drill bits for tang holes

T

thomster

Member
I could use some advice from the group collective here.
I'm having some trouble finding a set of drill bits that will cut more than one hole. I'm using Tap Magic, a Delta drill press, and a vice when possible, but in 1095 steel, they seem to dull the bit halfway thru 3/16ths steel. I talked with a machinist friend, he suggested Viking brand drill bits, screw machine length. I just got a small set off of amazon, https://www.amazon.com/dp/B01C5O1YHQ?psc=1&ref=ppx_pop_dt_b_product_details
I like the idea of these since they appear to locally made, (I'm in Minnesota). I haven't tried them yet. Can anyone recommend a brand/type of bits that will do the job and not break the bank? its a bit of a tower of babble out there trying to tell what is a higher quality drill bit from the ad copy.
Also, Am I doing something fundamentally wrong when drilling holes for the scales?
 
Are you drilling hardened steel? I buy just about all of my drill bits from Drills and Cutters.com. They work fine and last a long time. I resharpen my "F" drill bits. #30 for 1/8" pins and "F" for 1/4"
"F" drill bits
 
no, its before I've hardened them. I've been using bits bought at Northern tools or at Home Depot. I will take a look at the Drills and Cutters website. Thanks.
 
I buy the cobalt (Not Kobalt) bits from my local Ace hardware because I like the owners. I drill many holes before they crap out. Are you by chance using regular wood drilling bits? Something is off for sure if you cannot drill more than one.
 
I've been using the same #11 bit for a long, long time. Plain old black oxide jobber HSS bit. Whatever McMaster Carr sells under that heading.

Speed needs to be under 300 RPM. 250 RPM is better.
 
Like said before I also run on the slow side. Possibly you're work hardening your steel ,use proper pressure. I usually pull the bit out frequently to cool off and clean out shavings. Use lubricant or coolant I'm no machinist, but I use coolant from my mill, mostly because I hate the mess of oil it's also easier to gauge the temperature.
 
Sean Jones said:
It's possible that your 1095 steel isn't fully annealed. I've had that happen to me before. Also when I'm drilling steel I run my drill press at the slowest possible setting.
Click to expand...
I also ran into some 1095 that wasn’t annealed and had hard spots all throughout it. Cobalt bits helped. I wound up even having a carbide tipped masonry bit reground and it would get through as well.

Edited to add: accurate bit diameter is definitely questionable with the reground masonry bit...
 
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If you haven't already, I'll suggest getting some resources on cutting speed for various drill bit sizes and materials. In the most recent Hot Iron News (the quarterly newsletter of the NWBA) there was an article by a machinist called "Drilling Holes: A Few Pointers form a Machinist" and here's some info that might be useful:

"When drilling a small hole, the initial tendency is to have your RPM too slow. This often results in the drill bit breaking, because the pressure being applied (the “feed rate”) at low speed results in too much “chip load,” meaning it’s trying to cut too much in one revolution.

- Here is the simplest formula to come up with an RPM that will work with a wide variety of low-carbon steels: 240/drill bit dia = RPM

- What do you do when using a hand drill and you don’t know what RPM you are running? Start with guessing. We all can tell if the drill is running at its full speed or barely turning. For small drills, pay attention to your chip. If you start seeing your chip get very thick, you need more RPM and less pressure. For larger drills, if your chips are blue you are starting to run too fast.

- When drilling larger holes, a common practice is to drill a small hole in your material, and then work your way up. The reasoning is that it takes less force or pressure to move the drill through the material. The problem is that the drill bit tends to grab, which can break the bit . . .try using a pilot hole just a bit larger than the chisel point on your final drill bit, and drill the hole in two steps.

- a drill bit with a split point will take less pressure than a drill bit with a chisel point.

- Some drill bits have a gold coating and it’s probably a very good choice. This gold coating is harder and more slippery and works better than the substrate that the drill is made of. That doesn’t mean you can’t sharpen one of these drills - you just lose the benefit of the coating.

