Author Topic: Making a Brass Compression Fitting "Whipping"  (Read 232 times)

DDK

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Making a Brass Compression Fitting "Whipping"
« on: February 11, 2021, 09:54:35 PM »
I was curious to see if a swaged metal collar could be used instead of a whipping. 

Compression Fitting:  Brass, Union - used to connect 3/8" O.D. copper piping (see attached)
Rope: Maxim Glider 9.9 mm nylon (polyamide) core and cover.  Categorized as dynamic.

The fitting was a little undersized as it took some effort to get the nut and ferrule ring onto the rope.  First, I pulled back (but did not cut) some of the sheathing and stagger-cut some of the core strands.  I pulled the sheathing back over the core and traditionally whipped the end which bound the sheathing and some of the longer core strands.  This produced a nicely tapered end which made the initial threading of the nut and ferrule easy.   I may try 7/16" and 1/2" fittings on this same rope.

Another complication is that the interior of the union fitting I used had pipe stops (smaller diameter) in the middle of the fitting which prevented pulling the rope all the way through the fitting.  Because of these pipe stops, after the placement of the nut and ferrule onto the rope I whipped the rope right next to the ferrule and trimmed the remaining rope to a short stub which I pushed into the fitting body.  A future solution to this might be the drilling out of the fitting so that it is the same diameter all the way through which will allow pulling the rope all the way through the fitting.  This modified fitting body could likely be reused many times.

The nut was tightened onto the compression fitting body swaging the ferrule onto the rope.  The body was then loosened and removed and the nut was cut using a Dremel rotary tool and removed.  Once two sides of the nut are cut, the mostly cut nut can be easily pried and broken in half with screwdrivers.  I am considering trying a nut which is precut in halves.

The ferrule appears to be very secure on the rope.  Trying to move it by hand produced no movement that I could see.  The nice taper and smoothness of the ferrule is tidy, doesn't snag and nice to work with when untying knots.

In addition to some of the other modifications I mentioned, I would like to smooth the edges of the ferrule by sanding them before use as they come with fairly sharp edges.  I think the uniform swaging of the compression fitting is likely superior to the use of, for example, hexagonal ferrule crimping tools although the use of a crimping tool likely requires no development or modifications.

SS369

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Re: Making a Brass Compression Fitting "Whipping"
« Reply #1 on: February 12, 2021, 12:47:57 AM »
Hi DDK.

Seems like a lot of work/cost for a whipping.
Why?
There are numerous ways to terminate the ends of ropes.
One could use heat shrink tubing, liquid whipping such as Plastidip, and of course melting the ends works too.
One could even use thin wall copper pipe suitably crushed.
Personally, I would not want a metal end, but that?s my preference.
I guess this is a proof of concept endeavor, correct?

SS

PatDucey

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Re: Making a Brass Compression Fitting "Whipping"
« Reply #2 on: February 12, 2021, 03:50:34 AM »
Hello DDK, If the ferrule fits, yes, this is method that you can get a nicely finished crimp.  Some crimping tools can give the right squeeze, but leave a mark at the seam.  You can definitely drill out the pipe stop, but don't drill out the ID of the part of the union that the ferrule is forced against.
You can also drill out the nut to help get it on the line, but then you loose some of the seat that pushes the ferrule and gives you a nice finish.  If you drilled out the nut large enough to pass over the ferrule, but with enough edge to still hold a washer, maybe a washer could be used as the sacrificial piece.  You pass the line through the Nut, Washer, Ferrule, and then through the coupling.  Make up the fitting to get the desired crimp and when you take it apart, cut the washer with tin snips, and slide the nut off over the ferrule.

Pat

DDK

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Re: Making a Brass Compression Fitting "Whipping"
« Reply #3 on: February 12, 2021, 05:29:21 AM »
Hi  SS.

Yes, this exercise was mainly a proof of concept.  There have been occasions when my traditional whippings and melted ends have not been as robust as I would have liked.  Traditional whippings have loosened as I gripped them for tightening a knot or as I pulled them through a tight knot as I was untying.  The melted ends on the rope in this OP failed by the fused sheathing pulling away from the fused core when tying a stopper knot.  Melted ends, if not formed carefully, can be jagged and tear at the rest of the rope.  I am curious how swaged whippings will perform compared to my other types of whippings.  I'll let you know.

With regard to costs, an assortment of ferrules can be had for $0.15 apiece. The compression bodies and nuts do represent an initial investment at a couple dollars per size.  I can see how metal ends could be a concern even though the ferrules are thin so as to not add much weight to the end of the rope.

DDK
« Last Edit: February 12, 2021, 05:46:53 AM by DDK »

DDK

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Re: Making a Brass Compression Fitting "Whipping"
« Reply #4 on: February 12, 2021, 05:45:50 AM »
Hi Pat.

I also think that a properly fitting ferrule really is key and would eliminate much of the additional steps mentioned in the OP.  I think if the ferrule fits, so will the nut which would eliminate it needing to be drilled out.

I do like the smoothness and lack of seams produced by the compression fitting.  Interesting thought regarding the use of sacrificial elements to save the nut.

DDK

PatDucey

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Re: Making a Brass Compression Fitting "Whipping"
« Reply #5 on: February 17, 2021, 03:20:13 AM »
I think that you have found a ferrule to match the size of your 9mm line.  I don't know that I have any of that line here, but I do have a lot of other line that sometimes ends up on work that has exposed ends.  I have a few old crimp fittings in my junk drawer, I wonder if one of those will work on 550 Paracord.  This might be a project for when I have some spare time.  I'm thinking of putting a crimp on 550 Paracord, cut it short, and then melt the cut end so it forms a lump with the crimp controlling how much material melts.