drilling holes

[bironacad]

I was just wondering how long it should take to drill a hole in 1/4". I have some harbor freight silver and deming metal bits. To cut 3/4" hole on my drill press at 300 rpm's it took about ten or more minutes each hole. Is that about right?

I have been using a hole saw, the cool thing is that I can also use a longish 1/4" pilot bit to line up holes in tubing. I drill the 1/4" pilot hole straight through from one side then use the hole saw, flip the tube and drill the opposite hole. Both holes done not ten minutes.:thumbsup:

 

[accordionman]

HELLO TO ALL,
300 rpm is much too fast for a 3/4in drill.
most drill presses even on the lowest speed would
be too fast. 80rpm would be a more proper speed,
and with a proper coolant.
but the drilling of the smaller holes stepped up to
3/4in is also the way to go.
good luck to all.
accordionman
wlbrown

 

[PILOON]

The old blacksmith around here always kept a coke bottle full of water to cool his bits while drilling larger holes. Workrd for him.
He also had the grinder ajacent to the drill press for touch ups.

 

[djw250]

I have found that for holes larger than 1/2" that a bi-metal hole saw is the way to go. If you can afford them, the Milwaukee Hole Hawgs (annular bits) are very nice, but a decent bi-metal hole saw does almost as good.

 

[SandburRanch]

Like this. Start with the cutting edge parallel to the wheel face and rotate the bit up about an axis parallel with the cutting edge.

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There's something going on here Brad didn't tell you about and he may not even realize it since he is so accustomed to doing it. Take note of where his index finger of the right hand is. There are at least two reasons for it being there and one is not so it gets HOT.:laughing:

Just for fun, let's see if he can tell us why it's there.

 

[JB4310]

it should take 20 sec to drill that hole one shot no pilot on a good drill press your drills are prob very dull,

I'm sure his bits are dull but unless you had an industrial press I would use at least a couple of smaller bits first. IMO that's quite ambitious to only take 20 seconds with no pilot or step up. But that is only 1/4 thick, so maybe...

sharpening drills takes a nack not so easy to do.

Easy to do, just not easy to explain

I have found that for holes larger than 1/2" that a bi-metal hole saw is the way to go. If you can afford them, the Milwaukee Hole Hawgs (annular bits) are very nice, but a decent bi-metal hole saw does almost as good.

I've never tried a metal hole saw before, can it go thru 3/4 thick?
That's where I start having trouble, with 3/4 to 1 inch holes in 3/4 to 1 inch thick material.

I had to bring my last project to a buddy who has an industrial machine shop, couldn't for the life of me get a 1 inch hole thru 1 inch material, even with brand new bit and a decent drill press. He slowed his machine way down slower than mine could go to do it. I drilled the hole pretty easily, but this was a 7 ft tall drill press, very solid machine.

JB.

 

[Brad_Blazer]

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There's something going on here Brad didn't tell you about and he may not even realize it since he is so accustomed to doing it. Take note of where his index finger of the right hand is. There are at least two reasons for it being there and one is not so it gets HOT.:laughing:

Just for fun, let's see if he can tell us why it's there.

I mentioned an axis parallel to the cutting edge...

Looking at the video my finger does get pretty close to the wheel. I may not have mentioned that I use a very light pressure - hence the many passes to accomplish the edge. My grinder is an 8" cheapo with very little power - plenty for sharpening though. Still plenty of momentum to cause injury.

 

[SPYDERLK]

That's where I start having trouble, with 3/4 to 1 inch holes in 3/4 to 1 inch thick material.

I had to bring my last project to a buddy who has an industrial machine shop, couldn't for the life of me get a 1 inch hole thru 1 inch material, even with brand new bit and a decent drill press. He slowed his machine way down slower than mine could go to do it. I drilled the hole pretty easily, but this was a 7 ft tall drill press, very solid machine.

JB.

Yes. The big bits have to turn slowly and require quite a bit of push and torque. A high chuck speed will penetrate too little per revolution causing the bit to skate and chatter thus overheating and quickly dulling the edge.
larry

 

[SpringHollow]

Use an old time Cole Drill - it is amazing what they drill through turned by hand.

Ken

 

[R W]

Use an old time Cole Drill - it is amazing what they drill through turned by hand.

Ken

Good Idea. With a good quality bit and a small pilot hole to drill a 3/4 hole through a 3/4 piece of steel is reasonably quick and easy with a Cole Drill.
Using a decent drill bit and the slowest speed on a drill press the same thing should not be a problem.

