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.