laser on when connect

[beusx]

hi, i'm new user... i've a little "problem" , when i generate the g code and the program switch to the laser window, the laser go on for 2/3 seconds at the max power. how can i avoid this problem?
another quiestion...  there is possibility to view a preview of the work area? ( where the laser go to engrave)
i read the help but i don't find anything.
tnx and sorry for my english.

[Zax]

The first issue has been discussed here several times, the solution is to add a pull down resistor on the board or laser. It is not a software or firmware bug, it occurs when the microcontroller output is floating until Grbl has booted up. If you know how to load a hex without the boot loader that makes Grbl boot almost instantly which in most cases stops the pulse but it is much better to solve it with hardware as if the USB disconnects or something goes wrong the laser will fail "safe".

Yes, T2Laser has a virtual preview ("view") button which shows a simulation of the G-code and a trace or engrave frame option which previews the work area. You can find the trace / engrave frame feature on the Machine menu.

[beusx]

tnx so much for reply... ok for the 1 issue....
but the second, i need to see ( with eyes) where the laser go to engrave...a preview " on table" ( the same of "preview" on ElekCam) ... i hope u understand me... sorry for my english.
tnx again.

[Zax]

Yes, that's exactly what "Engrave Frame (Laser ON)" does.

It's in the Machine Menu and uses the laser power you set in the manual laser power box. So if you want to see it, set a low number, if you want to burn it set a higher value.

[beusx]

ok, so i have a problem with my laser.
when i click "engrave frame" or "trace frame"...it show me the full frame ... not where what i draw will be burned ( engraved ).
so how can i know where exactly my work will be engraved on the frame? 
tnx and sorry for my stupidity.

[Koskee]

I think I know what he's saying Zax..

Say if you do a sketch and have it set to 400x300 (one of the options) and then draw whatever on any part of the screen. When you go to trace it, it always traces the 400x300 area, not just the part  that will be burned.
Not sure how you'd implement this, but maybe if there was an option to do a low power burn @ laser power 1? I suspect this is already possible by overriding the laser power, but if there were enough people that wanted it,  could be separated into a button to help get a visual of what a full sized sketch might look like? I dunno.

[Zax]

Yes, that is correct as generally you would input the Sketch size for the work piece and not the whole machine area. So you want the frame to show you how to position the material.

If you use Center Start (without Absolute selected) it will frame only the drawing elements on the Sketch as shown, but of course you would need to set home to the center as shown by the orange origin marker on the view.

The other option would be to edit the frame mode text, replace Abs. (absolute, meaning the entire Sketch page) to Extents (just a rectangle bounding the engraved points). I realize this is a workaround, and of course it's simple for me to implement in the next version but no one has requested it. I will add a frame extents override option to the settings menu.

[beusx]

ok tnx . i'll try!

[Zax]

I will fix it in the next release so you don't have to manually edit the header or use center as workarounds.

[Koskee]

Thanks Zax. Should help make it more efficient/intuitive.

Had another off topic question for ya: I've seen a couple other members mention the use of a pause command, but as far as I can find the only mention of such a feature is in the grbl source code, linked to a specific pin (A1 - open door pin - I think it was?) . Is this what they are using to control the feature or is there a pause button in an update that I don't have yet?

[Zax]

There has always been a pause option, press the send button again. I recently added a stop button which terminates sending and returns home.

[Nosferatu]

Hi,

where should the Pulldown Resistor be placed on the Board ? Direct on the Socket (where the Arduino Pin is connected) to GND or at the three Pin Socket for the Laser ? What Value of the Resistor is recommended ?

Cheers
Nos

[Stonemull]

I added a 1k surface mount resistor on the laser itself between the gnd and ttl pins on the connector.
It still comes on but it just slightly brighter than the low power button, which is fine by me.

[Zax]

I agree with Stonemull that the best place is the laser module, that way if the TTL wire becomes disconnected it's safe, however, you can put it anywhere between the Nano and the laser and it will work. 1k should be fine, but others have said they needed 1.5-2.2k or the laser wouldn't respond.

[Nosferatu]

Thanks for the help. I will do the SMD-Resistor Mod. on the Laserhead.

Cheers
Nos!