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interrupted cut hole drilling

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memphisjed

Titanium
Joined
Jan 21, 2019
Location
Memphis
I might have a job coming with lots of holes (.1" diameter). The center of the hole is 1/32" from the edge of material. Will a stub length carbide drill chip itself up a lot and/or stay relatively straight? Hole depth is 3/8, material is cr steel or si bronze (client is still brain working with their client). Drill is fairly rigid (bpc).

I can slot the material with a ball end mill, but no. 10000 holes total.
 
memphisjed said:
Will a stub length carbide drill chip itself up a lot and/or stay relatively straight?

I can slot the material with a ball end mill, but no. 10000 holes total.
Click to expand...

Solid carbide drills don't like drilling 1/2 holes. The corner will break down quickly.

Can you machine the part to leave stock on that face, drill it and then cut that face? We do this regularly.

If not, then I would helix ramp the hole to size with an end mill. This will only take a few seconds more than spot drilling-drilling will take... but 10000 holes a few seconds adds up. Hopefully the part was quoted with some headroom.
 
Can you leave stock on that edge, drill the hole, then mill the edge off?

That drill will likely break. Surely won't be straight.

As booze said above, you could drill it smaller while still completely in the material, and then plunge an endmill into it.

If it isn't clear: If the hole is .100 and the hole is .031 from the edge, you could get a drill about .080 in diameter and drill through solid material (the center of the .080 hole will NOT be at the center of the .100 hole) and then get a 2.5mm endmill to plunge where you need it to be.
 
The only problem with milling that edge after the hole is a possibly hellacious burr on the side edge of the hole.
 
Mtndew said:
You type too slow :D
Click to expand...

unlike some forum softwares, this one doesn't tell me that there was a reply to the OP while i was typing. Hit submit, and bam, someone already beat me to it.


Booze Daily said:
The only problem with milling that edge after the hole is a possibly hellacious burr on the side edge of the hole.
Click to expand...

I was thinking that maybe you could re-run the drill through the partial hole. Or a second "beater drill" to take the abuse. HSS probably, if the original was carbide.
 
I would try to use either a Mitsubishi MFE drill or Nachi Aqua EX Flat. I use the Mitsubishi MFE drills a bit and they are great for drilling into angled surfaces or interrupted cuts. I have looked into the Nachi drills myself as well and they look just as good, but I have better Mitsubishi support in my area so I stuck with them.
 
Thank you one and all.
The naichi bit looks to be worth a test. If not then going to have the two step holes drill then mill. Not concerned about bur- tiny hole, tiny bur, and I have lots of experience with draw filing and tiny sanding.
 
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