Milling holes in Aluminum

[walter]

I need to mill bunch of small holes in cast aluminum. Can I use single edge cutter like Onsrud 63-620 or go with 2/3 flute tools?.

Thanks

[DareBee]

How small is small?
How many is a bunch?
What sort of machine do you have?

[walter]

50 small holes like .25" to .40" on a 3 axis without drilling attachment

Thanks

[psychomill]

You could,... preferably a 2 flute cutter though. Or you could rough drill the holes, then finish it with a mill. Lots of ways. How deep are the holes? If you're on a 3axis mill, why can't you drill it? What machine is this? Why do you need an "attachment"?

[DareBee]

Are these thru or blind?
What sort of tolerance?
What sort of machine are you using that will spin a cutter but not a drill bit?

[ger21]

Originally Posted by DareBee What sort of machine are you using that will spin a cutter but not a drill bit?

Probably some type of router, since Onsrud makes router tooling.

[psychomill]

Yeah, but generally those same routers can also hold a drill as well...... mine do....

Unless its a home built cnc and he doesn't happen to have the "attachments" to accomodate shanks other than 1/4 or 1/8....

[DareBee]

Ahhhhh
You can get drill bits sizing from 1/4 to 1/2 with a 1/4 shank, these will fit in the collet.
If you need the holes machined drill 1/64-1/32 undersize and machine with a 4 flute cutter.
If you need to machine the holes virgin then a 2 flute is probably the best, high grade coated carbide is also the best cutter choice (I prefer TiAln). It is usually best to remove as much material as possible with a drill first if doable.

[walter]

That`s the answer. Drill undersize and then machine with 4 flute tool. Just wanted to avoid drill wandering...

Thanks for all the answers, this forum is a great place!

[ViperTX]

I suspect that you'll end up snapping a bunch of carbide end mills by pre-drilling and then milling. Is this under some CNC control....if so then you could use a spot drill and then follow up with the appropriate drill bit.

To prevent drill bit walking (when not using a spot drill) use a split point drill bit and get the short ones designed for use in a CNC machine.

[walter]

Thanks ViperTX. How fast can you spin these CNC drill bits?

[DareBee]

I guess I assumed this was on a CNC machine and the holes would be interpolated.
Viper - I fail to see any reason why the cutters will be breaking?