Author Topic: A complete casting how to  (Read 11292 times)

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
A complete casting how to
« on: March 27, 2014, 08:21:00 PM »
I know it’s back some time that I contributed to this forum.
I am still busy with my model two stroke cylinder patterns.
To generate some pocket money to get on with the cylinder pattern I was asked if I would cast some old motorcycle carburetor body’s.
So I took this challenge with both hands and got in the workshop.
For all off us hobby casters I have made a complete how to.
I hope you can do anything with this process, and please when I am not clear to you do not hesitate to put your questions on the forum.
I hope that I can answer them.
Well first I started with the float bowl’s.

The first picture is the float bowl core mold
This core is made by the SS proces,


Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #1 on: March 27, 2014, 08:51:49 PM »
The SS process is a fast core making process.
You need for this process some fine sand, Sodium Silicate and a Co2 cylinder.
To get a good core you can start with a mixer off sand and sodium silicate by weight off 100 : 6%
So you need for every 100 grams off sand 6 grams off sodium silicate.
Then you mixed this very well, I do this with a old kitchen hand mixer.
When you shake the bowl where in you mix the two components and you see no lose sand around it shut be fine.
Then you fill the core mold with this mixer and press it tight in the core mold.
Depending on the core depth and wide it could be that you have to make thin holes in the core to let the Co2 gas thru the sand.
The recipe I use for the core sand is some different then the standard mentioned formula u find on the internet.
My recipe for the mixer is as follow 100 grams off sand with 10 grams off SS.
I found that the sand type has a lot off influence to the amount of SS you have to use.
How finer the sand the more SS you have to use.
I use Dansand ( a sand type delivered by Bemix).

The time for gassing  I do this in two stages.
First I gas the top with a rubber bowl.
Then I unscrew the bowl en gas every hole I made in the core so long that the gas is blowing  out.
At first you will notice that all the gas is adsorbed in the core.
When the reaction is complete you will see the gas is flowing over the core.
This is the point that the core is ready.
P.S. You have to gas all the holes you have made this way.

   Tjark.

Offline ths

  • Full Member
  • ****
  • Posts: 1801
  • Kangaroo Valley, NSW, Australia
Re: A complete casting how to
« Reply #2 on: March 27, 2014, 11:52:27 PM »
Hi Tjark,

Is that a sink or drain plunger you are using to deliver the CO2? Looking forward to more.

Cheers, Hugh.

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #3 on: March 28, 2014, 05:51:06 PM »
Hugh, your spot on, it’s a sink plunger bowl, very sheep only € 2,00 over here.
Forgot to post the picture off the holes made in the core sand.
Here it is;

     Tjark.

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #4 on: March 29, 2014, 09:43:21 AM »
This is the result off a short time off work.
Now it’s time to make the sand molds.
 
 Tjark.

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #5 on: March 29, 2014, 06:39:20 PM »
Now I going to make the sand mold.
I use oil bounded sand, this gives the most detail to the casting.
First I put the bowl pattern in the sand box.
Because this is a very simple pattern I use only one box.
The core is will close the base off the sand mold so there is no need for a second box.
I have forgotten to take a picture from the base with the core in place but I think it will speak for it self.



Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #6 on: March 31, 2014, 07:59:27 PM »
Made today some core’s for the carb body’s
This with the same method as the float bowls.

  Tjark.

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #7 on: April 06, 2014, 11:07:25 AM »
Started today with the sand mold for the carb body.
First pictures are the pattern’s off the body.
Then the first and second sand mold’s.
The last picture shows the core inserted.

     Tjark.



Offline stevehuckss396

  • Full Member
  • ****
  • Posts: 1554
  • Sterling Heights, MI USA
    • Steve's Miniature Sparkplugs
Re: A complete casting how to
« Reply #8 on: April 06, 2014, 12:29:10 PM »
What do you coat your patterns with to keep the sand from sticking to them?

Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #9 on: April 06, 2014, 01:18:43 PM »
Steve, I use baby powder and a very soft brush.
I also use it on the oil bounded sand to separate the two sand molds.
This works great.
You  can get special powder but for a hobby foundry its to expensive because I have to buy it in packages off at least 100Kg.
 
  Tjark.

Offline stevehuckss396

  • Full Member
  • ****
  • Posts: 1554
  • Sterling Heights, MI USA
    • Steve's Miniature Sparkplugs
Re: A complete casting how to
« Reply #10 on: April 06, 2014, 01:33:52 PM »
I meant the paint. I have a few patterns and they were sprayed with enamel. The sand sticks to them and I was told the enamel paint and the oil in the sand dont like each other.
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #11 on: April 06, 2014, 03:35:26 PM »
Steve the pattern’s are coated with Polyurethane.
The carb body’s are quit some years old and have an old type off urethane coating.
The pattern for the float bowls are coated with a new type off urethane coating.
You can find some more information at http://www.scabro.com/
And at this page https://toolingandcomposites.sika.com/en/solutions_products/04/04a008/04a002sa02ssa01/04a002sa02ssa01100/04a002sa02ssa01101.html

This is the page with type’s  off coating :
https://toolingandcomposites.sika.com/en/solutions_products/04/04a008/04a002sa02ssa05/04a002sa02ssa05100/04a002sa02ssa05104.html

There are complete block in where you can mill your pattern and coatings for your pattern.
If you need more information let me know.

   Tjark.

Offline ths

  • Full Member
  • ****
  • Posts: 1801
  • Kangaroo Valley, NSW, Australia
Re: A complete casting how to
« Reply #12 on: April 06, 2014, 10:20:11 PM »
Looking forward to the pour. Hugh.

