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Sunday, February 17, 2013

Green Monsters

"Green Monsters" is the name given to these more powerful motors. I just finished swapping out the old motors on two of the three axes of the CNC table. With stronger holding torque these, hopefully, will eliminate the occasional 'slip' problems I had previously.
Old motor left, "green monster" right
What better method to test these new motors than unleashing them on a piece of a aluminum! This next picture is a mystery boat part cut from quarter inch aluminum plate, as an initial test.
Test cut of aluminum
Further review of the existing electronics of the machine reveal that I am not getting %100 of the motors torque rating. The green monsters are rated at 400 oz-in. The previous motors are 260 oz-in. But the existing driver electronics can only supply up to 3.5 amps. The green monsters can take up to 4.2 amps (the old motors were set at 2.6 amps). So, while the new motors are better, there is still room for improvement by upgrading the driver electronics. Something to consider should I encounter problems in the future.

3 comments:

Colin said...

When you machine Aluminum, do you go full depth and one pass or multiple passes and a light finish pass at the correct size? I find the biggest problem I always have is the cutters. I use an older (tired) end mill for roughing followed by a specialized aluminum cutter to finish. As soon as the cutter heats the aluminum to 600/800 degrees F, the show is over, the aluminum becomes plastic and sticks to the cutter. Even with fluid pouring all over it. I have had one quickly clog. The Mazak faults and you have a mess.

Robert Sutton said...

Colin,

No way I could do it in one pass.

This piece was cut with multiple passes at 0.05 in depth with a feed rate of 10 inches per minute. This with a special single flute aluminum cutting bit. It took a while to cut. I am still trying to find optimal spindle speed. I already wasted one bit due to overheating.

A CNC plasma cutting table is what I really want, but cant really jusfy it (yet).

Colin said...

I was looking at a 42 for sale in Virginia last night. The owner bought it new in 1980. He added a long blurb about his rig and how the ketch rig doesn't work. Worth reading........
http://www.sailboatlistings.com/view/31922