 

[1grnlwn]

Two things to stay away from in the Chinese tool arena are Drill bits and taps. Total junk. I bought a set of titanium nitride bits and every one of them needed sharpened. And it didn't take long before I untwisted and broke one. Knowing this would I buy a 3/4" bit for $9? sure if I knew I would only use it for 3 holes total. But since a quality bit that size is about $85, it should be obvious that something is up.

 

[Transit]

Too much is expected of titanium nitride bits; Ti-n is nothing more than a ware coating like black oxide. It is the base steel that counts. Many Ti-n bits are nothing more than wood bits with a Ti-n coating. Even a cheep set of cobalt bits will out last Ti-n bits. Sharpening is a science and art; the general point angle is 115 deg, sharp point for soft stock like wood, plastic and a flat point for hard stock. The clearance angle behind the cutting edge is critical too, if it is too thin the cutting edge will chip and if too thick the cutting edge will skim over the stock. There are sharpening tool that are adjustable that gives you control of the point shape. Worth the investment? That depends on how often you need to drill holes.

http://www.woodcraft.com/Articles/Articles.aspx?articleid=267

 

[1grnlwn]

Too much is expected of titanium nitride bits; Ti-n is nothing more than a ware coating like black oxide. It is the base steel that counts. Many Ti-n bits are nothing more than wood bits with a Ti-n coating. Even a cheep set of cobalt bits will out last Ti-n bits. Sharpening is a science and art; the general point angle is 115 deg, sharp point for soft stock like wood, plastic and a flat point for hard stock. The clearance angle behind the cutting edge is critical too, if it is too thin the cutting edge will chip and if too thick the cutting edge will skim over the stock. There are sharpening tool that are adjustable that gives you control of the point shape. Worth the investment? That depends on how often you need to drill holes.

Twist Drill Sharpening Tips

My only expectation upon purchasing them was that they be sharp and drill mild steel. They did not meet my expectations!

 

[JoeL4330]

Thanks all....Maybe I burned these up and they need sharpening....I have never sharpened a bit....how is that done?

If you "burned them up" you changed the temper and sharpening won't have the desired result. You didn't mention cutting oil/fluid, but nearly every poster mentioned it ...it is absolutely essential ...and, when things are just right--the down pressure, the drill speed, and the sharpness--you get beautiful spirals, the proof that you've dialed in all the parameters just right.

As for the cutting fluid, it should be plentiful enough to cool...if you can't apply continuously, you might build a little well around the hole...maybe plumber's putty, to keep a little lake of fluid at the cutting edge.

 

[wdchyd]

If you "burned them up" you changed the temper and sharpening won't have the desired result. You didn't mention cutting oil/fluid, but nearly every poster mentioned it ...it is absolutely essential ...and, when things are just right--the down pressure, the drill speed, and the sharpness--you get beautiful spirals, the proof that you've dialed in all the parameters just right.

As for the cutting fluid, it should be plentiful enough to cool...if you can't apply continuously, you might build a little well around the hold...maybe plumber's putty, to keep a little lake of fluid at the cutting edge.

Now here's a guy that's done it......I drill all the time with huge drills and they never touch the stock without coolant/water......

 

[Iplayfarmer]

...you might build a little well around the hold...maybe plumber's putty, to keep a little lake of fluid at the cutting edge.

I agree with wdchyd. That's a pretty good trick. I may keep my putty by the drill press now rather than on the other side of the shop.

 

[Scotty Dive]

The responses to my questions are just terrific and why this forum is great.

I can get my drill press to move a little slower but not much. I did sharpen my bits and may be that will help. I usually spray WD40 while drilling but I guess that might not be the right product to use. I also get a sense that you have to put a fair amount of downpressure - something I tended not to do since I thought it would create heat and be a negative. I like the idea of the plumbers putty around the hole....thats a great idea.

 

[NCMau]

I have been using a hole saw, the cool thing is that I can also use a longish 1/4" pilot bit to line up holes in tubing. I drill the 1/4" pilot hole straight through from one side then use the hole saw, flip the tube and drill the opposite hole. Both holes done not ten minutes.:thumbsup:

Just wondering how thick of metal can be practically drilled with a bimetal hole saw.

 

[Transit]

The responses to my questions are just terrific and why this forum is great.

I usually spray WD40 while drilling but I guess that might not be the right product to use.

I also get a sense that you have to put a fair amount of downpressure - something I tended not to do since I thought it would create heat and be a negative. I like the idea of the plumbers putty around the hole....thats a great idea.

WD40 or any lubricant oil should never be used. You want to CUT not lubricate. The only benefit would be to cool the drill bit using lube oil. The down side is that lube oil has extreme pressure additives to prevent ware.