Copyright WWW.DBBP.COM | updated 3-December-2023


Project started October 2023,
Before cutting the frame we arre building a jig, using the welding table as part of it. The part we are working on now is to hold the steering neck in the correct position, inline with the centerline of the frame.

 
 
 
The idea is to do all the welding first and then clamp the whole assembly on the Bridgeport for final machining to make sure everything is perfectly straight. The slotted plate at the bottom was machined flat in the big lathe so the square tube (80 mm with 6 mm walls) will be perfectly perpendicular to the table. We had welded the neck pivot tabs 2 mm closer together than the final dimension. After mounting the whole assembly and "clocking" it within 0.01 mm straight in all directions on the milling machine, we machined the pivot slot to the final dimension.

 
 
 
 
The first new part of the frame was to be the neck, which we machined on the huge URSUS lathe. We started with a solid bar and drilled a 31 mm hole first. Then using simple G-code Aad machined the concave outside surface. The bearing pockets will be machined after welding to make sure there is no heat deformation there. Notice the huge machine and relatively tiny cutting tool. This ensures a very smooth surface. (no vibrations)

 
 
 

Next week we will fix the motormounts, transmission mounts and swingarm mounts to the jig and start cutting!

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