4cylndrfury's pattern and molding adventures

From molding systems to gating, what goes on at the molding bench will make or break a casting.
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4cylndrfury
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Location: Cincinnati, Ohio, USA

4cylndrfury's pattern and molding adventures

Post by 4cylndrfury »

Just a couple of shots of me molding up some stuff in the past...

First is from the thinnest casting contest over at BYMC forums from 2009..I think I came in 3rd or 5th or something lol. It was fun just to be in the same contest as some really talented foundrymen. Anyway, enough nostalgia!

The pattern: An impeller from a failed sump pump out of my basement
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Rammed up in my homemade K-bond sand:
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Poured:
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Flask opened:
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And the result:
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This was cast from some old extruded scrap, so not great for casting, and was also a little overheated...hence the pitted surface. It still came in at .04mm or so, not too shabby I guess!

The impeller is a pretty simple pattern though; flat backed and such. Here is a 14mm box wrench with an irregular parting line that required some coping down to part the mold:

drag rammed and coped:
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Cope rammed and sprues cut:
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Gates cut:
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Cast and mold opened:
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And the casting (to the left):
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Im happy with the detail my k bond sand is able to capture - you can see the lettering came out well! Its not as good as what I see from Harrys real foundry Petrobond sand...his stuff seems to carve like clay! But I havent found a cheap source of 100+ mesh silica sand, so play sand will have to do for now. It still molds pretty tight and it works for now.

This is my most ambitious pattern yet - a MAF adapter for an aftermarket automotive air intake. I hope for this to be my first mass produced item for sale. I say its ambitious mainly due to the mold requiring a core. The pattern is flat backed, but the core is large and the profile of the wall is pretty thin. Oil bonded sand can be packed to the point that it becomes quite dense and solid, so I decided to use k bond sand for the core. it keeps the cost down by keeping consumables - namely sodium silicate - out of the process. Ive only tried to cast it out once and it failed - I think the metal was too cool to flow well, and didnt fill the walls. I thickened the wall slightly in hopes of getting a full cast next time. Anyhow - PICS!

Pattern with coreprint:
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And the Corebox - an offcut of the same cardboard tube used in the pattern to ensure the core is a perfect match:

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I ram molding sand into the core with a lag bolt in it - gotta ram HARD for the core to be stable!

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Struck off and removed, the bolt is a perfect handle to let you drop the core into the mold, and position in the print:

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pattern in the Flask:

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Rammed, struck off, flipped, and coped. Since the pattern was originally designed to be molded without a core, the interior is packed with sand. Im going to make a flat back for this later:

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Pattern pulled and the core installed:

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And a birdseye view:

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Well thats about it for now. Ive got some other stuff in the works. Double top secret for now. Im hoping to market some of it later if it turns out to be easily cast. Im a little short in the tooling dept, so pattern making turns out a little less than perfect unfortunately. Id like to get my hands on a decent bandsaw, and tablesaw. *sigh*…one day…
"Simplicity is the ultimate sophistication"
-Leonardo Di Vinci

"The future's uncertain and the end is always near...."
-Jim Morrison
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Harry
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Re: 4cylndrfury's pattern and molding adventures

Post by Harry »

Nice, your sand is getting that well used color to it.

My sand is very plastic as you noted, I dont know for sure but I believe it is due to both the fine sand and excellent distribution of the clay in its initial mulling by the huge batch mullers IFSCO uses.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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4cylndrfury
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Re: 4cylndrfury's pattern and molding adventures

Post by 4cylndrfury »

ha yes, my sand certainly is a brownish color...i guess its a badge of honor? It started very green as that was the color of the oil. I dont remove much burnt sand except for what sticks to the castings. I brush that off into the trash.

Im thinking a switch to IFSCO sand may be best for me...not sure yet as I still have a decent little bag of Bentone clay left over. I might try to get a hold of decent sand and mull up what clay I have left. It cant hurt.
"Simplicity is the ultimate sophistication"
-Leonardo Di Vinci

"The future's uncertain and the end is always near...."
-Jim Morrison
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Harry
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Re: 4cylndrfury's pattern and molding adventures

Post by Harry »

Odd that it took on the color of oil as my sand takes the color of the clay which is red. Its not a huge investment if you wanted to try a box of my sand, might even be able to blend it with yours.

