drilling holes

[Scotty Dive]

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?

 

[smiley]

I think an Indian with a stone point could almost beat that time. It's been a while since I drilled a 3/4 hole but did 4, 1/2" holes in 1/4" the other day with a 1/4 pilot hole and although not timing it, don't think any of them took over 30 seconds. The 1/2 " drill happened to be a HF too.
You've got me wondering now so when I get a chance, will drill a 3/4.

 

[Egon]

It all depends on what you are drilling through, how sharp the bit is, how big the motor turning the drill is, how much down pressure is placed on the bit and the effectiveness of the cutting oil used.

 

[flusher]

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 prefer to use a step drill for holes larger than 1/2" dia on relatively thin material like 1/4". You have to flip the piece and drill from the backside to get a clean hole, but it's not hard to do with a little practice.

 

[tommu56]

I prefer to use a step drill for holes larger than 1/2" dia on relatively thin material like 1/4". You have to flip the piece and drill from the backside to get a clean hole, but it's not hard to do with a little practice.

Step drills are made for thinner material the step length should the maximimum thickness drilled.

I got some long drill bits from HF they were junk the angles were fine the metal wasn't I was drilling a 2x4 on edge and the bit just twisted when I hit a knot.

back to the op did you put a pilot hole in the metal i whould have punched a 1/4 or 5/16 as a pilot for 3/4 and you should be able to drill through it in about 1 minuet or less with the pilot

here is a link for a 1/2 inch drill it calculates out 3.2" per minuet

http://its.fvtc.edu/machshop1/drillpress/feedratecalc.htm

 

[bearcreek paul]

1 use a # 3 or 4 center drill oil or cutting fluid
2 step up to a larger drill 1/4
3 then go to 1/2 in
4 if your drills are good and sharp skip step 2
5 it pays to buy good high speed steel bits and a sharpener if you can't freehand sharpening bits.Center drills work great for starting holes,saves alot of time!$$

 

[Transit]

I use cobalt drills at the lowest speed, lots of cutting oil and enough pressure to cut spiral chips. You do not want the drill bit to skim across the cut face and work harden the stock.

 

[SixHoeBob]

A retired engineer gave me a 115 Pc. set of Harbor Scrap black oxide drill bits.
Soon as they touch steel, they unwind. It should be illegal to waste resources making garbage and shipping it halfway around the world.
I did not even bother to tell him when I smoked his Chinese planer on his project. Another $19 he wasted. I would think a helicopter design engineer would know enough to buy quality tools

 

[Egon]

Hole saws may be something to look at.:thumbsup:

 

[PILOON]

If precission is not all that important, quality 'core drills' at low speed do a good job as well. Just use cutting oil and you should be fine.
I have done 3" in 3/8 stock and the core or 'bell' is like new still.
Also did 2" in 1/2" plate.
Slow and cutting oil is the answer.
One trick is to pilot a 1/4" hole and then use a bolt as your pilot in the 'core' drill so as to avoid wobble,
Because core drills are designed for wood the stagger teeth tend to drill oversize from the stamped designation so you may need to buy 1/8 smaller.

 

[norbie454]

This does sound like inferior bits as a few others have brought to your attention. However when you drill a pilot hole, try and not go much larger then the web or the thickness of the tip point. If you have a high grade bit that is sharp it may tend to catch and spin in your chuck causing the shank to self destruct. You might want to go to your local hardware store and pick up a good quality cutting fluid in a 4 oz can. Remember the little extra cash you spend on cutting tools will make the experience more pleasant. Saving money here is not worth it, you do get what you pay for. Hope this helps out.

 

[radioman]

I used the HF 3/4 silver and deming drill bits with my cheap TSC drill press and transmission fluid. As long it was in a oil bath, It cuts just fine.It does take a bit but not 10 mins. I did noticed after the 5 hole, I had to touch up the bit in a grinder to make it cut again. I can't really see the bit being dull before using, but can tell when its in use.

I always back off every now and then to let oil seep in hole or add more to keep it cool. any whiff of smoke just makes it dull in a hurry with those cheap HF bits.

 

[Travelover]

I seem to remember a similar thread about this time last year.

Come on spring! :laughing:

 

[Scotty Dive]

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

 

[sal64]

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

it should take 20 sec to drill that hole one shot no pilot on a good drill press your drills are prob very dull, sharpening drills takes a nack not so easy to do.

 

[Travelover]

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

I'd recommend a drill doctor.

Amazon.com: Drill Doctor DD750X Drill Bit Sharpener: Home Improvement

 

[Transit]

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

That is why I have a set of Cobalt bits. Check around for how to sights on bit sharpening. The point shape makes all the difference.

 

[Brad_Blazer]

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

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.

 

[retiredmgn]

I think I was about 12 years old when my Gramp showed me how to sharpen a drill bit - freehand. The only trick involved was the twist at the end to ensure the trailing edge was lower than the cutting edge.
First job out of high school was in a factory producing printed circut boards. Lots of drilling involved. There was a jig for sharpening bits and guys would spend an inordinate amount of time getting set up to produce a 'perfect' bevel.
It just ain't that much of a mystery. Once you know how, 20 seconds at the wheel and you're back in business.

Drop by the house when you have a chance. I'm most always here. Free lessons.

 

[wdchyd]

The oil trick works but what you what to remember the object is keeping your bit cool.....not lubed.......

I routinely drill out high grade steel with HHS bits as large as 2.5".......the trick is to keep it cool with anything and slow down your rpms.......I have flood coolant set up on lathes, drill presses and milling machine......the coolant is 95% water and 5% water soluble oil (only to protect the machines from rust).....

When drilling something away from my machines I use plain ole water in an old dish-washing detergent bottle (garden hose works too)......the water will make a mess but it'll dry up with no oil spillage.......have someone hold the squirt bottle and feed it continuously while you put the boots to it......it works.....:thumbsup: