Thread: A Saturday at the backyard foundry

Dear Nick that is one name for a pattern plate. They can be single or double sided. The chemically bonded sands should be OK for core and used as is. I had access to linseed oil based core sand which had to be cooked and this was smelly This was made and used at the RMIT foundry school. I also purchased ready made stock core in different diameters One thing I could not see is are you venting the cope before separating the boxes. I used a 1 mm wire with a wooden handle and stabbed the cope numerous times down to the pattern. This helps with getting the gas out of the mould. Also a 2mm wire to vent cope and drag sides of any core prints after the the mould is separated
My muller had a gear box drive coupled direct to a motor. and would drive a thirty gallon drum of wet sand. The rollers went up and down acording to how much sand was in the drum and there was a stop to prevent the rollers from running on the bottom of the drum also there were two ploughs one pushed the sand away from the center and the other towards it. I am really enjoying this thread I wish you were not so far away.
Yours 4-6-4

Initially, I made venting holes. But they turned out to be unnecessary. The sand lets pass air through it good enough.
I have moulds out of core sand that are as "big" as a matchbox. You really can blow through them. I'm using them for very small parts with thin walls. The one that made the biggest problems has a wall thickness of 2 mm. To get that working, I'm casting it with vacuum. Now it works, but there's room left for a better finish. I need to experiment on that with different temperatures, smaller gate and different vacuum.

That's the part I'm talking about:
Attachment 218502
The surface is too rough for me. Maybe the vacuum was too high.
The vacuum pump is from a milking installation.


Nick

Hi Nick,

Thanks for a great thread, now I can't wait to get back home and do a bit of casting, I'm still in Linz for a while yet, but you've now got me thinking a saturday afternoon barbeque and casting day in Shepparton might be fun.

As far as petrobond goes, I don't worry so much about the burnt bits anymore, maybe just get out the worst black bits, and I just mix it in and sometimes a bit of a squirt of iso-propanol seems to work.

Regards
Ray

and I just mix it in and sometimes a bit of a squirt of iso-propanol seems to work.

I didn't believe that, but I tried it today.
And, it seems to work.
The sand I had, only had little burnt content. I'll keep observing wether that works. I'll cast tomorrow, so I'll have enough sand to experiment with.

I had phoned the manufacturer of my sand some months ago, because I was completely lost how much to add of what. The answer I got wasn't too helpful: Try 0.5% of oil. And then maybe 0.5% of bentonite.


Thanks!
Nick

Hi Nick,

I think I read somewhere that you can use methanol instead of iso-propanol, the oil I think synthetic two-stroke oil is what we use, I'm away from the workshop at present, so I can't check. (Actually, I think I'm only 2 1/2 hours from Munich by train.. OBB Railjet )

I'm curious as to how you have setup for vacuum casting, do you have a diagram?

Regards
Ray

I'm curious as to how you have setup for vacuum casting, do you have a diagram?

I'll have a posting and a video as soon as that works the way I want.
I'll make further tests this Saturday (I hope).
Basically, it's a box with a pouring hole out of steel. Inside the box, behind the hole is the mould (made out of core sand). Attached to that box is a vacuum pump. You switch on the pump, grab the small pot with molten aluminium and quickly dump it into the hole on top of the box.
Then wait a few seconds, remove the mold and cast the next part.

One mould already bursted. Well, I had to expect that (unsuited shape). But as it is within a containment, nothing happened.

BTW:
I found the receipe of the homemade Petro-Bond. It's called K-Bond.


Nick

einfach wunderbar

Originally Posted by fubar

einfach wunderbar

your not using profanities are you?

Originally Posted by MuellerNick

BTW:
I found the receipe of the homemade Petro-Bond. It's called K-Bond.

I notice in this recipe for for K-Bond they use isopropanol or methanol to gel the Bentone 34.

We used Bentone 34 extensively in the paint industry as an anti-settling agent and frequently made an intermediate Bentone 34 gel before adding it to the mill. The gelling agent we used was just plain methylated spirits, or standard industrial ethanol, ie the stuff you get off the shelf in the hardware store, ie Diggers brand.

This would be much easier to get and certainly a lot cheaper than isopropanol/iso-propyl alcohol.

(Actually, I think I'm only 2 1/2 hours from Munich by train.. OBB Railjet )

If that was a disguised question wether you can come by at a G&G: Yes.
The next one will be on Saturday in a week (18. August).
I'm a bit hard to reach by public transports ...
You could sleep in the shop.

If you are interested, PN me.


Nick

Originally Posted by MuellerNick

If that was a disguised question wether you can come by at a G&G: Yes.
The next one will be on Saturday in a week (18. August).
I'm a bit hard to reach by public transports ...
You could sleep in the shop.

If you are interested, PN me.


Nick

Just an update, Josh and I are off to Munich in the morning (OBB Railjet train does up to 200kph), and we are looking forward to a hot Munich summer's day (forecast is 29 C) and doing what we like best, melting bits of metal and talking with some like minded people over a barbeque and a few beers....

Should be a good day...

Regards
Ray


PS.. I'll take a few pictures if I remember the camera..

Just a reminder Ray, "don't forget the camera"

Phil

"don't forget the camera"

This is a restricted area. Photography absolutely forbidden.

I talked to the camera man from the last video and instructed him what takes to put a focus on. Unless he has no time, there will be an other video. This time with Ray an Josh.


Nick

Originally Posted by MuellerNick

This is a restricted area. Photography absolutely forbidden.

I talked to the camera man from the last video and instructed him what takes to put a focus on. Unless he has no time, there will be an other video. This time with Ray an Josh.


Nick

Hi Nick,
I have the popcorn ready to go. Looking forward to the movie (loved the book).

Phil