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Author Topic: Drilling soft Metals  (Read 5458 times)

JayDee

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    • JOHN DOWD
Drilling soft Metals
« on: September 16, 2007, 07:35:26 pm »

Hello,
Drilling Brass, Bronze, Copper or any other non-ferrous metal, with a standard drill bit, is not easy!.
The cutting edge of the drill spirals into the soft metal and can break the drill, or pull the drill out of the chuck.

The cutting edge has to be modified from the standard edge, but, once modified, must only be used to drill non-ferrous metals, used on Steel will destroy the drill bit.

Hold the largest drill bit you have, by the "chuck" end and look at the cutting edge, it sweeps down to a sharp end, this edge has to be made flat.
This flat must be vertical to the body of the drill, so instead of a sharp edge there is a small vertical flat where the sharp edge was before.
Do not "blunt" the drill, the flat should be in line with the body of the drill, a line drawn up across the flat should reach the Chuck.

This flat edge will enable the drill to produce "chippings" rather than the normal spiral cuttings, it will stop the drill from grabbing into the soft metal.
A small grindstone in a Dremel or similar tool, will quickly grind the very small flat required
The drill can now be run at the normal speed for the diameter of the drill and will give a much better finish to the hole produced.
A drill bit modified as above can drill Plastics, Lead, Aluminium, all the things that were "hard" to drill previously !!.
BUT !, if the modified drill bits are used on Steel, they MUST be resharpened first.

This is very difficult to describe and even harder to draw!!, but oh so easy to do !!.
Lathe tools also benefit from this method of making a small flat on the cutting edge, but they too can then only be used on soft metals, until they are resharpened.

John,    ;)  ;)  ;)
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Bluebird v2

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Re: Drilling soft Metals
« Reply #1 on: September 16, 2007, 08:00:09 pm »

hi there JayDee (John)

I cannot draw either, but did a scribble and hope this helps - and if you dont mind. also, it may help if you use paraffin as a coolant whilst drilling or machining non-ferrous metals.


aye
john e
bluebird
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JayDee

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Re: Drilling soft Metals
« Reply #2 on: September 16, 2007, 08:09:08 pm »

Hello Bluebird,

Hey thats one neat drawing !!.

Exactly correct too, yes, using paraffin helps, but it is not answer to the problem.
Drillbits are supplied sharpened for drilling Steel, on Non- ferrous or Plastics they are wrong, they can be used "as is" but once you have use a modded one you realise what you have been missing!.

Thanks a lot.
John.
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riggers24

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Re: Drilling soft Metals
« Reply #3 on: September 16, 2007, 08:12:36 pm »

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Bryan Young

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Re: Drilling soft Metals
« Reply #4 on: September 17, 2007, 07:09:02 pm »

Hello Bluebird,

Hey thats one neat drawing !!.

Exactly correct too, yes, using paraffin helps, but it is not answer to the problem.
Drillbits are supplied sharpened for drilling Steel, on Non- ferrous or Plastics they are wrong, they can be used "as is" but once you have use a modded one you realise what you have been missing!.

Thanks a lot.
John.
I'm probably wrong again but I find that the problem with drilling plastics and acrylics is that the stuff melts and keeps on making the hole bigger..and its a sod to get off a small drill bit. I've also found that when drilling aluminium it works just to drill a little, withdraw the drill and clean it as the end of the drill seems to get "compacted" with semi molten ally. Normally cleans out with a finger nail (still attached to the finger).
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gribeauval

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Re: Drilling soft Metals
« Reply #5 on: September 17, 2007, 07:35:30 pm »

I'm probably wrong again but I find that the problem with drilling plastics and acrylics is that the stuff melts and keeps on making the hole bigger..and its a sod to get off a small drill bit. I've also found that when drilling aluminium it works just to drill a little, withdraw the drill and clean it as the end of the drill seems to get "compacted" with semi molten ally. Normally cleans out with a finger nail (still attached to the finger).

