Alan_c
Thu 05 March 2009, 14:40
Another interesting project - machining manifold spacers for aftermarket fittment of side draught carbs. Material: Tufnol - electrical grade 8mm thick and 1.6mm cork gasket.
Procedure: screw tufnol sheet to table with two layers of cork gasket material clamped underneath the tufnol, machine the holes, insert screws with washers in the bolt holes securing the job to the table, machine the outside. All cuts three passes, two in the tufnol and one for the two layers of cork.
Feed speed: 1200mm/min
Plunge: 600mm/min
RPM: 18000.
Cutter: Solid tungsten two flute slot drill
3911
spacer with two gaskets (cut at the same time)
3912
No discernable chatter!
Lessons learned: slot drills cut tufnol better than compression spiral router cutters (regarding finish), slot drills need a MUCH slower feed speed than compression spiral cutters, Missed steps from having the feed speed too fast can NEVER be missed - loud bangs and much clattering :eek:. Slower feed speed results in almost no chatter (if it is there, its very difficult to see or feel)
Procedure: screw tufnol sheet to table with two layers of cork gasket material clamped underneath the tufnol, machine the holes, insert screws with washers in the bolt holes securing the job to the table, machine the outside. All cuts three passes, two in the tufnol and one for the two layers of cork.
Feed speed: 1200mm/min
Plunge: 600mm/min
RPM: 18000.
Cutter: Solid tungsten two flute slot drill
3911
spacer with two gaskets (cut at the same time)
3912
No discernable chatter!
Lessons learned: slot drills cut tufnol better than compression spiral router cutters (regarding finish), slot drills need a MUCH slower feed speed than compression spiral cutters, Missed steps from having the feed speed too fast can NEVER be missed - loud bangs and much clattering :eek:. Slower feed speed results in almost no chatter (if it is there, its very difficult to see or feel)