Part 3 of the Bagnall history and design information has been sitting on my blog in draft form for many weeks now needing me finish it off and publish. It will happen soon but I feel I need to interrupt those spasmodic additions with a project update.
I’ve grossly underestimated the time it would take to get all the third party parts together whilst the need to continue to earn a living has meant that it’s not always had my full attention. There, that’s my confession in place, now to expand on that a bit.
The 3D printed parts are all done – I think I may have to print the rest of the fireboxes but that’s it. That at least is something within my control. I have put a loco together for display purposes using 3D printed versions of the bits that will be brass castings.
I did this partly as a test build and because I needed pictures for adverts to go in magazines.
Whilst the 3D printing is within my power and control it’s the 3rd party items that have been a bit of a pain.
First, though I should commend Julie at York Modelmaking. Whilst I used to work there and know how to produce the artwork laser ready Julie took my e-mailed file, sent on a Saturday, turned into a pile of floors and posted to me arriving on the Tuesday.
The big delay has been the brass castings. I’m a bit annoyed about this because I think I led myself up this blind alley. For the last couple of years now I have been 3D printing patterns for other kit makers and sending them to the caster and from this I got some idea as to how long it was from sending patterns to them being castings.
I clearly got it wrong. What seems to have happened is that I took the optimistic view and didn’t account for demand pre Guildex and then post Guildex holidays!
I do hope you weren’t expecting the single piece one lump 3D print that seems to be a prevalent offering at the moment? As well as having twelve resin parts there are thirty six brass castings in the kit.
I wonder if a little diversion into the lost wax process is worthwhile here as it’s a phrase many will have heard but not know what it means. It goes like this. A pattern is made, printed in this case, which has to be designed with being able to be removed from a mould in mind*. This sometimes means things have to be made in two or more parts. This pattern is then sent to the caster who makes a split silicon rubber mould around it. This mould is then filled, multiple times, with hot wax (starting the wax part of lost wax) giving you multiple copies of the part in wax. These are then strung together in a Christmas tree of sprues with more wax (the blob you have to clean off your casting). These `trees’ are then suspended in a flask and a fine liquid ceramic goo is poured in, vacuumed to get all the air out and then warmed to make it set. Once set the temperature is increased to melt and then burn out the wax. (now that’s the lost part of lost wax). Now we have a flask containing a ceramic lump that has part shaped holes in it.
Molten brass is then poured in allowed to cool after which the ceramic is broken out leaving your brass parts. These are then cleaned to remove most of the ceramic but they don’t always get all of it out.
That massively simplifies the process and it has a large helping of art as well as engineering. There are many casters out there but many are jewellery specialists that do train bits but have no idea what the part is. I use one of the few that just does parts for trains (and does his own kits)
–* There is a way to skip the silicon mould stage now directly printing masters in castable resin bit it means a print per copy. It also needs different temperature profiles at the burnout stage
So having explained the process commercially a lap around the system is typically a three day effort. Waxes day one, moulds day two, cast day three. Also, it would be typical to have one set of castings done to check them for errors before ordering in bulk.
So, where are we with the castings for the Bagnall?
The first batch arrived in September, Generally they were fine with just two items needing further work or revision.
Then Guildex and holidays got in the way.
It was then into November before I got part two of the castings to check and they arrived when I was busy with something else so it took a few days to check them.
The current situation is that (as of Nov 29) the order is in for the production sets of castings and I await there arrival.
Once I have these I’ll get on with both assembling a final version, writing the instructions and packing kits. There is a slight thorn in the side of that plan in there i have a commission model to finish that is also top priority (isn’t everything?)
What else is happening Bagnall wise?
There’s transfers. At the moment these exist just as a one of for my loco(s) but I will investigate making them available if there is enough interest.
Due to a mistake in the printing process there is also a half size set which might do for another project below.
Having caused a drought with the supply of the 0n3o chassis and a need to do chassis for other models
in house rather than rely on commercial offerings a chassis is in development for the kit. I’ve started on the wheels.
There is also a 009 version in development due to popular demand (a friend gave loaned me the chassis to put a body on). Its still a work in progress.
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