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byawor

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Just wondering how it is made? Fairly expensive here at $10 per pound. I have some nice yellow clay, sieved it and mixed in a bit of oil kind of worked but sure will not pickup the details like the real stuff. Any suggestions?
Bob
 
Petrobond is a trademarked oil-based foundry sand.

I have seen one alternative to it that can be home-blended/mixed with off-the-shelf ingredients, called "K-Bond", as follows:

I would add one note of caution about using oil-based sand with the hotter metals such as brass/bronze and iron.
If you open the mold shortly after pouring these metals, you will get a large plume of smoke that will often burst into a huge ball of flame.
I learned this by opening a hot mold, only to have a ball of fire in the face.
Luckily I saw it coming and closed my eyes (I had just removed my faceshield).
Don't repeat this error.


K-bond

K-Bond, named for Kent State where it was developed by one of Tom Cobett's Students, Is an almost smokeless oil bonded foundry sand.
It is used for casting zinc, aluminum, brass, bronze and iron.

The recipe is:
*100 lbs. sand - 100 mesh or finer
*6 lbs. bentone clay (such as Bentone 34 or VG-69)
*3 lbs. synthetic 2 cycle motor oil
*0.2 lbs. (3.2 fluid oz) Methanol (dry gas)

Mixing:
Mix the sand and bentone clay first (wear a dust mask!), then blend in the oil thoroughly.
Small batches (less than 10 lb.) can be done by hand with good results, but a muller is preferred.
The small batches can be done with a cheap kitchen electric mixer.
Add the alcohol and mix thoroughly.

"The sand won't seem like much until the alcohol takes effect and then it will become like stiff cookie dough.

How stiff?
It bogs down my muller!

It will be much easier to handle when it is a day old and will get easier to use with time and use.

The sand gets powdery after it sits and it is best to mull it or warm it before use.

When green strength starts to fade, add in some alcohol.

... Ray Brandes, quoted from his old web site. Also the source of this recipe.


The definitive source:

Subject: The History of K-BOND
Date: Wed, 13 Feb 2002 13:05:03 EST

K-BOND was developed in about 1995 at Kent State University.
The Metal Casting program at KSU had been using Petrobond for about 20 years.

We set about to find a suitable alternative to Petrobond.

After about 3 months of testing, we had evaluated many sources of bentone and many sources of "smokeless" oils.
(By the way, Petrobond is also made with Bentone.)
We found that virtually all organo-bentones will work well.
With this in mind, we bought the cheapest one we could find.

For the oil, we settled on AMOCO Indopol L-100.
This was listed as being a "food grade" material that burned cleanly.
Later, we found out that Indopol is the main ingredient of most smokeless 2-stroke oils.

The basic recipe for K-BOND is:

100 lb. of very fine silica sand (100 to 150 GFN)
6 - 7 lb. of Bentone (cheapest you can find)
3 lb. of Indopol L-100 oil
0.10 to 0.20 lb. of Propylene Carbonate (or Methanol or Isopropanol)

If the sand become too dry to mold, we add more Indopol.
If it lacks any strength, first we add more Propylene Carbonate.
If that does not bring up the strength, we add more Bentone.

We have used this stuff several times a week for aluminum, bronze and iron castings.
We have never thrown out the pile, we just add too it.
We don't get a room full of blue haze when we pour our molds.
We make castings that are incredibly smooth with extremely fine detail.

I am personally very pleased that some of you have taken the initiative to use K-BOND.


Dedicated to Metal Casting Education...
Tom Cobett
Cleveland, Ohio


.
 
Just wondering how it is made? Fairly expensive here at $10 per pound. I have some nice yellow clay, sieved it and mixed in a bit of oil kind of worked but sure will not pickup the details like the real stuff. Any suggestions?
Bob
The biggest thing you need with Petrobond 9 K bond is they both need a muller. Note some will use car and driveway as sub for muller.

You look at natural bonded sand . It is lot simpler to use just add water and mix.

Dave
 
Just wondering how it is made? Fairly expensive here at $10 per pound. I have some nice yellow clay, sieved it and mixed in a bit of oil kind of worked but sure will not pickup the details like the real stuff. Any suggestions?
Bob
byawor this is the recipe that I used to make petrobond, I mix it in 10lbs batches at a time. I copy the recipe from sandramer. I've been mulling it by hand it takes a while but it is cheaper than purchase petrobond. Petrobond catalyst is(propylene carbonate) Purchase the finest mesh sand you can, I use 190 mesh.
 

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You have to mix the right kind of oil to make petrobond sand work, most motor oils don't work.
Any non detergent motor oil works. I mostly use Super Tech Non-Detergent SAE 30W it's the cheapest I can find in Fl. It must be non detergent, motor oil containing detergent and other additives will spoil the mix.
 
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You have to mix the right kind of oil to make petrobond sand work, most motor oils don't work.
I would the correct oil by the 55 gal drum when using Petrobond.
The catalyst I found alcohol work great and lower in cost.

