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post #1 of (permalink) Old 04-12-2007, 03:44 PM Thread Starter
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Machine Shop Question

Ive been putting together a fuel injection kit for my cj and im finally down to the last piece of the puzzle.

I took plans for a throttle body adapter down to a few machine shops. The only guys who said they would do it say it will take 3 hours on the cnc machine and cost 280-300 dollars.

This sounds pretty high. Are these guys trying to pull one over on me?

If its really this much I may just buy the material and try to make one by hand. I made one out of wood easily enough. How much harder would it be to do with aluminum?
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post #2 of (permalink) Old 04-12-2007, 05:04 PM
 
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Its fairly easy. If you use two gaskets, one from the throttle body and one from the jeep intake manifold you will have what it should look like on the two surfaces. They only have a small area of overlap, so you have to do some blending. I made my own from 3" thick piece of billet. It was a fun project. A hole saw cut the two openings, and a carbide cutter on a die grinder shaped it. I tried to keep the cross sectional area of passages consistent. 3" high like mine will cause hood clearance problems unless you have a body lift. Perhaps 2" thick plate would be easier, but a slice of billet aluminum was easier to come by.
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post #3 of (permalink) Old 04-12-2007, 06:31 PM Thread Starter
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ill give that a shot.
now, where to find some 3/4-1in thick aluminum.......
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post #4 of (permalink) Old 04-12-2007, 06:45 PM
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Quote:
Originally Posted by D7Guy View Post
ill give that a shot.
now, where to find some 3/4-1in thick aluminum.......
Metals Depot® - Buy Small Quantity Metal Online! Steel, Aluminum, Stainless, Brass

they are overpriced...but if you just need one small piece and cant get it locally..........

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post #5 of (permalink) Old 04-12-2007, 07:12 PM
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Well Lows sells about that size.. Its not to cheap how ever.

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post #6 of (permalink) Old 04-12-2007, 07:47 PM
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To answer your original question, I can't imagine a simple carb adapter taking three hours on a CNC. Three minutes should be closer. Take a look at the video linked on that "Billet block" thread to see how fast a CNC machine goes.

I can see it taking three hours on a hand-cranked machine. I charge $65 an hour to the average guy off the street, so a couple hundred might be reasonable. Doing it by hand isn't technically difficult, but doing a good job will take a lot of time.

EVERYTHING's easy for the guy who doesn't have to do it.
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post #7 of (permalink) Old 04-12-2007, 08:39 PM
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post #8 of (permalink) Old 04-12-2007, 08:46 PM
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Quote:
Originally Posted by Jim_Lou View Post
To answer your original question, I can't imagine a simple carb adapter taking three hours on a CNC. Three minutes should be closer.
But that’s after you already have drawn the part in say Solidworks and gotten the CNC code. Then allow time to cut a block off, clamp it in the machine and unclamp it after the machine is done. To that add a fee for the CNC machine usage, they don’t work nearly as cheap as you do if they are ever going to get it paid for.

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Those who understand binary and those who don't.
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post #9 of (permalink) Old 04-13-2007, 06:08 AM
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All true, but what D7Guy said was
Quote:
it will take 3 hours on the cnc machine

EVERYTHING's easy for the guy who doesn't have to do it.
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post #10 of (permalink) Old 04-13-2007, 06:46 AM
 
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I'm a CNC Machinist and what I can tell you is they are probably telling the truth for the most part. It's expensive to come up with a program, test it, debug it, and run it. 3 hours seems kinda long though...I run some pretty complex parts in about 1 hour.
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