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Re: Perhaps I was wrong....40HP? For you Tony!

Subject: Re: Perhaps I was wrong....40HP? For you Tony!
by jsup on 2008/12/23 18:37:30

Quote:

BeachBum wrote:

The hack & guess method ? How do you think a manufacturer got the original CAD file ? Then, after they get the CAD file, they will massage the tool path via a good cad/cam program.... Ie, the cam part being necessary unless you just want a useless cad file. (you could print it, but you can't machine it) Specifically, they are typically rounding the massive series of linear points they have to create a smooth path, this can be done in a variety of ways such as NURBS or simple G-code commands that instruct the CNC to automatically corner round each axes command transition. They can also shift it and massage the path, thus raising or lowering the roof for example or shifting the port enough to allow for a water jacket. But, I think I previously mentioned they massage the port design to get a casting.

Sorry, perhaps I wasn't clear. That's why I said that it still has it's place.

I don't really understand how digitizing a port is hard. If you can't probe it, you certainly can't cut it.

If a company that does digitizing does not have the correct probes, they should hire an outside company to do the digitizing or buy the correct probe.

Further, what company is doing 5-axis port machining and does not have the CAD geometry for the casting? If they had the geometry for the casting, they could do the porting in CAD before machining. Am I wrong?

For clarity sake in the old days before CAD availability, the process was to take a head, hand port it, flow the port, see what you get.

The next step was to take the next cyl, port it slightly differently, flow it, see what you get.

Repeat six more times per set of heads. Pick the best one, repeat on a new set of heads.

Sometimes, you hit the mark either by skill or by accident. This was the "old time" process in getting port design. Time consuming and expensive.

Enter CNC, and as you spelled out, you had to re create it in the way you outline.

With current technology that process can be simulated and fed to the CNC machine, hell, I've seen it first hand where a design was fed to a machine that literally spit out a 3 dimensional representation carved from a solid block.

That design will be tested on a wet flow bench to ensure what they got, is what they expected. If it is not, that information fed back into the CAD for modification and further simulation.

As time goes on and more information is gathered, the old grind and guess method will be eliminated completely.

That is the way I understand it.
Quote:

Spintron ??? Spintron is most commonly utilized for valvetrain issues.... when did they become involved in "creating" a tool path file for a cylinder head?.... thats new to me. I don't have any clue how that would work, can you elborate on how Spintron (the high speed cameras) would create a tool path ?

Spintron is a separate issue. Remember what I said, outfitted with high speed cameras.

As a wet flow bench is used to verify design scientifically in a static situation, which is the limitation of wet flow, the Spintron allows engineers to see how this stuff works under operational environments. Cameras are actually put inside cylinders to see what happens in those conditions. It is far far more than just a valve train analyzer. It does NOT create a tool path at all. It is a tool to better understand what happens when a design is implemented in the field under the conditions it will be working. Has nothing to do with tooling.

Quote:

btw, with a wetflow tested port, what happens to it after a porter modifies with his own cnc program from a wetflow perspective?

I guess it depends on the change. The wet flow is to find out what happens after a change, hand or CNC port. That's the piont of wet flow and why it is a significant step up from dry flow. But still, because static, is still not as good as Spintron.

SMC