Friday, October 25, 2013

Two Cross

Two cross frames just about ready for some clear coat.

BB wrap initial layers span the joint from DT to rear end.
 TT triple cable guide made from carbon wrapped titanium tube sections.  These are for solid casing from lever to derailleur/brake.
 Initial layers of HT wrapping.
 Finished HT wrapping prior to vacuum bagging and baking.
 Front of finished wrapped HT.
 Both cross frames sanded and ready for clear coat.

Tuesday, October 01, 2013

Cross Frame Ready for Paint

I've got the latest carbon frame 99% ready for clear coat etc.  Just need to slot the seat tube at the top and it's ready to go.

 The layers of carbon show through and even more with gloss clear applied.
The custom extended seat stay plugs to fit the ENVE rear end turned out nicely.
The frame is built for continuous casing.  This is one of the guides bonded on.  It's carbon wrapped around small a titanium tube.  They are bonded on but don't take any brake or shifting force.
Excellent clearance for 33C cross tires.  I could probably get some monster 42C tires in back and front.
Three triple top tube guides.  Again, carbon wrapped titanium bonded on.
Stay tuned for cross frame number two up next...

Sunday, September 08, 2013

Glued and Filleted

I picked up the dropout parts from anodizing and fit the seat stay assembly in the jig.  That was the last step before gluing the tubes together.  Below is the bonded seat tube joint.
Here is the head tube joint.  Prior to applying the joint fillets I rough sand the carbon (just a bit) and clean the whole frame with isopropyl alcohol.
This is a BB fillet in the un-sanded state. Once it cures I'll file and sand it to shape. The glass micro spheres in the epoxy make for easy shaping.
Weight of glued frame.  It should come in around 1050g all finished with paint. The ENVE cross rear end isn't all that light.
Lots of tire clearance here.  That's a 25mm shown.  Should be able to use a 35mm.

Monday, August 19, 2013

Cross Frame

I started building the first carbon cross frame.  It uses custom ENVE tubing, ENVE seat and chain stays (for cantilever brakes).

Here are the main triangle tubes mitered in the jig.  I carefully mark them before cutting to avoid any screw ups.

The ends of the ENVE seat stays come molded to bolt directly to dropouts.  I noticed the spacing was a little off for the Crumpton dropouts I'm using.  I set them up in the mill and carefully ground them down to fit.

Once I had them completed I fit them on the dropouts and checked the cantilever post location.  It was out by almost 1/2"!  This seat stay molding was obviously for a dropout with more offset from the axle.  ENVE did not supply a drawing when requested so I was hoping for the best.  Turns out I had some cutting and machining to do.

I cut the molded end with threaded insert off the stay and tried the Crumpton seat stay plug.  Still over 1/2" short given the amount I had to remove to eliminate the molded end.
My only real option was to machine a new set of stay end plugs with the correct offset.
In the end they turned out better than I'd hoped.  Now they just need anodizing.

Wednesday, June 26, 2013

Finished Frame

This is the finished frame.  It has a gloss over matte clear coat finish and weighs 890g.  Neil is pleased.

Monday, June 10, 2013

Ready For Paint

After some trial end error with the cable guide molding process I was able to complete the frame, attach the guides, fabricate and bond in the brake bridge etc.

Here I'm aligning the rear brake to mark the mounting hole location.  I make sure the pads are nicely centered in the slots.
Here is the brake from behind, again, nicely centered.
Here are the final cable bosses bonded on the down tube.  They slipped a little during bonding with one sitting slightly ahead of the other.  If I bother making carbon guides again I'll make a bonding fixture for clamping them on in a fixed position.
Here is the seat cluster sanded and ready for clear coat.
And the number Neil has been waiting for...the total final weight prior to clear coat.  Given the weight of the clear on Chuck's frame this one should come in under 900g.
Time to get some paint mask cut...

Friday, May 24, 2013

Carbon Cable Guides

I started working on some carbon cable guides for the latest frame.  After a few tests of two quick molds I manged to get an acceptable guide blank for testing.  Here is the progression from mold one, under compacted to mold 2 fully compacted and cured solid carbon composite.  These were made out of woven pre-preg and baked in the oven.
I ground, milled and sanded one into shape and test bonded it to a frame tube with DP-420.  I'll do some load testing to failure before applying them to the frame.
Another view.
The joint epoxy coating and sanding is almost complete as well.

Monday, April 29, 2013

Front Repair

Had a small setback with this frame due to a mislabeled tube and neglecting to measure said tube.  The head tube was not 44mm ID.  I noticed just prior to bagging for the oven, removed the pre-preg and baked the rest of the frame.

After grinding and prying off the wrong head tube I carefully replaced it after cleaning up the joint.  Everything was aligned in the jig to the same location.

Here is the new head tube installed and re filleted.
Below is the complete first layer of joint wrapping.
Here it is later on when I apply a woven layer.
And here is the final finished wrapped joint.
I have the wrapping with release cloth process down to only a few pieces now.
I only vacuum bagged the front portion of the frame this time since the other joints were already cured.  I'm leaving more slack in the bag now to allow for it to pull cleanly into the joint.
In the oven, under vacuum and ready to cure.