Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Changing the lens on the laser requires unscrewing the nozzle after removing the assist air fitting that collides with the focus pen holder:
Laser head – assist air vs focus pen
All the 12 mm open-end wrenches in my Drawer o’ Spare Wrenches being much too large, I finally got around to making a custom wrench:
Air fitting wrenches
The plywood wrench came from a traced scan of a similar wrench, then adjusting the jaw opening to 12 mm. It served to verify the overall shape & size, then became a template for the real wrench atop a scrap of 1/8 inch aluminum sheet with flaking paint.
Some bandsawing and filing later:
Air fitting wrench – at nozzle
A little wrench makes swapping the lens somewhat less tedious, which is a Good Thing™.
Whereupon the tube remains nicely tubular on both ends and aligned along the chuck axis:
Ortur YRC-1 – chucked cardboard tube
Which is why you save all that scrap material …
Yes, it’s the core from a toilet paper roll, which is way cheaper than burning through tumblers / mugs / shot glasses / whatever while figuring this stuff out.
Always disable the rotary’s stepper driver before connecting or disconnecting its cable.
The Ortur YRC-1 rotary has a pulley ratio of 1:3, so the step/rev value is three times the DIP switch setting on the stepper driver. For this setup, 1600 → 4800 step/rev.
The honeycomb frame is a parallelogram, not a rectangle. I align the cardboard baffle / fixture to the bottom edge of the frame and the rotary to the bottom edge of the fixture opening, but your machine will be different. The angular alignment may not be off by enough to matter, but consistency is a virtue.
The Rotary.lbset and Linear.lbset files live on a file server with daily backups. Such backups will come in handy when you inadvertently overwrite one of those files with the other one. Trust me on this.
The Rotary.lbset file does not have Rotary Mode enabled, because the KT332N does not home the Y axis in that mode. If your rotary lacks a home switch, then it doesn’t matter and you’re on your own.
The KT332N controller has a [Reset] button that allegedly does a power-on reset and reloads all the changed Machine Settings. This sometimes does not work as expected: power-cycling the controller is the only way to be sure.
The autofocus operation must hit the focus pad, which can be ensured by positioning the pen near the pad, jogging the platform a few millimeters under the pen, tweaking X and the gantry while peering down parallel to the pen, then doing the autofocus.
The focus pad has a crosshair clearing the chonky Ortur 3-step jaws, but I set the controller’s [Origin] at the foot of the pad’s base for more elbow room.
The Z axis distance field in LightBurn’s Move window does not accept formulas, so you must divide the workpiece diameter by two. Using a focus stick to verify the ensuing nozzle-to-workpiece distance is a Good Idea™.
The LightBurn Job Origin dot must be on the top row, because the KT332N does not go into regions with negative coordinates. With the chuck on the left and the [Origin] just to its right, the upper left dot locks the LightBurn selection to the physical limits.
Selecting [Use Selection Origin] puts the Job Origin at the upper left (per the dot) of whatever you’ve selected, not everything on the LightBurn workspace. [User Origin] then locks the selection to the [Origin] set on the controller.
The standard jaws for the Ortur Rotary loom over small-diameter workpieces:
Ortur Rotary Focus Pad – home offset adjustment
Some measuring and modeling produced petite 3D printed jaws:
Ortur Rotary – printed jaws
Admittedly, those jaws aren’t doing much of anything, but they’re not nearly as much in the way. You (well, I) can screw them in closer to the center to overlap the chuck jaws or another hole outward for slightly larger cylinders.
The solid model looks about the same:
Ortur Rotary Jaws – 2-3 show view
They build face-down with a little support under the screw recesses for a clean fit on the chuck:
Ortur Rotary Jaws – Prusaslicer
Teeny jaws might be handy:
Ortur Rotary Jaws – 2-2 show view
Screwing them in one hole outward lets them grip medium cylinders without sticking out from the chuck jaws:
Ortur Rotary – small printed jaws
The OpenSCAD code lets you pick which screw holes you want, but it does not error-check the perverse choices.
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Ruida laser controllers do not allow the platform to rise above the U=0 origin set by the autofocus pen = switch. While this isn’t a problem for flat surfaces, focusing on the exact top of a horizontal cylinder, particularly a small rod, may be overly difficult.
So a focusing pad seems like a Good Idea™:
Ortur Rotary Focus Pad – focus pen positioning
The general idea:
Align a flat horizontal surface with the rotary chuck’s axis
Do the autofocus operation with a well-defined landing zone under the pen
Jogging the head upward (= platform downward) by the workpiece radius puts the focused spot exactly at the right height
Remove the focus pad
Install the workpiece
Fire The Laser
The solid model:
Ortur Rotary Focus Pad – solid model
Features of note:
The chuck jaws fit into the recesses on the left end for a firm grip with good alignment
The lengthwise notch lies on the rotary axis parallel to the laser’s X axis
The crosswise notch is juuust rightward of the chuck jaws, marking the leftmost end of whatever you’re engraving
Because I added a home switch to the Ortur YRC-1 case, Jaw 1 automagically ends up on top after homing, thus automagically making the focus pad horizontal. Getting that right required fine-tuning the rotary’s home switch trip point, which turned out to be easier to do using the Home Offset configuration value after I replaced the cam I thought would work:
Ortur Chuck Rotary home switch – pulley cam
Instead, a simple M4 setscrew (standing proud of the pulley surface in one of the tapped holes for the real setscrew securing the pulley to the shaft) trips the switch much more repeatably :
Ortur Rotary Focus Pad – home trip setscrew
The setscrew on the right sits flush with the surface to prevent the switch roller from falling into the hole. The real setscrew underneath it locks the pulley to the shaft’s flat.
With that in place, a quick binary search settled on a Y axis Home Offset = 1.75 mm to put the pad level with the top of the rotary’s case, which is Level Enough™ due to my tweaking the machine’s foot elevations after jacking the whole machine up on risers:
Ortur Rotary Focus Pad – home offset adjustment
The Home Offset value:
The speed and acceleration values are much lower than used with the linear Y axis, because apparently Ruida computes the corresponding step values using the workpiece diameter in the Rotary section. Small diameters produce impossibly fast motions, which suggests they expect you to set the optimum values based on back-calculations from the object diameter; ain’t nobody got time for that.
Anyhow.
After autofocusing, the red-dot pointer now indicates the laser spot position, so jog the X axis and drag the gantry to put the spot on the axis mark:
Then jog the X axis to put the dot at the transverse mark just beyond the chuck jaws:
Ortur Rotary Focus Pad – red dot at origin
Hit the Ruida Origin button to set that as the user origin, so you can reference the LightBurn design to the hardware position.
Move the platform down by the workpiece radius, jog the nozzle along the X axis to get it out of the way, remove the focus pad, install the workpiece, and you’re good to go. The checklist visible beyond the bubble level shows it’s not quite that simple, but we’re getting there.
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I’d stuck four exercise mat tabs (scraps of a flooring project) under the feet, but the loading was much too high:
Prusa MK4 Foam Feet – foam snippets
It was really an excuse for some non-critical cutting with the 3 inch lens in the laser cutter:
Prusa MK4 Foam Feet – assembled
The foam cut nicely, albeit with a 1.3 mm kerf, and the chipboard & plywood seemed about the same. They’re 30 mm square and, should they flatten out, I have enough foam scraps for a larger set.
Unlike the 3018 feet, my deflicted ears can’t tell the difference with these in place, so I assume a standard MK4 squash-ball foot upgrade isn’t worth the filament.
The Smell of Molten Projects in the Morning 