CNC Heads?

[Knight rider]

I thought CNC porting was just to save time, you would first hand port a certain head, flow the head and when your happy with your design digitise the port than that becomes your master for the port when doing those heads ? Cheers

Edit and repeat ability would be a plus to all ports the same

[midnightbluS10]

Everybody talks about CNC heads, what usually I ask is, who did the original porting you are coping, or did you just tell the computer program to make them a certain percent larger? Just wondering why don't the sellers of CNC porting advertise who did the work the program is copying? Seems they might get more business? I port my own heads, I'm sure I leave HP on the table, but I just like the challenge of doing my own work. I have checked several CNC heads on my bench, most flow well, but the velocity is almost always a lot lower compared to the porting I do. And I just do a few engines a year so I don't claim to be an expert. Also seen some failures because the program takes out too much material, causing cracks and leakage as well.

Tell the computer to make it a certain percentage larger? Are cnc machines now using AI to CNC? You can't just stick a head in, type in that you want this hole this much larger and let it work. That's not how cnc works. If there's a pattern to follow, someone programmed that pattern.

The cnc machine only executes motions that are programmed into the machine. And the whole "who are you copying" isn't a good question to ask. You ask who did the master that the program was based on.

You can tell it I want the throat .020 smaller or I want less step over on the roof.

I have had many of my ports shrunk .050 on all walls. Then hand finish per application

But it's still basing that .020 smaller on what you've programmed into the machine initially, correct?

You're not just going to put a head in the machine that you've never worked on and then tell it to make a port 20% bigger, except this wall and I want that .020" thicker than the program decided it wanted to remove. You've got to have some sort of predefined pattern for it to follow to 'know' its going to make anything .020 smaller or larger, right?

[Walter R. Malik]

I thought CNC porting was just to save time, you would first hand port a certain head, flow the head and when your happy with your design digitise the port than that becomes your master for the port when doing those heads ? Cheers

Edit and repeat ability would be a plus to all ports the same

A lot of the times ... a good LOOKING port is made and copied for a CNC program.

The good places do exactly what you've stated but, that is simply only a portion of the CNC head porting marketplace.

[smeg]

Tell the computer to make it a certain percentage larger? Are cnc machines now using AI to CNC? You can't just stick a head in, type in that you want this hole this much larger and let it work. That's not how cnc works. If there's a pattern to follow, someone programmed that pattern.

The cnc machine only executes motions that are programmed into the machine. And the whole "who are you copying" isn't a good question to ask. You ask who did the master that the program was based on.

You can tell it I want the throat .020 smaller or I want less step over on the roof.

I have had many of my ports shrunk .050 on all walls. Then hand finish per application

But it's still basing that .020 smaller on what you've programmed into the machine initially, correct?

You're not just going to put a head in the machine that you've never worked on and then tell it to make a port 20% bigger, except this wall and I want that .020" thicker than the program decided it wanted to remove. You've got to have some sort of predefined pattern for it to follow to 'know' its going to make anything .020 smaller or larger, right?

It does not work like that, the program doesn't decide anything. It only cuts what shape it is told to cut. If you want to move a wall over say .020" you modify the splines that make the surface, blend, then remake the surface. Redo the toolpath and send to the machine to cut. The machine is only doing what you tell it to do.

[ou812]

I can tell you, Chad's stuff works!

[4vpc]

I thought CNC porting was just to save time, you would first hand port a certain head, flow the head and when your happy with your design digitise the port than that becomes your master for the port when doing those heads ? Cheers

Edit and repeat ability would be a plus to all ports the same

Add in the risk factor and fatigue too which is sometimes serious and permanently debilitating.

[SchmidtMotorWorks]

I thought CNC porting was just to save time, you would first hand port a certain head, flow the head and when your happy with your design digitise the port than that becomes your master for the port when doing those heads ? Cheers

Edit and repeat ability would be a plus to all ports the same

Add in the risk factor and fatigue too which is sometimes serious and permanently debilitating.

Once you get setup and learn how to model ports in CAD, using a die grinder will become rare.
It gives you complete control and visualization and analysis of the shape.
Also makes stepping up to CFD a smaller challenge.

[TMSJoe]

If you already have a file to copy you can change tool offsets. This will "shrink" or "enlarge" the ports without actually redesigning it. Computers only do what they are told. But you can lie to them.

