Investment casting and other bits from my workbench

[Z526]

So first off, this will not just be investment casting stuff but will also include some kit and scratch building efforts as well as possible kit development work, watch this space.

 

However this should be a fun way to start. Last year I was fortunate enough to have a work trial with a company that does investment casting for the jewellery industry and being the type of person I am I thought to myself 'Well this doesn't seem difficult at all'. Fast forward 9 months and I have have been purchasing equipment and slowly working towards doing this myself.

 

All the equipment needed has set me back around $5000 so far, a modest investment (pun intended?) that compares to a handful of HO scale ready to run Aussie locos.

 

The equipment is as follows;

• One electric pottery kiln, second hand and fitted with a digital controller for $3000
• One cheap as chips induction furnace, the finest product of the peoples republic of china, complete with a label saying made in Italy! $400
• A vacuum chamber and pump, from a well known auction side which was $100
• A wax injector again from China $650
• And all the consumables and odds and ends, investment powder, wax, mould rubber, so on and so on.

 

So having slowly got all this together I had the good fortune to lose my job last week due to the ongoing situation that I need not mention. This has afforded me time to get off my bottom and put together a trial run of all my equipment. 

 

20200324_091039 by John Halliday, on Flickr

 

This is the first mould I've made, it's a rubber that comes in two parts which you mix up, tip it over your master and let it set then cut the mould open, the cuts allow for the mould to be aligned between each injection and removal of the wax. as you can see it produced a reasonable wax chimney!

 

20200325_152955 by John Halliday, on Flickr

 

Next this was placed into a cheap and cheerful flask(it used to have sweet corn in it if you wondered) and the investment mixed, vacuumed, and poured over, the flask was them vacuumed again to be sure it is free of air pockets. Once set you and up with this;

 

20200325_163434 by John Halliday, on Flickr

 

then its onto the kiln, this runs on a 21 hour long program, however you can cast from the 18 hour mark as the last three hours it just sits at 500 degrees to allow you time to prepare your metal and other bits for the actual casting. Also handy to have that 3 hour window if you are unsure when you will be home to cast!

 

20200326_084816 by John Halliday, on Flickr

 

this is the flask ready for casting, now I neglected to take any photos of the actual pouring part because I wasn't game to hold a camera while slinging hot metal around however we can see the results.

20200326_144215 by John Halliday, on Flickr

 

One chimney, rather respectable for a first effort I feel. All the flaws in the 3d print have been reproduced rather nicely showing the level of surface detail that I can achieve. 

 

The exact nature of the alloy is a bit unknown as I just chucked some scrap brass in the furnace, this is something I will be working on in future to ensure I know with some certainty what the composition of the alloy is.

 

The next step is to purchase a small 3D printer capable of printing in a material that I can easily burn out. 

 

If any members have such a printer and wish to have items cast I'd be more than willing to give it a go if you cover postage costs for your 3D printed items and as long as they are of a suitable material.

 

stay safe everyone.

 

[clarkea1]

I'll be very interested to see how this develops.

 

Alastair

[Z526]

Some bits and pieces to report, will add pictures later today when I'm at the computer.

 

First up I successfully created the first tree of waxes instead of just doing one chimney at a time. I also decided to have a play and made a rubber mould of a slaters driving wheel that was sitting around to test if the wax I have is going to flow into structures such as the spokes of the wheel. It produced good results so if anyone wants to design and 3D Print the cast brass centres for those odd prototypes without a mass produced wheel this can be done if you can provide the prints. Naturally you'd have to add your own steel tire however the casting process reproduced the square hole for a standard slaters axle so well that it was a snug fit, so you could use commercially available axles. 

 

I also went to a local company and purchased some casting resin. I'll have a play with this to establish how much shrinkage it suffers while setting, this will enable me to produce accurate moulds for boilers ans such parts of the kits I want to make.

 

Been a little distracted coming up with a bell for a 3 chime whistle for a live steam loco this week as well.

 

Hopefully once out jobkeeper scheme(like the 80% wage guarentee in the U.K.) is up and running I'll havr funds to get hold of my own 3D Printer and this can really take off.