Why Is Porting Still Done By Hand?
05-16-2005, 08:50 AM
#11
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[quote name='falcoms' date='May 15 2005, 08:32 AM']Well, basically, I'm just wondering why people haven't started porting irons with CNC to get more accurite and consistent porting jobs done. Additionally, why take the risk of ruining an iron by a little slip-up of the bit popping out of the port or cutting too deep?
Just morbid curiosity!
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There are some ports being cut with CNC machines.
There are some problems. To gain any benifit you must be feeding that machine around the clock. An auto loading machining center has an overhead that is more than you make. The loan payment, insurance, maintainance, building and floor space rent and so on is the overhead. To do any number of plates you must do a setup and jig construction for each face of the 4 plates.
So you would run all of the front irons, then the front side of the center iron then the rear side of the center iron and last (or any order that makes more sense) the front of the rear iron.
Then you need long production runs (large numbers of parts) in order to keep costs low enough for anyone to afford to buy the service.
So say the shop owner needs 20 pieces of any iron to break even on the overhead before he makes any money. Where will he get that kind of business?
Two nut case motor heads in your office with 2 sets of iron to be one bridgeported and the other street ported is not going to get anything but a smile. This guy needs $4,000.00 a month out of his Milicron to keep it in the building.
But if you can find an old guy with some early paid off machines, he might do it just for laughs. But nothing on a commercial basis.
How many irons will be ported start to finish in the US this month? 100? 200?
If one shop was doing all of them, the overhead deal would be paid for those months, but then what? One reason that machine tool leasing has become more popular, is that overhead deal. You end up doing jobs that make little profit just to make the payments on purchased machines.
It is entirely doable.
Lynn E. Hanover
Just morbid curiosity!
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[/quote]
There are some ports being cut with CNC machines.
There are some problems. To gain any benifit you must be feeding that machine around the clock. An auto loading machining center has an overhead that is more than you make. The loan payment, insurance, maintainance, building and floor space rent and so on is the overhead. To do any number of plates you must do a setup and jig construction for each face of the 4 plates.
So you would run all of the front irons, then the front side of the center iron then the rear side of the center iron and last (or any order that makes more sense) the front of the rear iron.
Then you need long production runs (large numbers of parts) in order to keep costs low enough for anyone to afford to buy the service.
So say the shop owner needs 20 pieces of any iron to break even on the overhead before he makes any money. Where will he get that kind of business?
Two nut case motor heads in your office with 2 sets of iron to be one bridgeported and the other street ported is not going to get anything but a smile. This guy needs $4,000.00 a month out of his Milicron to keep it in the building.
But if you can find an old guy with some early paid off machines, he might do it just for laughs. But nothing on a commercial basis.
How many irons will be ported start to finish in the US this month? 100? 200?
If one shop was doing all of them, the overhead deal would be paid for those months, but then what? One reason that machine tool leasing has become more popular, is that overhead deal. You end up doing jobs that make little profit just to make the payments on purchased machines.
It is entirely doable.
Lynn E. Hanover
05-16-2005, 09:31 AM
#12
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[quote name='mazdaspeed7' date='May 15 2005, 10:10 PM']What? I still agree with BDC. CNC porting for boinger heads is an economical way to get a good port job. But it still has to be smoothed by hand to remove the CNC marks(because its faster than having the CNC machine take out its maching marks). But all the top port jobs are still done by hand. The CNC ports excel in their repeatability, but they are only as good as the person programming them. Ever notice all the race heads for piston engines are hand ported? Even with the prominence of CNC ported heads?
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Bingo.
People need to do their research before making assumptions.
The BEST piston heads are hand finished.
CNC allows for better repeatability, but it's next to impossible to get a "smooth" finish from the mill head tools.
-Ted
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Bingo.
People need to do their research before making assumptions.
The BEST piston heads are hand finished.
CNC allows for better repeatability, but it's next to impossible to get a "smooth" finish from the mill head tools.
-Ted
05-16-2005, 08:32 PM
#13
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[quote name='RETed' date='May 16 2005, 09:31 AM']Bingo.
People need to do their research before making assumptions.
The BEST piston heads are hand finished.
