Drill Press Help

C

Cburr84

Joined
Feb 27, 2019
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Im new to knife making and started my second blade. I’m sticking with the cobalt bits for high carbon steel. Is there a general length of these bits for the drill press? I notice some of the smaller ones go wayyy up in the chuck. Also, my couple decade old drill press is one speed and it’s like 3100 rpm, and when I try and drill into the steel, it stalls or something (the motor keeps trying to spin the bit, but the bit is stationary on the steel). I’m reading it’s best to slow the speed down so I’m getting the 8” WEN. For speed control. What speed do you guys use/recommend? Advice on bits is much appreciated as well.
Thanks
-Clay
 
Tighten the chuck with the bit places where u want it.really tight
And don't use much pressure when drilling
Use oil too
 
Steel drills best at low speeds...250-400 rpm is good for average size bits...Larger bits heat up faster so slowing down the speed will save the bit and keep from work hardening the piece being drilled. Cobalt bits are more expensive but perform better overall than cheap bits. I will resharpen cobalt 1/8' bits until the flutes are gone and I have larger cobalt that have lasted years.
 
Most of your "big box store" drill bit sets will be "jobber" length. If you go through a more specialized store like mcmaster-carr, grainger, msc, etc... you can get different lengths, styles and materials. For 99% of holes that your average knife maker needs, the HSS (high speed steel) jobber bits will work just fine, ASSUMING proper feeds and speeds. A good cutting oil will help keep things cool and help the bits to last (cut) longer. A good "cheap" cutting fluid is the sulfurized oil made for pipe cutting/threading machines. You can buy a gallon of it for about $20, or I think Home Depot has 16 oz bottles for about $8 or $10. A bottle will last you for years.

As for how much stick out to leave, I normally choke up on the drill shank as far as I can without grabbing the spiral flutes of the bit, unless I need extra length to keep from hitting a clamp with the chuck. Or if the bit has flats, I'll go to the end of those. Longer bits tend to flex more (especially smaller sizes), so that's something to keep in mind if you need a precise hole. Unless you're making folders, this normally isn't an issue, and at that point you should probably be using undersized bits with reamers anyhow.

Lastly, it sounds like you need to tighten or replace your current drill press's belt. I imagine you should be able to drop the speed down a bit more as well?
 
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Here is some general drill press advice for new people from a machinist.

1) Secure your part with either a vise or a clamp, do not simply hold the part in your hand. As soon as the drill breaks through the other side it could grab a burr, torque the part and spin or "helicopter" on you quickly.

2) Center punch or center drill the spot you're going to drill prior to using your twist drill. Otherwise the drill will "walk" and your hole will be eccentric and out of location slightly. You can mark the steel using a automatic spring loaded center punch and then follow that with a standard center punch to enlarge the mark.

3) Choose the correct speed (RPM) for the material and diameter for the drill you're using. To do this you need to do some research, the drill manufacturers or machinery's handbook will list suggested SFM / FPM (Surface Feet Per Minute) for their different types of drills and materials. To convert SFM to RPM's use this formula, SFM x 3.82 / Diameter of drill. For example 15 SFM x 3.82 / .125 (1/8 Drill Diameter) = 458 RPM, now choose the closest setting your drill press will allow. To change the speed on your drill press open the top sheet metal enclosure and adjust the belt to the corresponding diameters shown on the diagram on your drill press. For M42 Cobalt Jobber length twist drills which is the industry standard length, you'll generally be drilling in the 15-30 SFM range for annealed high carbon steel, tool steel and stainless steel. When in doubt start on the lower side of the suggested values.

4) When possible use a cutting oil it'll extend drill life and produce better finishes, do some research as different materials perform better with different oils. For most annealed cutlery grade steels https://www.crcindustries.com/products/truetap-174-hd-heavy-duty-cutting-fluid-16-fl-oz-03400.html or a similar sulfurized oil product would be a good starting point. WD40 is NOT a cutting fluid / lubricant, it's only a protectant.

Hope that helps some, If you have any other questions let me know.
 
Are you sure your drill press is single speed? Top usually opens on them and you usually have a couple step pulleys that offer a variety of configurations to adjust speed. Even the cheapo $65 HF bench top one I started with years ago had the step pulleys. Google your drill press...maybe you have had variable speed and didn't know it. I just discovered the delayed timer on my oven after 13 years last week.
 
Just a note on drill bits: They are differentally heat treated! They are hard at the tip and back through the flutes onto the shank. The shank is dirt soft at the butt and get harder about 2/3 or 3/4 of the distance from the butt to the start of the flutes. The drill chuck jaws are made to bite into the SOFT portion of the shank. If you insert the bit too far into the chuck, the chuck jaws will be riding on the hardened part and will not grip, thus the bit spins when to much torque is applied. To find out exactly where the transition is between hard and soft, drag a sharp scribe down the length of the shank and note where the depth of the scribe mark changes.
Jim A.
 
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