PWM Logic High pin 4 not working on Laser output

[baccus61]

Hi,
I have been testing until I am blue in the face and I still can't get the laser to modulate on pin 1 and 4 of the laser output pins.
Logic LOW on pins 1 and 3 works well and goes from 4.8 volts down to 0.9 volts when adjusting the laser power.
I tried connecting up pins 4 and 5 and putting in a pullup resister but it wouldn't work either, and I tried about 5 different value resisters from 1K to 10K.
I tried setting up "laser with no pre fire" in the software with the same result. No pulse!

The pins on the general purpose outputs for air assist etc are always at 4.8 volts and I cannot turn these on or off in software.

Vector cutting is the same and I can only cut at 1 setting, about 80% of the rated output.

Any thoughts on this anyone ????

regards
Rich.

[baccus61]

I'm doing a run of 190 pieces for table decorations for a gala dinner right now and I DO indeed have power control on pins 1 and 3.
I did a test engrave on a piece of cardboard and it just burnt all the way through it to the table and I noticed that I had the power settings in software and also the HMI set to 90%.

I set the software and also the HMI to 10% and it engraved with about the right amount of power. I put a meter on the 1 and 3 pins and I was getting 0.7 volts which seemed about right.

I'm not going to change any settings right now as I need to finish off the job run but as soon as I do that I will be checking the settings and then setting up the rotary attachment for another run of 140 glasses needed in 2 weeks time.

I hope I can get it all sorted out long before then as time is running out.

I will post all results here for later use.
regards
Rich.

[Tech_Marco]

What is the model of RF you're using?

Send me detail output information and I'll forward that to my engineer to evaluate the data

[baccus61]

Hi Marco,
I'm using a 30 watt RF Universal Laser.inc metal laser tube.
Here is a link to my YouTube channel for a video of it running (old software and not the new one from LightObject)

http://www.youtube.com/watch?v=wi4dKAseDCg

I would still like the air assist to be able to be turned on and off through the software but I still haven't found a pin combination that works when the laser is running. The 4 GPO pins are always on and typically 4.8 volts.??

[Tech_Marco]

The link won't work. It's blocked and I can't open it

[Tech_Marco]

Hi Marco,
I'm using a 30 watt RF Universal Laser.inc metal laser tube.
Here is a link to my YouTube channel for a video of it running (old software and not the new one from LightObject)

http://www.youtube.com/watch?v=wi4dKAseDCg

I would still like the air assist to be able to be turned on and off through the software but I still haven't found a pin combination that works when the laser is running. The 4 GPO pins are always on and typically 4.8 volts.??

I just talked to my engineer, he said that he would go ahead to make a simple circuit board for that purpose. But you need to install a electric 'air valve' to your machine to work along with the circuit board . Remember, the air-pump will not be turn On or Off but the valve. Only doing this way will ensure air 'on time' when needed. Follow me??

[baccus61]

Hi Marco,
Wouldn't setting up and air valve to be turned on be the same as I have now with a solid state relay?
I switch my air pump on with a 2.5 - 7 Volt DC solid state relay. (SSR)

Another problem I am having is that I can't seem to get rid of the overstrike when I engrave. I set the parameters up about 200 times over the past few days and it doesn't matter what I do it always seems to overstrike by about 1mm.
I reset and also restarted the computer, I pulled the head off the rail and rebuilt it, Tensioned all the belts, Tightened all the pulleys and I still can't seem to get rid of the overstrike.

If I engrave under 100mm/sec it doesn't seem to do it but I can't lower the power enough to only engrave a little bit into the Acrylic I am using so it burns in about 1.5mm deep which is way too much.
Faster than 100mm/sec and it has an overstrike of about 1mm. I thought it was probably something loose on the machine but I have ruled that out by rebuilding each component.

I set the lines per mm to different amounts from small to large but it doesn't look good with a large stepover and a small stepover burns too deep. I ended up with 0.075mm step over which is about the best compromise.
I have wasted about $100 worth of acrylic mirror so far and I end up with about 1 in 5 bad parts. there doesn't seem to be any consistancy to it. Sometimes it engraves good and othertimes it will warp the font with a wave shape like something is loose but it always goes back to the start point so it's not losing steps.

