Sodium Silicate RU for core making in cast iron molding.

New and improved improved core bolt anchors. I got to worrying that the steel anchors pictured above in post 17 might act as chills and cause localized increased hardness (not white iron, just maybe 5 or ten Rc points) near the points where they were inserted in the core. Yah, yah, most likely worrying about nothing. So, the next iteration is as pictured made from aluminum 3/4" round bar and tapped 1/4-20. You can see they have a couple of flats ground on the OD near the base of the anchor to prevent rotating in the sand. They are intended to be placed in the sand with the wide base buried deepest in the sand.

These have proven to hold very securely in my sodium silicate cores. Much better holding than the threaded inserts I tried and as well as the steel truncated pyramids. They also hold much better than the zinc alloy inserts that have the very coarse interrupted external threads intended to be used in wood. That type of insert, shown in the photo below, pulled out way too easily. And if that were not bad enough, they also partially melted being zinc.



New and doubly ;-) improved anchors that hold well and are durable:



Incidentally, the sodium silicate/sugar/coal cores have consistently performed very nicely with holding good molding detail but very easy shake out and no burn-in or burn-on.

Denis

 

Very nice, I need to cast some of those.

 

Well, when you have hammer, I guess everything looks like a nail. ;-)

I machine these in about 2 mins each start-to-finish.

Denis

 

Well duh!

But, I'd have to find a 3/4" round bar, that means casting one, and it will take me a lot longer than two minutes to machine one before I bore and thread it.

And with the quality of my castings they would grab the sand better.

 

Is your 5% sea coal addition based on sand weight?

 

Yes