Why Is Porting Still Done By Hand?
05-21-2005, 03:00 PM
#31
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Join Date: Aug 2004
Location: Houston
Posts: 76
If money were no object and the person programming the machine had enough patience to get everything loaded in exactly right, there is no way any human hand could repeat the consistency of a cnc. A machine could also do the finish work at the same time. Unfortunately just loading the program in would be a challenge in itself. You need a pretty creative way to get that machine's bit down the runners and at the right angles. Not saying that it is impossible, just not easy. How many housings will aperson go through trying to figure this out? I think with enough effort from a willing person that a cnc program can work out very nice. But they'll also have to load in many different porting configurations for many different styles of housing. That's alot of work to get that extra little tenth of a percent consistency maintained. It would also be alot of money. That's probably the single biggest issue. I know how cheap it is to go out in the garage and break out a die grinder. Can porting be done good with a cnc? Why not? Is it worth it? Each person will have to make their own judgement on that one. I wouldn't mind some cnc ported housings if I could get them for the same price that it costs me to port my own. For me it isn't a good deal. For a race team, maybe it is.
05-21-2005, 11:31 PM
#32
Senior Member
Join Date: Feb 2003
Location: Calgary
Posts: 564
They were charging about the equivalent 250 a motor, and its done in less than an hour..
A friend of mine has been working on cnc for housings locally, hes almost ready to offer it up, it will be in the same price range.. There is no magic to accurate machining, the setup and the programming is not that difficult for someone that does it every day, my friend started as programmer for plastics injection molds that were quite complex, a port in a iron is a pretty simple task for someone with his back ground...That manifold adapter took him 2 hours from looking at the s6 and s5 gaskets to the finished product and cost 140.00.. It fit like a like glove...
I've seen tons of buggered irons from porting mistakes, search this forum for some prime examples... If I was blowing the money on new irons, they would only see a cnc machine for porting..Maxt
A friend of mine has been working on cnc for housings locally, hes almost ready to offer it up, it will be in the same price range.. There is no magic to accurate machining, the setup and the programming is not that difficult for someone that does it every day, my friend started as programmer for plastics injection molds that were quite complex, a port in a iron is a pretty simple task for someone with his back ground...That manifold adapter took him 2 hours from looking at the s6 and s5 gaskets to the finished product and cost 140.00.. It fit like a like glove...
I've seen tons of buggered irons from porting mistakes, search this forum for some prime examples... If I was blowing the money on new irons, they would only see a cnc machine for porting..Maxt
05-21-2005, 11:53 PM
#33
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Join Date: Sep 2002
Location: Savannah, Ga
Posts: 2,763
My money would still be spent on a skilled artisan doing the porting by hand. I just still dont think it would be the same. Show me a CNC port that looks like the one BDC posted in the "porting efficiency" thread without hand finishing.
05-22-2005, 07:51 AM
#34
Junior Member
Join Date: May 2005
Posts: 1
My guess is that it has more to do with who owns the knowledge rather than whether one method is better than the other.
I suspect that most top porters come from years of building and developing engines.
Their experiance comes from engine building not machining. They have probably specialised over the year to doing ports as a major part of their business but building engines is basically what they do. They aren't machinists. If they do a great job with what they have why would they invest in CNC and learning it?
On the other hand if you know CNC you would need to learn how to make a great ports which I suspect would take time to learn and is therefore not cost efficient for a machinst to just go into the porting business.
Yes - CNC is high precision (probably higher than that needed) and CNC machine don't make slips but then top porters don't either.
I suspect that most top porters come from years of building and developing engines.
Their experiance comes from engine building not machining. They have probably specialised over the year to doing ports as a major part of their business but building engines is basically what they do. They aren't machinists. If they do a great job with what they have why would they invest in CNC and learning it?
On the other hand if you know CNC you would need to learn how to make a great ports which I suspect would take time to learn and is therefore not cost efficient for a machinst to just go into the porting business.
Yes - CNC is high precision (probably higher than that needed) and CNC machine don't make slips but then top porters don't either.
05-23-2005, 01:04 PM
#35
Senior Member
Join Date: Feb 2003
Location: Calgary
Posts: 564
[quote name='chalmers888' date='May 22 2005, 04:51 AM']Yes - CNC is high precision (probably higher than that needed) and CNC machine don't make slips but then top porters don't either.
[/quote]
Even the top porters make slips... Precisely why the alot of the top porters are using CNC...One can never be to accurate, remember the porting on our engines is also our "cam" timing, having everything phased properly is one of the keys to power...
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Even the top porters make slips... Precisely why the alot of the top porters are using CNC...One can never be to accurate, remember the porting on our engines is also our "cam" timing, having everything phased properly is one of the keys to power...
