Tag: Improvements

A box of air filters that Came With The House™ (and fit nothing therein) surfaced during a recent heap probe and prompted a quick-n-dirty project:

It replaces a tired box fan (barely visible at the top) that’s been shoving air around the basement to equalize the humidity.

The quintet of 140 mm fans seems quieter, although they don’t move quite as much air. Given that I have no way to know how much air circulation is enough, it’s likely sufficient.

The strip of black tape covers a hole for the knob on the fan power / speed control, although I cranked it up to full throttle and expect to leave it there:

The controller sits on a platform cut from 1.5 mm cardboard:

The 3D printed holder came with the controller. I cannot imagine how they have enough time to print a holder for each controller; maybe it’s a QC check for a 3D printer manufacturer.

I intended the controller to sit on the other side of the middle fan, but realized I had to cut the opening after mounting the fans and got the chirality wrong; the wiring in there layout leaves something to be desired.

The fans mount on a sheet of cardboard cut from one side of a Home Depot Extra Large Box and the bottom of the filter box comes from the other side. Because I don’t have a deep emotional attachment to the filters, they’re attached to each other (and the bottom sheet) with hot melt glue. I do have a slight attachment to the fans, but four dabs of glue hold each one in place. More gaffer tape holds the fan sheet to the front of the assembled box, in the unlikely event I must get in there again.

Hey, it’s Christmas: good things come in boxes, right?

The focus “pen” = switch on the OMTech laser stuck out far below the nozzle:

The nozzle is 18.5 (-ish) mm above the surface with the laser beam focused to a tight spot. The brass (-ish) tip of the pen flew about 5 mm above the material, requiring considerable attention to the placement of magnets, clamps, and similar accoutrements around the material on the platform.

Having dismantled the pen while replacing its wiring, this seemed like a good time to figure out how to get more clearance under its tip.

Removing the pen nose shows the tip on its 3 mm screw inside the spring pushing the tip downward:

I replaced the original spring (on the bottom) with a softer spring, mostly because the tip exerted what seemed like entirely too much force on the material. That makes no difference for acrylic & plywood, but anything squishier required deploying the focus gauge after I remembered the problem.

The other end of the screw is impossible to photograph in situ, but the tapered head seats in a recess leaving several millimeters of air below the proximity sensor. I made a little steel slug to reduce the pretravel by filling that gap:

The spigot on the slug (turned from 7/32 inch steel rod) aligns it with the screw head, with high-viscosity cyanoacrylate adhesive holding it in place:

The surface finish of my slug matches their tapering, so I figure it’s about right.

A setscrew near the top of the pen clamps the proximity sensor with a few millimeters of adjustment:

The slug reduces the pretravel to nearly zero with the sensor at the bottom of its range.

The brass tip had been twisted onto the screw as far as it would go, so I cut a few millimeters off the screw to put the tip closer to the pen nose:

Even with reduced pretravel, the tip nearly vanished into the pen body before tripping the sensor, so I unscrewed it two turns = 1.4 mm.

With the pen back in the machine and plugged in, measure the switch travel with a step gauge:

Protip: Measure the as-cut height of those steps, then either shim the bottom of the gauge with tape of a suitable thickness or add that much to the layout and cut another set.

With a good step gauge in hand:

• Slide it underneath to just touch the tip
• Note the measurement = A
• Slide it further until the switch trips (red LED on)
• Note the measurement = B

Figure B-A, round up to the next millimeter, then set that value as the Home Offset for whatever axis moves the platform. My tweaked pen had 2.5 mm of travel, so I used 3.0 mm:

Adjust the pen position to put the tip more than the Home Offset below the nozzle (I picked 5 mm) to ensure the switch will trip before the nozzle contacts the platform, then do an Autofocus.

Measure the distance from the nozzle to the platform (mine was 5.5 mm), subtract that from 18.5 mm (the known focused distance for my laser head, as above), and set that as the Focus Distance:

Another Autofocus should then put the nozzle exactly 18.5 mm (or whatever your machine needs) off the platform / material.

This shows the pen now flies 5 mm below the nozzle:

The step gauge shows it’s 13.5 mm above the platform, much better than the previous 5 mm.

The switch trips juuuust before the nozzle hits the material:

I should lower the pen a millimeter, but that’s in the nature of fine tuning.

Happy Dance!

Although the Ortur YRC-1 chuck rotary comes with a long cable, the connector doesn’t match anything in my heap, so an adapter of some sort was in order. The box includes three different adapters for various machines, none of which I have, but which served as raw material.

One of the adapters put the motor winding pairs together, which seemed like a Good Idea™:

That view has the stepper motor flipped 180° from its normal orientation; the motor cable connector normally points downward from the bottom.

