Messages

31

General Mach Discussion / Re: PWM signal not showing correctly

« on: August 30, 2012, 09:00:54 AM »

No, mine is not even anything close to the pwm screengrab that you have attatchd. I`m starting to think that my version of mach 3 is very old. I have seen that the ports and pins setup tab dont have the pulley setups on it. This can only be seen by clicking another link further down from ports & pins. Also the spindle speed is not on the 1st screen either. I have looked for this box to try see what the spindle is running at, but its nowhere to be seen. This version was installed over a year ago, which make me believe that the pwm section might have not been working correct in this version.

I`m 1st going to try to see if i cant get all to work by tackling the easy things first before i try the z axis motor option. The pwm seem to be working great if it works with the s word commands in the gcode.

Can you possibly tell me what your scope settings were ?

Thanx again for your time and input.
Much appreciated
Andre

32

General Mach Discussion / Re: PWM signal not showing correctly

« on: August 30, 2012, 08:18:33 AM »

Wow, ...what are the scope settings on ?  I had my scope dialed to .1 and .2mv on both knobs...if that makes sense. Is a 20mhz scope sufficent to see these waveforms ?

Yes, i can say again, that i get nothing even close to this out of mach3..and all of this is why i cannot get the laser to output to different power levels.
The other thing i was thinking of is that the version i installed is too old maybe ? The version i have dont have the pulley ratio boxes on the ports and pins settings popup..its on a separate link lower down , and the speed of the spindle box is also not on the front screen as i have seen on others ...might this be why i have all of these problems ?

33

General Mach Discussion / Re: PWM signal not showing correctly

« on: August 30, 2012, 07:23:56 AM »

No, nothing yet.
Last night i hooked up my scope to a radio control receiver to view the pwm output. I can see the square waveform ,only parcially , which make me believe that the pwm on mach3 might be more difficult to view than i expected. After playing around and taking everything into consideration, i hooked up the servo tester board to try adjusting the pwm signal manually ...basically same as all the other testing circuits i have seen , but adjusting the power level manually. This obviously works, which make me believe that the problem might be at the Homann controller itself.

I was thinking that the controller might be adjusted to high on the output side , so it will output a high power level all the time...not sure, but i have not checked this closely enough yet.

If i fail to get it all working and the problem is not the homann board level adjustment, i will then revert to the next thing that i have though about.

By using  a 3rd stepper motor on the z-axis , i can adjust the trimmer pot manually by building a unit that will turn the trimmer up and down by setting the GCode on the z axis. I have read some comments bout this , but have not actually seen it in the workings.
This works correctly as i have played around with the little controller board , but then i was thinking how on earth would i control the trimmer pot automatically if i have to turn it by hand now.

The z-axis should work fine for this, but the only thing that i wonder about is if the z-axis will turn the pot fast enough to adjust the power level correctly. I cannot remember the amount of trimming required to adjust the level, but i think this is the way to go and i should come up with a very workable solution. Once i have played around with the amount of turning that is required for the different power levels, the idea should work great.

It would be fantastic to hear from someone that has done this already.

Comments anyone ?

34

General Mach Discussion / Re: PWM signal not showing correctly

« on: August 29, 2012, 07:29:05 AM »

Wel, i 1st had pin 16 as the output pwm pin , then changed it to pin 1 to make sure it was not something on that specific pin. When i disconnect the pin, i get no laser output ..or if i make it the wrong pin number, it also stop the laser to work, so it has to be the correct pin. I even removed the wire that goes to the controller unit to make sure it wasnt that, but nothing changed.

I`m really confused.

But i have another plan. I`m going to take one of my radio control esc`s and use a pwm generator unit that they use for testing servos. This will generate a pwm signal on the input of the controller unit. This should show when i run the laser , but obviously it will use the pwm singal of the servo tester. This should work right ?
The servo tester generates a nice pwm signal. I have scoped this before to get an idea of the pwm signal.

But i `m still confused for now 

35

General Mach Discussion / Re: PWM signal not showing correctly

« on: August 29, 2012, 04:00:00 AM »

I`m willing to try anything that i have not done before inside the GCode..

