Have a challenging feature that is giving me fits at the moment.
I use a machinist calculator application on my phone for all drilling applications, and it is normally spot on. You plug in drill size, max rpm, material (w/ hardness), and drill size/material and it spits out the feed and speed.
This particular feature is a .070" hole to depth .425"
Calculator spits out 3077 RPM with a 2.039 IPM F/R at .006 IPR.
I've broken two drills now, both HSS, and it seems like I am hitting hard spots in the material. I've seen this before in stainless, but I'm confused because I drilled 4x .0625" holes within an inch of these and it seems like a localized hardness would've likely affected them as well. All drill bits are black oxide coated HSS and new so dullness shouldn't be the issue.
I also center drilled first, which although likely not necessary with this small of drill I prefer to do it in case the bit is "flailing" a little before it makes contact.
Any suggestions?
I use a machinist calculator application on my phone for all drilling applications, and it is normally spot on. You plug in drill size, max rpm, material (w/ hardness), and drill size/material and it spits out the feed and speed.
This particular feature is a .070" hole to depth .425"
Calculator spits out 3077 RPM with a 2.039 IPM F/R at .006 IPR.
I've broken two drills now, both HSS, and it seems like I am hitting hard spots in the material. I've seen this before in stainless, but I'm confused because I drilled 4x .0625" holes within an inch of these and it seems like a localized hardness would've likely affected them as well. All drill bits are black oxide coated HSS and new so dullness shouldn't be the issue.
I also center drilled first, which although likely not necessary with this small of drill I prefer to do it in case the bit is "flailing" a little before it makes contact.
Any suggestions?