CNC allows for better repeatability, but it's next to impossible to get a "smooth" finish from the mill head tools.
-Ted
[/quote]
IDK, My dad is a machinist by trade and programs and builds precision (1/100 of a micron) grinders and has done mills accurite to 1/10,000 of an inch, so I don't get why it's termed so impossible to do it. You don't need any majorly fancy machines to do it, just a CNC kit bolted on to your basic vertical mill, zero it in, and away you go. You guys are talking like we are going to the extreme that we can't do it without multi-million dollar machinery. It's just not the case.
I bet you a program could be layed out in cad that knows where the seals pass by and you enter what port you want based on that, run one of 3 or 4 programs on each set of irons, with the mill set to zero in on the iron every run before cutting so you can have some error in placement in a vice or something, and do the irons for MAYBE $1k for a bridgeported set. So big deal, you have to place the irons in the mill twice so you can cut one plane (actual port) and then the other (side of iron), for the time saved, it's well worth it and you get a decent profit if you do it as a business. That and you can make your guarantees of power made much more accurite and to tighter tolerances because the port is so repeatable. I mean by hand you can see anywhere up to 50hp difference on a bridgeported engine with the same equipment all around from the same shop, same person, just because the ports are not as repeatable because of sheer human error.
To me CNC would be the best way to go, bar none. I think it's just because rotarys aren't popular enough to warrant using such equipment. Like one person said: How many irons are going to be ported this month? About 100-200 max. Not nearly enough to go super high-tech like some boinger shops are. It sucks IMO, but such is life I guess...
People need to do their research before making assumptions.
The BEST piston heads are hand finished.
CNC allows for better repeatability, but it's next to impossible to get a "smooth" finish from the mill head tools.
-Ted
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IDK, My dad is a machinist by trade and programs and builds precision (1/100 of a micron) grinders and has done mills accurite to 1/10,000 of an inch, so I don't get why it's termed so impossible to do it. You don't need any majorly fancy machines to do it, just a CNC kit bolted on to your basic vertical mill, zero it in, and away you go. You guys are talking like we are going to the extreme that we can't do it without multi-million dollar machinery. It's just not the case.
I bet you a program could be layed out in cad that knows where the seals pass by and you enter what port you want based on that, run one of 3 or 4 programs on each set of irons, with the mill set to zero in on the iron every run before cutting so you can have some error in placement in a vice or something, and do the irons for MAYBE $1k for a bridgeported set. So big deal, you have to place the irons in the mill twice so you can cut one plane (actual port) and then the other (side of iron), for the time saved, it's well worth it and you get a decent profit if you do it as a business. That and you can make your guarantees of power made much more accurite and to tighter tolerances because the port is so repeatable. I mean by hand you can see anywhere up to 50hp difference on a bridgeported engine with the same equipment all around from the same shop, same person, just because the ports are not as repeatable because of sheer human error.
To me CNC would be the best way to go, bar none. I think it's just because rotarys aren't popular enough to warrant using such equipment. Like one person said: How many irons are going to be ported this month? About 100-200 max. Not nearly enough to go super high-tech like some boinger shops are. It sucks IMO, but such is life I guess...
05-16-2005, 11:47 PM
#14
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Youre missing the point though. Porting is as much art as science. Do you expect some of the master porters to give up the tricks that make their ports magic so you can try to put it into a CNC machine?
When it really comes down to it, a proficient porter can do a set of housings quicker than you could set it up to be done with a mill and hand finish it(because hand finishing is always required on cnc porting). I can do the rough porting for a streetport on the intake in about 20 minutes with carbide bits and an air die grinder. The time consuming part is the hand finishing.
When it really comes down to it, a proficient porter can do a set of housings quicker than you could set it up to be done with a mill and hand finish it(because hand finishing is always required on cnc porting). I can do the rough porting for a streetport on the intake in about 20 minutes with carbide bits and an air die grinder. The time consuming part is the hand finishing.
