Sunday, January 10, 2010

Fast Moving Projects

The shelf above my new desk has been dubbed the "Fast Moving Projects" shelf. This is where projects are to be placed that are being worked on, as opposed to those one sitting in drawers awaiting being began. The idea is that I can only fit so much on that shelf, so I have to finish off something on there before I can start something else. This way hopefully things will get finished and not too many projects will be on the go at any one time.

The past few day have seen the bending up of some fine wire handrails for the GHG brake van I started about a year ago, some soldering on a set of points, and doing some experimenting with using PVA white wood glue to make flush glazed windows, but more on that another time.

Back in September last year I wrote about wanting to build the one off Dairy Farmers bogie Milk Tanker, BMT1.

Well today saw the first steps towards making it actually happen. I had already bought a NSWGR E Flat Wagon kit, which made up the basis of BMT1. Today saw the slow process of replacing the mounded plastic truss rods with fine wire ones. I tossed up not bothering going to this level of detail, but after looking at the moulded ones for a while I decided that I'd regret it if I didn't give it a shot. So the rod sections were cut from the bits that mount them to the wagon floor, and then those mounting pieces had to have very small holes drilled into them to accept the wire. Not a difficult job, but very fiddly. Next the wire needed to be bent up to the correct profile and length, so once the first one was made and to the correct dimensions, I made a simple little jig so the others could be bent to the same shape and then trimmed to length as the were test fitted. It was nothing more than an off cut of pine and three thumb tacks bit it worked a treat. If you are ever doing something that will require a degree of repetition, I cannot recommend making a jig enough.

So far, only the truss rods are done, the brake cylinder and air tank are fitted underneath and the head stocks are in place, but even sitting on the bogies it is starting to take shape. Pictures is the wagon in front of a picture of BMT1.

Observant people may notice that BMT1 appears to have a slightly different position for the air tank (?) and I'm not sure if I can make out a brake cylinder. However this first one is very much an exercise in trying a few different techniques out rather than shooting for a prize winning version first go so I'm not going to go overboard worry about every single little detail. Besides, I don't have any real good images or plans of the real thing so it's very much making it "look" right.

I bought some PVC tubing from Bunnings which will make up the twin tanks. The diameter of the tanks works out to 23.6mm in HO. In buying the PVC tubing however, I must have fallen into a bit of a trap for young players. A few weeks ago I bought some PVC tubing that was advertised as being 25mm. It looked a bit large to me but anyway I grabbed it and put it away until Yesterday when I pulled it out and it measured 33.7mm o.d. and 30.1mm i.d., so I'm not too sure where they get 25mm from???

So this morning another trip to Bunnings to buy the right sized PVC tubing. Once again I picked up the 25 mm tubing which looked too big, but being a bit smarter this time took it to the tool section and measured it with a ruler. Sure enough, 33.7mm. Measuring the 20mm PVC tubing nets a measurement of 26.6mm o.d.

With the real diameter of the tanks working out to 23.6mm in HO, I may have a look at cutting a longitudinal section out of the tubing and then squeeze it back together and glue it to get it down to close to the right size. I guess about 9.4mm will need to be removed to bring the overall diameter down to the required size. Can you m.e.k. PVC tubing???

As an aside, you can also buy 25mm electrical conduit in four metre lengths for about $5 instead of about $2.50 per metre for the plumbing PVC. Had I been able to fit it in the car I may have gone that way, although how many tankers am I going to build?

As nice as it is getting some of these projects done I do need to get back into the shelf layout and hope to get a module underway with some tracks and points down soon.


Sarails said...

your query on MEK'ing PVC, is a yes. The plumbers glue is just PVC with a pink dye to allow plumbers the ability to see where they have placed the glue.

You may find that takingout the 9.8mm will give you too much spring in the tube, so if you give it a go, be careful to let the MEK dry for a while, and make sure you find a good clamp to keep it closed

Darren said...

Yes it is quite springy with that much cut out, but I did have a bit of success with one tube using super glue. The challenge is getting the exact amount taken out of the tube, and getting the cut dead straight.

Not sure If I'm going to keep up with this technique or look for another type of tubing. Maybe roll some 10 0r 20 though styrene, or even very thin brass or something???

Although I've got a hot air gun so I might see if the pvc will soften if given some gentle persuasion with some heat.

The good thing is that the inside diameter of the tubing as is, is pretty much spot on for the o.d. I need, so with careful application of glue I can slide the cut section within the tube and hold it in a perfect tubular shape.