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Drilling AR500


Jan 27, 2021
Can anyone offer guidance for drilling 5/8” holes in 3/4” AR500 plate?

We have high pressure TSC available. We use YG Dream Drills for other work but they are not rated for this hardness.

We plan to try a 16mm regular and -INOX version starting on the low end of the recommended range for both speed and feed for stainless. 900 rpm and .005 IPR. We figure the material is tough and makes small chips so it behaves similar. The concern is we won’t push fast enough and will work harden the material.

Any experience on specific tools and/or procedures that work would be welcome. We have not agreed to do this project yet. We figured We would take a risk to see what it takes first.

We read through the archives and will have it quoted by a waterjet shop.


Cast Iron
Mar 18, 2013
Washington st
I've done it plenty on old school manual equipment with hss drills the trick is SLOW speed and rigid feed

No rubbing allowed!

On a vmc I would spiral mill a slightly tapering hole then mill to size.

Ps no coolant it's worse than nothing when milling AR. air blast is my first choice


Feb 8, 2020
Kennametal solid carbide GO Drill (MSC pricing) is pretty comparable in price to YG dream drills believe it or not and will definitely cut AR500. If you're drilling a lot of holes, definitely consider an insert drill for that large of a hole. You can pretty much choose any tool manufacturer for an insert drill as long as their insert grade is made for hardened material. I've had good luck with Seco Perfomax but they are spendy (their website calculator is the bees knees) . The worst thing I've found out about AR plate is that it is either already magnetized or will become magnetic very easily, so recutting chips that stick to the material is a real possibility (this really applies to milling more than drilling).


Hot Rolled
Jun 21, 2019
At is easy enough to drill IF you don't get in a hurry. I use insert drills, many brands and types, no problems with any. But I run slow with lots of coolant to flush chips. Last time I ran an 0.830" drill I fed it at 0.004 per rev. I believe around 250 rpm. Good chips, nice holes and no problems.

Ran on a Cincinnati #2 vertical with ( well aimed) flood oil coolant.


Apr 18, 2006
Austin, TX
I ran a lot of it as well as A514 a few years ago and used Iscar chamdrills with the TSC on with the coolant richened up and air blast. Got great life if I ran the rpm at about half of what they claimed was possible and a steady feed.