The answer Bryan is to drill SLOWER and use a coolant.  ;)
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Captain Povey

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Re: Drilling soft Metals
« Reply #6 on: September 25, 2007, 12:54:13 pm »

Hi All, The problem I have found with drilling aluminium is that I drill too fast both in rotational speed and in feed so heat is generated and the stuff welds its self to the cutting edge. Drilling slower with coolant is good but if the hole is small and deep the coolant has a job to reach the cutting edge as it cannot get past the rising swarf. Big drills often have holes through them to overcome this and deliver the coolant where it is needed but for the small drills a woodpecker action, as it is sometimes referred, to is useful. I think there are also some special drills for these materials which have different cutting and flute angles which allow the swarf to clear faster. Cheers Graham.
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Tom Eccles

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Re: Drilling soft Metals
« Reply #7 on: September 25, 2007, 07:58:17 pm »

There is a wonderful little publication called ZEUS. published by Buck & Hickman of Coventry U.K. which offers lots of information on such diverse topics as drill sizes, thread data, ISO fits, hardness comparisons sine & tangent charts, bending allowances etc. I used mine extensively as an engineering inspector.

I recommend it to the house.

Clegg
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Captain Povey

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Re: Drilling soft Metals
« Reply #8 on: September 25, 2007, 10:28:29 pm »

Hi Clegg, Yes I still refer to my Zeus as well. Not sure Buck and Hickman still exist but there is a lot of stuff on the J&L Industrial Equipment on-line site. Cheers, Graham  O0
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White Ensign

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Re: Drilling soft Metals
« Reply #9 on: February 09, 2008, 11:05:04 am »

.... had the same problem, went back to the data sheets. Drilling aluminium you should start by pre-dilling with smaller dia and use a coolant agent. I use white spirit or pertroleum, works brilliant. Most important is just do little steps, brake the chips coming out as they get the bore out of direction.

Hope that was out of any help,
Jörg
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bogstandard

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Re: Drilling soft Metals
« Reply #10 on: February 09, 2008, 01:28:36 pm »

The best drills to use for non ferrous, if you can still find them are bullet point drills, great for sheet metal as well. They drill straight as a die without centre drilling. A lot of drills now are being ground with four facets, these have a much shallower angle and will start cutting straight without the use of a centre drill, and cut with much lower pressures. The only metal that should be done with a zero rake angle (as described before) is brass.
Coolants are, ali - paraffin, brass - none (if brass comes off as a spiral, it is most probably an alloy, normal brass comes off like sharp splintery dust), copper - tallow (if you can catch one) or full cream cows milk, everything else just standard cutting oil, but if doing a quickie, WD40 for everything.
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Bunkerbarge

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Re: Drilling soft Metals
« Reply #11 on: February 09, 2008, 03:21:27 pm »

Hi All, The problem I have found with drilling aluminium is that I drill too fast both in rotational speed and in feed so heat is generated and the stuff welds its self to the cutting edge. Drilling slower with coolant is good but if the hole is small and deep the coolant has a job to reach the cutting edge as it cannot get past the rising swarf. Big drills often have holes through them to overcome this and deliver the coolant where it is needed but for the small drills a woodpecker action, as it is sometimes referred, to is useful. I think there are also some special drills for these materials which have different cutting and flute angles which allow the swarf to clear faster. Cheers Graham.

The trick there Graham is to regularly "clear" the drill tip by removing the drill regularly after going another couple of mm.  This clears the build up of swarf from the drill and allows coolant to the tip.  On a small diameter deep hole you may be clearing the drill every few seconds but it is the only way to ensure a clean accurate cut.

Soft metals particularly do not generate a long swarf that will travel up the flutes and the chips will simply pack into the area of the tip and cause overheating, build up on the tip, the cut wandering off centre and damage to the sides of the hole.
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IainM

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Re: Drilling soft Metals
« Reply #12 on: February 09, 2008, 08:41:30 pm »

On the subject of Tallow ........
get a pack of Richmond Irish Recipe sausages and a lean mean griiling machine and 9 minutes later you have a goodly amount of tallow!
Eat sausages whilst waiting for the tallow to cool off.

Two for the price of one ...... whahee  :D

Great for turning copper in the lathe or for tapping holes.

Iain
(Can you tell I'm an Aberdonian?)
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