Everybody talks about CNC heads, what usually I ask is, who did the original porting you are coping, or did you just tell the computer program to make them a certain percent larger? Just wondering why don't the sellers of CNC porting advertise who did the work the program is copying? Seems they might get more business? I port my own heads, I'm sure I leave HP on the table, but I just like the challenge of doing my own work. I have checked several CNC heads on my bench, most flow well, but the velocity is almost always a lot lower compared to the porting I do. And I just do a few engines a year so I don't claim to be an expert. Also seen some failures because the program takes out too much material, causing cracks and leakage as well.

Tell the computer to make it a certain percentage larger? Are cnc machines now using AI to CNC? You can't just stick a head in, type in that you want this hole/port this much larger and let it work. That's not how cnc works. If there's a program to run, there's a pattern to follow, and someone programmed that pattern. No matter what it's doing. Someone programmed it to do that. You don't just stick parts in and tell it to arbitrarily a pick space and remove material of its own choosing, which is how you've explained it, it seems. It doesn't just take material out anywhere.

The cnc machine only executes motions that are programmed into the machine. And the whole "who are you copying" isn't a good question to ask. You ask who did the master that the program was based on. It sounds like you're trying to throw shade if you ask "who are you copying".

[smeg]

If you already have a file to copy you can change tool offsets. This will "shrink" or "enlarge" the ports without actually redesigning it. Computers only do what they are told. But you can lie to them.

Everybody talks about CNC heads, what usually I ask is, who did the original porting you are coping, or did you just tell the computer program to make them a certain percent larger? Just wondering why don't the sellers of CNC porting advertise who did the work the program is copying? Seems they might get more business? I port my own heads, I'm sure I leave HP on the table, but I just like the challenge of doing my own work. I have checked several CNC heads on my bench, most flow well, but the velocity is almost always a lot lower compared to the porting I do. And I just do a few engines a year so I don't claim to be an expert. Also seen some failures because the program takes out too much material, causing cracks and leakage as well.

Tell the computer to make it a certain percentage larger? Are cnc machines now using AI to CNC? You can't just stick a head in, type in that you want this hole/port this much larger and let it work. That's not how cnc works. If there's a program to run, there's a pattern to follow, and someone programmed that pattern. No matter what it's doing. Someone programmed it to do that. You don't just stick parts in and tell it to arbitrarily a pick space and remove material of its own choosing, which is how you've explained it, it seems. It doesn't just take material out anywhere.

The cnc machine only executes motions that are programmed into the machine. And the whole "who are you copying" isn't a good question to ask. You ask who did the master that the program was based on. It sounds like you're trying to throw shade if you ask "who are you copying".

To do it correctly, you don't want to change the offset and make a port x amount bigger as this will make the throat bigger as well and make it too big. To do it correctly you change the surface while making the throat the same then cut it, a bit more complicated than just changing an offset

[econo racer]

I do not know how to download pictures but I saw a set of cnc ported import sbc heads on Ebay. In the picture it looks like the intake port is ported too far and out to the push rod. Looks like a hole came thru. Could be a bad picture but if anyone wants to look it up it looks wrong.

[cv67]

post a link up?
Those pinch areas dont have a lot of meat I busted through one too...nothing a sleeve/little epoxy couldnt fix.
Seems the ports moved over some and they raised the roof a little over traditional design i could be wrong.

[econo racer]

On Ebay listed as Chevy SBC 215cc 70cc angle plug Full CNC bare head $622.05 Speed master. Look at the bottom of the intake ports I am in no way affiliated with this company so you look and see what it looks like.

[6.50camaro]

Hard to tell from those pics no real close ups . But I have seen were if the cnc cutter did not touch the original as cast port wall it comes out looking darker or shaded like that in pictures . All has to do with lighting and camera angle. Really need to see in person or a lot better pics .Dan

[cv67]

May not have needed any cutting where there isnt any
Guide bosses are completely gone, still has a ridge@seat. Not much done on exh
Youd think they would have some kind of cfm posted wonder whose it is?

Refurbished units? Does that really mean defective and fixed by chance?

https://www.ebay.com/itm/Chevy-SBC-350- ... 2545!US!-1

[MadBill]

When I enlarge it, it looks like identical breakthroughs epoxied up.