I haven't got much hair left but I press on.
Being able to engrave and cut in the same file is really really good and I don't know how I got on without it before.
It's just a couple of ittle bugs that are getting up my nose.

I also wish I could stop the machine from homing everytime I turn it on. I would like to leave the machine setup in the one spot all the time and the homing sequence on a large table is a P.I.T.A. and wastes a lot of time.
Is there a way to stop this?
regards
Rich.

[Tech_Marco]

Rich, how long you haven't cleaned the focus lens? It may be a focus lens issue. Just open up the laser module, the one contained the focus lens, and take out the lens to check whether smog cover it up. If so, you got to clean that up or laser beam being diffused and cause problem. Also, send me pictures of your work and I'll forwad to my guys for evaluation. But one thing for sure wrong is that the #1,#3 is not supposed for RF laser. I review the manual and it said that for the RF laser, the connection should be #1 and #5 where #1 and #4 is for CO2 laser

[baccus61]

Hi Marco.

That would be too easy but is something that could be easily overlooked. I have cleaned the lenses and the mirrors and the output coupler on the laser (which is actually quite difficult) and also checked for any movement on the laser table mechanics because the double strike seems too evenly separated.
When I adjust the return interval it doesn't make any difference unless I set it to about 0.8mm and up to 1.2mm and the overstrike is about what the settings are. When I go lower than that the isn't any difference and the overstrike is always about 1mm in size.
It's enough to ruin any engraving I do. If I slow down the speed then the laser burns in too deep which is no good for glass engraving.

Today I had another good look at the mechanical side of things and found a ruined belt on th X axis from the motor to the reduction pulley. "GREAT", I thought!
I had tensioned it up that much I broke all the tensioning strands inside it. There was no visible evidence of anything wrong on the outside but it had a lot of stretch and the teeth were almost flat from riding on top of the pulley's teeth.
I thought I finally found the problem but I was wrong.

It cured the wavey font engraving but the 1mm overstrike is still there.

If I engrave lower than 80mm/sec then the overstrike is barely noticeable but the laser burns too deeply so I have to engrave faster than 150mm/sec which gives me the overstrike. It's a real conumdrum. I seem to think it's mechanical in nature because no software setting changes it but I have not found anything wrong with the setup.
I thought the speed of engraving had something to do with it but I have engraved faster with the old Linkmotion setup and Leetro controller and there wasn't any problems with that. (I just couldn't get the size right when engraving and that's why I changed to the Lightobject controller)
I have bought a set of linear slides for the Y axis that I will install probably after the Xmas rush and see if that changes things for the better. It should make a little bit of difference to the stability of the Gantry.

I just hope I can still engrave mirrors because that is our best seller around Xmas time. With the 30 watt laser I have to engrave at 3"per/sec so I hope everything will be OK. It takes an hour to do a 300mm square mirror at 340dpi.

I engraved 40 glasses today using 2% power and 200 mm/sec speed and I had to use a very simple Sans-Serif font due to the overstrike but if I don't say anything the people won't even notice it's there. Sometimes compromise is a good thing. but I can't do anything fancy though or I get a double image !!!!!

Later on tonight when I am back home I will post my INI. file so others may get a good head start and save them a lot of problems. This will only be useful for people with a large gantry set up like mine though.
I have one for the X-Y and also one for the Rotary attachment which works but is not completely tuned in yet.

The pins #1 and #3 are the only ones I can set power with and also turn on and off with the HMI (Human Interface) control pad. All the other ones will not work with the HMI or are always at 4.8 Volts. I cannot change them. Likewise I cannot alter the settings on the GPO pins for air assist etc. They are always on too.

One thing about having a well equipped workshop is that you can make or modify anything you want. Sometimes life is good.
Thanks
Rich.

[Tech_Marco]

Rich:

You don't want to turn On and Off of the air-pump but controlling a valve is better way. Remember, air need be there at all time. If you do On & Off on the pump, the pump can NOT response so quick as laser. The laser could be tens times per second for engraving so you will drive the pump "Crazy"! Think about auto-shop where an air tank get refilled once a while to support all thsoe air-driven tools. Same therory.
You want the air-pump keep pumping air with air pressure but use a valve to control instead.

