Tobho's HT1-Inspired Cement Mixer Muller Build

Picture of a casting? I hope to get some of this miraculous sand.

 

pulled straight from sand, still blazing hot.

 

I thought it was 2stroke oil..

 

yes non-detergent 30 weight ... but go to a real
auto supply and order a gallon, they seldom have it on the selves, but in the back or in the warehouse, the gallon saves you a pretty penny

V/r HT1

 

Seems there's a fair amount of choices out there.

Perhaps get a small sample of your sand, apply a teaspoon (few milliliters), add Isopropanol, mull well - and then see what happens?

 

"Hydraulic oil" is also pretty close to pure mineral oil with some anti foaming and anti-wear additives in it.

 

And has a usefully low viscosity as well...

Petrobond tends to want a runnier oil than thirty-weight in northern climates, and seems to benefit from it in general. (Have thought about using sewing machine oil....)

 

if you are only doing(Light) aluminum castings , you will need very very small additions of oil occasionally , cast a 12 inch billet 12 inches tall, and you will need an oil addition. lots of heat over long period of time

here is the thing, smoke is oil burning off so if your molds barely smoke or dont smoke at all, you dont need to add oil, and as mentioned repeatedly, petrobond looses green strength when it sits or if it gets cold , ignore the color change it will happen

lastly remember 11 minutes is the optimum mull time , so if you think your sand is loosing green strength, mull it longer( and no i dont mull for 11 minutes thats insane, it would take me 5 hours to mull all my sand )

V/r HT1

 

When I read that, I immediately thought of this video that I watched yesterday, about 24 minutes into it his petrobond smokes like crazy and then actually catches fire.

 

I had that happen last summer when I cast the bronze bell. I had hauled the mold into the barn so I wouldn’t have to wrangle all that sand outside and as soon as I cracked it open it immediately filled the building with smoke and then ignited. I had waited a half hour, but between the higher than normal temp and the mass of the casting I guess it was inevitable. The extinguisher was at hand but I didn’t need it. Lesson learned.

Pete

 

The office chair boneyard.

 

when I worked in the foundry on USS Prairie, we used to regularly get Petrobond fires, Why, well we would put down about 4 tons of sand at a time, and pour right after lunch, we could not leave for the day until the sand was mulled, so melt and pouring would get you out to about 14:00, wait half and hour, brake out molds, and hour to mull, half hour to clean up you are on liberty at 16:00, so we often broke out brass and bronze molds, that had been on the floor cooling 20-30 minutes , sand catches fire, just shovel it up into a small pile, it goes out


V/r HT1

p.S. terrible practice dont try at home,

 

I'm sure that's right, safety considerations aside, seems like a great way of ruining otherwise perfectly good sand.