Natalie's 2.x Build

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Re: Natalie's 2.x Build

Postby eilatan » Tue Nov 29, 2011 9:30 pm

bdring wrote:In normal run mode WP and ground should be connected to each other. There should be no voltage between them. WP probably has a pull up resistor so when it floats it goes high (5-ish V) when not connected. You have a problem in your safety loop wiring. Check continuity on each switch. Terminal to terminal on your switches must all be connected.

When checking continuity you either use the beep (preferred) or the ohm setting. You are looking for resistance not a voltage.


So i just checked for resistance between the WP and the ground, i got a reading of -134.4 ohms. which tells me that there is current running through somewhere. I rechecked all my connections and cant find short anywhere. I agree that the problem is in the safety loop wiring, but i am having trouble pinpointing where the break is. I removed my current reader from the positive line and gave the wires a direct connection. That allowed my interface panel to have some movement. So i have only my cover switched wired and the x and y limit switches are off to the side so that there is no interference. I did tap the ends together to make sure i would get a reading from mach, and i did. Also when push my emergency stop button it breaks the connection. One interesting thing i did notice was that when i have the cover open the WP and Laser lights on the LP/s come on. Cover closed, the lights are off. seems like it should be the opposite. Also, when i push the manual trigger button from the interface panel i get a pulsing, but the pulsing feels like its outputting to the y axis motor..

Thanks in advance for any suggestions.
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Re: Natalie's 2.x Build

Postby bdring » Wed Nov 30, 2011 1:40 am

Not much of this make much sense. I don't know what negative resistance is.

You should be measuring WP to ground at your laser power supply terminal block with it disconnected from the laser power supply. The resistance should be very low, like a few Ohms or less. There should be no voltage in this setup, so no current. If there is voltage, there may be a short on the board or one of the external connectors.

Connect your meter to ground on the PCB. All mounting holes are connected to ground on the PCB, so that is a good place to clip on. In voltage reading mode connect the other end of the meter to both WP and ground on the disconnected laser power supply terminal block. If you measure a voltage, you have a problem.
Bart
"If you didn't build it, you will never own it."
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Success!

Postby eilatan » Sat Dec 03, 2011 11:02 pm

I apologize for the confusion. Rookie mistake, i not only had the cover switch wired wrong but also had a few wires mixed up on the interface panel. So my laser is firing, and firing from mach! I have done a few test runs, both through cut2d and the engraving plugin for mach. I havent done anything too big yet because i wanted to get my exhaust and the air assist in place. Now that i have that set, i have a couple questions. The focusing mirror i ordered from light object is 18mm, I was under the impression then that the material must be 18mm away from the mirror in order to be focused. Slight problem there. My limit switch assembly on the gantry hits the bed before 18mm is reached. The air assist nozzle that i ordered from bart seems built for a 50mm lens. While i do get a nice looking cut with the air assist on, at max power there is an obvious etch, but no cut through. Is this something to be concerned about? I am only using 3/32" basswood to test so if im thinking correctly, that should cut through right? im running my cut at 30 ipm and max power. Does it need to go slower? at this point is it just about testing different speeds and power to get it right or is there some change that i need to make?

Another point. The round piece that goes around the threaded rod and connects the belt for the z axis motor keeps slipping. The screw that holds it in place is tightened but eventually loosens. has anyone else run into this problem. if so any solutions?
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Re: Natalie's 2.x Build

Postby Gadroc » Sat Dec 03, 2011 11:20 pm

You are confusing diameter of the lens with focus length. The lens that lightobects sell are 50.8mm focus length and either 18mm or 20mm in diameter.
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Re: Natalie's 2.x Build

Postby eilatan » Sun Dec 04, 2011 12:13 am

Makes sense, thanks for the clarification. So then the air assist is at about the perfect depth. So then is it normal that at 30ipm it etches maybe 1/3 the depth of a 3/32 material? Or do I just need to play with settings and run more tests?
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Re: Natalie's 2.x Build

Postby Gadroc » Sun Dec 04, 2011 12:27 am

No absolutes on setting to cut / engrave. Each combination of power supply, laser and optics will give slightly different results so people will just be able to give you a beginning setting which you'll have to test on yours. For example to get a clean cut with 1/16th acrylic I use 4mm/s cut speed using 6.2ma power. I can cut it much faster but the edges are a little rough. That's with a converted K40 machine using 40W tube and PWM power supply. I have not really tried to cut wood yet.
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