Here's a question from the Volume 2 - Issue #4 issue of RodMaker magazine:
"I have a question that I was hoping you could help me with. I
build all of my own cork grips out of individual rings. Although I have
used a "Cork Clamp" like the one Flex Coat sells in the past, my current
method involves the use of a threaded rod and wing nuts. I glue up the
rings on the rod, then use washers and wing nuts to clamp the rings
together. This method seems to work pretty well, except I cannot seem
to get rid of the glue lines! They are extremely thin mind you, but they
are still there. To be honest, they don't show up until I get into
400, 600 and higher grit sand paper. I am currently using Flex Coat
slow cure epoxy, or Devon slow cure expoxy. I apply a VERY thin layer
to each cork ring, and them apply a good deal of pressure via the wing
nuts. Am I using too much epoxy? Is the fine grit paper polishing the
glue lines so they are visible? Am I not using enough pressure?
I have spoken with several other builders, and they don't seem to have
a problem. One very well known fly rod designer told me that he uses
waterproof glue and the lines disappear. The only problem I see with
polyurethane wood glue is that it needs air or moisture to cure. I am not
sure about its strength either.
The frustrating thing is when I look at commercially produced rods there
aren't any glue lines at all! Are they doing something special to the
cork after it is made into a grip? Possibly bleaching it?
I am hoping that you have some suggestions on how I can eliminate
this problem!" ~ Andy . . . San Antonio, TX
Your clamping procedure is fine, the adhesives are fine, and I doubt you
could actually use too much epoxy since any extra would be squeezed out
of the joints when the grip is compressed in the clamp. In fact, I think
you answered your own question when discussing your sanding routine. If
you're going much higher than 400 grit paper, you may well be polishing that
very fine glue line between the rings.
Without seeing one of your grips, it's hard for me to decide how much
of a problem you are actually having. I suggest not worrying too much
about using too much epoxy, and instead make sure you completely cover
the mating surfaces with an adequate amount. The cork is quite porous and
will absorb quite a bit of epoxy with any excess squeezed out as you
tighten the clamp. I'd tighten the clamp until the grip is about 1/8 inch
less than the length of the grip would be if we counted the normal ring
lengths. In other words, if you've got fourteen 1/2 cork rings, you'd be
looking at a 7 inch grip, so I'd tighten the clamp until the grip is
6 & 7/8 inches (it will spring back to 7 inches after you remove it).
Assuming the rings are squarely punched, this amount of tension should
be sufficient to contact all mating surfaces and push out any unnecessary
adhesive. The resulting thin glue line will be quite strong.
A smooth surface finish requires sanding through many grades of
progressively finer paper. I like to use Garnet paper and do my
rough shaping with 40 and 80 grits, then finish shaping with
110 and 150 grits. From there I begin finishing the surface with
220 and 320 grits and finish up with a quick going over with
400 grit silicon carbide paper. The resulting grip is super smooth
and shows very little in the way of any glue lines.
The Urethane glues are extremely strong and durable, although the
brands I have tried were just a tad "rubbery" and did not cut at the
same rate as the cork. While the glue lines were minimal, I could
easily feel them with my hands and don't think they would be very
comfortable to fish with. Perhaps some brands do not exhibit this
tendency.
I do want to point out, that since you are not painting or top coating
the finished grip with any type of opaque covering, a keen eye and
close inspection may well discern the presence of the glued joint.
This is normal and should not be viewed as a flaw resulting from
improper technique. As far as the commercially made rod grips, I
hope you are not referring to catalog photographs, which in some
cases, are retouched and depict a fair bit better grip than what is
found on the actual rod. ~ Tom Kirkman
Publishers note:
If you have any tips or techniques, send them
along! Help out your fellow rodmakers!
~ Publisher, FAOL
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