Offline Bezalel

  • Full Member
  • ****
  • Posts: 376
  • - Skype:Bezalel2000
Re: A complete casting how to
« Reply #13 on: April 06, 2014, 10:57:15 PM »
Nice Work Tjark
 
I think I'm going to enjoy this thread  :)
 
What do you coat your patterns with to keep the sand from sticking to them?

Steve, I would have to agree with Tjark,  talc powder works pretty well with most pattern coatings, to stop the sand sticking to them.
 
My prefered coating is a good quick drying sanding sealer that also has talc in it as a filler, seems to work quite well, even when I forget to talk the pattern before adding the facing sand.
 
Bez
 
edit: dumb spell ckecker.... can't know the difference between talcing and talking
« Last Edit: April 07, 2014, 05:43:07 AM by Bezalel »
Queensland - wet one day, humid the next

Offline stevehuckss396

  • Full Member
  • ****
  • Posts: 1554
  • Sterling Heights, MI USA
    • Steve's Miniature Sparkplugs
Re: A complete casting how to
« Reply #14 on: April 06, 2014, 11:00:33 PM »

My prefered coating is a good quick drying sanding sealer
 
Bez

So are you talking about a sandable automotive primer?
Do not be like the cat who wanted a fish but was afraid to get his paws wet.

Offline Bezalel

  • Full Member
  • ****
  • Posts: 376
  • - Skype:Bezalel2000
Re: A complete casting how to
« Reply #15 on: April 07, 2014, 04:43:05 AM »
wood sealer
used for filling open grain timber

Queensland - wet one day, humid the next

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #16 on: April 07, 2014, 06:57:03 PM »
Had some time today to make a couple of pour’s.
Have made some pictures off the process.
First I had to fire up the furnace.
I use charcoal as fuel.
The temperature I can control with the fan speed.
I use a cast iron pot for melting.
This will not dissolve  in the aluminum, steel pots will dissolve, polluting the aluminum with iron.

Hope that the pictures speak for them self, if not I hope I can answer the questions .

  Tjark.


Offline ths

  • Full Member
  • ****
  • Posts: 1801
  • Kangaroo Valley, NSW, Australia
Re: A complete casting how to
« Reply #17 on: April 08, 2014, 10:48:48 AM »
That came out well, looks good. Any problems to report?

Hugh.

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #18 on: April 08, 2014, 10:17:00 PM »
The only thing what went wrong is one mold where I did not compress the sand enough.
This carb body was quit rough on the outside.
This one ended up in the furnace to got meld for the fourth carb body.
So I ended up with three carb body’s for this day.

    Tjark.

Offline RMO

  • Full Member
  • ****
  • Posts: 126
  • Rexburg, Idaho, USA
Re: A complete casting how to
« Reply #19 on: April 09, 2014, 03:59:21 AM »
Nice work Tjark, I will be asking questions when I get my foundry set up.  You make it look easy.

Mike :praise2:

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #20 on: April 09, 2014, 09:01:00 AM »
Mike,  It’s not that difficult if you have a furnace,  molding sand and good scrap aluminum you can make a start.
I had some help from a guy who sell’s casting equipment to casting firms just after the financial crises.
I had send mails to a lot off those firms before and  never got a reaction.
So the financial crises has not all bad things to offer.
Green sand recipe’s you can find on the net.
You can make this type off molding sand at home.
This is a water based sand.
I have two barrels off green sand where I made a start with.
Later on I have bought 300Kg off petrobond sand.
If you do not have that big castings you can use the original parts as pattern and make a start from there.

    Tjark.

Offline Zephyrin

  • Full Member
  • ****
  • Posts: 766
  • near Paris, France
Re: A complete casting how to
« Reply #21 on: April 09, 2014, 10:56:25 AM »
It looks so easy to do while reading...
Thanks for posting this thead, a clear and positive view, really the kind of nudge which helps to have a go.



Offline nick

  • Full Member
  • ****
  • Posts: 57
  • Play up, play up and play the game........
Re: A complete casting how to
« Reply #22 on: July 23, 2014, 07:52:27 AM »
Is the furnace made from a gas bottle? Are there any instructions about for making one? :) :)
Who I am is best not discussed, for I have been many things in my time.....

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #23 on: July 23, 2014, 02:47:14 PM »
Nick, there are a lot off plans on the internet.
If you are serious thinking to build a melting oven  you can find some books with a good drawings and description how to.
Mine is built from a liquid gas tank and an old car ventilator who I can regulate in fan speed to control the temperature off the meld.
I have chosen for a charcoal melting furnace for the following reasons,
A gas fired oven produces moister when burning charcoal not.
An oil burner takes   a lot off space what I not have.
Maybe it’s not the best choice but I am very happy with it.
I did not build it, I bought it from someone who was casting for many years and did switch to a electric furnace.
Also you have to think about the metals you will be melting.

       Tjark.

Offline mhirst121

  • Full Member
  • ****
  • Posts: 75
Re: A complete casting how to
« Reply #24 on: July 23, 2014, 06:22:53 PM »
Thanks for the write up Tjark. I have just finished my furnace and have just done my first melt with it, it is a liquid propane bottle lined with furnace material and fired with a 1 1/4" propane burner. Now I just have to make up some patterns and obtain some green sand so I can really get things going.
May be back to ask some questions when I get round to this part!!

Cheers,
MartinH
Carlisle, Cumbria, UK
A creative mess is better than idle tidyness !!

Offline Tjark

  • Full Member
  • ****
  • Posts: 353
  • Woldendorp, Netherlands
Re: A complete casting how to
« Reply #25 on: July 23, 2014, 08:01:29 PM »
Martin, your first meld must be a great feeling.
Mine was anyway.
When you have questions please put them here, when I can I will answer them.
Otherwise there will be a lot of people with more knowledge then I have and are be willing to respond I think.
Wish you a lot off success with the pattern making and first casting.

    Tjark.

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal