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nervis1
02-12-2004, 08:05 PM
I'm going to cut a street sign for my dad and One cnc is giving me 3-6 ipm feedrates for wood with a 2 flute HSS end mill at 6k-7.5k spindle speed. I'm tempted to quadruple that but what do you guys think?

TAB
02-12-2004, 11:40 PM
nervis1,

Need to know what the tool geometry and depth of cut are. Additionally the type of wood would be useful as the speeds for pine or balsa would be different than that for oak, iron wood, puprle heart, etc.

nervis1
02-13-2004, 08:26 AM
Pine, this is going to be a street sign, numbers and such. DOC is 0.25, speed from nothing to 7500, in wood faster is better eh? I see those routers go 20-30k.

This piece is just simple pocketing and contours.

ballendo
02-13-2004, 09:57 AM
Hello,

Wood is just another material, like steel or aluminum...

And NO, faster is not better. You can pound the material--or your cutter-- to death with wood just like the aforementioned metals!

In ANY cutting operation you want CHIPS; not dust. They cool the cutting operation, and assure you that you're not beating things to death...

This matter if you're putting a finish on the wood especially, as the pounded to death parts will have closed pores--if open pored wood, and burnishing. Which will make for an uneven finish...

More router bits are ruined by heat than anything else.

Going too fast for your cutter will tend to tear the wood, rather than cut--chips too thick. This isn't usually a problem with the high speed router spindles, but with your slower mill it may be.

So, on to answers: More flutes increase the effective cutting speed of your spindle. Since your spindle is slow, you may want to use more flutes than you would with a "regular" router.

Next, since the typical router--hand held-- turns 20K rpm, and a typical pull-rate is about 60-80 inches per minute; work backwards from that... Your spindle is 1/4 the speed(at7500), so use 1/4 the feed, means 15 to 20 IPM. (For this setup you'd use "typical"cutters, and NOT "adjust" flutes...)

Hope this helps,

Ballendo


Originally posted by nervis1
Pine, this is going to be a street sign, numbers and such. DOC is 0.25, speed from nothing to 7500, in wood faster is better eh? I see those routers go 20-30k.

This piece is just simple pocketing and contours.