- another common option you may have at the hardware store will be a cobalt drill bit and this is usually the best drill bit you can find there for drilling steels.

- Cobalt increases what is called “red hardness.” and the higher the % Cobalt, the better the bit holds up to heat.

- When drilling stainless steel, at least 5% cobalt holds up well and you’ll need to slow your cutting speed

- For stainless, you need a sharp drill bit (Will the cutting edge of the drill scratch your fingernail? If not, it’s not sharp enough for stainless

- You do not want your drill bit to rub. This can cause “work hardening.” To keep your drill bit from rubbing you need a little higher feed rate or more pressure. If you’re not making a chip you’re rubbing.

- use oil, or coolant with a higher percent of cutting fluid, not water. Stainless needs the lubrication."
 
billyO said:
If you haven't already, I'll suggest getting some resources on cutting speed for various drill bit sizes and materials. In the most recent Hot Iron News (the quarterly newsletter of the NWBA) there was an article by a machinist called "Drilling Holes: A Few Pointers form a Machinist" and here's some info that might be useful:

"When drilling a small hole, the initial tendency is to have your RPM too slow. This often results in the drill bit breaking, because the pressure being applied (the “feed rate”) at low speed results in too much “chip load,” meaning it’s trying to cut too much in one revolution.

- Here is the simplest formula to come up with an RPM that will work with a wide variety of low-carbon steels: 240/drill bit dia = RPM

- What do you do when using a hand drill and you don’t know what RPM you are running? Start with guessing. We all can tell if the drill is running at its full speed or barely turning. For small drills, pay attention to your chip. If you start seeing your chip get very thick, you need more RPM and less pressure. For larger drills, if your chips are blue you are starting to run too fast.

- When drilling larger holes, a common practice is to drill a small hole in your material, and then work your way up. The reasoning is that it takes less force or pressure to move the drill through the material. The problem is that the drill bit tends to grab, which can break the bit . . .try using a pilot hole just a bit larger than the chisel point on your final drill bit, and drill the hole in two steps.

- a drill bit with a split point will take less pressure than a drill bit with a chisel point.

- Some drill bits have a gold coating and it’s probably a very good choice. This gold coating is harder and more slippery and works better than the substrate that the drill is made of. That doesn’t mean you can’t sharpen one of these drills - you just lose the benefit of the coating.

- another common option you may have at the hardware store will be a cobalt drill bit and this is usually the best drill bit you can find there for drilling steels.

- Cobalt increases what is called “red hardness.” and the higher the % Cobalt, the better the bit holds up to heat.

- When drilling stainless steel, at least 5% cobalt holds up well and you’ll need to slow your cutting speed

- For stainless, you need a sharp drill bit (Will the cutting edge of the drill scratch your fingernail? If not, it’s not sharp enough for stainless

- You do not want your drill bit to rub. This can cause “work hardening.” To keep your drill bit from rubbing you need a little higher feed rate or more pressure. If you’re not making a chip you’re rubbing.

- use oil, or coolant with a higher percent of cutting fluid, not water. Stainless needs the lubrication."
Click to expand...
Fantastic advice
 
^What BillyO said^ to add to that, if you are using 3/16in drill bits for 3/16in pins you may find the pins to be too tight. The thread below might help you out. Also, I buy my drill bits from drillsandcutters.com.


Pin & Hole Sizing - What method do you use?

I'm still on a vertical learning curve with knife making, having done a couple dozen at this point. A reoccurring issue is how to get a tight (but not too tight) a fit when installing pins in a knife scale. For instance: when drilling for a 1/8" G10 pin that measures .125 I'll try a 1/8"...
knifedogs.com
 
All great replies here. Any cheapo drill bit will do what you’re trying to do if it’s sharp and you’re running slow. The bit may not last long, but even the cheapest chinese drill bit will drill a bunch of holes in annealed steel. The steel is the culprit here, I’m convinced.

I also buy the inexpensive jobber drills from Drills and Cutters. They work great and all I do is stainless.