05-17-2005, 10:13 AM
#15
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[quote name='falcoms' date='May 16 2005, 05:32 PM']IDK, My dad is a machinist by trade and programs and builds precision (1/100 of a micron) grinders and has done mills accurite to 1/10,000 of an inch, so I don't get why it's termed so impossible to do it. You don't need any majorly fancy machines to do it, just a CNC kit bolted on to your basic vertical mill, zero it in, and away you go. You guys are talking like we are going to the extreme that we can't do it without multi-million dollar machinery. It's just not the case.
To me CNC would be the best way to go, bar none.
[/quote]
it doesn't matter if the machine is acurate to .00001".... it doesn't NEED to be that acurate. the housings are all different and there ARE casting flaws, varying wall thicknesses, etc... no way the cnc would work except for maybe the port oriface, or cutting bridges, but even then you'd have to zero the machine everytime.
plus, you'd need a 5 axis mill to get into all the spots you need to get into while porting...and even then it still wouldn't be as good as if you did it by hand.
To me CNC would be the best way to go, bar none.
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it doesn't matter if the machine is acurate to .00001".... it doesn't NEED to be that acurate. the housings are all different and there ARE casting flaws, varying wall thicknesses, etc... no way the cnc would work except for maybe the port oriface, or cutting bridges, but even then you'd have to zero the machine everytime.
plus, you'd need a 5 axis mill to get into all the spots you need to get into while porting...and even then it still wouldn't be as good as if you did it by hand.
05-17-2005, 11:33 AM
#16
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Son, how much CNC Programming have YOU done? How long have YOU been a machinist (Chucking up parts in daddys CNC Machining center does not count). And most importantly, how many housings have you ported?
05-17-2005, 12:22 PM
#17
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You guys are all soo mean to this poor guy sticking up for his father's profession.
...so the master porters aren't going to give up their porting secrets...unless you are the people doing this, you won't know either.
I have worked with CNC machines at school (i am an engineering student)and it wouldn't be extremely difficult to make this work effectivly. A buisness that does basic machining of the ports and then hands the irons back and says, now all you have to do is smooth out these machining marks like this..... would be more economical. Bottom line is that the major risk of ruining the side housings from an inexperenced hand piloting a dremel is reduced and there is a potential for the cost to come down on port jobs if a shop already had access to the machinery.
Does anybody know how many side housings are scrapped because a do-it-yourself porter slipped or wasn't sure how far to go etc... I don't know myself but I am sure that this occurs.
The ports might not be as significantly opened as a master porter and his guide of hand, the port job won't nesesarily be a complete purchace that is plug and play, but the potential to have more affordable and consistant port job is increased.
As for the actual machining and individual rotor housings...the irons may/will have defects, but they are created with tolerances and if they did not meet the required tolerances, then mazda would not have put them into the market. Im sure somwhere somebody has or can get the manufacturing tolerances on every part of these engines. And in the worst case senario, new irons can be a pre-requisite if used ones can show significant wear that would be detrimental to the engine's life expectancy.
Also to my knolege, all of the commercial "porters" (persons whom are expert in the art of rotary porting) are located in california or florida...or at least the majority are. A generic Jig could even be marketed on the internet for cheap with generic port specifications/tolerances so that one could go to a local machine shop and have it done there.
"Good" is a subjective word, so saying that it would not be as "good" is a basic opinion. I might go as far as to say that a CNC port job would be "better" than a hand port job because their tolerances are more consistant than a hand port job.
Im not saying that my word is final..but this is my 2 cents.
...so the master porters aren't going to give up their porting secrets...unless you are the people doing this, you won't know either.
I have worked with CNC machines at school (i am an engineering student)and it wouldn't be extremely difficult to make this work effectivly. A buisness that does basic machining of the ports and then hands the irons back and says, now all you have to do is smooth out these machining marks like this..... would be more economical. Bottom line is that the major risk of ruining the side housings from an inexperenced hand piloting a dremel is reduced and there is a potential for the cost to come down on port jobs if a shop already had access to the machinery.
Does anybody know how many side housings are scrapped because a do-it-yourself porter slipped or wasn't sure how far to go etc... I don't know myself but I am sure that this occurs.
The ports might not be as significantly opened as a master porter and his guide of hand, the port job won't nesesarily be a complete purchace that is plug and play, but the potential to have more affordable and consistant port job is increased.
