Pouring cup or pouring down the downsprue?

Tops · Jul 9, 2022

On my naturally aspirated burner, being all the way open with the air shutter does not seem as good as being a little restricted (70-80% open), and a stiff cross breeze used to mess with it until I made a little horn for it. Too far open or a breeze would make it 'pop'. I should have sprung for one with a gauge...

Burner orifice is about .040" (1mm) = 0.00126 sqin or 0.00811 sqcm area
Air intake (3 slots 1.610 x .335")= 1.5458 sqin or 9.9729 sqcm area

John Gaertner · Jul 9, 2022

Thanks FishbonzWV. I do appreciate the helpful details. Jgaertner

Melterskelter · Jul 9, 2022

HT1 said: ↑

ok going all the way back to my apprenticeship we where taught to ram pertrobond as hard as we could with out making the flask lift, so if you are pushing sand out of the bottom of the flask you are ramming too hard,
with a proper hand rammer, and using 3.5 inch tall flask sections (dimensional lumber) I put down facing tuck it in with my finger tips, then fill the flask more then full, then aggressively peen the the sand as hard as I can holding the flask down with one hand on 12X12 flasks that is fine, any larger of flasks, I clamp the flask down to the bottom board or matchplate, this will about half fill the flask, then you fill it again, and peen it, then use the Butt to finish it off flat, you might have to add a little sand in the corners to fill them, this is not the hardest you can ram sand, but it is close, if I have a troublesome pattern, I will try a softer ram, sometimes you can get a pattern out of a slightly softer ram when a hard ram will take sand with it, especially in high details, like lettering ( the triangle in "A" being the absolute worst)

if you have a pneumatic rammer, I would use about the same technique UNLESS the pattern had a tall section, then you need to mark that so you dont hit it with your rammer, and you may need to make multiple passes with the rammer, short and skinny irregular patterns, are difficult to work with and require a degree of finesse that has to be learned by experience

V/r HT1

P.S. your second and any additional rams say you are using 8 inch deep flasks can be softer then the first , the sand directly in contact with the pattern is the only area where sand Hardness is critical UNLESS your pattern is VERY heavy , like billet in brass or Cast Fe , so dont ill yourself trying to get the backing sand crazy hard its a waste of energy
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Melterskelter said: ↑

"hard ram refers to how tightly you pack the sand it's measured at the surface with a precision instument"

While I really like putting numbers on various factors in the foundry, it is really not a practical thing to do for way to many of the variables we deal with. HT1 is suggesting a way that would allow him, in Florida, to measure just how hard he rams his PB and John several hundred miles away in VA could actually objectively compare how hard they each have rammed up a mold. They would not have to resort to using necessarily vague and ill-defined terms like hard ram. But buying the device linked is not likely in the cards for almost anyone on this site. (Does ANYONE own a sand hardness tester like the one linked above?)

I have been wracking my brain to think of a cheap universally available testing method. Here it is: The Golf Ball Drop Test. I know HT1 lives in the golfing mecca of the world so he can likely get his hands on one. And most likely John can get one too. Maybe next time HT1 rams up a mold nice and "hard" he could drop a golf ball from a few measured heights and measure the diameter of the indentation. Then John and anyone else interested now or in the future would have something to objectively compare.

Based on my not-so-calibrated thumb, I do know that the top rammed surface of a mold will be much greater than the hardness of the mold cavity surface. I often ram deep molds in two "lifts" for that reason. So measureing the top rammed surface hardness will not fully tell the tale. Some destructive testing of the mold cavity, say parting line, hardness will also be needed. I'll see if I can find a golf ball around here before I ram green sand this morning.

Denis

Added: If someone find it difficult to measure the indent diameter, just count the numbers of bumps left by the dimples in the ball. 5 bumps= very hard. 10 bumps=medium. 30 bumps=soft. ;-)
Click to expand...

I did some testing of "golf ball drop" as a means of testing sand hardness. (Some clever folks may refer to this as the "goof ball drop.") It does work and does discriminate degrees of softness quite well. Its most redeeming feature is that tool cost is low---one Titleist VP-1 Pro ball and one tape measure. I dropped from 18 inches height which I chose arbitrarily. Rather than bury the info here in this thread, I will start a new thread in the sand casting sub-forum.

Here is the thread:http://forums.thehomefoundry.org/in...test-using-a-golf-ball-and-tape-measure.2294/

Denis

John Gaertner · Jul 17, 2022

Hello Forum, I was hoping to get some casting done last week but the weather here in VA was not favorable. I did get to test my LPG burner with pressure gauge installed. I took my old "Foundry101.com" burner all apart and put it back together with a 0-60 PSI gauge down stream from the pressure regulator. When I ran the furnace it was clearly running with a much better, neutral blue or clear flame. Very different from the previous situation where it was very yellow flame and lots of burner noise. It worked best at about 6 to 8 PSI. I melted some old, left over sprues and feeders and made ingots out of them. It did seem to take longer to get to temperature than before but that is a OK trade off for a more neutral flame. Once cooled, I cut them in half on the band saw and I do not see any signs of porosity in the ingots.

I receive a shipment of finer Petrobond to use as facing sand for my axle covers patterns. I will try ramming a couple molds with this new sand and see whether I get better results with the new burner set up and finer sand? It is going to be a while, as the 10 day forecast is not promising for casting. Very hot and humid!

Al2O3 · Jul 17, 2022

John Gaertner said: ↑

It worked best at about 6 to 8 PSI.
Click to expand...

That's right about in the middle of the 1-15 psig supply pressure range referenced on the similarly sized Reil burner. NA burners are dead simple but you'll have to see how it suits you. If you decide you want higher melting power, a forced air burner will have higher capacity if you don't mind the complication of a blower, and as previously mentioned, it can make tuning somewhat easier (and a different power/fuel consumption levels) since fuel and air can be independently adjusted. Forced air burners also tend to be a less sensitive to downstream conditions in the furnace. Good news is your burner can be used with or without forced air.

Best,
Kelly

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