Laser updates

[Fletcher Boyd]

Hey folks, I'm documenting the changes I made to the new cutter today.

Nozzle size drilled to 5mm: I noticed after cuts that the head was hot to the touch and the hole in the end of the nozzle was quite small. I've drilled it out to 5mm and the problem has either lessened or gone away.

How: Loosen the hex bolt on the right hand side underneath the z probe and pull the bottom part of the head off. Next unscrew the lens assembly from the air nozzle and set aside carefully as the lens is only recessed 10-15mm below the edge. Finally the air hose can be unscrewed and the nozzle tip taken away from the machine for drilling.

Z height: Tentatively set to 10mm after some playing. Cutting through 3mm at 22-24mm/s. This will need to be fine tuned at some point soon but will also need to be adjusted when the z axis is re-calibrated.

How: Open RDWorks and go to the User tab on the right. Default values are shown and will update to the correct values when the read button is selected. The z offset is set in Other -> Focus depth. Hit write to send your changes to the laser.

Z axis re-calibration: Since the laser provides accurate coordinates on the control panel this one was fairly easy to diagnose. When moving the bed the laser was showing a travel of 650mm at a speed of 300mm/s when in reality the bed had around 15mm of travel. This indicated that the Z axis stepper wasn't correctly configured.

Steps per mm set to: 0.09597

top speed set to: 3mm/s

How: File -> vendor settings (default password is RD8888) -> Z axis -> read ->. The acceleration was set by feel to approximately match the other lasers. The acceleration was reduced from the default 5000mm/s to 5mm/s which seems to be working okay. (higher values produced a whine, lower didn't move the bed or produced a grinding sound). The Steps per mm were set by using the inbuilt configuration tool. Tell the software how far the head moved and how far it thinks it moved, steps are adjusted accordingly. Repeat until accurate. Right now we're around 3% out because I didn't have precise measuring tools on hand.

Other notes:

Origin is currently defined by the origin button rather than where the head is when you press start. This is useful because it means you can move the head/e-stop without losing your starting position. Seems to be a good mix between relative and absolute in laser cut.

By default stored jobs aren't deleted when a new file downloaded. The clear function is under the Docs tab (make sure to hit "read" first) rather than anywhere near the download button. Job times shown in this tab aren't how long the will take but are instead how long that particular file has been cut. (a 5 minute job cut twice will read as 10 minutes here)

When a job is selected on the cutter a preview of the job is displayed. For complicated jobs this render can take 20-40s and the laser is inoperable during this time.

Adjusting the Z height is done by hitting Z/U and then using the left and right arrows

Auto Z leveling is done by hitting Z/U and scrolling down to Auto focus (bottom option)

Current top speed of the X axis (and thus engraving speed is 500mm/s. The machine doesn't appear to be adversely affected at this speed. 

X/Y are reversed within RDWorks, the vendor options can be used to reverse the direction of the steppers if desired)

The start/pause button is in the same location as the Esc key on the old controller, be careful.

The origin point is stored between power cycles, if you don't set the origin point it will be whatever the last person used.

Current steps to cut:

1. Turn on laser cutter/compressor and chiller/extractor (orange power box)
2. Open RDWorks
3. Import DXF or draw
4. Set colours
5. Define colours under the Work tab. Scan=engrave. Basic options can be changed by selecting a colour and adjusting the values underneath. More complicated settings such as scan gap (interval) can be accessed by double clicking on a colour.
6. Download job, you'll be given the option to set a name.
7. Focus the laser by positioning the probe over your material and selecting Auto Focus. (Z/U button -> Select Auto focus from the menu using the up/down arrows -> hit enter) The bed will raise until it activates the probe (red light) and will then move around a bit before dropping to the focus offset. This appears to be normal
8. Set your origin point by positioning the head at the top left of your material and hitting the Origin button. (the head can now be moved freely without affecting the start position of the cut, this includes turning the machine off)
9. Hit start/pause (bottom right)
10. Any material that drops through the bed can be retrieved by opening the bottom panel (interlocks fitted, not locked)