Casting Windmill Parts from Original Cast Parts. Celastic for Adding Draft

Denis...would it be possible to flip the long arm casting upside down and put the long arm in the drag? It would make feeding it with a riser much easier. Forgive me if I missed something and am speaking out of my ass. LOL Also I noticed the shrink is right beside the riser and the riser itself may have kept the spot on the arm hot longer causing the shrink in that location. The arm being tallest part of the casting may actually be feeding the casting like a riser. If you cant flip it upside down maybe you can add a large round shrink bob on top of the arm itself to feed it...just have to cut it off. Just trying to throw out some ideas to help. Looks pretty darn good for the first attempt though! Congrats!

 

Thanks, Billy. I guess I could flip the whole works. I did it in this orientation so I would be filling the mold from the bottom thinking that was generally preferable. As you said, the long arm acted like a riser and fed the casting. I think for the next try I will switch the riser to the short arm side and make the riser taller as an open riser to the top. I have plenty of metal for the riser as the melt for these two parts only filled my crucible half way and still I had 15 pounds extra. Please don’t ask why I did not use an open riser the first time! I suspect that would have prevented trouble.

I will likely add in some parts to cast along with this next time and I should not be so rushed. Last time I was in a time crunch and had only time to mold these two parts. Also will draw on a very accurate and visible RED part line on the pattern so my down coping can be done more precisely. This what they must mean by “ learning curve.”

Denis

 

After padding the pattern piece and fairing it, I molded it again for casting tomorrow. The area that previously lacked draft drew perfectly this time. But I found a new area where the draft was not adequate. That caused just a small but annoying fracture on the opposite side of the long arm. On close inspection I can see that the last couple inches of that portion of the arm has slight reverse draft. I was able to tamp the fractured sand back into place, but it still frustrates me not to have a clean pull. So, I will pad and fair that area too. I need to make at least one ore copy of the wishbone as two were requested.

I also moved the riser out of the crux of the wishbone to the long arm side. There the riser will be much further from the arm And should allow the arm to freeze out before the crux does. The area of greatest thickness is marked in one of the photos. The riser will be an open riser extending all the yay to the top of the cope. The previous riser was blind and half a high.



I’ll post pics of the “unfair” area later.

Denis

 

Here’s a pic where the pattern piece curves the wrong way for drawing it out of the sand.


The lesson learned and , unfortunately relearned, is to not trust castings to be straight where you’d expect or to have draft where you’d expect. Hopefully I will not have relearn this lesson many more times!

 

Here is the area filled in with Celastic. It tapers from the left from less rhan a sixteenth to zero. If you look closely you can see the Celastic as slightly lighter in color than the underlying prior filler.


We’ll hope that allows a completely clean draw next time.

Denis

 

Yesterday I melted 45 pounds of iron and cast 3 molds containing 5 part cavities. 4 out of five poured correctly with one not quite filling due to operator error.

The first mold contained impressions of 3 smallish parts. Two are clamps to hold round bars and one is a box lid whose function I do not know. Ed could fill us in on that. The box lid did not wuite fill correctly as I think I (for reasons unknown) placed it too far from the splash basin and with its thin was just slowed down iron flow too much so that the metal cooled and thickened enough to lack 1 teaspoon of iron and thus a flaw in the wall.

Side note: since the patterns are iron, I was able to draw the 3 small patterns using a strong magnet "spike."


The general layout. There is no reason the box could not have been closer to the splash basin.
It is unlikely the box needed a riser as it is quite thin-walled.

Coping down to the two clamps----the black areas

I guess I forgot to take a pic of the core that was pinned into the print of the square box so that the box had a 1/8" thick top and walls.

The results.

You cna see the core sand in the square box. the core was pinned in using 3 wires.
The defect in the box is at the left side where there is a dip in the wall.
The metal is very shiny indicating it was cool by the time it tried to fill the mold cavity.


Here is the rake which cast just fine---it has a few small fins which will be easily cut off.
I had more metal in the crucible than needed so I ended up topping off the pouring basins and having a little overflow. But I did not end up with a heel in the crucible that way.



And the wishbone which cast just fine with only moving the riser. The riser is awfully large, but it was easier to just cut it over-sized than to fiddle with optimization. As it is, it did feed the casting a tablespoon or so of iron. Note the tumble home of the pouring basin well-seen in these images.
The tumble home has really worked extremely well to completely eliminate slopping of iron out of the basin as I pour.


Here are pics of the failed box.


