"Rick Morel" wrote in message
...
Skip, I really hate to throw in a very negative note, but...
I've used that Devcon commercial stuff quite a lot. You really don't
realize just how difficult that stuff is to sand. Imagine you welded
around to build up the shaft and then take that metal down with
sandpaper. That's pretty much how the Devcon is. When they say can be
"machined", they do mean machined with a lathe, milling machine,
drill, etc.
One thought. Take that 2" drop off and verify it'll fit over the shaft
snugly, even, in fact preferably if it has to be heated a bit. Camfer
one end. Apply the Devcon to the shaft, letting it build up a bit.
Coat the inside of the drop off with some kind of mold release. Heat
it up and slide / hammer it over the area and fasten in place. Remove
all the Devcon squeezed out. After it's cured, hammer and cuss to get
the drop off "mold" off.
Rick
Hi, Rick, and group,
I just got off a long phone call with Devcon, before seeing this.
This stuff (Devcon PN 62345, AKA Versachem 47709 for automotive and the
like) hardens from the outside in, and as a result I'd identified the
problems you cite.
While I like the idea of the slicer, and it basically is what the SKF folks
have one do if the surface being repaired is like mine, except that the
epoxy not only fills underneath, but (also) secures the sleeve, which acts
like your slicer on the way to its resting place.
It's the securing part which has most of my attention in your suggestion
(getting it off might require another cutting episode, like my driveshaft!),
but also that I'd need something about 30" long to go over the repair area
as well as have something to beat on to get it to that point.
Once on, particularly if I had to heat it to get it off, I'd be afraid of
compromising the epoxy if I had to notably heat it to expand enough to make
a difference (though aluminum should expand markedly faster than SS, I'd
think). Hammering to try to get it to go UP - against a chamfered end -
would be pretty interesting, too :{/) If I could manage a small enough
portion - looking at my pix, with the ruler showing approximate actual area
involved - perhaps by peening I could get the aluminum expanding
sufficiently to slide off, but I'd sure hate to have that sort of abuse wind
up causing shattering of all that work I'd just done. (I'm trying to not
only fill the pits, but end up replacing that 2-8 thousandths of an inch of
missing material, recall. I suspect that whacking on it might cause some
flaking of that very thin stuff - and I'd be left with sharp 1-4 thousandth
inch [half the 2-8 missing now] edges of the stuff remaining...)
In working with West System, and the AdTech fairing compound I used on the
hull, I've very successfully sanded it "green" - that is, partly but not
fully cured - no tack, but able to make an impression with a tool. Does this
stuff act the same way? My contact at Devcon made it sound like I couldn't
touch it until the outside was hard, but then, it would already be as hard
as it would get, just not all the way to the bottom.
Of course, I'd expect to take it down in stages, like I did the polishing on
the anchor roller system repair I did, but I was using power tools, and
dimensions weren't critical as I'm trying to make them here, and that was a
great deal of work. So, I'm stuck with hand tools, and, as you've
identified, don't want to be faced with taking down hundredths of an inch of
steel equivalent.
Thanks for the heads-up. I'll try some test spots on some of the
scaffolding around the boat and see how they respond to my attempts and
timing.
Other comments and ideas solicited :{))
L8R
Skip
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