Carbide drill for 316 stainless - recommendations needed

[Thad]

Just now, gcode said:

yank should be able to help you with that 

I'll just punch the burr right in the face.

[Thad]

Would the part flexing during drilling cause a larger burr? There is no support underneath the part. The part is quite rigid (has a strengthening bead) but it does flex a bit under pressure.

[crazy^millman]

10 minutes ago, Thad said:

Does anyone have any advice on controlling the burr? The exit burr is quite heavy.

Edited to say that I'm running at 100 SFM and .002 per tooth. (1486 RPM and 3 IPM).

Mill it. Drill by it's very nature on thin stainless will push a bad burr. If you are worried about a Right hand tool sucking up the metal then use a left hand spiral tool that will push it down. Harvey Makes a decent selection of them. 

Down Cut 3 Flute Slow Spiral

1 minute ago, Thad said:

Would the part flexing during drilling cause a larger burr? There is no support underneath the part. The part is quite rigid (has a strengthening bead) but it does flex a bit under pressure.

Yes pulling through too quick and pulling the burr and not cutting the material. We have used 2 x 4 behind sheet metal when push came to shove and had to drill stuff in the field 25 years ago. 

[Thad]

We're adding the white hole and we're making due with the check fixture as our holding fixture (clamps not shown).

 

From the front. See the gap below?

 

That's 6" from the top of the green plate to the surface where the new hole is going.

Need quick turnaroud, no real time to order more tooling, etc. We'll have someone run a chamfer on then on the drill press if we have to. We just need to get them done and out the door.

[crazy^millman]

Stick a thin piece of sheet metal in there to give some stability. Just make sure not near the drill so it can't grab it and throw it like a razor. 

[Tim Johnson]

2 hours ago, Thad said:

Does anyone have any advice on controlling the burr? The exit burr is quite heavy.

Edited to say that I'm running at 100 SFM and .002 per tooth. (1486 RPM and 3 IPM).

That's why we use a flat bottom drill but you need material against the bottom of the part and under the hole to lessen the burr no matter what kind of drill you use.

 

2 hours ago, crazy^millman said:

Mill it. Drill by it's very nature on thin stainless will push a bad burr. If you are worried about a Right hand tool sucking up the metal then use a left hand spiral tool that will push it down. Harvey Makes a decent selection of them. 

Down Cut 3 Flute Slow Spiral

Yes pulling through too quick and pulling the burr and not cutting the material. We have used 2 x 4 behind sheet metal when push came to shove and had to drill stuff in the field 25 years ago. 

I agree with the crazy millman. Helical circle mill the hole with a 5/32" or a 3/16" coated end mill.

[Guest]

16 hours ago, Thad said:

We're adding the white hole and we're making due with the check fixture as our holding fixture (clamps not shown).

 

From the front. See the gap below?

 

That's 6" from the top of the green plate to the surface where the new hole is going.

Need quick turnaroud, no real time to order more tooling, etc. We'll have someone run a chamfer on then on the drill press if we have to. We just need to get them done and out the door.

You could drill 90% of the way down, then break through the floor with a smaller drill and clean up the remainder with a smaller endmill, it, extra tool changes, but might save you on the deburring.

Helixing down seems like it would be tough on the tools

[Tim Johnson]

2 hours ago, byte said:

You could drill 90% of the way down, then break through the floor with a smaller drill and clean up the remainder with a smaller endmill, it, extra tool changes, but might save you on the deburring.

Helixing down seems like it would be tough on the tools

I helical bore and helical circle mill in 316 quite often. The helical circle mill would helical bore thru the hole at a smaller diameter then give a finish circle pass to remove the burr.

[Guest]

1 minute ago, Tim Johnson said:

I helical bore and helical circle mill in 316 quite often. The helical circle mill would helical bore thru the hole at a smaller diameter then give a finish circle pass to remove the burr.

 

2 hours ago, byte said:

Helixing down seems like it would be tough on the tools

 

[Thad]

17 minutes ago, Tim Johnson said:

The helical circle mill would helical bore thru the hole at a smaller diameter then give a finish circle pass to remove the burr.

I'm doing that with an 1/8 coated OSG end mill and it's almost burr free. 

You guys RAWK! 

[jeff]

19 hours ago, Thad said:

Does anyone have any advice on controlling the burr? The exit burr is quite heavy.

Edited to say that I'm running at 100 SFM and .002 per tooth. (1486 RPM and 3 IPM).

Backside deburr tool? Drill a little smaller and endmill the hole to size?

Not much you're going to be able to do if you're just drilling.

[Tim Johnson]

1 hour ago, byte said:

Helixing down seems like it would be tough on the tools

 

Yeah, I was also told drilling 316 with a flat bottom drill was a bad idea for the same reason.

[Thad]

They thought it would take 20 hours. Just finished up 550 parts in 10.5 hours.    

Thanks again for all of your input.