So, I had this idea to make a sand-cast aluminum part, and took a similar one to a foundry my buddy recommended. Short story long: I need help with patterns. I've read a bunch of stuff on patterns, and on casting - both here on the HAMB and elsewhere. But at the end of the day, you're going to have to make a bunch of pieces as part of the 'learning curve'. Anybody here in the PNW do this work? Thanks in advance! -Bill
Hey Ian, thanks for the reply! One piece has four identical cores, and the other doesn't have any cores at all. That one would be pretty simple to make as a two-sided board kind of pattern. Either would cast up in a flask about 2X3 feet. Quan***ies... small. Like fifty pieces. Now you can see where spending $25K so someone can make payments on that 4 axis CNC mill kinda' puts a crimp in the program, huh? Hoping I can find an old guy who knows how to do this stuff, and help guide me around a lot of the 'learning curve'... This stuff isn't rocket science. But I think there is a little bit of art to it. You know, the kind of thing that you can't learn by reading. thanks, Bill
Look in the Yellow pages for a foundry near you. Ask them. Around here there are old semi retired guys working for $100 an hour making patterns.
If you are lucky, you can find a local foundry that will work with "loose patterns". Cost per part will be a little higher, but you don't have to worry about match plates etc. Most are more interested in larger scale production.
I've been buying old casting and pattern making books off ebay. The woodworking part is "easy"; core design, I'm still learning.
if the foundry you went to wont tell you how to make a pattern then go to another foundry, asking questions on here about how to make a pattern without being clear about what your trying to cast would be all but imposable. what little i have worked in a foundry and what i have been told about making a pattern is you pour from the bottom up.
Hey thanks guys! Yeah, I read the thread about casting (a couple times); have also been to the backyard casting page, too. One problem is that I can't POUR anything here at my condo... for some reason, the pussies around here are afraid of molten metal! So, I'll have to PAY to pour every part I want made. And, if there's any "lessons" on a set of patterns, it costs more than just my time. At that point, it's worth finding the old guy who can show me how to do it. I suppose I could always just "1-800-MASTERCARD" a solution, but that raises its own issues for me right now. So, I'll BTTT this for the (other) insomniacs... hopefully I'll find someone who can help me save some aborted pours! Thanks again everyone! -Bill
bill: give me a call i can give some pointers, tips and things to know about casting that most wont tell you scott
Before you even start thinking of making a pattern you will need to obtain a patternmakers contraction rule. Basically, each type of metal contracts at a different rate when going thru the cool down process. The rule is graduated in the measurements you will need to make the pattern according to the metal you wish to pour into the moulds. ie if the part you wish to copy is 12" long and you wish to cast it in bronze you will measure your pattern at 12" using the 'bronze' scale' on the rule. The pattern will actually be 4% longer than the sample, when cooled the part will be the same size as your sample. Just a note from the wise, patternmaking is a highly skilled job and often they work to the same tolerances as engineers and machinists. If you get the pattern wrong it's an expensive exercise to find out after your part is made.
QFT! A guy on speedtalk posted that he had some patterns made for regular cast iron by the guy who does his stuff for stainless (which is what most of his parts are made from). Well, the parts came out horrible, and the second foundry that he took the patterns to said that it was because the gating/sprues/risers and stuff were all wrong for the material. BTW, it was a pleasure talking to you, Scott. UnklIan, you've just sent me several hours of homework, with all of the links on that page... -Bill
I love reading posts about pattern making.....that's what I do for a living! Believe me, when I say that pattern making is a dying art, most of the guys that used to do it are long gone. I started my apprenticeship 10 years ago in a factory that makes pumps. And luckily I got to do some of it the old fashioned way....hand carving with spoke shaves, chisels, etc. Then, we purchased software that does both 3-D modeling and actually writes the programs too. Since most of the guys were older, they didn't want to learn it, so I volunteered. Now 95% of all our new pattern equipment is modeled and then cut from billet aluminum. I love to do the pattern work the old fashioned way, and every once in a while I still get to do one. I just wanted to add a couple things.....Yes you must build the pattern bigger....due to shrink factors....and cast iron, aluminum, and stainless all have different shrink factors.....we use what are called "shrink scales" still available from Starrett! Also, most foundries will charge you a minimum set up for the first run.....even if you only want 5 pieces, you may be charged 250 to 500 dollars! Good luck with making your pattern, would love to see what you are making, maybe I could help!
ditto to what has been said here,, if you need another patternmaker's point of view and or advice pm me,, maybe i can help
The best casting book I've found so far is : http://www.amazon.com/Complete-Hand...=sr_1_1?ie=UTF8&s=books&qid=1277425944&sr=1-1 But I'm sure that only scratches the surface. Maybe someone can suggest a GOOD book on casting pattern design.
The Jalopy Journal
