Building my second cnc router

[HomeCNC]

I wish I knew more about electronics. It is interesting that your motors are higher on voltage but lower on amps than my servo motors. My motors are only 36 volts but are 5 amps. I wonder what is better, more voltage or more amps?

[ToyMaker]

Which is better, volts or amps?

It depends , One way to look at it is by power.

Here's some arithmetic;
Eric's motor: 110Vdc @ 1.1A, R=E/I, Ohms = 110/1.1 = 100 Ohms
Current at 80V, I=E/R, Amps = 80/100 = 0.8 Amps
Power P=E*I, Watts = 80 * 0.8 = 64 Watts
Horsepower 1 hp = 746W, 64W = 0.08 hp

Jeff's motor: 36Vdc @ 5A
Power P=E*I, Watts = 36 & 5 = 180 Watts
Horsepower 1 hp = 746W, 180W = 0.24 hp

So... under full rated load Jeff's motor is going to put more "rubber on the road" so to speak. I think that Eric's motors will deliver a higher no-load speed because of the higher drive voltage (the motor has to turn faster to build up the counter emf).

robotic regards,

Tom

[balsaman]

Tom, correct me if I am wrong. The motor will draw something less than the rated current when not loaded. Loading the motor will make it draw more current. If that is true, i will be able to make it draw 1.1 amps at 80 volts (the gecko's have a max current trim pot), so watts is 88, and the HP is .117 in, something less out, as the motor isn't 100% efficient.

I think both motors will work fine (I hope). Probably Jeff's are better.

Eric

[ToyMaker]

Eric:
You are right. Your motor will draw a lot less than rated amps when not loaded. In fact it will draw just enough power to overcome the friction in the bearings.
But that is not the whole story. I think the Gecko drives are choppers. That means there is the frequency of the chop signal and the inductance of the motor coils to take into account too (it's a never ending story ).

robotic regards,

Tom

[balsaman]

I will find out I guess. I know those motors will have lots more torque and speed than the steppers!

I managed an hour or two in the shop today. I got the base of the machine done. I am glad I won't have to paint this one. I hate paint!

This thing is rather large. How come it always looks smaller on my computer screen?

Eric

[paulried]

Because you need to get a bigger computer screen!

I want one that has a sticker on it that says "Images shown on this screen may be larger than real life" like the mirror on my car!

[HomeCNC]

Well knowing you, your motors were most likely FREE!!!! And free always beats most anything.

[balsaman]

Hi everyone.

Today I cut the gantry sides out of 6061 aluminum plate. I cut it 1/8" oversize on a bandsaw then used my wood router to clean up the sides and cut the pockets in for the extruded aluminum. My wood router doesn't like the aluminum too much but it's fine if the feed rate is kept down. This was all done at 3" per minute up to 9" for some lighter cuts. Turned out pretty good.

here is a pic of the router cutting aluminum...lots of chips. The dust collector was going but most of the chips stayed behind.

[balsaman]

Finished parts. Pockets are .125" deep. They keep the aluminum channel from turning with just one bolt in the middle. I will also add some triangle gussets to keep things rigid/square.

[balsaman]

Trial fit. It's going to work!

[balsaman]

One more....

[HomeCNC]

Alright Balsaman, another aluminum built router on the way. You will be able to do much more with this router than cut balsa. YOur going to half to change your name!