Deep hole with small drill

[Vern Smith]

I need to drill .75 through 6061. I would like to keep the size close to .062, no larger than .076 (#48) Can I make it with a parabolic? Suggested feeds and peck amounts? I can only turn 4,000 RPM.

Vern

[Geof]

Doing one or many?

In cases like this I tend to get really conservative; lots of nice rich coolant flooding the drill, run at the 4,000 rpm, feed very slow at 1 ipm and peck every 0.05" maybe even less.

Awful time consuming if you are doing lots but then you start slow and crank things up until drills start breaking then back down a bit.

[Vern Smith]

I'm not sure what many is I will be drilling 300 holes in 100 pieces. We are not under much time pressure here so chips per hour are never the number one priority. I checked the prices and these little guys don't grow on trees so it would a fair expenditure, relative to the value of the finished part, to get the 300 holes with one drill. I'm assuming the parabolic drill is the way to go.

I'm getting some really strange Haas faults from my G code on the new Haas lathe when I use the bar puller. The fact that I had to write the bar puller code probably has a lot to do with it I plan on spending some time with it tomorrow and will ask for your expertise on the Haas lathe forum. Can you see over the snow drifts in your front yard?

Vern

[Geof]

30,000 holes? That would qualify as many.

Snow drifts, what snow drifts. We are having an El Nino winter with temperatures well above freezing and no snow for the Winter Olympics that start in a couple of weeks. I drove up to our cabin in the mountains yesterday, just over a hundred miles inland at an elevation of 3500 feet and the temperature was +2 Celsius.

[Donkey Hotey]

Hmmm...that's almost 13D. I'm with Geof, buttery coolant, slow feed and lots of pecking. You might even drop the RPM some. My worry is that the drill will pump the coolant out of the hole before it actually gets to lubricate anything. You'll also have a problem with chips packing up in the flutes (hence the frequent pecking).

How long are the flutes on the drill? Do you actually have 0.75" worth of flute to eject chips or will they pack up while down in the hole?

I might even spot the hole locations just so the bit doesn't wander on first entry and break from being off-center.

[Geof]

Originally Posted by Donkey Hotey ....My worry is that the drill will pump the coolant out of the hole before it actually gets to lubricate anything.....

If you keep it completely flooded with coolant it cannot 'pump out', that would create a vacuum in the hole and simply suck more in.

Spotting is a given of course.

[Delw]

vern
I do a .055 dia drill at 8500rpm 3.1 IPM and .040 pecks with regular coolant .650 deep
on my old machine same drill size part and everything it was 3500 at 1.5-1.7ipm. with 0.025 pecks. Once my new balance collets get in I am hoping to run 12k at 5-7ipm.

My old acroloc vibrated too much at 6500rpms and threw the drill size off so I had to run around 3000-4000 rpms on small drills in that collet tool holder. I ran oil in this machine. sure wish I could run it in the fadal and haas but the mist is way to much.

I use cobalt 135º split points from................ ooops , can't remember the name tan and white package USA made. if the holes are deeper than .750 I use screw machine drills down to 3/4" flute length then switch tools to a normal or extended length to finish the size..

on the haas with the .055 drills I am getting about 150-200 holes per drill before I start cussing.

[Vern Smith]

Thanks for all the input. I have the flood coolant and it sounds like some of you are doing similar things with regular drills so I should be ahead of the game with the parabolics. I have a question on pecking. My software has a pecking cycle and a deep hole drilling cycle which is the same as the pecking except it rapids all the way out of the hole after each peck then rapids back in to a preset amount above the previous peck depth. Are any of you using the deep hole type of pecking or is that unnecessary?

A little optimistic to think I can do 30,000 holes with one .062 drill am I , I fat fingered the numbers.

Vern

[rowbare]

Check out the videos I posted here: http://www.cnczone.com/forums/showpo...77&postcount=5

For the number of holes you have to do, it may be worth talking to those folks.

bob

[Geof]

Originally Posted by Vern Smith .....I have a question on pecking. My software has a pecking cycle and a deep hole drilling cycle which is the same as the pecking except it rapids all the way out of the hole after each peck then rapids back in to a preset amount above the previous peck depth. Are any of you using the deep hole type of pecking or is that unnecessary?..... Vern

Are you referring to G73 HIGH SPEED PECK DRILLING and G83 NORMAL PECK DRILLING CANNED CYCLE?

I always use G83 mostly due to laziness because I never all the entries that are need for G73 to have it occasionally pop right to the surface to get rid of chips. I have proved to myself that just pecking to break the chips without retracting to get rid of them does not work, the chips eventually pack up in the flutes.

[Vern Smith]

Geof,

As you well know, I would not know G83 and G73 from G string However, I have always used the pop up every time option which my software calls deep hole drilling. It adds very little time to the cycle and I always hoped would extend the life of my drills. I have always used cobalt drills as well for the same reason. They are a little more expensive though. I see most all the parabolic drills are cobalt.

Now to the Haas lathe choking on my G code

Vern

[BobWarfield]

These little tiny holes are where an aux high speed spindle would be nice.

Best,

BW