Critique my flaring technique

fehdxl · #1 10-30-2011, 08:48 PM

With all the discussion on this thread, I thought I'd share how I've made my flares and solicit positive/negative feedback.

Please, let's not debate the type of material used, rather the technique of making the flare.

So without further adieu, here we go.

1- Rolling the coil out on the table produces a relatively straight line.
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2- Cut the tube with a vibrating tool like this, rotary grinder, hack saw, or similar. Do not use a plumber's cutter! It crushes the tube, leaves a bad ridge, and won't work for flaring.
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3- Put the tube into the bending tool. Carefull not to scratch the tube...some of the edges on the tool will do it.
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4- This bender can only do a maximum of 90 +/- degrees. Some can do more...up to 180* I think.
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5- Now that I have the tube bent in the appropriate shape. Let's address the ugly ends. BTW, no need to make the ends pretty first only to mis-bend and have to start all over.
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6- Important that the end is square...a light touch on this sander does the job.
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7- Lightly clean up the scratch marks from the sanding on the scotch-brite wheel.
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8- Just a very light touch on the scotchbrite wheel to remove the side burr. Don't take away any material, just the burr.
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9- This one technique to address the inner burr. Don't go too much...a light touch is key here.
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10- Here is another technique. I find I like this better on the 3/8" tubing.
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fehdxl · #2 10-30-2011, 08:49 PM

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11- Final polish with some maroon scotch-brite to make sure all the scratches are removed.
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12- On this type of flaring tool, flush with the edge is appropriate for making the flare.
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13- Don't forget the ferrule and B-nut else you get to start all over!
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14- Here's what it looks like ready for attaching the cone shapped part of the flaring tool.
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15- Flaring for about 1/8 to a 1/4 turn, followed by reversing to relieve the pressure, then repeat seems to work best for me.
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16- Dont' forget to use a little lube. Any type will work. Helps keep from scoring the flare.
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17- Here what it looks like when finished. After a couple practice flares, you'll be able to feel the added resistance when the flaring is complete. Don't push through the extra resistance, or else you'll over do it.
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18- Post flaring, I visually inspect and polish with maroon scotch-brite again.
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19- This shows how wide the flare is. I believe this is the maximum it should be. If it were any wider, it wouldn't fit into the B-nut well. Experts out there confirm? Update: indeed this example is at or exceeding the maximum limit. 3/8 tubing should result in a flare that is 0.460 - 0.490 inches in diameter.
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20- This is to show how close you can have a bend to the end of the tube.
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fehdxl · #3 10-30-2011, 08:49 PM

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21- Could have been 1/2 inch shorter...but that would be it.
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22- Here you can see how the flare fills the B-but, but not too much. You can also see all the junk/residue in the tube which needs to be cleaned out.
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23- So I dump some thinner in the tube, shake it around, and then blow it out with compressed air.
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24- Here's the final product. We'll leave the discussion on how much to torqe the B-nut for another thread.
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So, that's how I do it. Nomex is donned...please let me know the good, the bad, and the ugly.

Hopefully you'll all be able to tell me I did just fine and that others can learn how to make a better, long-lasting, and safe flare!

-Jim
40603

N427EF · #4 10-30-2011, 09:24 PM

Let me be the first to say that your flares are way too big.
This causes unnecessary thinning and hardening of the aluminum.
There is absolutely no need to have a flare that is larger than the ferrule.

You do not want to squeeze the flare into the die, extend it a bit further
out of the die and use approximately 4 half turns to make a flare on a 3/8 tube.This will create a flare that is just a tiny bit larger than the ferrule.

You can use a sharp tube cutter,deburr the inside,scotch brite ouside, flare, scotch brite again and you are done.
Gently bend tubing by hand unless you need to make a tight radius.

az_gila · #5 10-30-2011, 11:26 PM

How does your flare diameter compare to the dimensions in this spec?

flion · #6 10-31-2011, 12:26 AM

Off the topic of flaring, you can do more than 90 degrees on that bender, though it takes more than one operation and, if you go past the handle, you will have to offset the bend slightly (think the difference between a ring and a spiral). It takes some practice to do it smoothly but, hey, that's what all that practice tubing from Van's is for, right?

MauiLvrs · #7 10-31-2011, 12:26 AM

Quote:

Originally Posted by fehdxl

12- On this type of flaring tool, flush with the edge is appropriate for making the flare.....

Are you sure that is accurate?
I believe that the tube should extend 1/8-1/4 inch beyond...

Tom Martin · #8 10-31-2011, 04:48 AM

I believe that these are an excellent set of instructions. I like to use a tubing cutter as it will make sure that the end is square. When using a tubing cutter make sure you have a quality cutter, Ridgid for example, with a sharp blade. Make very light cuts and there will be very limited deformation of the tube. A couple of licks with the deburring tool and a light pass with 3M pads and you are good to go.
I have used the same flaring tool as you are showing, making small back and forth movements to set the flare. By feel, there is a very definite moment when the flare has set, do not over flare. Use of a lubricant is essential to making a successful flare.
As for how big the flare should be this is how I was taught by a 40 year mechanic, 20 years ago (that makes for a lot of flares!)
Using the "hair scale" which is, as described by the 40 year mechanic, the essential measurement system used in the construction and maintenance of airplanes. As this is a family site we will discuss the beard hair measurement system.
a blonde beard hair is thinner then a brown beard hair which is thinner then a black hair. Need to file a piece a bit more, take off a black hair of thickness, not enough; try a blond amount! The hair scale is a very accurate way of visualizing incremental differences, try it!
Now, when I say extend the tubing a blond beard hair past the holding fixture you will know exactly how much that is. This will give you very consistent flares.
I have been using the Van's supplied tubing for years and years with no problems.

WenEng · #9 10-31-2011, 08:59 AM

If I rely on MS33584 for Jim's 3/8 tubing example I would look for an absolute max diameter of .484 with an allowable undersize flare diameter of .474. SAE J533 shows .46 to .49 as acceptable diameters. Does it really not matter which standard I apply?

az_gila · #10 10-31-2011, 11:16 AM

Quote:

Originally Posted by WenEng

If I rely on MS33584 for Jim's 3/8 tubing example I would look for an absolute max diameter of .484 with an allowable undersize flare diameter of .474. SAE J533 shows .46 to .49 as acceptable diameters. Does it really not matter which standard I apply?

For the lower end number, the "J" spec specifically allows a "slight flat" on the outer edge. This is not shown in the MS spec. and could easily allow for the 0.014 difference...