Denis

 

Those pesky thin walled castings can be a pain in the ass! LOL Nice job though!

 

Thanks, Billy. Here is the rake after getting trimmed up with angle grinder.

 

Wonderful Denis! That box lid actually holds a wooden bearing, for the pump rod to run up and down in (I previously filled in the holes). The box bearing combo sit on top on the finger portion of the take (fingers are previously filled in).

 

Thinking a bit more about the thin-wall box, I likely increased its chance of slow filling with resulting incomplete filling by having it be one of three patterns all linked to the same splash basin. Obviously, the iron would take the path of least resistance. The other two molds in the flask are much chunkier and would flow easier. So, the iron would tend to go to them first and only finish filling after the other two are filled. In that time the iron front has been progressing slowly and cooling in the box. The result should have been anticipated ... We’ll do it again, but not in a free-for-all circuit. I may also use twin gates to allow filling from both ends toward the middle.

Denis

 

Well, I finally got the wishbone pattern to draw cleanly today. About time!





Here is a still of the drag.


With any luck this mold should pour nicely. I will use the same riser setup as the most recent prior pour.

Denis

 

Yesterday I cast the windmill parts and an 18” straight edge. Things turned out well. I was particularly concerned about that little box. It shared a flask with the chunkier bracket. Previously I set up the runner so that the chunky casting was in parallel with the box casting. That allowed The iron to decide whether it wanted to go to the chunky casting first or to the box but did not necessarily require that they both feel simultaneously. I think what happened was the Chuckie casting did fill and then the box subsequently tried to fill but by that time the Metal had called Sam and in the box did not feel fully. Today I did some thing a little different where I used a single pouring basin and had two sprues coming off of it. That way there was a equal head of pressure to both the chunky casting and simultaneously to the box and this time the box filled just fine as did the chunky casting. The wishbone also cast just fine using the same basic riser and runner set up as before and then the 18 straight edge also cast well.

 

One added note: I am going to anneal the little box. I has only a 1/8" wall and therefore cooled in the sand very very rapidly. Not enough to make white iron (Rc 60+) but a little harder than is ideal at Rc 30. That would machine satisfactorily, but not quite as easily as soft grey iron at around 10 to 15 Rc. I am sure my customer will appreciate nice soft iron to drill and shape. So, I am currently firing it in my kiln in a stainless sleeve to 1400F. The sleeve should prevent any oxidation as it is crimped "airtight" and I put a postage-stamp-sized bit of brown paper in there as well to consume any oxygen.

Yes, I did use ferrosilicon in the melt added 1 ounce in 50 pounds only a minute prior to pouring. Still, with that thin a wall, the iron is essentially quenched. All the other pieces are nice and soft as I tested them with my hardness tester and did a little milling here and there for cleanup.

Denis

 

I did put the box in SS foil with a “getter” and heated it to 1400F last night Holding it for 45 mins at 1400. I took it out this morning after a slow cool. It tested around 15 to 18 Rc. That is in the range of “normal” grey iron and I did confirm it does file and Mill nicely as I milled off the nubs from gating.

Here it is in the double-crimped SS foil pouch. I fold the edges over twice and use a plastic hammer to crease the folds tightly shut.


After heat treat. Note no discoloration or oxidation.


With the nubs milled of.


Denis

 

Cool post Denis! We have tried a lot of different chemistry recipes for thin castings. We actually have a special chemistry for the thinner castings such as the BlackLock series and the new bakeware series that I dont think are even in stores yet. I think the most important thing we do is the late ferrosilicon inoculant in the stream. I know we run higher C, Si and Phos on our thinner items but I do no think it makes the iron that much softer...probably just more viscous. I will ask our metallurgist about that and see if I can get more insight.

 

Did you actually mean to post “less viscous”?

Denis

 

Ha! I did...caught between fluid and viscous...good eye! But yes...we tend to use higher phos to make it less viscous and more fluid.LOL Our normal range is around .25 but we raise it to .35 on thinner castings.

 

Denis ... those look great!! I guess I better get working on the rest of those two windmills.

 

Ed’s parts are all ready to go. I worked to fit them into a single UPS flat rate XL box dimension of 1 cu ft. I had about 6 cu inches to spare!! Everything is tied down very securely and wood box inside corrugated for shipping. I am 10 pounds under the 50 pound max.

Not shown is the bubble wrapped bundle of small parts stuffed in snuggly. And the wood inner box had a 3/8” plywood top screwed down prior to encasing the whole works in cardboard.

Sigh....
Denis