4cylndrfury's pattern and molding adventures
Posted: Fri Jun 03, 2011 12:27 pm
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
Rammed up in my homemade K-bond sand:
Poured:
Flask opened:
And the result:
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:
Cope rammed and sprues cut:
Gates cut:
Cast and mold opened:
And the casting (to the left):
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:
And the Corebox - an offcut of the same cardboard tube used in the pattern to ensure the core is a perfect match:
I ram molding sand into the core with a lag bolt in it - gotta ram HARD for the core to be stable!
Struck off and removed, the bolt is a perfect handle to let you drop the core into the mold, and position in the print:
pattern in the Flask:
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:
Pattern pulled and the core installed:
And a birdseye view:
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…
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
Rammed up in my homemade K-bond sand:
Poured:
Flask opened:
And the result:
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:
Cope rammed and sprues cut:
Gates cut:
Cast and mold opened:
And the casting (to the left):
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:
And the Corebox - an offcut of the same cardboard tube used in the pattern to ensure the core is a perfect match:
I ram molding sand into the core with a lag bolt in it - gotta ram HARD for the core to be stable!
Struck off and removed, the bolt is a perfect handle to let you drop the core into the mold, and position in the print:
pattern in the Flask:
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:
Pattern pulled and the core installed:
And a birdseye view:
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…