As for the actual machining and individual rotor housings...the irons may/will have defects, but they are created with tolerances and if they did not meet the required tolerances, then mazda would not have put them into the market. Im sure somwhere somebody has or can get the manufacturing tolerances on every part of these engines. And in the worst case senario, new irons can be a pre-requisite if used ones can show significant wear that would be detrimental to the engine's life expectancy.
Also to my knolege, all of the commercial "porters" (persons whom are expert in the art of rotary porting) are located in california or florida...or at least the majority are. A generic Jig could even be marketed on the internet for cheap with generic port specifications/tolerances so that one could go to a local machine shop and have it done there.
"Good" is a subjective word, so saying that it would not be as "good" is a basic opinion. I might go as far as to say that a CNC port job would be "better" than a hand port job because their tolerances are more consistant than a hand port job.
Im not saying that my word is final..but this is my 2 cents.
05-17-2005, 12:34 PM
#18
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[quote name='laundryhamperman' date='May 17 2005, 12:22 PM']"Good" is a subjective word, so saying that it would not be as "good" is a basic opinion. I might go as far as to say that a CNC port job would be "better" than a hand port job because their tolerances are more consistant than a hand port job.
Im not saying that my word is final..but this is my 2 cents.
[/quote]
AGAIN: Laundryman PLEASE state your experience? HOw many engines? How much actual machining have you performed. Spouting off a bunch of college textbook crapola doent cut it here.
Im not saying that my word is final..but this is my 2 cents.
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AGAIN: Laundryman PLEASE state your experience? HOw many engines? How much actual machining have you performed. Spouting off a bunch of college textbook crapola doent cut it here.
05-17-2005, 01:52 PM
#19
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Machines dont have the human "touch." Porting is every bit as much art as science.
You still need to do the finish work by hand, CNC porting on cylinder heads is for consistent mass removal of material. Porting of rotaries doesnt involve mass removal of material, its more of a fine reworking of the ports. This is why CNC ic impractical for rotaries.
You still need to do the finish work by hand, CNC porting on cylinder heads is for consistent mass removal of material. Porting of rotaries doesnt involve mass removal of material, its more of a fine reworking of the ports. This is why CNC ic impractical for rotaries.
05-17-2005, 03:19 PM
#20
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I would agree that machining does not have the human "touch"...and for that reason i give credit to the very skilled people who port these motors and give credit to a hand ported motor over a machine ported one.
Being stubborn and saying that it couldn't be done effectivly is closing doors b4 they can be opened for examination.....saying a rotary won't work b/c piston engines work well is a satire to this point. banzaitoyota...where is your R&D to prove that it won't work? I've backed most of my thoughts where you have simply slammed on the people pro-cnc....or not even pro-cnc, but ppl who simply give the idea credit that it could work under the right conditions.
Again subjectivly...I think that a hand port job would be "better" than a machine port [B]because[B/} a human can better smooth the edges and shape the port to a greater extent allowing greater overall flow and effectiveness of the port job to increase power.
and for your reference...i have well over 100 hours of CAD work (including custom designing for personal interests) and 5 hours or so CNC Mill/Lathe experience as well as a semester working with an automated assembly line. From experence, it doesn't take much to set up this equipment, just the know how to work proficiently. The majority of the time spend is behind the computer and waiting for the machines to complete their job.
Being stubborn and saying that it couldn't be done effectivly is closing doors b4 they can be opened for examination.....saying a rotary won't work b/c piston engines work well is a satire to this point. banzaitoyota...where is your R&D to prove that it won't work? I've backed most of my thoughts where you have simply slammed on the people pro-cnc....or not even pro-cnc, but ppl who simply give the idea credit that it could work under the right conditions.
Again subjectivly...I think that a hand port job would be "better" than a machine port [B]because[B/} a human can better smooth the edges and shape the port to a greater extent allowing greater overall flow and effectiveness of the port job to increase power.
and for your reference...i have well over 100 hours of CAD work (including custom designing for personal interests) and 5 hours or so CNC Mill/Lathe experience as well as a semester working with an automated assembly line. From experence, it doesn't take much to set up this equipment, just the know how to work proficiently. The majority of the time spend is behind the computer and waiting for the machines to complete their job.