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.

 

[smiley]

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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'm going to beat the safety drum again with a lesson learned the hard way. Be sure that the tool rest is in place when you're sharpening drills or using the grinder for anything. While sharpening drills when I worked at Remington Arms, on a grinder that the wheel was worn down and someone had removed the tool rest. A big no-no to start with. to make up for the lack of the tool rest, I rested the drill on 3 fingers on the guard instead of just the index as shown. when making the little twist that retiredmgn mentions to cut the trailing edge, I rotated a little to far and the wheel grabbed my third finger, sucked it in and stopped the 1 hp industrial pedestal grinder.
A funny thing happened though as I walked down the halls the 1/4 mile to first aid, with a bright red paper towel around my finger and a trail of blood following me. The plant manager happened to be coming the other way and saw the situation so was going to help me to first aid to make sure I didn't pass out. We went about 10 ft with him trying to hold me up, when suddenly he started getting whoozy and rubber kneed. Some other employees grabbed him and sat him down before he passed out, while another one walked the rest of the way with me. Most of the meat and scarred up skin grew back but there's still no feeling there after 45 years.
KEEP THE TOOL REST IN PLACE!!!

 

[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]

---------------------------------------------------------------------
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