Regarding the RF issue, did you do setting on the software? It must set to "RF" rather than CO2 for Pin#1 and #4. In fact, my guys are using RF in the shop and they have no problem about it. I'll discuss with them about the 1mm offset issue. But still, it's better to send us some images to see how the 1mm ended up with the result.

For the over-burn problem, can you use power to correct it? Is it just happening at the starting point or ... ?
What about at the end? FYI, there is one of the main issue that Mach3 won't be a good software to do engraving on CO2 laser but has to go through DSP controller. I think I'm one of the few who can use my 3Axis controller card to do engraving on Mach3 without the over-burn (still have a minor over burn though)

It's delay issue and it won't happen to CO2 laser. For the RF, I got to ask my guys why it happen. Was it because of wrong connection (#1,#3) or other issue. Wait till the guy from vacation

[baccus61]

Hi Marco,
All the set-ups I have used so far turn on the Air assist at the start of the job and leave it on until the job is finished then turn it off. It isn't tied in with the laser pulsing and so doesn't go on, off, on, off, etc with the laser.

I would like to be able to set up a job that takes 3 hours to do and come back whenever I want and the air assist is turned off. Right now I can't do this as the air stays on, wasting power, and wearing out the pump until I turn it off manually.
It's a bit of a pain.
I will try and make a video of what is going on and send to you or post to my YouTube Channel.
I have rewired the controller about 15 times so I have wires all over the place so it doesn't look pretty but it does work.
When I finally settle on a controller that works with the software properly OR I get it all sorted out, then I will rip all the wiring out and do it properly and neatly but until then It stays ugly.

I have set the proper setting in the software for the "RF laser with pre ignition" and 5KHz frequency so it should work with pins 1 and 5 but it doesn't. They stay at 4.8 volts all the time no matter what I do so the laser is always on. The same with the GPO air assist pin. Always on!

The only way I can correct for overburn is to lower the speed to under 100mm/sec but the laser power is usually too much at this speed and burns too deeply. I have set my laser power settings to 2% Min and it shouldn't even be working at this low level. The sticker on the side of the laser tube says 7% minimum power setting.
Under 100mm/sec it is still too strong for glass engraving.
Rich.

[Tech_Marco]

Ok, I'll discuss with my enginner see if a solution for you. Do you have a scope by any chance? I just want to know whether the output (4.8V) is pulse (it should be) or DC.

FYI, I want to carry "micro oscilloscope" that support up to 1MB only but it is very small, as small as small MP3 player (or a credit card size but thicker). I think it's good tool to have for most CNC and laser guy

[baccus61]

Yes, I do have a 4 channel, 100Mhz scope but I'm only a novice on using it. I bought it to tune up some servo motors but only used it once 2 years ago so if you could walk me through how to connect it to the board then I can give it a shot. I think it's pretty simple just connecting it to the output pin and negative and then setting the right frequency multiplier.
Thanks. Rich.

[Tech_Marco]

Yes, it's pretty easy. First of all, set the Volt/Div to 1V. I'm assuming you have 10 by 10 division so that the center line is lay on 5 by 5. 1V/div means that the top line is 5V and bottom line is -5V while the cetner is 0V. We know that the output is 5V at most (4.8V in your case), so that the pulse or DC will not exceed the viewable area. It should let you you see either a straight line on top of the screen once your probe connected. Now, come to the Time/Div. I believe that the pulse from the card shouldn't go over 5KHz. So, set 1ms/div or high should be good enough to let you see the wave-form (if any).

Simply connect the Pos(+) of the probe to the #4 and then connect the ground of the probe to the pin #1 (Ground). If output look like something other than a straight horizontal line, it means that the output could be pulse. Then tune the Time/Div knob either higher or lower see should get you a nice square the wave-forms. It could be square wave in different pulse width.

Try it with laser power off so you won't file beam by mistake!

[Tech_Marco]

Rich:

Which card do you have? Can you send me a picture of the card you received?
Also, try connect #1, #4 for a RF laser. On the software side, there are two different RF modes. Try one of each.

For the 1mm over-strike, my engineer said it must be wire issue. It's better you post pictures here to address your case.


Marco