Classic Body Drill Speed?

[Toestr]

I'm going to be drilling my classic Body for a sight rail and I'm wondering what the ideal drill speed is? The holes will be 7/64" maximum (6-32 screws). The generic speed charts I've looked at online say 3000 rpm across all materials for that small a hole, but I figured I'd ask those with first hand experience.

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[netsurferdude2]

For Stainless, you want a slower speed.
6-32 tap drill size is a number 36 (.1065")

go about 900-1300 RPM

Edit. Here is a simple chart that you can use without having to calculate the speeds

[BrickHaus]

Small drills get tricky as you noticed the constant surface speed ramps up, but on stainless too fast is still too fast.

are you using a drill press or a hand drill? id personally keep it slow as possible, maybe 7000-900 rpm. Or half trigger max on your hand drill.

[Jordan]

You guys worry about speed? I just use a sharp drill bit and cutting oil.

[LukeAO]

You know these bodies are 304 stainless right? Meaning you will need to use carbide, pretty sure you will just burn up a HS drill bit. There's plenty of 'how to' info online for drilling 304.

[Toestr]

Thanks guys. Yes I'm using a drill press. I've drilled a classic body before with these high speed drill bits, but it was more akin to Jordan's method I figured I'd do it 'properly' this time.

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[scottieb]

With stainless it is best to go slow, apply pressure, and use some goop or oil.

[Alexndl]

This
You want to keep temperature as low as possible for stainless

[LukeAO]

Step 1. Drill bit
When drilling into stainless steel the choice of drill bit will ultimately determine how successful you will
be. Cobalt drill bits are considered the best option due to their ability to withstand the high
temperatures created when drilling harder metals.

Step 2. Speed
Many people have a tendency to drill at as high a speed as possible assuming that the faster the drill bit
is turning the quicker it will drill the hole. This is a big mistake, particularly when drilling stainless
steel. Stainless steel is not the hardest of metals in its natural form, however as pointed out by Chip
Lawson in his piece ‘Know How: Drilling Stainless Steel’, stainless steel will ‘work harden’ fairly quickly
when heated, and one sure way to increase heat is to drill fast. Once the stainless steel is work hardened
it will become very difficult to drill.

There are many drill bit speed charts available quoting revolutions per minute, in reality not too many
people will be able to relate to these figures. Our advice would be to drill at as slow a speed as your
power drill will allow.

Step 3. Pressure
Another misconception is that maximum pressure will result in maximum results. Excessive pressure will
have the same effect as drilling at a high speed, it will cause unwanted heat build up. The best approach
is to start off with a light pressure increasing slowly until you achieve nice spiral cuts coming from the
cutting face. Once achieved do not exceed required pressure.

Step 4. Lubricant
It may seem obvious to some that when two metal surfaces are moving against each other under
pressure that lubrication is necessary. However many will drill metal without any form of lubrication. A
good drilling Lubricant will reduce the friction and assist in controlling temperature build up. There are
many types ofdrilling lubricant available including oils, sprays and pastes. Our advice would be to use
one rather than not using any.

Step 5. Take a break…
Even with a slow speed, reduced pressure and good lubrication heat build up is inevitable when drilling
stainless. It is important therefore to stop drilling from time to time to allow the drill bit to cool down.
We would recommend you do not drill for longer that 30 seconds without taking a break. As All fasteners
say in their article ‘Drilling Stainless Steel the Right Way’ drill the material on short bursts. The larger
the drill bit size the faster the heat build up will be so this time should be reduced for larger drill bit
sizes.

https://ttp-hard-drills.com/drilling-stainless-steel/

[flyweightnate]

Tap magic or some high- sulfur oil is great. I have had good luck going SLLLLLOW and pushing until I see a thick chip. Short chips mean you need more pressure/ more feed, to keep the hardened bit of stainless in the chip, not under the drill (where you're going to try to go next).

I have had good luck with sharp HSS bits for small sizes if I'm only doing a few. A good cut keeps the heat down. Just don't even think about using some cheap, dull bit. Spend a few bucks at a real store, not Ryobi or Craftsman junk. Even Irwin was good enough for me, off Amazon. But I'm not gonna buy a cobalt bit for my one-off because it's just for me, and my drill is so wobbly I'd probably break the bit. HSS is more forgiving.

[Spider!]

While we're at it; given a regular HSS bit, is there ever a reason where you need to go faster outside of efficiency and heat removal?

[Siress]

Efficiency of what? That could cover all aspects - so there's nothing left to consider.

[flyweightnate]

Stick-slip. At speed, transient behavior averages out. The drill remains "loaded" in a torsioned state. You can keep heat localized, if the material is removed faster than the heat is transferred. And your lubricant hardens under pressure. Slow down, and the lubricant can flow away more easily, the heat transfers to areas you don't want it, and in extreme cases, the drill winds then unwinds as the material exhibits stick-slip or chips break in segments.

Is it likely or common in stainless for these things to happen? Not sure. But on a physics level, they're all possible.

[Spider!]

Siress , just cutting time was what I was referring to. I was thinking that if I have time, and I manage heat build up, that a non-production setting will usually be fine with lower speeds.

Interrupted cuts and vibration are indeed a problem. I have also had some steels harden when I've been too slow.

[Siress]

Sometimes you have to raise the RPM to prevent the bit from walking at depth. Sometimes to improve surface finish. I'm sure there are many reasons given that so much is involved. Whatever it is, going faster than ideal will always be a tradeoff with tool life.

[LukeAO]

I've drilled a classic body before with these high speed drill bits.

You dont actually need any help, you got it right the first time, do that again.