THanx will give this a try when i get home..

Andre

36

General Mach Discussion / Re: PWM signal not showing correctly

« on: August 29, 2012, 03:50:46 AM »

Hi

No, i have used the code as described by other laser users. No M3 command , just the M commands followed by a axis movement as described in other threads. ..below is an example :

11 G0X0Y0Z2
21 G1Z-2F100
25 S100
31 M11P1 (laser on)
41 G1X10Y10
51 M10P1 (laser off)
61 G0Z2

37

General Mach Discussion / PWM signal not showing correctly

« on: August 29, 2012, 02:55:18 AM »

Hi All

I have been at this problem for weeks now. My laser switches the beam either on 100% or off , there is no control of the laser intensity when i use S10, S100 , S1000.
The signal coming out of the selected pwm pin (1 in my case) , does not show on my scope as a square wave at all. When the signal switches on to fire the laser, it just show the trace on the scope screen to jump up a few notches ...still as a straight line and the amp meter shows 30MA. That is all that happens. I have played with the base frequency and kernel speed, but the same results keep showing. Basically the GCODE only responds to the on/off code (M11p1 & M10p1)...there is no control by using any 'S' command. My question now :

How difficult is it to see a square wave pwm signal on the scope (My scope is capable of signals up to 20 megaherts)  ? I have played with all the knobs trying to see any signal, but nothing, i mean the square wave should show up quite easily  ..??

The other thing that is worth mentioning is that the printer port cable is about 2 metres long running all across the machine to the other side where i have found a nice place for it to sit inside the machine....can this possiblly cause problems with the pwm signal ?

I know that i should have a clean pwm signal before i look for the problem down further. Why would the trace on the scope only show a shift in the trace line itself instead of a square wave ?? I have played around with the base frequency from 5 all the way up to 9999999 , in which case mach3 make it 41666 or something like that.

Should i be bothered by the pwm signal not showing correctly, or am i totally on the wrong track here ?

Any help would be greatly appreciated as i`m not sure where to go from here.

Andre

38

General Mach Discussion / Re: Laser Focal lens selection method

« on: July 05, 2012, 07:10:11 AM »

Hi

Yes, the actual one that came out is GaAs lens. On Ebay they go for about $60.
So what you saying is that once i have measured the distance from the lens down to the workpiece surface , that is more or less the distance. So it will either be 38.1 , 50 , or 60mm , as this is what i have seen on Ebay.

I will do some measurements tonight. I have not even thought about that the lens need the the round side up and the flat side down, but now that you mention it, i have seen it like that when i took the lens holder out for cleaning.

Thanx for the info Tweakie
much appreciated
Andre

39

General Mach Discussion / Laser Focal lens selection method

« on: July 05, 2012, 01:17:14 AM »

When my laser focal assembly fell on the floor and the lens inside broke in small pieces, i was really wondering if it was possible to find a replacement lens. When i got onto Ebay, i  was astound that this little piece was readily available.
My problem is now that there are different lenses with focal sizes and colours.
How do i know what the focal length is. The lens that broke was dark grey in colour. Is there a reason for the lens colours ? I have seen orange one`s and my one that broke is grey in colour. Does the colour mean anything ? What focal size do i go for? I have seen 40mm, 50mm and so on ..i`m confused. How do i make this selection?

The lens size in diameter is 21mm, so i have that one covered, but what about the rest. The method for getting the focal distance correct when the laser was still working was to put a small piece of perspex 2mm thick under the cutting nozzle. The laser has a big tube (1,8 meters long) that has a spec of  100Watts.

I was thinking of measuring the distance between the last mirror that shoots the beam down up to the focal mirror position, and take this as the Focal distance measurement..

Any info will help.

Thanx
Andre

40

General Mach Discussion / Re: Cnc code for laser switching

« on: June 07, 2012, 04:09:15 AM »

Ok, fantastic. Im starting to get the idea

Never thought of  treating the laser power adjustment as a  toolchange, but it must get very tiring when you run a big project.
I will give Lazycam a try with the post processor you attatched.

Thanx again for the help and recommendations 

Regards
Andre