My luck has been bad with 1/8 compression fittings. Maybe its just me, but I figured others have had this happen too. Have you ever installed gauges and gone to tighten down the compression fittings and had this happen?


The ferrule tends to get crooked and then it doesn't seal. Happened a lot to me, as I was making a gauge holder, I had the gauges in and out a LOT. Drove me nuts. My fuel pressure gauge has been useless for over a month because it leaked the anitfreeze out. My dad told me I was just tightening them too much, so I let him do one and it did it to him too. I have seen the compression nuts with a retained ferrule in them, and those work good, but I can't find any, online or locally. Have also seen brass inserts you can stick in the end of the tubing to reinforce it at the compression ferrule, but nobody has them for 1/8, only found 3/16 and up. Trying to find a metal tubing small enough would be tough, but I thought back to my days of building and flying model planes and remembered all the little tubing and fittings I had used on those. I went to my local hobby shop and they have 3/32 brass tubing. Only a couple bucks for a few feet of it. It is a tight squeeze, so I put just a film of grease on the tubing before I put it in. Slipped it in 5/8 or so.


I recommend putting the brass in before cutting it, makes it much easier to push into the tubing. My tubing cutter won't go this small so I had to cut it with a razor blade and a smooth rolling action.


Next put it all together and give it a little snugging.


I pulled this one apart to snap a pic. It was sealed up, no leaks and it was not very tight. When the ferrule is lined up right, there is no need to tighten it a lot, just snug it up. It has just a little crimping action on the ends and its straight. Just like it should be.


Worked so well I thought I would share.
Aaron

 

nice dude a sticky for shure!

 

Nice job!. Copper tubing also works awesome instead of the plastic tube that comes with the gauges.

 

Whenever I have to use this type of a fitting I will always set the ferrule by using a spare fitting outside where it can be held straight.

You can get this size tubing inset from Graingers, http://www.grainger.com/Grainger/items/1VDC2

Hose-Man, Napa and from most any decent Heavy Truck Parts, 1/8" tubing is used on the Air Shift button that is attached to the shifter, I always carried a small bag full of the ferrules and couplers in my toolbox when I went on Road Calls.

Also I will never use the poly tubing that comes with the gauges but will replace it using Nyflex nylon air brake line instead, this can also be had from your local Truck Parts.

Inserting the brass tubing inside the tube is a good idea; a good Hobby Shop has a lot of neat things you never thought existed.

Jim

 

They make a special fitting for going from brass/metal to plastic and they work quite well. We had these at work and were used for boiler instrumentation connections. They are available at many sources. Here is what they look like:

http://www.aircraftspruce.com/catalo...lofittings.php

 

Jim and Trebor, those are exactly what I was looking for, I guess I just wasn't looking in the right places. I called all kinds of places, drove all over Mesa and got nothing. I did not however check my grainger catalog. The catalog sits right here on my desk and a grainger store is 3 miles away.

 

It was connectors like those that made me rip all the plastic fuel tubing out of my 2000 truck. I then got some really nice rubber, diesel fuel safe hose and run that straight to the gauge. No isolators as they leak at -30. Anything colder than -35 and those plastic lines cracked on me as well. Not fun at all. I had a needle valve and a ball valve to to shut off the fuel if need be. It was the only way to keep the fp gauge working.

 

I use cone ferrules like are used on truck air shifters and replace the crummy white tube with air brake line

 

A good hydraulic shop has sleeves made for 1/8" line. Good work making them, I know they are hard to find.