Friday, October 02, 2009

Friday Feature: Laser Etched IA Wagon

AmFet writes: Well, I was going to try and come up with one of our pithy punny titles, but decided against it....

This has just flown off my workbench; an IA wagon laser etched in 0.5mm styrene.

First, the top (with my hand for scale):

Now, the undergubbins:

SO now you can see how it ended up, this is what really happened in the background. The wagon was designed on AutoCAD 2008 using a plan from the TranzRail Fleet Catalogue...honestly, when you are working in this scale you dont need a full blueprint. It was saved in DXF format and passed to a friendly laser cutter here in Lower Hutt. When I finally got it back via Mark Andrews (Cabbage) it looked like this:

The styrene is covered by a self adhesive paper; I think this protects the styrene and also has the benefit of holding everything together. I had visions of turning up to Cabbage's and being handed a handful of non-descript parts. Also, Cabbage altered my plan to turn it into a "cutting template" by butting pieces together, thus minimising the number of cuts that needed to be made by the laser.

First job is to peel off the adhesive paper from one side, which had the rather satisfying effect of popping all the holes out of the main girders. However, it did show up an error in the design. The Truss at the bottom of the photo shows that the link between the two "knees" was way to thin (0.3mm) and some broke while the paper was being pulled.

The pieces were then removed from the backing sheet and all traces of the adhesive paper were removed from all components using the scalpel to pry up a corner, then pulling with end up with a pile like this:

This is one of the girders once removed:

The girders have been designed to drop into slots in the deck so they positively locate. The original idea was to assemble the girders with the trusses as a sub-assembly, then put the deck on top of that. However, with the weakness in the trusses it was decided to put the girders onto the deck first, then cut the trusses in half and slot them in individually from the outside....which actually ended up being easier than it sounds. The trusses themselves are made up of 2 x 0.5mm laminates, so they are 1.0mm thick when installed.

This very blurry photo shows the girders and trusses installed, but before the sides went on. The one thing I learned is that I suddenly have to learn how to drive the macro settings on my camera!

The sides are slotted to fit in with the twistlock pads...again, it allows for the positive location of the parts...something we tried hard to design in. Of the whole assembly, this was by far and away the hardest bit; trying to glue and hold in one location, then move along. Then the bogie bolster pads went in, and finally the wee headstock end on the cutout (at the top of the photo).

And thats pretty much it!

Still to add are the headstocks (which will rely on coupler choice) and bogies. Then its detailing (twistlocks, handbrake, etc), followed by a cleanup (some filling may be needed) and paint.

For the production model (and yes, it will be available to order as a "scratchbuilders aid" for around the $20 mark), I will redesign the trusses so they are a bit beefier and less prone to breakage. I put the thing together using a scalpel, tweezers and Tamiya runny glue (the green top variety) with various other prodding and holding devices in about 90 minutes...but I think 30 mins was taking up with me grinning stupidly at the model going " Yeah!"

So thats the IA....The guy here at work who designed the HK has just seen these pictures and wants an HK in Nz120 for his desk, so that will get added to the well as a VRB, OM.....

Sigh, back to my day job.

A big thanks to Cabbage and AKF for their help in the production of this wagon.


worzel said...

Strewth, thats a bewdy doohicky, bet your'e chuffed with that! Good on yer mate!

manaia said...

how mutch did it cost?
I would like to here an update on how you get on with the bogies and how the wagon corners.
by the way I LIKE!

regards Manaia

Amateur Fettler said...

There is a set of TrackGang bogies on order to play with, so an updated report will be forth coming. Cost....Well, there will be hardly any markup (just a wee bit to cover running around and sourcing styrene, etc), so it is pretty cheap! I really just want to be able to cover the original cost of this, not interested in really making any profit...its all about the scale, you know!!

woodsworks said...

I have always purchased my styrene supplies in bulk from Mulford Plastics in Auckland. I still have a heap of 0.75, 1.0mm etc in both black and white, can cut to special size if it's of any use. What breed of sticky paper is applied? The laser cutter I use does a reasonable job without paper, so the result should be spectacular with paper (if I know what it is and how to apply it) I might end up working for the guy shortly, too, so the possibility of low-cost cutting arises....