new symmetry model has been developed
Material: ebonite, special plastics etc.
design not suitable for urushi coating (a different model will be created adequate for urushi coating in the future)
below photo shows a sample of this model (unpolished state, a further polishing process will be applied)
comparison to prior symmetry model
overall thickness and length reduced
(cap size reduced, below photo shows a modified version of symmetry cap, original is 10mm longer)
barrel length and thickness reduced, thanks to improved thread machining precision
grip thickness slightly reduced, while thread section much reduced.
also the design @ intersection between thread endpoint and grip endpoint changed,
this design change much increased overall strength of the intersection point
bock nib housing can be threaded in now, instead of previous press fit design.
a small internal thread is perfectly machined deep inside the grip section, which was quite a challenge.
previous versions suffered from:
1. precision problems
2. rough overall finishing
3. rough thread finishing
newer versions solved all these problems, although additional surface treatment process will be required for urushi versions.
both external and internal threads are perfectly machined.