Thread: Greg's laser Zero On/Off

Hi Noel
As long as the laser can operate with 5 dc volt then yes you can connect it to an output pin on the Bob and power it that way.

Switching it on and off would be part of the Macro to zero the X and Y axes.

If you hang for a while I have crosshair lasers in transit and will be writing the VB code to a macro in the fullness of time. I might add it to the console project thread for my own reference later. I did all the wiring and codes for the LeBot console last night and found it unvaluable to go back and read how to do it.

Rod - again - thanks for the rapid response.

I already have the crosshair laser and have made a holder for it on my new spindle mount.

I am ok with connecting the laser to the BOB (with a resistor to lower it to 3.3 volts. What has got me confused is how Greg uses the Mist Coolant control to swith it on and off. I can't seem to find any reference to Mist coolant in mach3.
Maybe just not looking properly - I know it is M7 but don't know how to connect that to the laser.

Anyway - will look forward to your additions to your çonsole'post - as you said - I find this a great reference to look back to whenever I forget something to do with the console, or pokeys.

ps"have attached some code for on/off, zero laser, and auto-zero tool which I found on the net.

Cheers again.
Noel

Whoops - doesn't seem to have attached - I'll try again.
Noel

Hi Noel,
Go to "Ports & Pins" and selct the "Spindle Setp" tab and in the second box on the left is "Flood Mist Control"
Uncheck the "Disable Flood/Mist relays"
On the "Mist M7 Output#" box put in 5 and this will agree with the script code of Output 5.
Click "Apply" then click on the "Output Signals" tab.
Enable Output #5 and put in the port and pin that you are connecting the laser to. Not sure if it should be active low or high but try both until you jag it. I think it should be active high.
See how you go on this and let me know if it works - as I said I need to do this myself soon.

Can you let me know how you use a resistor to reduce the 5 volts to 3.3 volts and what value resistor do you use?
Thanks for the code that will save me some time not having to debug my own.

Noel

I am sitting in a hotel in Washington. Only a couple more days till we head home.

This is the code I use to turn the laser on and off,

If IsOutputActive(OUTPUT4) Then
DeActivateSignal(OUTPUT4)
Else
ActivateSignal(OUTPUT4)
End If

And this one to move the spindle into position,

DeActivateSignal(OUTPUT4) 'This turns my laser off
Code "G91 G0 X -33.2 Y -57.5" ' put the relevant offset amounts here
While IsMoving ()
Wend
Code "G90" 'set things back to absolute
Msg = "Zero X and Y DROs?" 'question for message box
Style = 4 + 32 + 0
Title = "Laser Zero"
Response = MsgBox(Msg, Style, Title)
If Response = 6 Then 'if reponse is yes then zero the DROs
SetOEMDRO (800,0)
SetOEMDRO (801,0)
End If

Greg

Hi Guys
thanks for the response.

Greg
Many thanks for bothering while you are away (hopefully enjoying youself) to send detailed response. Thanks

Rod
Thanks also, and have attached a pdf file of a mud-map drawn for me by my electronically-gifted friend (also named Greg).
As you will see, Greg suggested that I place a 1.7v/150^^ resistor in the circuit from 5v to the diode(laser) then to earth.
He said that the way to work out what resistor is need is to subtract the voltage of the laser (3.3v) from that of the supply (in my case, 5v) , the result is the size of the resistor (for me, 1.7v).

Hope this makes sense.

Cheers
Noel

Can one of you gents please post a link to these lasers or atleast a picture?

thanks
Michael

Can i chime in here? That circuit is used to set the current for a LED usually around 20 milliamp, determined by the input voltage.
Laser diodes are different from LED's (although they are similar, just pushed harder). Putting a resister in series with the laser in my opinion would not be the best way and might not allow the laser to work as .. a laser.. due to current being limited by the series resistor. Can I suggest a better if not a little more complicated way to guarantee the laser will operate as expected. Use a voltage regulator to set the voltage to 3.3volt and let the laser draw the current it needs. Refer to
LM2937-3.3 - 400mA and 500mA Voltage Regulator
An LM 317 adjustable regulator could also be used to set the 5 volt to 3.3 volt out for the laser.
Just my thoughts.
regards
Peter

Found it in one of the CNCZone posts for those of you interested in this unit

DealExtreme: $4.06 Red Laser Module - Focused Cross (3.5V~4.5V 16mm 5mW)

Here is a link to the thread over yonder:

http://www.cnczone.com/forums/showth...t=48752&page=1

/Michael

Thanks Noel

Peter,
I had a look at the LM317 - how do you adjust the voltage on those?
Also on the LM2937 it looks like you have to attach caps to either side - is this the case or are they built into the component?

Try this little program. Very useful (I even use it at work).
I also have order a laser diode now that my machine build is well under way.

I setup a laser crosshair on my unit, after readings Greg's original post. I must admit, when I looked at automating it with Mach3, I decided that the return was far less than the effort involved. I hooked mine up to a
2 X AAA battery holder, with an inbuilt switch, from Jaycar for about $5. Switching it on/off when I need to use it takes very little effort.

Hi Guys
Yes - my 'techo'guy is in agreement, and says that if we can wait a weeh or two until he is back from holidays, he will make aa couple of untis, all nicely mounted in boards.
""Noel - Yes, he's probably got a point Noel, I WAS using a LED as the model -- if the laser needs a constant voltage rather than a set current the way to go is with a voltage regulator
I am unaware of any regulator that will give you 3.3 from a 5 volt input, most of them (and the LM317 is one such) need about 2.5 -3 volts headroom to do their job -- but that should
not prevent you using one, just run it from the 12 volt rail. The LM317 is adjustable with 2 resistors (or 1 resistor and a pot) from 1.2 - 37 volts and comes in a few variations package wise
It has a maximum current capacity of 100 ma in a small TO-92 package up to 1.5 amps in a TO-220 package and the larger is probably the best for your application because it will run cool
forever at the small current you need without having to manufacture a heatsink. If you want to go for total overkill there is also the LM338 which is a 5 amp version and would just loaf along
at this current. I have all of these here in the cupboard so you can just take your pick. I would like to see the datasheet for the laser, do you have a link to the manufacturer. The reason is that
I am wondering if a constant voltage source with adjustable current limiting may not be the way to do it, just uses 2 of the regulator chips set up in 2 different modes.
Kate and I are off to Canberra Saturday morn but I can organize a package of parts and the circuit to run the regulators before then if you need them -- if there is no major hurry, i can make a PC Board
and build the regulator for you when we get back.""

At this stage I am going to wait and see what he comes up with in a couple of weeks. If it works (as fully expected) - are there others out there who might be interested in one?
If so, just email me.

Cheers
Noel

Hi Noel,
I have said it before but just to get it off my chest one more time I hate this mumbo jumbo electronics.

I think your techo is heading off on a tangent. The objective is to get 5 volts from the output pin of the Bob to run the laser. The laser needs to be switched by Mach3 control thorugh the bob to operate the laser. If I read his response incorrectly refer to my first sentence and then wack me on the back of the head.

I may be able to help you here as I emailed one of my nurdy mates (I say that with respect) and he came back with this regulator but also with a couple of questions that I couldn't answer so while it looks promising for getting 3.3 volts from a 5 volt source it may not be.

So rather than get bogged down with detail about something I know very little about I went back to the spec of the laser crosshair ( link ) and found out the one I got will work on 5 volts. It only costs $6.50 AUS so rather than bother anyone with making a regulator I think this might be a better solution - for me anyway. It is held up with the air traffic in England but will let you know if it works straight out of the Bob.