Drilling Speeds
#9
I'm wondering how accurate this is

http://images.meredith.com/wood/images/p...dchart.pdf

I have some aluminum and brass to drill - diameters won't be more than 3/8" and the speeds listed are about 2x what I thought.    Can I use a light oil such as 3 in 1 as the cutting oil or should I have some actual cutting oil?  The blanks have already been drilled to 7mm.

I changed the title because I'll actually be drilling these on my lathe.
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#10
Considering that the chart has been around for ages, I trust it and use it often as my guideline.
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#11
(02-14-2018, 01:22 PM)crokett™ Wrote: I'm wondering how accurate this is

http://images.meredith.com/wood/images/p...dchart.pdf

I have some aluminum and brass to drill - diameters won't be more than 3/8" and the speeds listed are about 2x what I thought.    Can I use a light oil such as 3 in 1 as the cutting oil or should I have some actual cutting oil?  The blanks have already been drilled to 7mm.

I changed the title because I'll actually be drilling these on my lathe.

,,,,,,,,,,
Dave, you didn't mention that you were going to be drilling brass in your email, but just to let you know that brass requires a different angle to the cutting face than aluminum...To prevent {or reduce the likelihood} of the bit "grabbing", you need to use a stone and knock that angle back just a bit..It doesn't take much but it needs to be just a tad {like 1/32"} more "blunt" on both cutting edges..You should do the same when drilling sheet metal of any type to prevent the metal grabbing and riding up the flutes as it exits the work.
Often Tested.    Always Faithful.      Brothers Forever

Jack Edgar, Sgt. U.S. Marines, Korea, America's Forgotten War
Get off my lawn !
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#12
(02-14-2018, 08:50 PM)Timberwolf Wrote: ,,,,,,,,,,
Dave, you didn't mention that you were going to be drilling brass in your email, but just to let you know that brass requires a different angle to the cutting face than aluminum...To prevent {or reduce the likelihood} of the bit "grabbing", you need to use a stone and knock that angle back just a bit..It doesn't  take much but it needs to be just a tad {like 1/32"} more "blunt" on both cutting edges..You should do the same when drilling sheet metal of any type to prevent the metal grabbing and riding up the flutes as it exits the work.

Hi Jack

is that the angle of the tip of the bit, or the angle of the bevel on the cutting edges?
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#13
(02-15-2018, 08:43 AM)crokett™ Wrote: Hi Jack

is that the angle of the tip of the bit, or the angle of the bevel on the cutting edges?

,,,,,,,,,,,,,,,,,,
Dave, it's the angle of the spiral drill flutes...the standard angle is too steep for metals like brass, copper and bronze...You just need to "blunt" that edge a little so the bit doesn't "ride up" the flutes..That's another reason to have dedicated bits just for brass...They don't work very well for drilling steel...

I found a video that explains it very well......starts about 43 sec

https://www.youtube.com/watch?v=pAngKHIZgyA
Often Tested.    Always Faithful.      Brothers Forever

Jack Edgar, Sgt. U.S. Marines, Korea, America's Forgotten War
Get off my lawn !
Upset





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#14
Thanks Jack. I don't mind having a separate bit for this work. I will only be drilling 1 size hole. I'll get a bit in the diameter I need and modify it.
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#15
Get some cutting wax while you're at it. Lots of names but it's cutting tool coolant in stick form. Much cleaner than oil.
Blackhat

Bad experiences come from poor decisions. So do good stories. 


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#16
(02-14-2018, 01:22 PM)crokett™ Wrote: I'm wondering how accurate this is

http://images.meredith.com/wood/images/p...dchart.pdf

I have some aluminum and brass to drill - diameters won't be more than 3/8" and the speeds listed are about 2x what I thought.    Can I use a light oil such as 3 in 1 as the cutting oil or should I have some actual cutting oil?  The blanks have already been drilled to 7mm.

I changed the title because I'll actually be drilling these on my lathe.

Timberwolf is correct, modify the spiral edges. You can still use the same bit for steel , wood etc. You do not need any lubricant for brass. Kerosene , WD-40  or any thing like WD-40 is good for aluminum. Aluminum tends to gall the spirals, kerosene or WD-40 prevents it. 
mike
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