The rotary has no strain relief for the cable, so I stuck a cable clip on its left side (in the normal orientation):

That arrangement captures the adapter, immobilizes the wiring at the motor, and puts all the strain on the more easily replaced cable, which is now a length of flexy 24 AWG silicone ribbon cable.

I don’t have a connector matching the Ortur adapter, but JST SM pins seemed about the right size:

Entombing that mess with a squirt of hot melt glue should keep them out of trouble.

You can see my matching JST SM connectors on the right end of the ribbon cable :

A cable clip stuck to the front cross member of the machine frame (just beyond the angled magnet) holds the unplugged end out of harm’s way when the rotary isn’t present.

The ribbon cable burrows through the guts of the machine to the A/B terminals of the smaller stepper driver in the electronics bay:

Flipping the front-panel switch to enable the rotary driver / disable the Y axis driver enthusiastically spins the chuck when the controller thinks I’m jogging the Y axis:

Making it do something useful requires more pondering.

Having picked up a small rotary intended for Ortur diode laser machines during Black Friday, I knew using it with my OMTech 60 W CO₂ laser wasn’t going to be plug-n-play. The usual connection for a rotary in a CO₂ laser is directly into the stepper motor driver for the Y axis, so the stepper motor in the rotary must handle the same current as the Y axis motor. The OMTech laser has NEMA 23 steppers set for 3.5 A, which would quickly fry the NEMA 17 stepper in the Ortur rotary.

So the general idea was to run the rotary from another stepper driver set for an amp or so. A separate driver would also let me choose microstep settings more suitable for a rotary.

A simple SPDT switch enables the appropriate driver:

NB: Leaving the ENA pins of a stepper driver disconnected enables the motor output and passing current through them disables the motor; why that function was not labeled DISABLE remains a mystery.

So the switch looks bassakwards, but it connects the -ENA pin of the disabled driver to GND / common, with its +ENA pin tied to the supply.

Translating that doodle into hardware required drilling holes in what passes for the laser’s front panel:

The new driver stands up in bottom of the electronics bay:

The loose wire over on the left is a remnant of the discovery that the KT332N controller’s General output bits do not behave as expected. While you (well, I) can set their state through the display’s MENU → DIAGNOSES screen, the controller unilaterally slams them low = active while running a job. To be fair, the manual does say “General output, reserved”, but I had to find out the hard way.

The +ENA terminal comes from the +5V supply, along with the other + terminals. The -ENA terminal goes off to the switch, along with two wires from the existing Y axis stepper driver:

The 1.8 kΩ resistor sticks out of a ferrule doubled up in the 24V terminal feeding the driver and connects to a wire into the +ENA terminal. Two wires from the switch connect to the -ENA and GND terminals, join the -ENA wire from the rotary driver, and crawl through the machine to the front panel.

The new power supply on the far right completes the electronics bay installation:

Obviously, the wiring situation is completely out of control.

Up top, though, it looks like it grew there:

Now, to figure out the settings …

Edit: The 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.

In the process of replacing the laser cutter’s OEM 24 V 6 A power supply with a 15 A supply, one of the two screws holding it in place remained stuck in the underlying sheet metal plate:

You can’t see either of the screws from that position, but they’re in the upper-left and lower-right corners. The offending screw is, of course, on the top, tucked between the top of the supply and the wire raceway. The bottom screw came out easily and I could maneuver the supply out of the way.

Vigorous persuasion involving a bent-nose pliers and muttering got the screw out and revealed the problem:

The reason why the screwdriver didn’t get much traction in the head also became obvious:

Folks on the LightBurn forum seem astonished when they discover their fresh-from-the-factory has loose screws, missing screws, and occasionally the wrong screws.

I always wondered where the switch pointed to by the conspicuous label might be:

Unlike most supplies, it’s inside the case:

After you spot it, you can also find it just below the tip of the arrow in the previous picture. I suppose putting it inside the case prevents it from being inadvertently flipped, but somebody had to dismantle All. The. Supplies. to flip that switch for the USA-ian market.

The dataplate also became visible:

You’ll recall the 5 V 2 A output was dedicated to the red-dot pointer drawing about 20 mA.

In contrast, the 24 V 6 A output handled:

• X axis stepper driver: 3.5 A peak
• Y axis stepper driver: 3.5 A peak
• U axis stepper driver: 5.1 A peak
• KT332N controller &c: 1 or 2 A
• Gantry LED strip: 0.25 A

The stepper drivers are set to drop the motor current by half when they’re idle, which means their load would be only around 6 A. That’s as delivered to the motor windings, with the power supply’s average current being lower by roughly the ratio between the motor’s rated voltage and the power supply voltage. The instantaneous peak current, however, is the sum of all those currents.

At some point I must measure all that, but for now I want to shoehorn a bigger supply in there to take care of the additional load of the rotary stepper driver, plus the existing platform lighting and improved electronics bay blower.