Charlie, I think we're on the wrong branch... A confessional

As I write this on the train to work for the first time (coming up in the world ;) ), I'd like to reflect on the possible directions this blog could take; for the 5 people who know this place exists, anyway.

As you are no doubt aware, my SLA 3D Printer is taking a god-awfully long time to come to life, partially because of life concerns (my main PC upgrades being a prime example), but nonetheless, i'm beginning construction proper.  The frame members are complete, ready to join and looking pretty good considering this is my first time with an angle grinder!  The Plywood Panels are ready to be assembled as required and accept paint.

Another thing that constantly nags my attention is the fact the virtually no progress has been made on the Shapeways side of Tawe TMD; there are several reasons for this, but the main offenders are:

1. Material Properties – WSF (polyamide) is tough enough for a model railway wagon chassis, but produces lesser detail than early 2000s N gauge models, I.e, the period where it was seriously mooted that this scale was dying!  FUD is acceptable, but far too brittle in tests, with W Irons and springs falling off only enough force to bruise a gnat.
2. Service – Shapeways is under heavy strain right now, it's a new startup riding a technology that is a newborn amongst giants.  These are not a good combination for rapid delivery and processing, with minor changes in models taking 3 weeks to be delivered and a further week for testing and modification.
3. Research – Diagrams of the ancient wagons I intend to populate my Shapeways store with are hard to come by, and when I do finally find them, they’re often fuzzy with poor detail.

1) is unavoidable for the time being, we'll need newer technologies to print more useable materials before I can seriously consider making entire N gauge wagons (chassis included!) in a 3D Printer. 2) is up to Shapeways to sort out, or If another company can sort that out I'd love to hear about them :).  3) is a bitch, but not entirely unsolvable in many cases.  With regards to my current 3D printed wagons (the Metro Brake and the Rigid 8), I'm sorry to say that these wagons are suspended for the time being, while it's possible to make decently detailed models, 3D Printing really has to catch up strength-wise before I can consider selling them as a serious product.  I may consider a hybrid approach of etches and 3D prints, as EtchedPixels seems to be getting on quite well with, but I'll need to learn my way around brass etching first and my first attempts are a stain on my modelling career that shall never be spoken of again.

Somewhere, Bob Symes weeps for future generations...

In other news, I will be visiting the British Festival of Railway Modelling in Doncaster on the 7^th of February.  I've never been to either Doncaster or this particular show, so it ought to be fun on both counts.  This neatly brings me to another announcement – There shall be reviews on this blog!  Oh yes, the time has come.  Given that I now work hours slightly worse than 9-5 (8-6, though I get an hour's lunch in which to write features, or bilge if you refer my personal blog), I'll probably examine smaller products for more intimate reviews; things like whitemetal kits, brass kits, 3D Printed wagons and static objects.  I'm itching to sample the state of our hobby's 3D printed items firsthand, even the best pages don't tell you much about things like ergonomics (for things like handles), surface quality and ease of construction.

As for features, I'm not sure they'll come to prominence for a while.  I am only 23 in a hobby dominated by retirees, retirees who can drop the hammer and call me out with their all-spanning experience!  That's a funny thing about Railway Modelling, it's probably the only industry I know of where you can survive by being stubbornly old fashioned - many business are still able to survive on mail order alone, Dean Sidings being a prime example, and their Pug conversion for the hornby 0-4-0 got a feature in Parker's Guide (a smashing modelling tips publication from Hornby Magazine).  My thoughts are along the lines of ideas about the state of the industry and where we can go from here, and some things damn well need to be dragged into the 21^st Century!

In spite of the ageing demographics our the hobby, I am confident that it will survive, if only because Heritage Lines remain National Treasures somewhere between Stephen Fry and Spitfires.  Despite all the dreadful rhetoric of the “breakdown of family values”, there are still a great many people not quite so blemished, and can thus appreciate there's more to life than power over others.  I picked up a leaflet about that National Model Railway Museum at Ashford at a show, and I can understand why people may be worried by the line “think about the future of our hobby”, but rather than see terminal decline, I see the opposite – I see people looking out for us and ensuring we don't fade into history like a thief in the night.  In short, I see...  Immortality...