I did find nature bonded sand did a great job too. A lot cheaper just add water and mix.

Dave
 
I mixed up another batch thought the mold was ok but when I poured some aluminum the casting was terrible. I think I will just bite the bullet and buy some Petrobond
 
I mixed up another batch thought the mold was ok but when I poured some aluminum the casting was terrible. I think I will just bite the bullet and buy some Petrobond
When you say it was terrible casting do you mean surface finish, Gas Porosity and or Pouring Metal Defects ? Can you supply some photos of your casting ? There is a lot of multi-talented people on here that may be able to help you.
 
And we just like to see casting pictures of any type too !

.
He are my first attempt at sand casting. I kept them around for reminders of how not to do it. Don't laugh too much, please.
DSC00046.JPGDSC00047.JPG
I did improve over time, I think ?
DSC00048.JPG
 
When you say it was terrible casting do you mean surface finish, Gas Porosity and or Pouring Metal Defects ? Can you supply some photos of your casting ? There is a lot of multi-talented people on here that may be able to help you.
I agree
A few photos of sand casting before and after would help

Petrobond needs more venting.
Natural bond can have to must water.

Dave
 
Those castings actually look quite good.

It is important to pour aluminum at about 1,350 F, since if you get it much hotter than that, you can get a very rough surface finish.

When I started casting aluminum, I was getting it either too hot or too cold, and I finally broke down and purchased a pyrometer.
Many make their own pyrometers with a purchased thermocouple, and a multimeter that can read the output of the thermocouple.
I will look for that style of meter, but they are relatively inexpensive, as are the thermocouples.
You may already have a pyrometer.

Surface finish is a pretty easy problem to solve, and I really don't see any other problems.

Your castings look solid, and that is a real plus.

Nice casting work !

.
 
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For the little bit I have done much prefer mold of steel or graphite. Picture attached oil pump
Bob
 

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He are my first attempt at sand casting. I kept them around for reminders of how not to do it. Don't laugh too much, please.
View attachment 151826View attachment 151828
I did improve over time, I think ?
View attachment 151829

I would say you are pouring too hot. I always use a thermocouple to check pouring temperature or use an electric furnace with temperature control.
I would advise you buy a small quantity of real Petrobond or equivalent to test your technique before experimenting with home brew recipes.
Rich
 
I agree
A few photos of sand casting before and after would help

Petrobond needs more venting.
Natural bond can have to must water.

Dave
Sorry but I disagree.
I have never had to add more venting than normal greensand moulding in more than 10 years of using this sand.
Rich
 
I would say you are pouring too hot. I always use a thermocouple to check pouring temperature or use an electric furnace with temperature control.
I would advise you buy a small quantity of real Petrobond or equivalent to test your technique before experimenting with home brew recipes.
Rich
creast I think you may be confused,I am not the one who is having a problem with using petrobond. I have been home brewing petrobond for over 10 years now. I was just showing examples to byawor who was the op who was asking for the recipe and having proplems.

"I would say you are pouring too hot"
The first photo was a example of using too coarse sand and poor tamping of the sand.
pour temp was 1350 deg f.

Second photo was example of a short shot and poor gating.
pour temp was 1350 deg f.

Third photo is a pour using a tapered sprue. pour basin and a sand core.
pour temp was unknown. Pyrometer was not working at the time.

I do agree with you about needing little to no venting using petrobond over green sand.

 
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Those castings actually look quite good.

It is important to pour aluminum at about 1,350 F, since if you get it much hotter than that, you can get a very rough surface finish.

When I started casting aluminum, I was getting it either too hot or too cold, and I finally broke down and purchased a pyrometer.
Many make their own pyrometers with a purchased thermocouple, and a multimeter that can read the output of the thermocouple.
I will look for that style of meter, but they are relatively inexpensive, as are the thermocouples.
You may already have a pyrometer.

Surface finish is a pretty easy problem to solve, and I really don't see any other problems.

Your castings look solid, and that is a real plus.

Nice casting work !

.
You are too kind GreenTwin.
 
I find 740C (1350 F) is a good temp if using new ingot, when using returns (scrap or what ever bits you can get) you can take that temperature up to 780 C (1436 F) this aids in the fluidity as the more you recycle the more of the other elements such as silicon burn out and this reduces the ability for the Ali to flow around the mould. These are tap temperatures as well, by the time you go from furnace to pouring the first mould you will most likely have lost at least 20 degrees. With our Petrobond we use a fully synthetic light gear oil, it works really well and doesn't smoke as much. I vent Petrobond the same as greensand as neither have the porosity to naturally allow gasses to escape, specially if your doing brass and bronzes.

wce4 not bad on your first sand mould attempt, I have seen far worse from people who have been in the industry for 25 plus years. Best thing about this industry specially as a hobby, if at first you don't succeed melt it down and have another go. For those that want to mix their own sands, I have had great success using an old kitchen aid mixer with a paddle or doe hook for small amounts. As I always tell my students, there is always more than one way to do something, though some are far better than others.
 
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