Adjustable height

[John Dickinson]

Mine is one of the cheapy A4 cutters as I am sure a lot of the ones that have been converted to RAMPS are.

Adding vertical to these is a matter of buying the table dodad for about £150. That seems to me to be a bit stupid, moving the whole work piece up and down when all you need to do is move the lens.

I made this. The stepper bit is out of a Sony CD/DVD drive. The lens goes in the top of the green bit, the air assist blows mostly below the lens but a little bit above to try to keep the top of the lens clean

Work in progress, no software yet. I intend to add a switch on the end so that you can do auto focus on it.

[Turnkey]

very neat!

[ajf]

That's excellent! 

[John Dickinson]

Here it is powered by Marlin and running an up/down Gcode file.

https://youtu.be/JaLAWAKfQe0

Because the stepper is such low power it does not need any limit switches. All that is required is to wind down the full travel distance, the motor will stall when it hits the work. The lens is a known distance from the end of the air spout so when it hits the work it is only necessary to rewind it such that Focus = airspout + rewind and you have an auto focus mechanism.

Very very easy and cheap.

[Shane Graber]

Nice!  In the video it seems a bit wobbly when height adjusting. Is that going to cause issues?

[John Dickinson]

It is a bit wobbly because the blue bit is a bit loose. I am contemplating whether to print another the same or to print a complete bit with the mirror holder integral. That will allow me to put the lens closer to the stepper and make it all a lot better. It will also reduce the moving weight of the machine which means faster speeds and more accuracy.

[John Dickinson]

Decided to use a PIC to control it at this stage. At power on the stepper rewinds to the top. When you press the button it sends enough pulses to wind all the way down but because it hits the work piece the stepper stalls. It is a very low power stepper so it doesn't matter if it stalls. Once it has sent enough pulses for full travel it rewinds such that distance up + nozzle length = focal length.

I am thinking that it can run from a couple of batteries and probably last for months between recharges. No need to bother with adding it to Marlin and it can be fitted to an original laser with Moshidump or Lasercrap.

https://www.youtube.com/watch?v=olbXzzw2X2Q

[John Dickinson]

First prototype:

https://www.youtube.com/watch?v=fpK6MPFawUs&feature=youtu.be

It runs fine off a PP3 battery, current draw is 100ma when running the stepper and about 10ma when it has finished. Battery can be switched off once focused so the PP3 should last for months.

[John Dickinson]

https://www.youtube.com/watch?v=iau8jthQAew&feature=youtu.be

I added more rigidity with stainless tubes that also carry the air for the air assist. Looks like something Frankenstein may have in his lab now.

[John Dickinson]

Finished and installed.

https://www.youtube.com/watch?v=4TkQ8bnXQ-Y

Not connected to Marlin but the PCB will take one IO line from Marlin to focus and set another one into Marlin when focused.

It is also possible to remove the PCB altogether and just drive the stepper from Marlin using the Z axis (or extruder if you prefer) to control it directly.

[TheSniper]

Curious: YouTube reports your vids are not avail?

Sam

[m keyno]

hi guys , why don’t use such ready-to-use module such as this link and this link and add the sensor like this,I thinks , it is not  best to waste time on hardware whereas variety of tools available in market
I follow up and review couple of  open-source firmware   what if  can automatically control the height of tools such as laser head and plasma.  I review couple of  firmware’s  in Github which are originality design for 3D printer device and not for cutting machine such as laser & plasma CNC  , most of those presume base on readiness of cutting tools whereas in actual industrial CNC each tools initialize and check during the machining

I build the 100 watt laser CNC with modified Marlin firmware  by TurnkeyTyranny on RAMP1.4 which is linked wirelessly by Bluetooth to RepetierHost, it was good step to start but the original code suffer from minor defect and unfortunately code not maintained anymore, but some cool guys such as HakanBastedt  & Wurstnase merge TurnkeyTyranny code in new update Marlin firmware for Due, But still auto focus leaser head or torch high controller feature not implemented

Right now Manually  Control the laser head height is possible with function such as action_laser_focus_custom(),  and I think ,in two ways we can control the  tools heights  during printing our cutting

One with help  of separate modules and one is totally implemented  in firmware

In the first method (hard way) we could use the Arduino module to command the z axis whenever new bias with per set  g-code height come out, and when adjustment performed active the readiness pin  which is controlled by g-code M266 command before each  cutting   

In the second way we could use the function such as laser_set_focus(currentZ) in loop function , in this case we need use I2C to request the height from sensor module   

unfortunately I'm novice in programming but I hope with help of cool guys in Github , finally make the reliable and standard  firmware for cutting machine like laser & plasma CNC

also I hope have your comments on this idea