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View Full Version : Help!! Machining Alum with a cnc router.



duraflap
03-21-2005, 11:57 PM
I need help with machining alum with my cnc router.
Can you help me out?
Thanks in advance

psychomill
03-22-2005, 12:40 AM
What kind of help do you need? Can you be a little more specific? What problems are you having?

duraflap
03-22-2005, 11:54 AM
Hi there
I'm using a .250 spiral up bit with a spindle speed of 10K, the slowest speed on my Porta Cable 3 hp router.Cutting dry at about 40 ipm feed speed and multiple passes of .05 using kerosene brushed onto the work surface for a lube. This all works great on T6 alum but not on softer material. I've played with the feed speed and cutting depth with no improvement so far.
The problem is that the soft alum sticks to the bit and if I continue, will fuzz up the cut and pile the material up the sidewall instead of creating chips.
I realize the spindle speed and dry cutting are not prefered, do you have any options for me?
Thank you for your help
Dennis

DareBee
03-22-2005, 01:18 PM
A 4 flute cutter should run closer to 80 IPM at that RPM (2 flute would be about right), but your biggest problem is coolant/lube. You really need to get a heavy dose of it on there. You could also try a TIALN coated cutter, might help keep the chips from welding.

psychomill
03-22-2005, 03:22 PM
Coolant!! :D

Kerosene is not enough lubricity especially at your minimum RPM with that size cutter. May want to try a slower helix tool as well since you can't get slower on the rpm. The helix angle may pull the material too fast for your set up. Are you cutting an extrusion?

duraflap
03-24-2005, 10:15 PM
Tomorrow I get to play with this problem again. I'll try these suggestinons and hopefully have a home run. Thanks to you all, I appreciate the helpful suggestions.
Dennis

duraflap
03-24-2005, 10:18 PM
Just a different thought. Does anyone know of an electronic speed reducer that will work on the big Porta Cable router? Anyone know how to slow the router down?
Thanks

JRoque
03-24-2005, 11:52 PM
Hello. I've had problems cutting aluminum with 4 flute endmills. TiAlN, 2 flutes @ 6000 RPM does the trick for me.

As for the Porter Cable speed control, there's nothing you can add externally to slow it down. If you really want to do that, and void the warranty in the process, you can remove the speed control on-board the router and wire it directly so you can use an external speed controller for universal motors. A few things to keep in mind: common speed controllers might exceed the power rating of the motor, at lower speeds you won't have full HP output, lower speeds will not operate the fan at the required rate and overheat the motor.

I also own a PC router which I used for about 2 months before giving up and making my own spindle with a DC motor. Life's good now or at least better than before.

JR

Nono
03-25-2005, 12:04 AM
Anytime that I have cut aluminum there has been a high stream of coolant. Sounds like high RPMs means faster feed rate and less depth of cut but definatly more coolant. Sound fun whatever you are cutting

duraflap
03-29-2005, 12:11 AM
Well, The T-6 x still cuts just fine and the 4043 still gums up the bit and makes a mess out of the work piece. So... JRogue, how did you go about building your spindle from a DC motor? Would you care to share your ingenuity with this dummy? I think it is a great idea!!
Dennis@duraflap.com

duraflap
03-29-2005, 12:13 AM
By the way, thanks to all of you for your input, it is all helpful...many thanks
Dennis

JRoque
03-29-2005, 07:50 AM
JRogue, how did you go about building your spindle from a DC motor?

With a little help from my friends. Actually, a lot of help. Until I can get all the details under my machine log, check this thread (http://www.cnczone.com/forums/showthread.php?t=7004) for the entire discussion.

Regards,
JR

Don C
03-29-2005, 08:02 AM
go to a single flute bit, this will be like cutting at 5000 rpm. I use moble one water soluble coolant. The faster the travel the cooler the bit. I can cut 1/8 cuts at 70ips.

duraflap
03-30-2005, 09:50 PM
Thanks to you Don
I haven't tried your advice yet but it makes sense to me. I'll give it a test and see if this doesn't help my situation.

Don C
03-30-2005, 10:01 PM
Go to hartlauer-bits.com I use 63-725 bit. They also have a lot of good facts on the web site. I cut a lot of 1/4" aluminum in my sign shop. I have two old gerber AR400 machines.

duraflap
03-31-2005, 10:06 PM
I placed an order for the single flute bits today, they will be here tomorrow. From the info that the dealer gave to me, this should make a big difference. I'll keep you advised.
Thanks again
Dennis

Don C
03-31-2005, 10:22 PM
Their a great source for info and they supply most of the bits for the sign shops.
Thanks
Don C.

screensnot
04-01-2005, 02:32 AM
Try using alcohol as a coolant.

DareBee
04-01-2005, 07:46 AM
Try using alcohol as a coolant.

If you can't see straight it will look cool :wave:

JRoque
04-01-2005, 07:51 AM
Try using alcohol as a coolant.

Are we talking about a 6 pack or is alcohol really an option as a coolant? I thought alcohol might get things just a tad hotter being that its likely to catch fire and all that.

JR

Don C
04-01-2005, 07:52 AM
Its not a coolant problem as much as a lubricant problem. The speed of the cut will cool the bit, but the aluminum will clog up the spirals. I use moble one water soluble coolant. Its around $5 a gal at any graninger store and will make around 30 gal. when it dries up it doen't leave a lot of mess. I use a pressurized bottle and a cap tube from a A/C unit for a nozzle.

screensnot
04-01-2005, 09:40 AM
Flood coolant is best thats for sure. But when that is inconvenient for whatever reason, I use regular isopropyl in a spray bottle. Works great for light cuts on aluminum. Just a little mist every now and then. The quick evaporation cools really well.