SF Cyclotouring

Ride reports and other ramblings from a San Francisco cyclist.


UBI Framebuilding Class - Day 9

5/21/2015 - Day 9



  • Final Frame Machining
    • Heat distorts tubes - makes them non-round
      • Back of HT at top and down tubes
      • BB at chainstays
      • Need to ream/rethread with special tools
    • CAUTION: Use lots of cutting fluid
    • Seat Tube Reaming
      • CAUTION: Turn clockwise only!
      • Work over a workbench to protect the cutting tool (in case you drop it)
      • Never lay the tool down on a hard surface
      • Brush off the chips on the cutter blades
      • CAUTION: very sharp teeth/blades!
      • Check for burs, remove with file
      • Test with a known-good seatpost.  If it fits, you don't need to do anything else
      • Don't clamp frame by the seat tube, but clamp on TT as close to the working area as possible
      • The ST reamer is adjustable: measure diameter of reamer, start at 27.0mm
      • Seat tube should be horizontal, which helps prevent the reamer from falling down inside your frame
      • Put a rag or bucket on floor under the work area to catch chips and fluid
      • Put cutting fluid in ST and on reamer blades
      • REMEMBER: turn clockwise only
      • Do this step BEFORE cutting the seat tube slot
    • Head Tube Chasing and Facing (Park Tools)
      • Choose the right size of cutter (1 vs 1-1/8 inch)
      • Do top first
      • Headtube should be vertical
      • Position centering cone at bottom of HT
      • Debur both top and bottom of HT
      • Install the lower cone and bearing, then the spring, then the locking collar
      • Tighten just enough to remove any slop in tool, THEN add two full turns on collar
      • CAUTION: only turn tool clockwise
      • Adjust by 1/2 turns as needed
      • Remove all silver and cut into steel
      • Don't push down on the tool
      • Examine chips for silver vs. steel
      • Turn tool slowly
      • Release tension and keep turning before removing the tool to prevent chatter marks
      • Check for an even cut across top of head tube (at least 75% around)
      • Turn tool with both hands to ensure an even cut
      • NOTE: Debur HT after cutting operation
    • BB Chasing and Facing
      • First drill BB cable guide
        • Tap a 5mm hole, use #19 drill bit
        • Locate guide with derailleur cable strung from shifter boss to rear cable stop
        • Pay extra attention with curved stays to avoid impinging on chainring and/or tire clearance
      • Clean out BB; remove flux and dirt and excess silver
      • CAUTION: Watch for left and right threading
      • CAUTION: Stop if there's any binding
      • Turn both sides of tool in same direction to start (top handles towards rear of bike)
      • Once there's good purchase, you can focus on one side
      • High-pitched squeal means you're cutting into silver
      • Continue until cutter is buried in BB shell, plus 1mm
      • Remember to reverse tool a quarter turn for each cutting revolution
      • Remove non-drive handle
      • Replace with facing handle
      • Control cutting pressure with 6mm allen key
      • Cutter stays in BB shell
      • Switch sides - watch center post
      • Repeat facing operation
      • Replace cutting handle
      • Remove cutting tools slowly
    • Fork crown facing
      • CAREFULLY clamp fork crown in vise with blades facing out away from workbench
      • CAUTION: There are two sizes of 1-inch crowns: NJS (27.0mm)  or ISO (26.4mm)
      • Use Park facing tool
        • Cap on top
        • Collet inside
          • Black for 1 inch
          • Blue for 1-1/8 inch
        • Tighten cap to center collet
        • Put cutting fluid on blades
        • Tighten cap to remove any wobble
        • CAUTION: only turn tool clockwise
        • Feel for a change in cutting action (silver vs. steel)
        • Use even downward pressure with both hands
        • Check for an even cut (at least 75% around)
  • Alignment Table
    • Mount frame onto BB Post
    • Check w/Surface Gauge
      • ST at BB
      • ST at TT
      • HT at DT
      • HT at TT
    • Check w/V-gauge at HT, ST, and rear dropouts


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