05-23-2005, 01:10 PM
#36
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Join Date: Jul 2002
Location: My BIG ol TURBO-DIESEL
Posts: 5,181
Considering the fact that I have difficulty finding a shop willing to do small parts runs (90-100 units) due to the loss of set up time on their bigger contracts. I fail to see how you can afford to do 3 setups and 3 programs at a reasonable cost in order to port 1 engine. This does not even count the different styles of porting.
MAXT: I fail to see the cost effectiveness of what you are quoting. I want a name and a number of someone to talk to. Are you saying $250 for all 4 ports (ie 3 different setups, or is your price $250 PER Housing. BE SPECIFIC
MAXT: I fail to see the cost effectiveness of what you are quoting. I want a name and a number of someone to talk to. Are you saying $250 for all 4 ports (ie 3 different setups, or is your price $250 PER Housing. BE SPECIFIC
05-24-2005, 10:15 AM
#37
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Join Date: Nov 2002
Location: Honolulu, Hawaii USA
Posts: 925
Unless some high end CNC shop is doing stuff for charity, I don't see how it adds up.
Hell, I'll pay $500 for CNC ports!
I got cash on hand.
You guys wanna make good on your offer or you just spouting BS?
Sure, a high-end CNC can make mirror smooth finishes, but who the (*^#(*@$( wastes their time making rotary engine ports?
Sure, once the CNC coding is done, everything is repeatable - again, who the hell would waste their time with rotary engine ports?
-Ted
Hell, I'll pay $500 for CNC ports!
I got cash on hand.
You guys wanna make good on your offer or you just spouting BS?
Sure, a high-end CNC can make mirror smooth finishes, but who the (*^#(*@$( wastes their time making rotary engine ports?
Sure, once the CNC coding is done, everything is repeatable - again, who the hell would waste their time with rotary engine ports?
-Ted
05-24-2005, 12:30 PM
#38
Senior Member
Join Date: Dec 2003
Location: Minneapolis,MN
Posts: 500
Im with ted. I have a bunch of engines under my belt now and I would never waste my ******* time going to a machine shop and try to explain to them what I want.
I just had an engine pinned and let me tell you it was not an easy thing to comunicate. I could not imagine dealing with the ports. It would actually be more setup time becuse you would need to change bits as well as use a zillion axis mill.
We got the charity rate of $175/hr. Clearly those of you who think it would be better to CNC ports have no clue.
Also, what would the benifits be over doing them by hand. I can think of none! It would cost thousands just to get tooled to do it. Baahhh, Im done here.
Those of you that thin cnc is the way to go, have you EVER ported an engine???
I just had an engine pinned and let me tell you it was not an easy thing to comunicate. I could not imagine dealing with the ports. It would actually be more setup time becuse you would need to change bits as well as use a zillion axis mill.
We got the charity rate of $175/hr. Clearly those of you who think it would be better to CNC ports have no clue.
Also, what would the benifits be over doing them by hand. I can think of none! It would cost thousands just to get tooled to do it. Baahhh, Im done here.
Those of you that thin cnc is the way to go, have you EVER ported an engine???
05-24-2005, 01:40 PM
#39
Junior Member
Join Date: Aug 2003
Posts: 19
If you want to get your intake runners polished check out Extrude Hone; they do abrasive flow machining. I don't know if they will/can port the runners but they can polish the entire intake for under $600.
I might try it when i get a new engine.
I might try it when i get a new engine.
05-24-2005, 06:25 PM
#40
Senior Member
Join Date: Feb 2003
Location: Calgary
Posts: 564
Sometime I wonder why I even bother...
Who spends their time doing ports like that, hmm... People that are serious, thats who...
They guy I know, is working from from irons I gave him with with radius corrections plotted in, its not going to be mainstay work for his CNC machines, but shop filler in between large jobs, its better to have a machine making 250.oo then nothing...In between molds sometimes the cnc can sit for a week with nothing going in or out of it..
The problem with this kinda of stuff as someone mentioned you cant go to a machine shop and expect them to know you want or expect, and if its an hourly based shop,you are going to pay primetime money for every minute thats spent on it, be it machining , plotting or talking, but its not like that for places that have CNC machines that are in a niche market, but have down time to fill once the bread and butter is done, and thats the difference, anything they do over above their standard fare is gravy...
I am going there saturday for an update..Maxt
Who spends their time doing ports like that, hmm... People that are serious, thats who...
They guy I know, is working from from irons I gave him with with radius corrections plotted in, its not going to be mainstay work for his CNC machines, but shop filler in between large jobs, its better to have a machine making 250.oo then nothing...In between molds sometimes the cnc can sit for a week with nothing going in or out of it..
The problem with this kinda of stuff as someone mentioned you cant go to a machine shop and expect them to know you want or expect, and if its an hourly based shop,you are going to pay primetime money for every minute thats spent on it, be it machining , plotting or talking, but its not like that for places that have CNC machines that are in a niche market, but have down time to fill once the bread and butter is done, and thats the difference, anything they do over above their standard fare is gravy...
I am going there saturday for an update..Maxt