This photo is of the prototype during the
earlier phases of construction.
November 11 & 12 2009 1.0hrs - 766.0 total. Had not
received e-mail from West Systems yet with their mailing
address, contact info, etc. so called and talked to tech for
quite a while about their product and possible problems.
Gathered up the used, left over glue cups, stir sticks and
brushes with the associated hardened glue residue and
sent it in to West Systems along with samples of the
fresh epoxy and resin. Also dug out the receipt from two
years ago where they sold me the glue and wrote "West
Systems" on the receipt, even though the cans are from a
third party. Now just need to wait for the results. Am
not doing any more work on the plane till this gets
Click on each thumbnail below to open the full size image. After
viewing, use your browser's "Back" button to return to this page.
Already cleaned out joint
on left, new crack is
developing down long
Have started to chip
away rotten, fractured
|The more I look, the more cracks I find! Some of these happened when
I twisted the joint very slightly or tapped on the frame with the side of
my hand using about 5 to 10 pounds of force.
Split down the
strip. Looks like the
Glue looks like its rotten.
It flakes and fractures
This one I just barely
bumped the piece with
my arm, there was a
loud crack, and this
Again, this one looks
like the plywood
November 23 2009 1.0 - 767.0 total. John from West System called. The glue is definitely theirs.
The samples of cured epoxy that I sent showed correct ratios and no contaminants that might cause
this. They are stumped. I personally think its got to do with the fact that this time of year we have
less than 1% to 2% humidity. I've even heard it called negative humidity because any moisture is
sucked out of things.
November 30 2009 1.5hrs - 768.5 total. Took a shop light and carefully examined all of the
longeron glue joints. Some of them appear to be OK, but the majority are either cracked, or crack
when I tap the frame next to them. At one point I grabbed the fuselage structure and shook and
flexed it in the jig and heard several loud pops as more joints let loose. The upper and lower
longerons seam to be crack free, as well as those areas I didn't steam. It might be that only those
joints that were close to the areas that were steamed have been affected? It doesn't make sense as
West System has said that the steaming after curing won't hurt it? I've posted the pictures above so
that the guys at West can have some more examples of the problem. I hope to hear more from
them again soon.
December 8 2009 3.5hrs - 772.0 total. West System and I finally managed to spend some time
together on the phone. They are fairly certain that the issue is the lack of humidity. Evidently the
shrinkage of the wood, which I've been told by the guys at the wood shop can be significant, is
enough to not only cause the wood itself to crack, but even to over stress the glue joint. They also
pointed out that I'm being way to stingy with my fillets. We discussed a number of subjects including
if its OK to have the structure under stress by gluing straight pieces into curved shapes - rather than
pre-forming the curve, and then gluing it in place. They say that most wooden boats are built with
significant curves glued into the structure without any pre-forming. They said that having a structure
with opposing stresses built in actually makes the structure stiffer. The humidity level in my shop was
at least above 30 to 40% during the autumn, and is now somewhere below 10 - my gauge bottoms
out at 10%. I know that in my office at work its about 2%. We decided that if I had sealed the
wood while the humidity level was higher, it would maintain the moisture in the wood longer - drying
out at a greatly reduced rate, and might have prevented some of the cracking. We discussed the
idea of sealing the wood while it is very dry, but I was opposed to that idea as it is only this dry a few
months a year, whereas, if I add humidity to my shop, I can keep a relatively constant level all the
way through the construction process, sealing the wood as I go. With that in mind, I went out and
bought a high capacity humidifier and a humidity gauge and installed them in the shop. I'm planning
to try to keep it around 25% to 35%. I've started cleaning out the cracked joints to allow them to
be re-glued, this time with much larger fillets. I've ordered a new set of glue, some syringes, some of
the West System stir sticks that have a large fillet curve on one end, and some other stuff. Its good
to be working on my project again!
December 20 2009 4.5hrs - 776.5 total. All the new glue and accessories arrived a couple days
ago. They packed the box with foam pellets which didn't hold up very well against the US Postal
Service parcel post system. The cans of glue were slightly crushed, but fortunately didn't leak. Today
I started closely inspecting every joint and cleaning out the cracked joints. With the humidity level
around 35% for the last couple of weeks, much of the wood has swollen back up in size so that
some of the cracks are almost invisible. Have made it all the way down the port side and am starting
on the starboard.