The instructions on the wiki are out of date from what’s in the current process (it does not mention the 3-d printed turtleneck height estimators). With a thumbs up, I propose changing the current section to read:
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Focus tool
NOTE: this process is quite easy… the second time you’ve done it with confidence, and very difficult to explain in writing. Before you leave class, be sure you are confident executing the process – your instructor will give you the time it takes after class to practice until you’re like “ok yeah that is pretty easy”.
Place your material on the machine bed, and pin it down well using the magnetic clamps. If your plywood has a slight bow, turn that smile into a “meh” – that is, put the low part on the bed and then pin the edges down using the clamps. Keep in mind that as parts are separated from the whole piece they will relax in Z, changing the effective focal length. DO NOT USE material with enough bow to potentially cause a head collision.
Now that your work is flat and secure to the bed, find the 3-d printed Lightcone Turtleneck focusing device specific for the laser (the name is etched into the back). Look closely at the nozzle of the laser cutter and the nozzle. Dorian and Tarkin have a similar process but slightly different physical mechanism for knowing the fit is correct.
Dorian: On the collar there is a little flat collar about 1" (25cm) above the nose. The correct fit will have about 1mm of vertical play, up to a easy sliding fit, between top of turtleneck and bottom of collar with the turtleneck flat against your work
Tarkin has no collar but it will unmistakably match with the nozzle when you slide the turtleneck against it. As with Dorian, once you have less than a millimeter of Z-gap between “it’s flat on the work” and “it’s in its happy place with the nozzle” you’re good to go.
Now that you know what you’re looking for, you will now:
- with the machine stationary, place the turtleneck’s base flat on the work and judge the distance from its top to the collar ring / happy place.
- Move the turtleneck away from the nozzle, and jog the Z height to be close
- Slide the turtleneck towards the nozzle to see what direction to move for the next jog, then move the turtleneck away again before jogging the Z-height
- Your goal is 1mm-ish of clearance above the turtleneck with its base flat on the work, and a bright tight spot on the base of the turtleneck.
Please take care that you do not adjust the z-height while the turtleneck or anything else is near to collide with the head. It’s NOT important to get a close running fit – any further dial-in of the z-height should be done by running an engraving test pattern.
You’re not trying to find the optimal z-height to the little 3-d printed doohickey or even to the top of the work – you’re trying to find the optimal z-height to the 1/3 point of the material (if cutting) or to the top of the material (engraving) or perhaps somewhere 5mm away for rastering (see below). When you set the X-Y origin, you’re either finding a safe corner to either start cutting away from or to then use advanced techniques for finding an absolute reference spot. Think of this focusing step similarly: as a goodenuf setting for most work or as the starting point after which you are referencing the material itself.
Quirk: The machine bed can shift laterally by several millimeters in the X and Y, when Z is moved. Please adjust the Z BEFORE making any precision placement of origin. Until this is fixed, the Z should not be moved to different places within a job as the XY alignment may shift.
Technical notes:
- For reference, the focal point is 6mm from the tip of the cone.
- Although the head, like most designs, has an adjustable tube, we do not operate by adjusting the tube. Please to ensure the tube is all the way up before continuing.
Rastering time can be greatly reduced by first using the focus tool to set the sharpest spot size, and then purposefully defocusing the beam to get a broader spot size. Lowering by 7mm corresponds to roughly 0.5mm line interval and 14mm is 1mm line interval. If you do so, increase the line interval by the corresponding amount by NEED INSTRUCTIONS HERE
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This part I plan to remove, or should be rewritten:
Once you reach the proper height, nothing else needs to be pressed and you can continue to use the machine. The control panel will read out around “Z 3000mm”. This number is not important. In cases where you need to deal with thick material, you may raise the bed from this point by as much as -5mm. If so, this readout can be used to measure simply by relative values. e.g. “Z 3002.7” after using focus tool. To achieve focus -2, press Z UP until the display reads “Z 3000.7”