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

On to Day 10