indeed... i speak from experience :)
Since the advent of CNC there is a lot more fag smoking, tea drinking and arse scratching time available and you probably aren't encumbered by leather gloves set in a permanent clench. You can even smoke real fags instead of rollies because you aren't depending on it going out when you suddenly get busy with monotonous regularity.
We aren't newbies, we all know the problems with aluminium are it's bad habit of clagging the cutting edge and extruding when you want it to cut.
When faced with a tiny tool we also start to get nagging doubts about being able to transfer enough power to the tip. Watts = radians/second * Nm and the more Watts the more it is going to bend and once it starts to bend significantly, the more the chance of overloading it with a dig in.
I haven't found sub 3mm tooling in high helix with a rebate on the flutes and the carbide tinies tend to be coated with other than aluminium nitride so that helps not a lot.
Add to that the impossibility of getting anywhere near the correct cutting speed. If you could do 50k rpm the enormous feed rates required to maintain a cut above collet/tool eccentricity means you know that ain't going to work.
Even so, I wouldn't step drill it. Presumably you've turned a blank for the pulley and removed any surface hardening from the extrusion, if it isn't cast, and there is no oxide layer to wear an inconvenient slot in the flutes. Personally I'd go for around 2000 rpm, feed it at 1 -> 1.5 mm/s on a 3 flute, start with .25mm DOC, increasing if it seems good to go.
Standing over it with a blow gun, a pot of Rocol RTD and a brush could be an exceptionally good idea even if this temporarily suspends tea, fags and scratching
16-01-2011 #14leather gloves set in a permanent clench
they where cold and uggly first thing on a winters a morning and you had to curl your fingers to get them in but it was allways heart breaking when you had to trade them in for a new pair :)
everyone seems to be using latex now, not the same (i must be getting old)
42T pulley with 0.25mm DOC and 1.5mm/s will take 170 mins. Maybe a little less if I get rid of some rapids in Gcode, but not much.
Chip thinning may enable me to run the cutter a bit faster for the same chipload a significant amount of the time. I can quite easily add that to my program.
I'm warming to the make a tailstock (anyone got a spare!) and just use slitting saw idea. I can stop the 63mm slitting saw bending by machining some 50mm steel disks and sandwiching it between those on the arbor.
By Ptee in forum Projects, Jobs & RequestsReplies: 3Last Post: 17-01-2014, 05:07 PM
By HankMcSpank in forum Tool & Tooling TechnologyReplies: 5Last Post: 04-04-2013, 10:52 PM
By davy in forum Items For SaleReplies: 4Last Post: 10-11-2012, 04:55 PM
By johngoodrich in forum Tool & Tooling TechnologyReplies: 1Last Post: 17-09-2011, 12:02 PM
By D-man in forum Projects, Jobs & RequestsReplies: 1Last Post: 05-07-2010, 10:47 AM