Thursday, September 09, 2010

Glue it up!

My 6061 Alu tubing arrived this week.  I cut off a piece and turned it down in the lathe to fit the inside of hte steering tube.  It's hard to read the scale in this picture, but it reads 5 grams, so the pre-joining weight of this frame comes out to 995 grams.

It's also hard to see that I turned this offset, so the wall that will be tapped is thicker than the one opposite.

Here you can see the reinforcement through the mounting hole for the front derailer hanger, and a shot mid-way through tapping the hole.

I'm pleased with how this detail is working out.

Next is putting everything together in the jig and checking alignments one more time, then cleaning and gluing the joints.  You can see the high-tech methods used to hold the top-tube in position during the curing of the glue.  The bike will cure in the jig at least 24 hours before moving on to other steps.  In this case, it will probably sit until Sunday.

Then came a detour to service a few bikes that have been waiting.  Mostly just cleaning, and changing an inner-tube.

The later is interesting.  I did a 45 mile ride Sunday, most of which was off-road.  So I took my rough-rider with the Cross tires.  UCI legal, BTW, with a 32mm width.  Getting home from the day-job on Monday, it's clear that the front tire is flat.  After pulling the tire tonight, and inspecting the inside, there is no evidence of a hole.  Looking at the tube reveals a different story with a 1.5" long split in a seam.  I'm guessing it let go with a bang when no one was around to pay any attention.

It's import to work to a sequence and schedule when building frames.  By this I mean that there is no room for impatience - which could lead to shortcuts (never work), or expecting materials to be ready before they are. 

Besides the service work above, there's another important task prior working further on this frame: I need a place to vacuum bag!  If you've been paying attention, my shop is very small, and very full.  To wrap the joints requires space to mix epoxy and wet out the carbon fiber, as well as a big flat space for the bag itself.  Fortunately, there's a table in the shop dedicated to this function.  But when not wrapping and vacuuming, it gets re-purposed.  Consequently, the last task for the evening was cleaning up this space.

Tasks still remaining include building and shaping the fillets around the joints, and laying down a special reinforcing layer of knit CF that will be applied and cured  before doing the main laminating of the joints.

More soon.

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