The Bucket Foundry

[husaberg]

Fellers, your timing is good. We are doing a little project where we have 3d printed out some short manifold stubs. We then created a 2 piece mould using a Vinamold equivalent, creating the inside and outside shapes of the printed item. Then into the cavity (after the printed item was removed) we poured in moulding wax. Beautiful, good surface reproduction etc.
Then what to do next. Firstly we set the wax model into a plaster/sand/water mix. After semi drying for a day or so, we put it into an oven and gradually melted out the wax, going finally to around 110 deg. The wax appeared to be basically melted out, but there was still a surface residue. Anyways, as we were doing a piston cast, we put the plaster mould on the furnace and its temp probably was around 250 or so. Then we splashed some metal in. Started off ok, but then lots of bubbles and aeration of the metal, and no minor shortage of thick smoke.
When cool, we broke away the plaster and one could see that the casting started off ok at the bottom, but went to shit further up. The plaster though, showed that the wax had permeated into the surface to a depth of around 10 mm or so. I guess this was the cause of the problem as it was heated and started to vaporise and burn. Maybe we should have baked the plaster to a mush higher temp, say 600 or so, before casting to burn off all the wax within the plaster
The other option was to invest the wax,. However with some investment we have here, as soon as the wax item is removed, the investment just runs off. Sort of what you'd expect. So, to counter this, the advice was to cover the wax with shellac. However, even this is not great with the investment, which is water based, still running off.
Thoughts?

Awhile back there was a video with plaster mix used, from memory it was baked at a very high temp.
Give me a few minutes I will locate it.
https://www.youtube.com/watch?v=1rgfT-PlXqU
different process but 1hr at 850c degrees. 5.51 minutes on vid.
just looked again and most of the wax was out at only 150 degrees c for 1/2 hour 5.15 minutes on video



plastic but 1 hour or more 1000 deg.
cherry red
about 18 minutes in
https://www.youtube.com/watch?v=WWVVSZP3Au4


On entirely different subject Have you ever run us through how you make the pistons Ken. Because it has always intrigued me to how it is done.

[Yow Ling]

Hi Ken, I did an investment casting for something to do, Instead of wax I used casting resin, wax would have been way easier. I just used 50/50 plaster and sand. Let it cure for a couple of days then put it in the furnace for about an hour and a half. The resin fumes were pretty nasty and i really should have done it outside, but how would i learn from that. The plaster block was pretty hot the heat I put in would easily have melted 2 crucible of aluminium. when it came out there was no trace of anything in it, so I think you just need to go way hotter.
When they do commercial investment casting , after getting the wax out they fire the ceramic at more than 1000 degrees c the by product of this is spotless insides and maybe a stronger mould

[diesel pig]

On entirely different subject Have you ever run us through how you make the pistons Ken. Because it has always intrigued me to how it is done.

I second that, some pics and info would be great.

[ken seeber]

Fellers,

Investment. Learned a bit more today and how to be embarrassed. Turned out that I just hadn't properly mixed the investment slurry, it had settled out more than I thought. Also learned that hair spray can also be used to coat the wax as an alternative to the shellac. Still have to be reasonably quick in getting the first layer of supporting sand on.

Husa and Yow , thanks for the vids, but had seen them before, but didn't realize the importance of getting the temp up so high. Loved the safety procedures that old mate was using doing the 3d printed PLA investment and casting.

Think I'll have a go with both the plaster and the investment slurry approach. I'll post some happy snaps when done.

How we make pistons? Go to http://www.strikeproducts.com.au/features.asp Down the bottom there is a feature article plus some other blurbs from over the years. However, if you want to drop in one arvo for a tour and beer you are welcome!

[husaberg]

Fellers,

Investment. Learned a bit more today and how to be embarrassed. Turned out that I just hadn't properly mixed the investment slurry, it had settled out more than I thought. Also learned that hair spray can also be used to coat the wax as an alternative to the shellac. Still have to be reasonably quick in getting the first layer of supporting sand on.

Husa and Yow , thanks for the vids, but had seen them before, but didn't realize the importance of getting the temp up so high. Loved the safety procedures that old mate was using doing the 3d printed PLA investment and casting.

Think I'll have a go with both the plaster and the investment slurry approach. I'll post some happy snaps when done.

How we make pistons? Go to http://www.strikeproducts.com.au/features.asp Down the bottom there is a feature article plus some other blurbs from over the years. However, if you want to drop in one arvo for a tour and beer you are welcome!

Cheers Ken.
For those that are to lazy to look

loved the article on spark erosion, the tighter the rules the more cheating that is tried.

[Flettner]

OK, what's happening? I got stories to tell but what about others, post some stuff?

[ken seeber]

OK, what's happening? I got stories to tell but what about others, post some stuff?

