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#11
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Once you cast the heads unfinned with the ports laid out in the desired
configuration, what would prevent you from using an electroplating method to grow the fins out, with the air gap pattern between the fins blocked out to prevent metal deposition? Then grow them out to the extent desired, or larger and grind them down based on testing. A.L. Phoenix |
#12
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On Jan 18, 9:41*am, " wrote:
On Jan 18, 2:00*am, Stealth Pilot wrote: why does steve bennett's name ring a bell? is he 'great planes'? ----------------------------------------------------------------------------------------------- Yes, unfortunately we failed to connect ------------------------------------------------------------------------------------------------- We connected today. Had a very nice visit, including a tour of the shop, varmint gunnery program, engine building and hummingbird offensives. Given a bit more time we might have touched on airplanes :-) -Bob |
#13
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On Jan 16, 4:08*pm, " wrote:
Based on the parting-line flash of new, stock heads, they are cast using two molds. *To cast INDIVIDUAL heads it will take at least THREE molds of FOUR different types. *Anyone having actual experience with finned aluminum castings is encouraged to offer their opinion. -Bob Hoover I'm still of the opinion that lost foam is the way to go. To this end I have been trying to get my hands on some more UN-expanded styrene beads. (Bean bag foam doesn't have any puffy stuff left in it) Seems that EPS beads are no longer available in small retail quantities as they have been deemed hazardous by some alphabet bureaucrat somewhere and the result is the hazmat fee is more than the beads. That and I read some duck hunter blew up his kitchen. If someone knows of a source I'm interested. I'd prefer to not have to buy a whole pallet load, but if that is what it takes to get it here............................. ======================== Leon McAtee |
#14
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#15
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On Jan 19, 10:59*pm, Anthony W wrote:
Where's the company that sells the stuff? That's the trick. I don't know, other than Dow and some other primary manufacturers. So far the e-mails have either bounced or come back "sorry can't help" *Maybe one of us are near them and would be wiling to pick them up for you and ship them to you in a plain brown wrapper... Tony ========================== Leon McAtee |
#16
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![]() wrote in message ... On Jan 16, 4:08 pm, " wrote: Based on the parting-line flash of new, stock heads, they are cast using two molds. To cast INDIVIDUAL heads it will take at least THREE molds of FOUR different types. Anyone having actual experience with finned aluminum castings is encouraged to offer their opinion. -Bob Hoover I'm still of the opinion that lost foam is the way to go. To this end I have been trying to get my hands on some more UN-expanded styrene beads. (Bean bag foam doesn't have any puffy stuff left in it) Seems that EPS beads are no longer available in small retail quantities as they have been deemed hazardous by some alphabet bureaucrat somewhere and the result is the hazmat fee is more than the beads. That and I read some duck hunter blew up his kitchen. If someone knows of a source I'm interested. I'd prefer to not have to buy a whole pallet load, but if that is what it takes to get it here............................. ======================== Leon McAtee Perhaps I'm missing something, but why not just CNC machine an existing foam block? I realize CNC time is expensive, but I would expect the tool speed to be much, much higher cutting foam than cutting billet aluminum, and the cost of the discarded material would be less. As I understand it (and it's a fairly tenuous understanding), the idea of the lost foam is that you pack the sand around the foam, and when the molten aluminum pours in, the foam goes away because of the heat, leaving the sand form in place, but maintaining the sand's geometry until the metal get there. I understand the car manufacturers do it as a two-step process, making a mold for the foam pieces, then using the molded foam to make the part. But for low quantity production, carving the foam from CAD files seems like it might be practical. Tim Ward |
#17
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On Jan 20, 9:10*pm, "Tim Ward" wrote:
Perhaps I'm missing something, but why not just CNC machine an existing foam block? If you have ever tried to mill 2 pound foam you would understand :-) It tends to tear and the "chips" cling to everything with static electricity. I realize CNC time is expensive, but I would expect the tool speed to be much, much higher cutting foam than cutting billet aluminum, and the cost of the discarded material would be less. Actually for the project that is being hashed out CNC just might be the best way to do it for the average home builder. No one would have to have anything cast, just down load some G code from a file and have any old CNC shop make a head............... But casting is the cheap way for those of us that have the tools to do it. If I had a 5 axis mill in my shop I'd already be working on the G code. Who knows, maybe once we get a proven set of head castings someone with a digitizer might just make the required files available as freeware??? As I understand it (and it's a fairly tenuous understanding), the idea of the lost foam is that you pack the sand around the foam, and when the molten aluminum pours in, the foam goes away because of the heat, leaving the sand form in place, but maintaining the sand's geometry until the metal get there. You have a pretty good grasp of the essentials. One Advantage of lost foam is that once you make up the tooling to make the foam castings you can make things pretty quickly - and with fantastic detail. Time wise it can be quicker than CNC and you can do some things that just can't be done with CNC, like water jackets in a head. ======================== Leon McAtee |
#18
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On Tue, 20 Jan 2009 21:03:36 -0800 (PST), "
wrote: On Jan 20, 9:10=A0pm, "Tim Ward" wrote: Perhaps I'm missing something, but why not just CNC machine an existing f= oam block? If you have ever tried to mill 2 pound foam you would understand :-) It tends to tear and the "chips" cling to everything with static electricity. I realize CNC time is expensive, but I would expect the tool speed to be much, much higher cutting foam than cutting billet aluminum, and the cost= of the discarded material would be less. Actually for the project that is being hashed out CNC just might be the best way to do it for the average home builder. No one would have to have anything cast, just down load some G code from a file and have any old CNC shop make a head............... But casting is the cheap way for those of us that have the tools to do it. If I had a 5 axis mill in my shop I'd already be working on the G code. Who knows, maybe once we get a proven set of head castings someone with a digitizer might just make the required files available as freeware??? As I understand it (and it's a fairly tenuous understanding), the idea of the lost foam is that you pack the sand around the foam, and when the mol= ten aluminum pours in, the foam goes away because of the heat, leaving the sa= nd form in place, but maintaining the sand's geometry until the metal get there. You have a pretty good grasp of the essentials. One Advantage of lost foam is that once you make up the tooling to make the foam castings you can make things pretty quickly - and with fantastic detail. Time wise it can be quicker than CNC and you can do some things that just can't be done with CNC, like water jackets in a head. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= 3D=3D=3D=3D=3D=3D=3D=3D Leon McAtee Fascinating reading. You guys have metal working skills way beyond my experience. So maybe this is a stupid question but might it be easier to add a water jacket to an existing head |
#19
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![]() "Tim Ward" wrote in message ... The biggest obstacle to CNC machining is down inside the ports. While it is done every day, it requires more tooling than most economical CNC shops possess, and would probably add greatly to a job as small as four heads. |
#20
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On Jan 21, 7:13*am, (Drew Dalgleish)
wrote: So maybe this is a stupid question but might it be easier to add a water jacket to an existing head Not a stupid question at all. In fact it has been done to the air- cooled VW head and isn't all that hard. Far less work than making a casting. IMHO water cooled aircraft engines have some real advantages. BUT.............. There are lots of individuals that prefer the simplicity and reliability of an air-cooled noise maker. =========================== Leon McAtee |
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