Pyro Optical Pyrometer. I showed 2650* on the cast iron scale, but might have gotten that reading off the back wall. I need to check my batteries, I changed to a three pack of AA's because the 4.5 volt battery isn't commonly available. Another melt in the works with the conventional pattern so I will have time to sort out some of the issues.
One physical clue that was taught to me and has been unfailingly accurate for me has been heating until the iron pool no longer forms a skin of scum after skimming. It just sits there like a beautiful mercury pool. That occurs just a little below 2550 like about 2530. I use 2550 as a pour temp for a fairly thin-walled casting that seems to work well. So, if your pyro says hot but your pool still scums, believe the physical sign. ;-) Denis
Nice pool after I slagged, like Tomato soup, and poured nicely except for eating the hole in the Kush head. I looked back at the successful lost foam I did and believe I am mixing up some of Campbell's recommendation for gates with the requirements of lost foam. Choking the sprue on lost foam is a non starter.
Like tomato soup in appearance or consistency??? Don’t understand. Was it shiny like a mirror? The pool should be totally reflective if it is over 2550 Denis
Poured the lower guide. I had a core left from the upper guide, but had to sand it down for the smaller diameter lower. I didn't have a long enough core print for the amount of overhang I needed, so I used a copper wire to hold it until I could set the cope. Since the knife gate feeds the thickest section, I added a riser and it served its purpose based on the amount center shrank.
That casting looks very good. Yahoo. Nice surface finish. I am a little unsure about the function of the riser which appears to be 1/2 the diameter (1/4th the volume) of the sprue. The riser did show a fair bit of central depression indicating it did some feeding, huh? Denis
The riser is behind, the sprue is in front topped with my version of the straight sided pouring basin. I'll try to get a better shot of it tomorrow. It is 1.5" in diameter and the metal pulled a center cylinder about 3/4" deep. I didn't screen this pour, but it looks like some junk stayed on top of the basin, and the rest about half way down the sprue. It was still about 300* here so I buried it in the ashes to cool the rest of the way overnight.
Now I see very clearly the feeding you were talking about. What puzzles me at times is the fact that I will see similar shrinkage on a casting's risers. But the next time I do a repeat of that same casting with the same iron and at the same temp, I may see little or no shrinkage/feeding. I am still trying to figure that one out. My other comment is that you seem to have a lot of "crud" on the surface of the pouring basin. Is that what you usually see or unusual in your experience? do you have a sense for what causes it to form or accumulate there? Obviously it is better there than buried in your casting. Nice to see that the bore of your arm cleaned up nicely---success indeed. Denis
That's my typical sprue surface. For this pour I slagged and returned the crucible to the furnace for some additional heat and to see if I could take a pyrometer reading on the surface. If the slag won't clump with the Borax, I just push it to the rear and pour. It is in the 30's here so I don't want to lose too much heat and can rely on choking the sprue to clean the feed. I had thought there was some inclusion part way down the sprue, but it was solid all the way, no junk, so the offset pouring basin might turn out to be of some benefit .
I finished the bore and slotted the mounting holes. Here is mocked it up with a length of the ram bar stock to verify the alignment.