Okay, maybe a little too high on myself there...

How to reduce STL errors: Get your 3D Printed items error free for Shapeways

We've all been here, red faces flagging up all over our models thwarting our attempts to produce consistently printable models.  Just to emphasize how annoying this can get, here is a screenshot of my Caswell Flats STL just after export from Google Sketchup:

Just you wait until you introduce curves into the model...

See those red areas?  Those are degenerate faces, and they can do much more besides making the model unsightly, up to and including causing a non-manifold model - all 3D printers require the model to be "watertight" or manifold to print, that means there must be one consistent shell.

Having gained much practice in handling STL files, usually through frustration, I thought I'd put it to use by outlining these three tips to flush out the degenerates and, better yet, prevent them from happening in the first place:

1.  Get Netfabb

Let's face it, computers being computers, no CAD program is ever going to produce a perfectly error-free *and* a detailed, high-resolution model first time (even if such a program did exist, the cost would be horrendous); enter Netfabb - a slick, attractive application that makes light work of banishing the reds.  The Basic version is free to download and use with no time limits, and it fixes most errors with automatic ease; it is, however, limited to the most basic of STL sins and cannot, for instance, Wrap Part Surface which reconstructs the shell of a model to close up the holes.  For £200 you can upgrade to Netfabb Private, which allows access to all the tools you'll ever need to fix STLs (I personally cannot comment on their effectiveness since I only use basic, still, one for the future investments list).  There is a hideously-priced Professional version costing 1500 Euros, which I'd only suggest if an automatic nesting algorithm sounds vital to you.

2.  Reduce the resolution of your models before exporting to STL

Not a sure-fire fix, but one that can get your models from 'RED ALERT!' to 'that'll do'.  Resolution pops up in many different ways, for instance Creo Elements Direct (which I strongly suggest you get if you want to model curves) features an 'Facet Accuracy' setting, accessed via Right-Clicking the Part, selecting Part Properties, then the Facets tab; This will give the option to set either the minimum distance or angle the model will be permitted to render.  This is the result if I go for the insane resolution of 0.5 degrees:

Aside from bringing my new AMD R9 290 Graphics Card to it's knees, this is what 5244010 triangles and 250mb of Chassis looks like.

So you're thinking it's not too bad, except that 73 shells and 144 holes are produced...  Netfabb ran out of memory trying to fix it (silence...).

Let's go down a gear to 1 Degree and see how it is:

Errors around the Pinpoint bearing holes are reduced :)

The repair I tried in Netfabb Basic did little if anything to reduce those lines, although this exercise illustrates a point:  Reducing the resolution not only rids you of reds, but it also reduces strain on your Graphics Card as it renders the model and it makes smaller files with the 1 Degree file being 67.6mb.

3.  (Sketchup Users) Use Solid Inspector

Sketchup hit the spot for many modellers when it introduced it's extension warehouse, myself included - trawling the internet for obscure, often poorly-optimized plugins is now banished to the past along with floppy disks and those chirpy modem things.  One of these plugins to come to our rescue is Solid Inspector, a straightforward function which highlights any issues with Sketchup models by circling surplus lines with orange and holes with red:

This is a rather severe example, but you can hardly blame us when you take the Tumblehome into account.

That was the body of No. 394 of the Chesham set of Metropolitan Bogie Carriages, at which me and Matt Wickham at Bluebell Model Railway (click here for some video of the carriages running) have been beavering away on for some time; Admittedly finding the actual rogue lines and holes is still tricky since the circles don't always scale to your viewport, but as a general indicator it's a godsend which can mean the difference between printing and self-inflicted pain.

The Takeaway:  3D Printing, not 3D Perplexity

There may well be other methods I have failed to mention, but I can sum this post up thus:  Don't rely on your eyes to find faults.  A CAD model, unlike your hands, CNC machines and even reality, can scale down into infinitude, theoretically to the Planck Length and below; that said, god help you if you want to zoom back out again!