers intersect? Surely a point in 2d space has the same co-ordinates, whichever layer we consider? Or - are you unloading the cutting mat to clear waste after each layer is cut? Andy

Oops - I've just sorted out a PC problem which meant I couldn't view video, I'm now seeing much of the information I needed. The video instructions are very good, however I wish I'd been able to find it in text somewhere. Andy

Ron, After reading that post, I went back to have another look at the photographs you uploaded, and noticed that the machine seems to have a problem in tight corners, and when cutting a curved line. Your bridge girders were excellent - perfection in fact, but the railings are rather more intricate, and I wonder if they are too intricate for the capability of the machine, or whether it is possible to fine tune its operation. I'm tempted to buy one of these, primarily for producing the beading layer for laminated plastic paneled coach sides, and I hope that my expectations of the machine are reasonable. I'm trying to understand how the shape is created. Is it the blade which moves, the job, or both? Does it behave rather like a flatbed plotter, moving the blade along the X axis and the bed along the Y axis? Presumably the blade is lowered at the start of a cut, then the blade (or job) is moved to the end of the cut, and then the blade is lifted. Looking at some of the small pierced apertures in the railings, it's clear that if the path of the cut is curved, then the blade is moved in a curved path while twisting to follow it. Straight blades like to make straight cuts, and so twisting the blade would cause it to act like a lever between the two sides of the cut, distorting the plastic sheet on the outside edge. If that happens to be the waste side of the cut, I wouldn't expect it to be any problem, but if it is the job side, there may be some tendency to move the job relative to the bed, or whatever you have for keeping the work piece in place. How is the work held down? If I were cutting these shapes by hand with a scalpel, I would adopt different strategies for cutting different kinds of shape. I would not cut exactly to the finished line of a curve immediately, but gradually remove selected areas of material such that the cut distorts only the waste side. I would prefer to lower the blade to 'start' both ends of a straight cut before moving it to join them, since the tip of the blade is not symmetrical, and I'd like a vertical end to both ends of the cut. Does the machine take the file you give to it and decide for itself in what order to do the work? If there's an opportunity to impose some user control over this, it might be possible to create additional shapes for cutting first, in order to mitigate the distortion. Andy

One of the attractions in this thread is seeing you go ahead and build models which anyone else would immediately dismiss as impossibly difficult. Having that cutting machine available to you is certainly a great help - modelling cast iron components from laminations would just look awful without accurately-cut layers. I'm sure that in years to come, this layout is going to be spoken about in the same breath as The Madder Valley, Craig & Mertonford, and Buckingham. It's a great privilege to be able to watch it being built. Keep up the amazing work, Ron!

I'd have used regular Araldite for this. Not the quick-setting variants, they don't hold as well. I did once make some steps quite similar to yours by cutting and folding some thin aluminium sheet into a cradle, holding all the components in place for soldering, but that was itself a time-consuming job, and I was no quicker in getting my steps made. Andy

I wonder what astonishing reality you might have achieved with your existing masterpieces, had this technology been available to you several years ago...

Oops - sorry, I must have skipped a post, since my question has already been answered. Old age setting in...

I like the compactness of your diode matrix circuit, Ron. I presume this will be sited very close to the indicator, to minimize the fibre optic distance. How do you intend to control it, i.e. change the indicator aspect?

A few days since the last update. Hope all is OK, Ron?

Ron, Since the faces of your theatre displays are simply plates with a matrix of holes drilled into them, I wonder if you really need to use multiple fibre optic strands? Have you considered using segment displays (assuming you could find them the correct size)? You'd still get light shining through the correct combinations of holes. It might be difficult to adjust the brightness, but it would be a lot less hassle putting them together. Andy

That's the downside of having a place in the sun, Ron. When I get around to building the main line between Birmingham (Snow Hill) and Wolverhampton (Low Level), I'll do it where no one will ever want to come and interrupt my endeavours by wanting to stay awhile for a holiday. (Hmm... that's probably Birmingham or Wolverhampton, then.) Andy

Ron's been quiet for a few days. The anticipation of another mind-blowing update is beginning to build...

The quantity of Plastic Weld Ron gets through would almost justify a pipeline.

Ron, why is it no longer possible to import Plastic Weld? Is this due to legislation?

I was trying to think how I'd produce the lettering, and to be convincing, the edges really need to be very crisp. Etching in thin N/S might not do the job. There's always a cusp around the edge, and that would need to be taken off with a file (not so easy with thin material) or abrasive paper. It would be a fiddly job, to say the very least.