This casting is not mine, but an acquaintance, and happens to have been done using 3D sand printed molds. I believe this is Hoosier Pattern's work. The reason I'm posting it is I was quite surprised by the massive feed system and general size of the mold. The size of the casting is roughly 22"x 12" x 6". Probably 15-20lbs. Those ten risers are at least 2 1/2" in diameter by 8"tall. That's 4lbs each or 40lbs. I estimate the runners to be 2"x 2"x 80" overall length. That's 32lbs! So 72lbs of feed system without the gates, sprue or pouring cup.......wow! The casting is 15-20lbs at most. So they have at least 4x, probably 5x more metal in their feed system than the casting. For my similar lost foam castings my feed system would typically be .5x or 50% of the casting weight as opposed to 400-500%. The common thread is, for one-off castings, when you have a lot of time/cost/money invested in a mold or pattern, the cost of metal and remelting metal is small compared to the cost of a failed casting and having to do it all again. A couple of other things that were of note to me: The risers are long way from the part and I bet the gates freeze very soon and isolate the risers from the casting. The gates at the top of each riser (into the bottom of the intake manifold) can't be doing much other than making sure the risers don't break off during shake out. If I had the freedom of 3D printing, I'd print a nice offset pouring cup with weir. The last shape I would choose for a pouring cup would be a cone shaped dish, and the sprue appears to be a mostly straight non-tapered cylinder, hard to tell. I guess they rely on the filters in each runner to cure all ills that may create. I was trying to estimate the ratio of sprue/runner/gate. Looking at it, seems hard to believe the combined cross section of lower gates are as large as runners, so a somewhat or slightly pressurized system? If so, that wouldn't be my preference, but those filters probably slow things down quite a bit. I suspect the sheer size of the mold is just a matter of the available space in their 3D printing system. I'd guess 700lbs of sand. With my process and barrel flasks, it would probably be ~400lbs. -Always interesting to see the choices of others. Best, Kelly
I'd venture you're right on your time vs material cost assertion. The sand print probably took ages and so cost quite a bit in terms of machine-time. If I understand correctly, the danger would be in not having enough gates/risers rather than too many. Having too many won't change the print time, but it will lower the chance of feed problems. At least that's how I'd look at it (not being anything close to an expert).
Kelly, did you mean Hoosier Pattern instead of Hoosier Profiles? I think Profiles is also in Decatur, Indiana and does stuff for English wheels, etc. I had a chance to tour Hoosier Pattern in conjunction with helping with their iron pour for the Decatur Sculpture Walk this year. Gracious hosts and a first class factory and crew. https://hoosierpattern.com/
this pic is the most interesting only one of the risers the second on the bottom obviously fed properly. they all may have, but you can see the open top on that one indicating piping the sprue piped extremely deep . Im assuming the too odd squares in the runner after the sprue is some sort of filter the ingate on the upper section of the riser makes Zero sense, it cant possibly feed, and might suck metal out of the casting The lower ingates are too small, but that would be offset by the extremely oversized risers ( the risers will act as extreme sources of heat warming the sand so metal will flow longer then expected) the runner is definitely much larger then i would expect it to needed to be, though that might be that they followed a 1x4x4 gating ratio, so with 10 ingates at minimum size forces the runner to need to be huge like it is, the oversized sprue maybe explained by what I assume are filters, filters act as your choke and can cause you to do unconventionally things as far as the sprue is concerned( you got to get lots of metal very quickly to the filters) and you have to account for any expected clogging of the filter ... if you think it will get 30% clogged by dross, you increase its size 40% interesting piece, would love to know more about it V/r HT1 if i took a SWAG i would say they had this gating system designed by software, with some questionable data input
My first thought was, when do we get the consumer version of this technology? 3D printed molds and cores at home would be amazing!
You can't retire yet. Cheapest sand printers I can find, $5000, are not up to snuff yet... https://iro3d.com/ Click their gallery for details pics.
Even if it were lower-cost, if you use it a lot, the sand probably becomes the most expensive part. For commercial SLS machines (IIRC) they only suggest re-using a low % of previously used sand due to possible contamination. The reused sand has to be really well filtered b/c unless the particles are all uniform, the layer distribution mechanism ends up dragging chunks across layers. IMO, lost-PLA seems about as close to an 80% (good) solution for the hobbyist. It's a game of rapidly increasing costs and diminishing returns after that. Commercial outfits can make up for the shortfalls with volume production, but they're also likely running a tight margin w/ the machines and materials (or charging an arm and a leg). Again, all just my opinion/guess.
Such high-end tech used for such a low end result. I agree with HT1 about the quality of the inputs. The surface is quite nice though! I couldn't agree more. There are still issues in getting a watertight 3d print too. A large format resin printer might be a nice option in the future but they will still want a pretty penny for the resin I'd imagine.
There are plenty of online services were you can order 3D prints for lost-PLA. You don't even need to own and maintain a printer! Or find a place to store a personal hoard of consumables, worry about your house burning down b/c a spaghetti monster got out of hand, etc. Let somebody else worry about all that. Join the "I don't own a printer" revolution today, it's free! (Full disclosure, I use to own a 3D printer. It broke )
That's the way, my Motorbike Cylinder get's casted in about 3 weeks. I will post the pics I get from the company. The benefit: the foundry asks 1200€ for the first prototype...every following casting will cost about 250-400 € depending how much they cast at once. Conventional foundries asked over 40.000€ for 5 pieces
I saw this too and thought it was a step in the right direction. $5k is steep but consider what people spend on CNC tables, 3D printers and machining gear. Also these sort of technologies start expensive and filter down over time if there's a market. Or someone may figure a more DIY version. What happened with digital imaging, audio and printing are good examples. I also think 3D printed molds are as legitimate as using 3D printed or purchased silicone patterns. Still plenty of room for skill and craftsmanship to get the final product right.
Just saw this post. Wow! Lot of metal going nowhere on that job! We use Hoosier sometimes. Great company! Will do whatever you want to their ability. I design gating with model when I send but they do a little gating work as well if you need it. I would say the customer designed that monster. Ill see if I still have some of the molds they made for us to share.
Definitely not the case. He just sent them a solid model of the part.....they did the rest including parting lines, feed, and vent system. Best, Kelly