Another lad from Ontario

Glad to be here! I have already seen some glorious things going on and maybe I could add a little to the scrap pile (but preferably the "keepers" pile.)
I first got my fingers burned many years ago in the UK. Took up residence in Canada 45 years ago and have been in and out, mainly out, of casting work since I landed. Somehow it never really leaves your blood if you follow. Nothing quite like the smell of burning Petrobond in the morning I guess!
I have long had a hankering for making Art Deco style aircraft such as were produced from the 20's right in to the 50's. Silvery, streamlined, and sleek. No windows, rivets or seams. Just the simple escence of the medium. Wow, sounds poetic!
Having a basic skillset and now free to experiment due to retirement, off to work. Still working too. I will post a few snaps of what I am up to. As they say, "a picture is worth a thousand words.

I am casting the models in either aluminum or one of the zinc/aluminum alloys. They start life as what I will call a "soft model" which I build up with a various materials, plaster, polyester resin, clay, wood, plastic etc. This model I convert into an aluminum master pattern via a sand casting. Sand may be petrobond or water/bentonite bound Mansfield sand.

Once I have cleaned up this "master" I then convert it into an aluminum die by a rather nifty procedure of encapsulating it to it's predetermined and logical joint line in aluminum. If you can imagine making say, a plaster mould of an item, instead of pouring plaster over the model, I pour aluminum. In the case of a two part mould, repeat same method on the other side of the model. The die is not restricted to a two part split. It may well be built up as a multi part tool on complex parts.

Now, these "dies" are not high pressure tools. They are what we used to call "gravity casting dies" in North America we call them "permanent molds." Here the metal is poured into the cavity by hand under atmospheric conditions.
One or two interesting facets of this way of doing things is: the joint lines do not need to be linear, they can be as convoluted as may be. The mating part will follow faithfully to it's predecessor(s). There is no need to have access to any machine tools unless we call a drill press such. When I was a boy, I could make a straightforward two part die in a day. It now takes me an extra day to reach the same state. In fact I used to pride myself on being able to make the die and have sample castings on the floor within a day. Not any more. Remember these dies are made from aluminum. They are light and do not need elaborate mounting before running. They are literally hand held and clamped up with "C" clamps.

Another little aside, the castings that come from these tools do not exhibit any contraction from the original pattern. I am casting like metal onto and into like metal from start to finish so the coefficients of expansion/contraction are always in harmony.
This feature matters very little of course when it comes to what is, at the end of the day, decorative work such as what I am involved with.

I thought that this would be a short intro to my reason for being here but it seems to have turned into a "How it's made" episode.
Please feel free to drop me a line if you need a little, but not too much, enlightening.
I will add a photo of a very simple die for an Me109 to show just how basic this can be. I hope there are not too many snaps!
John

 

Welcome. That's some impressive work, I think we'd all love to watch that episode of How it's made!

 

Hi Kelly, did you get my reply to this? I can't see it here and I hate to appear ignorant!
John

 

Hello Jeff, strange, but I have never photographed or filmed the actual act. Many snapshots of finished project but nothing filmed. Must get down to that before the Reaper arrives.
John

 

Yes, maybe I should put it out there!
John

 

At the very least, give us lots of pictures of not just of your finished pieces but your processes and works in progress too, we love that sort of stuff.
P.S. Love your profile pic of the Lanc. I work at it's home base so I have great good fortune of seeing it on a regular basis.

 

I'll select a few more snaps of the dies and patterns and post them up. I should by now have recorded the sequence of events from start to finish explaining how it all goes together. Very, very much a grass roots effort as I indicated. Almost akin to those brilliant videos from India showing the gentleman making spare parts for motorcycles and such.

The Lancaster still brings tears to my eyes.
You work "in" or "near"?
John

 

Oh no! Another bad pour!!
It looked so good too. I wonder where it went?
I'll redo it this pm.
John

 

I work at the airport that is home to the Canadian Warplane Heritage Museum but not in the museum itself. However, my office has a very good view of the airfield so I frequently see the museum's aircraft rolling past my window.

 

Bliss!

 

Then you'll probably enjoy this, I took this pic at work during an airshow a few years ago. Two Hurricanes, two Spitfires, a Mosquito and the Lancaster, the sound of those ten Merlin engines almost directly overhead was glorious!

 

Hello Kelly,
I understand your interest in the ability to cast sound heavier sections of the models. This feature, in many aspects, is self evolving. The best term I can come up with is "progressive solidification" where the naturally high chilling factor of the mold material, aluminum, is aided by the flow of incoming material to feed the heavier sections of the part as solidification takes place. As there is little or no contraction/shrinkage taking place between the cavity and the finished part due to like material being used for both die and casting.
All a bit of a mouthful but the best way I can explain it!

Yes, I do preheat the dies before starting to cast. A few reasons for this.

1. Introducing molten metal, even very low melting point materials, into a cold cavity can and will result in a rather nasty volcanic event due to the rapid generation of steam liberated from the ambient moisture on the surface of the die.
I have a sneaky feeling that this is not what you were getting at but is well worth reminding ourselves about from time to time.

2. Thermal shock. No material likes to be shocked by the sudden and local escalation of temperature. This can ultimately lead to distortion of the tool or at least the local deterioration of the die surface.
I don't think that this is what you were thinking of either but well worth reminding ourselves of anyway.

3. After a fairly light pre-heat the mold surfaces are coated with a commercial die coat. Foseco 140. An rather heavy coat is applied to the feeding system to aid in the final feed of the last section of the cavity.
The coating applied to the cavity serves two functions. One, as a thermal barrier between the incoming flow of metal and also acts as a slightly pebbly texture which aids greatly in the breaking up of the very thin but tenacious oxide skin which forms on surface of aluminum the moment it meets oxygen. This local "turmoil" on the surface of the incoming metal allows for a much improved filling of the cavity, particularly of the thinner sections.
This is my theory anyway and maybe more in line with your question!
I hope this uploads this time.
Regards,
John
John

 

Way beyond Bliss. Nirvana?

 

I love your castings, I've often thought about trying something similar.

I work on Hurricanes (well did, the last one leaves the hanger this week) Hopefully we will get another project or I may have to find a desk job.

 

Incredible stuff!

Thanks for sharing your great work. I'm eager to see and hear more.

 

I read of your joy when you got fixed up with the Hurricane project. I hope that there is something in the pipeline to keep the team together. Sad and frustrating to see a unit broken up.
I have been working up a pattern for a Hurricane, on a much smaller scale of course, and I'll post it up here in a moment. The wingspan on this fellow is about 20" if I recall.
I see now the photo is a mix of various types but the Hurricane is at 12 o'clock
Spitfire at 2 o'clock
Mosquito at 6 o'clock
Vulcan at 9 o'clock
Mustang at 10 o'clock
Why on earth I listed them I don't know as I'm sure you can ID them!

Cheers, enjoy the game today,
John

 

Those are very cool patterns! If we could get a Mosquito build in it would be so cool, there was talk of a few other possibles but the money is just silly for 'heritage' planes that are not flight worthy.

Looking forward to your threads on the process if you get chance to post some up.

Off to the pub now to watch the game ................