Drilling problems

Guindesigns

Guindesigns

Well-Known Member
Ok I am having problems adding lighting holes to my blades. I get about half way threw and it just stops cutting.
I've tried going faster and slower. two different types of cutting oil and different bits alone with guide holes.
all it is doing is causing my drill bits to get super stupid hot and not cut and causing my steel to heat up some so hot its changing colors. thankfully this is pre heat treat.
I use a craftsman .5hp bench-top drill press. and titanium bits right now.
I'm thinking like Tim "the tool man" Taylor need more power!! but before i go buying a new drill press (which i hopefully don't have to do) any advice??
 
Try better bits....like cobalt. And cutting fluid. Even steady pressure....not hard. Let the bit cut...don't rush it. Its not a drill press power issue.

If the above doesn't work, then we need to look at steel type and internal condition.
 
You want to drill very slow- like 300 RPM or whatever your drill press has for the lowest speed.

I started off with a 10” bench top drill press- probably the same one you have but 30 years old. There was a limit to how big a cut I could take. I’d start with 1/8” and work my way up. That got tiresome so I just drilled a zillion 1/8” or 3/16” holes.

Power does matter- a 1HP drill press will cut a 1/2” hole with no pilot hole. But power is not what’s causing your steel to get super hot. That sounds exactly like what everyone else has said- dull bits or cut speed is too fast and you’re hardening the steel.

On a side note: a Drill Doctor is worth five times what you pay for them. Being able to sharpen bits in a matter of seconds is a godsend and will also save you a lot of money on bits.
 
John Wilson said:
On a side note: a Drill Doctor is worth five times what you pay for them. Being able to sharpen bits in a matter of seconds is a godsend and will also save you a lot of money on bits.
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That's what I was going to suggest John. I've had one for years and use it all the time, I've sharpened hundreds of bits to like new in just seconds. that's one of the best tools in my shop. other than specialty small bits for folders and the like, I haven't bought a standard fractional bit in a few years. ---Christmas is coming Guin. ;)
 
bladegrinder said:
That's what I was going to suggest John. I've had one for years and use it all the time, I've sharpened hundreds of bits to like new in just seconds. that's one of the best tools in my shop. other than specialty small bits for folders and the like, I haven't bought a standard fractional bit in a few years. ---Christmas is coming Guin. ;)
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Same here, Steve. I've gotten a whole lot of mileage out of a pretty basic drill index. Another huge positive that comes with having sharp drill bits is that the tip doesn't wander when you're trying to start a hole. If your bits are dull then no amount of center punching is going to get the bit to bite where you planned.
 
I have run into this on forged blades so I assume you are forging them. Why not just anneal it? Or am I missing something? Worst case since you have the holes already marked by the drill bit just hot punch them and clean them up?
 
drilling can be a challenge but here are some things to consider.

Generally, the bigger the drill bit, the slower the RPM. Most every drill press has speed adjustment pulley's to get RPM's from around 250 up to 2400RPM. Some drill presses may have a bigger range.

Materials are rated by machineability. Softer materials = go faster. Harder = go slower.

A simple rule of thumb for drilling carbon or stainless steels is to divide the diameter into 200 (the number 200 is a rough machineability industry number for steel.)
so for a 1/8" bit ..... 200 divided by .125 = 1600RPM
1/4" bit....... 200 divided by .25 = 800RPM

I usually keep my drill press around 1200RPM and adjust my feed rate accordingly.

If the hole is 1/4" or larger, clamp the work piece and pay extra attention to adjust the drill press speed. It's safer and you get a better hole. I have seen a 10lb drill press vise climb a 1/4" drill bit and helicopter. It destroyed the drill press.

Feed rate is the pressure you put on the bit while drilling and can't be measured so you observe the chip. A nice steady pressure with the occasional slight lift to break the chip helps. Keep the flutes empty when drilling holes in material deeper than the diameter of the drill.

Breaking through is where it usually goes bad. Strengthen your grip (if hand holding) and slow your feed rate way down when you feel the bit starting to break through. Some times let it dwell (no down pressure) for just a second or two. You want the break through to be 1/4 of your feed rate to allow material to be removed rather than gouged into a drill flute and sending your part on a helicopter ride.

Use cutting lube. It keeps the drill cooler so it stays sharped longer. I have a small tin of Tapamatic wax that I dip the drill bit into before and after drilling to keep the bit cool. I get much longer life this way.

Quality drills make a difference. "Cobalt" drills take heat better so they don't lose temper as fast resulting in a sharper bit longer.
Drill Doctors are worth the money I think. I don't use one for drills much smaller than 1/8" dia.

Rule 1: avoid using carbide drills unless you have to. They break so easy it's stupid. I loath using them but sometimes you have to.

Generally, you run carbide at twice the speed of HSS or Cobalt drills. Slower speeds kill carbide.
 
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No I'm stock removing
Chris Railey said:
I have run into this on forged blades so I assume you are forging them. Why not just anneal it? Or am I missing something? Worst case since you have the holes already marked by the drill bit just hot punch them and clean them up?
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There are many good suggestions here. For what we do cobalt is good. If you find you have work hardened your blank a carbide "straight flute" drill will help with that. (Granger, MSC) Feeds and speeds are important to understand. Then there is coolants. Almost as important as a cobalt drill. There are many good machining f&s calculators online. They would give you an idea of where you should be at. If nothing else slow is good.
 
I've run into this with some steels, 15N20 particularly. When I do, I run the blades through normalizing and thermal cycling and it seems to fix the problem.
 
Another plug for cobalt drills is that most have a "split point" that means the center web is almost non existent. They can grind them that way because cobalt in incredibly tough. The web (that little thickness of material between the two flutes at the very point of the drill) Is what creates the heat.(a lousy grind does too) usually the cheaper the drill the fatter the web....more heat in drilling. a small ketchup bottle with coolant in it can also help with heat. I have even used water and detergent in a pinch. liquid really helps drop the temp....drench it...water with a water soluble cutting fluid is cheap...lol.
 
Quill travel is how far your spindle( with chuck and bit) moves down as you pull the handle. Most drill presses have quill locks to stop the spindle at a set point for repeatable drilling of blind holes so they're all the same depth.

Check to make sure your drill stops/locks aren't set which would limit your drilling depth. Its a good thought and a quick and easy thing to rule out.
 
Guindesigns said:
not fully. but it hasn't been harden yet.
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All of these are good suggestions, you can see different people will solve problems in different ways. If you heat the trouble section then cool it as SLOWLY as possible I bet you will be able (with a good bit) to finish your holes. Assuming your drill stops are set correctly.
 
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