OK Neil, you're right...here's my current plaything. Basically a friend in Tassie wants to make a custom inlet manifold for a 2 litre 4 cyl race car. He sent me two flange plates, abrasive jet cut in 10 mm alloy, with one profiled to suit the head face & ports and the other to suit the throttle body face & port profiles. Knowing the angles and the spacing of the two plates, our task is to fill the gaps. That's what engineering is about a lot of the time. Fortunately, the spacing is equal, allowing us to just use 4 identical gap fillers, inlet runners really.
So, drawing these up in SW, we then printed one out on our FDM printer. This was then cleaned up a bit with spray putty etc and you can see it in the pics. After that, we used Vinamould, or local equivalent, to make a mould of both the inside and outside, using a simple fixture to hold the top horizontal when pouring the V. After this was done, we then created 4 sacrificial waxies. To these I added a wax pouring cup and riser. No downsprues feeding upwards from the bottom, just splash it down from the top.
Did do an initial plaster mould, but it didn't really work for the reasons mentioned in the earlier post. In between times, I got some investment slurry, and started on this yesterday, but it'll need many dips and sand coats, to get any thickness, probably cos we are only using really fine sand. I think next week I'll go back to the plaster/sand mould approach. Here's a couple of pics anyway.



Watch this space I guess. Wotcha got Neil?

[Flettner]

Wotcha got?

Just updates, ongoing projects.

I've had this gear hobb machine for, I don't know, years I think. Bought it sight unseen and was a bit of a dog. I've rebuilt the head ($1000 in bearings alone) and now payback time. I've been cutting gears for the Heat Ranger engines, it's a nice machine now I've got the hang of it. Just worked out the auto off system today so now I can walk away without fear of the cutter carrying on into the work clamping fixture. Finaly another piece of the engineering puzzle I don't have to rely on other people.

Ken, would you be better off just 3D printing sand core boxes and a 3D mould, straight off the drawing?

[Flettner]

Sleeve engine sitting in the YZ 2010 frame.
Heat Ranger heads being machined in the lathe
Cylinders ready for Nikasil

These same cases will host the FOS and a few other cylinders I have in mind, kind of donkey cases if you like.

[ken seeber]

Wotcha got?

Ken, would you be better off just 3D printing sand core boxes and a 3D mould, straight off the drawing?

Neil,
Yep that was an option as also was the option to just CNC them from stock. However I wanted to take the opportunity to learn a bit more about the lost wax process. Thinking of bigger things here.

In addition, we have now got a couple of alternative filaments that are worth trying :
1. PVA that supposedly dissolves out in water, after investing
2. HIPS that dissolves out in Limonene after investing
3. Wax filament that hopefully can be processed just as a moulded waxie.
Obviously all these three are suited to one-offs only

As they say, "so little time and so many things to do"

Your bits looks great....... "Job Satisfaction 101"

[WilDun]

OK, what's happening? I got stories to tell but what about others, post some stuff?

At the moment things have gone quiet here - struggling with my joints (ie the joints in my body ) and my home workshop machinery (found that whoever owned my lathe before had been mucking around with the gearing), also trying to get other domestic things running properly. - so I've been coming in here (forum) now and again to follow the goings on and hope to glean more knowledge from you guys, not that I'll really be able to use much of it.

At the moment I'm teaching a relatively young guy (niece's husband) to use the lathe etc. it's good to find someone actually wanting to learn, a rare thing these days when people just expect things ready made and don't want to know about how it's done, or care - very refreshing!

My furnace etc? - well it's still almost there!

Guess it's better to end up being the silly old fool pottering in his workshop than sitting around hoping to find a hobby and ending up playing solitaire or snakes and ladders like so many do!

Keep up the good work you guys who are trying things, do it while you still can, I'm always interested and I'm sure quite a few others are too, it's probably just that we're a bit over awed by what we see, so we don't actually contribute much ourselves.

[Flettner]

Wil, I know what you meen, people are just not interested in how things are made any more ( generalizing ). The guy you are teaching will gain a life long skill. Next he will need a lathe at home then he will say " I can't understand how I opperated all these years without one! " If I was PM every house would have a lathe.
Keep at it.

[F5 Dave]

Forget 'Books in schools' we need 'Lathes in homes'

[Grumph]

Neil,
Yep that was an option as also was the option to just CNC them from stock. However I wanted to take the opportunity to learn a bit more about the lost wax process. Thinking of bigger things here.

In addition, we have now got a couple of alternative filaments that are worth trying :
1. PVA that supposedly dissolves out in water, after investing
2. HIPS that dissolves out in Limonene after investing
3. Wax filament that hopefully can be processed just as a moulded waxie.
Obviously all these three are suited to one-offs only

As they say, "so little time and so many things to do"

Your bits looks great....... "Job Satisfaction 101"

Ken, from what i've heard, most production line "lost wax" type casting now is done using expanded foam as the core for the ceramic shell. i understand a lot of the late model car cylinder heads are done like this. I can only assume someone's come up with a non toxic foam to get around the emissions problems of burning it out. It obviously involves having moulds for your foam cores which represent the main investment (no pun intended)

[WilDun]

Forget 'Books in schools' we need 'Lathes in homes'

True Dave, but try and get ACC etc. to agree with that! you'd have to have every safety device in the book attached to it plus an extra levy for lathes in the home.
In fact, if centre lathes had just come on to the market now, they would be banned straight away with no chance of ever making it.
Furnaces and foundrywork? - forget it!
How about roll cages for bikes? - no?