So is it the Bit or the Drill Press?

Hankins

Hankins

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Dec 7, 2008
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OK I fess up to not owning a top notch Drill Press as it has a bit of slop built in...
But seem to be going thru bits even good quality Cobalt ones too fast.
So is it the cheapo Drill or the bit quality that makes them wear out relatively quickly?
Feel free to chime in...
 
Hey,

Guess we should ask, First if your using a lubricant of any type? Also, what speed are you turning those bits at? In our shop we use a few standard 12 speed drill presses and use cobalt bits also and run them at 200fpm with hole shots of lubricant and they last upwards of 6 months drilling through all kinds of alloys from straight carbon alloys to high stainless alloys like S30v etc..Finally how much slop would you say your machine has, usually all drill presses have a bit of play we have found, but excessive play could mean you need to get a new bearing for the spindle . If so they aren't that hard to replace and cheaper than a new drill press.

Regards,

Velocity Knives






Hankins said:
OK I fess up to not owning a top notch Drill Press as it has a bit of slop built in...
But seem to be going thru bits even good quality Cobalt ones too fast.
So is it the cheapo Drill or the bit quality that makes them wear out relatively quickly?
Feel free to chime in...
Click to expand...
 
Nathan the Machinist has a thread on the front page on drilling holes. What I really took from his post was to not feed the drill too slow, to use more force in feeding. If you feed it to slow you dull the bits. This rings true based on my experience and it is similar to operating a bandsaw.

Of course, it could be your machine. To see how true it runs you need a dial indicator. Measure runout on the exposed spindle above the chuck, spinning it by hand. Ideally no more than 2 or 3 thou runout in the spindle. Then chuck up a perfectly round rod (a machinists transfer punch or drill rod would be good) and measure the runout again. If you get a lot more runout at the chuck then its the chuck thats the issue. That would make sense because the cheaper units use very cheap chucks and they don't always center the bit perfectly. You can replace the chuck with a better quality one if thats the issue.
 
I use bits from Jantz in a cheap press, I only use oil when drilling something thicker than 3/8", and drill dozens of holes before I need to resharpen. I think the key is feed rate. I run the press on the slowest setting and try to use enough pressure to make one long curly-q of steel. I go by feel and ease up just before the bit breaks through. I also feel the bit between holes to be sure it isn't hot. This is just what works for me.
 
It is just a 6speed press and I am running it at 2nd to the slowest speed. Run-out is not good since I can wiggle the end by hand when fully extended.
Suggestions on a Good Quality drill Press? Was looking at the the one from Woodworkers source.
 
I would suggest putting it on the slowest speed and leaving it there. Most cheaper drill presses run a little fast for our purposes, IMO. Nathan's advice in his sticky is true to my experience, you want the bit fully engaged and cutting as soon as possible after you make contact with the material, and avoid letting the bit rub the bottom of the hole without cutting. This also helps with the runout, if you maintain proper feed pressure and your bit is factory sharpened (or properly re-sharpened) with a perfectly centered point, the pressure at the tip will keep it centered as you feed it through the material. Letting it spin in the hole with no feed pressure or resistance at the tip will allow the bit to wobble and scarf the sides of the hole out.
 
Are your bits getting dull, or jagged/chipped on the cutting edge? Those are two totally seperate types of "worn out" bit. Excessive slop, chatter, and bad fixturing could be the cause of mangled cutting edges, where as feed and speed and heat can be the causes of dullness.

Also, what size bits are we talking? I don't personally like to see the "put it on the lowest speed and leave it" advice. Small bits need much higher speeds and care with the feed to avoid flex. Won't matter so much on thin stock, but for tiny holes on thicker stock, it can be a big deal.
 
In looking for a drill press, the purpose the press was designed for will matter.

A woodworking press will run faster than a metalworking press. It does not need as heavy bearings or need to be as sturdily built.
That is why a metal drill press is more expensive than a wood drill press.

If you drill metal, do yourself a favor and get a metalworking drill press. You don't use wood bits, do you?
 
For me the speed of the drill press has had the greatest impact on how long a bit lasts and how well it cuts. The slowest speed on my drill press has proved to be the right speed, 250 rpm, in most instances. I can run it a bit faster on material an 1/8" or less with good results but I choose to run it at the slower speed and take my time. When I drill material thicker then 3/16" I use lubricant.
 
Nathan's post on drilling is on the money... Machinists drill tons of holes... I only worked in a machine shop for a summer, and fabrication shops here and there, plus dabble in my own shop and I have drilled thousands of holes, I'm sure a working machinist has probably drilled tens or hundreds of thousands of holes. Their experience and training is invaluable here.

Within reason if you have set up your work and clamped everything in place properly, once the press is loaded up some slop won't matter, provided the bit is true and evenly ground. If you have quality bits, and use them properly so they cut (see the spiral chips) then they will last and last. If you use too little pressure, you're trying to wear a hole rather than drill it. The spindle speed doesn't change this, they need to cut. And usually the drilling speed should be lower than most people realize, or expect. There are plenty of tables out there for drill speeds, based on the diamter of the hole to be cut, the material thickness has next to nothing to do with the spindle speed. Although thicker material will benefit from cooling and clearing of the chips as you go. Google is your friend.

Too many of us think cheap bits are a bargain... They are a cutting tool like a knife, the same things hold true, quality steel, quality heat treat, and proper usage determine edge retention.
 
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