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Cutting Aluminium
« on: May 05, 2015, 08:03:52 AM »
I bet it has been asked a thousand times but here goes.

I'm attempting to cut some Aluminum sheet 12.5" thick,
Some pockets will go right through up to 2" diameter. A profile around the plate will be approx 9" x 4"
There will be a few 6mm slots.

My bench mills fastest speed is 2100rpm
If I use a 10mm 3 flute slot drill and cut at 0.5mm per pass , what speed should my table be running at in inches per minute to get best results.
I'll mist with white milky stuff from a spray bottle.
Is .25mm per pass too little ? What is the easiest grade of aluminum to cut?

George
One step at a time!
Re: Cutting Aluminium
« Reply #1 on: May 05, 2015, 08:08:23 AM »
I bet it has been asked a thousand times but here goes.

I'm attempting to cut some Aluminum sheet 12.5" thick ..............
 

George

Hi George,
 No, actually I think that is a first.  ;D

Russ
 :)
Re: Cutting Aluminium
« Reply #2 on: May 05, 2015, 08:34:14 AM »
I bet it has been asked a thousand times but here goes.

I'm attempting to cut some Aluminum sheet 12.5" thick ..............
 

George

Hi George,
 No, actually I think that is a first.  ;D

Russ
 :)
Brilliant :-)
One step at a time!

Offline rcaffin

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Re: Cutting Aluminium
« Reply #3 on: May 09, 2015, 03:03:42 AM »
Quote
I'm attempting to cut some Aluminum sheet 12.5" thick
I will assume you are going to use several passes, maybe 0.25 mm...
Quote
My bench mills fastest speed is 2100rpm
If I use a 10mm 3 flute slot drill and cut at 0.5mm per pass , what speed should my table be running at in inches per minute to get best results.
Evil fortune descends on he who mixes his units!
That said, you could start at 400 mm/min and see how that goes. It does depend a lot on your machine.
Quote
Is .25mm per pass too little ?
That totally depends on the rigidity and horsepower of your machine. That said, you should be able go up to 0.5 mm/pass without any problems, IF you are using a MILL. If it's a router ... 0.25 might be right.
Quote
What is the easiest grade of aluminum to cut?
That's a trick question. imho, the best cutting alloys are Fortal, 7075, 2011 and 6082, in descending order. But they cut OK. I use air-blast and the odd puff of kero/oliveoil mist for them.
The softer bending grades - 5nnn, 6060 etc, are like soggy chewing gum and are a pig. They clog the cutters - which then glow and break.

Cheers
Roger
« Last Edit: May 09, 2015, 03:05:16 AM by rcaffin »
Re: Cutting Aluminium
« Reply #4 on: May 09, 2015, 06:10:36 AM »
Thanks Roger, your comments are welcomed, I also love the comment "Evil fortune descends" I'll bear it in mind.   ;D it was 12.5mm thick really.

Best regards

George
« Last Edit: May 09, 2015, 06:13:19 AM by Len-Tikular »
One step at a time!
Re: Cutting Aluminium
« Reply #5 on: May 09, 2015, 06:19:07 AM »
12.5 inches ???????, or 12.5mm thick.

Let's assume 12.5mm thick on possibly a 1.5hp triac, but then 2100rpm is a bit slow for a triac.

With a 10mm 3 flute slot drill you should be able to run around the plate with one cut at about 150 - 200mm/min. Slotting or pocketing will be slower at about a third of open face cutting. I would suggest a two flute slot drill to get the swarf out better, you'll sacrifice a bit of cutting feed speed but benefit with swarf removal.

6082 is your friend with this sort of job, machines well and is cheap to source.

Offline dude1

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Re: Cutting Aluminium
« Reply #6 on: May 09, 2015, 06:28:17 AM »
you could get a 2 flut coated cutter one for aluminum and run a lot faster
Re: Cutting Aluminium
« Reply #7 on: May 09, 2015, 07:17:05 AM »
It's also going to be difficult to produce a 6mm slot with the 10mm cutter ... especially 12.5" deep.
Re: Cutting Aluminium
« Reply #8 on: May 09, 2015, 08:01:12 AM »
Thank you all, I suppose thats what I get for mixing inches and milli things  ;D

Here's a picture of my Mill, just to clarify. It's an Eagle25 purchased in UK. I think it is much the same as the Rong Fu 30 maybe ?
It has a 1 Horse motor.

Chuck fellows (and others) did a great job of converting their machines so I thought I would give it a try.
I'm not sure I like the Z axis conversion so I went searching and found a couple of alternative methods that I'd like to try.
I have attached a picture of my preferred route, I just hope the owner 'Pertsa' over on homemodelenginemachinist forum responds to my message.

And thanks daniel, I get myself some coated 2 flute cutters.

Regards to all

George
« Last Edit: May 09, 2015, 08:06:13 AM by Len-Tikular »
One step at a time!
Re: Cutting Aluminium
« Reply #9 on: May 09, 2015, 03:18:58 PM »
If you clog up an end mill throw it in some lye ( sodium hydroxide) and it will dissolve it right off without damage to the cutter. Small machines are a bit of a problem with spindle speeds.  You really want a high speed spindle because you don't have the ridgidity to use large cutters, yet you'd like to be able to drill a good size hole, which takes torque.  My homebuilt CNC has a minimill spindle at 3800 rpm, and a router from 8000 to 35000 rpm. Its not real stiff so in aluminum the router is way better.