Once you get this sorted out, I highly recommend buying a Drill Doctor for sharpening your bits. It will not only save you piles of money over its lifespan, it will save you from the many many hours of frustration of trying to milk one last hole out of your last dull bit. Life’s too short.
 
This is great information, I will check to see what my drill press speed is at.
the comment from BillyO - "You do not want your drill bit to rub. This can cause “work hardening.” To keep your drill bit from rubbing you need a little higher feed rate or more pressure. If you’re not making a chip you’re rubbing." I was getting into cases where I wasn't making any chips, so I think I've been work hardening in some cases. I will look into getting a drill doctor!
 
Looking over that https://drillsandcutters.com/hss-stub-drills-fractional/ they have 3 different grades in the HSS grouping, but no place did I find what the difference is between grades. Contractor, Qualtech, and Drill American groups. Anyone know the difference in the grades? The first two have similar prices, and even Drill American isn't much more in price.

I'm think the cobalt might be best drill for money, especially for SS - comments?
 
Ok.....here's some of what he had to say about stainless:
- When drilling stainless steel, I have found at least 5% cobalt holds up well.
- Stainless is tougher than low carbon steel but it is not necessarily “harder” so it’s more like drilling rubber than glass.
- For stainless, you need a sharp drill bit (Will the cutting edge of the drill scratch your fingernail? If not, it’s not sharp enough for stainless).
- You’ll need to slow your cutting speed down to somewhere close to 35 to calculate your RPM. (what this means is that the equation above changes to 210/drill bit dia= RPM)
- You do not want your drill bit to rub. This can cause “work hardening.” To keep your drill bit from rubbing you need a little higher feed rate or more pressure.
- use oil, or coolant with a higher percent of cutting fluid, not water. Stainless needs the lubrication.
- You need bit with increased web thickness if you are being aggressive and drilling through a tough material like stainless.
 
KenH said:
Looking over that https://drillsandcutters.com/hss-stub-drills-fractional/ they have 3 different grades in the HSS grouping, but no place did I find what the difference is between grades. Contractor, Qualtech, and Drill American groups. Anyone know the difference in the grades? The first two have similar prices, and even Drill American isn't much more in price.

I'm think the cobalt might be best drill for money, especially for SS - comments?
Click to expand...
I believe those are brand names, not grades. I have bought some of all of them and see no difference.

Cobalt does hold up longer for drilling stainless, but if you have a drill doctor handy it doesn’t really matter. A quick touch up = a new bit. I don’t sharpen anything thinner than 1/8 though. I buy all the small stuff in multiples. My drill doctor is ancient and doesn’t like to hold anything that thin.
 
I have drilled hundreds of thousands of holes with hand drills in 304L and 316L (and A36). Hand drilling is very easy to overheat bits. Most bits will fail on the very first overheating. My strongly held personal belief is, there is not a drill bit made with better hot hardness than CTD's "Black & Gold," 135* split point, which is a Norseman brand. They are cobalt, but I'm unsure exactly which, but I'd guess M42. I can look it up tomorrow if anybody wants to know. Now that I've been buying them instead of using them for many years, I've been given samples and substituted and tried other stuff to see if we could save a buck. No other bit comes close, even from the same CTD/Norseman factory.

I don't necessarily think it's needed for knives, but if heat and/or over revving is the issue, these are the ticket.
 
I agree with John. I use a drill doctor and I know I have some bits I've sharpened hundreds of times that are over 30 years old. sometimes I'll stop drilling a hole if I notice it not cutting and sharpen it right then. I drill mostly stainless and usually I'll sharpen what ever bit right before I use it just so there's no drama, it only takes two minutes.

Anything 3/32" or under just gets replaced. the small bits are always cobalt, they'll last longer. most others are good quality HSS.
I call B-S on all these bits claiming to have titanium coatings or whatever they claim to make them last 10 times longer.

I guarantee you if you get a good drill doctor, years down the road after you realize how many bit's you've saved you'll wish you got one sooner. :D
 
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