A muller is a must for petrobond in my book, especially if you are going to batch your own.
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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4cylndrfury
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Re: 4cylndrfury's pattern and molding adventures

Post by 4cylndrfury »

What do you charge for a big flat rate box full of sand? Ideally, id like to get some petrobond clay...the bentone stuff is quite expensive and i think the PB stuff is probably cheaper, that way i can mix my own in 100# batches and save some in the long run.

And yes, a muller is a ways up in my priority list...a 20# lpg tank sized muller with a wheel and plow setup is what id really like. I need to save some money and get some supplies from surplus supply online. Im already wanting to go with a compressor-less siphon burner, i want to build a muller, and Im also trying to get my hands on a little buzz box 110 welder...so many tools, so little money :lol: . Hopefully if i can get started making some money selling some maf adapters and a few other ideas i have brewing, i will be able to save faster and get moving with some of these grand schemes im always cooking up.
"Simplicity is the ultimate sophistication"
-Leonardo Di Vinci

"The future's uncertain and the end is always near...."
-Jim Morrison
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Harry
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Re: 4cylndrfury's pattern and molding adventures

Post by Harry »

The premixed sand is $50 for a single box (40 lbs). I had pricing set up with a break on a number of boxes... will have get that pricing back up over here. I have clay catalyst and oil too if you want to batch your own but two really important things are a good initial mulling and the correct sand. Failing either of those you just wont get the same results which I why I suggested getting a box. The 40 lbs is enough to do a fair sized flask and will give you a baseline to work from on what to expect from your sand.

That part above you showed with the thin fins is pretty impressive, you might not see any gain with my sand... hard tellin' not knowin'
I'd rather laugh with the sinners than cry with the saints the sinners are much more fun...
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Nudge
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Re: 4cylndrfury's pattern and molding adventures

Post by Nudge »

What is the wall thickness on that last part you are making 4cylndrfury?
I like that 14mm spanner it's slick 8-)
I like to build "Stuff" using Stuff that costs Stuff All!
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4cylndrfury
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Re: 4cylndrfury's pattern and molding adventures

Post by 4cylndrfury »

The wall thickness on the MAF adapter is about 3mm or so, not terribly thin, but hard to fill with (comparatively) cool metal. I tried to cast it with the first melt of my NEWEST CRUCIBLE. The walls of said crucible are about 1/3 thicker than the last one I was using, so I wasnt familiar with its characteristics. The thick walls make for a long heat up to melt temp. I guess I underestimated the time needed, and poured too cold. I plan to make a new mold for a new crucible, still thick walled, but I will be adding a large dose of powdered graphite to the dry refractory mix to aid in thermal transfer...hopefully reducing the heat time. A topic for another thread perhaps.

Harry, that sounds very reasonable. I may order a box or 3 here very soon. My current sand supply is small and leaves a little to be desired. The possibility exists that I may end up trying to take my foundry to the next level and take a real shot at turning it into a full time revenue generator. Your exploits have been a real inspiration in that regard.
"Simplicity is the ultimate sophistication"
-Leonardo Di Vinci

"The future's uncertain and the end is always near...."
-Jim Morrison
dallen
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Re: 4cylndrfury's pattern and molding adventures

Post by dallen »

4cylndrfury wrote:ha yes, my sand certainly is a brownish color...i guess its a badge of honor? It started very green as that was the color of the oil. I dont remove much burnt sand except for what sticks to the castings. I brush that off into the trash.

Im thinking a switch to IFSCO sand may be best for me...not sure yet as I still have a decent little bag of Bentone clay left over. I might try to get a hold of decent sand and mull up what clay I have left. It cant hurt.
Find out who sells sandblasting media in your area, they will have silica sand in the 100/120 range, they actually should have several differant grades.

Thats where I get mine.

David
David and Charlie aka the shop monster

If life seems normal your not going fast enough" Mario Andrette
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