The Smell of Molten Projects in the Morning
Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Making the world a better place, one piece at a time
Somewhat as expected, the scrap can slowly and inexorably pulled the tape off the workbench.
So I did what I should have done originally:
Those are M5 button-head screws in rivnuts drilled into the workbench frame:
With a dab of threadlock holding each screw in place, this should be forever:
Now, I must make sawdust / swarf / chips again …
Having just cleaned a bunch of gunk out of the bottom of the worm bin, we decided to try a layer of window screen to keep both gunk and worms out of the sump.
A roll of window screen Came With The House™, minus label or provenance, that felt like some sort of plastic, perhaps with a glass core.
The bin has a 19-¼ inch = 488 mm ID with 10 thin support struts around the perimeter. Laying out a circle and cutting it accurately by hand seemed like a chore, even though the screen cut easily with ordinary scissors.
The diameter just barely fit on the laser’s 700×500 mm platform, so I laid it out in LightBurn:
For lack of anything smarter, I applied the same setting as for the faucet gasket material (30 mm/s at 25% of 60 W) and Fired The Laser.
As far as I could tell while the laser was trundling around the circle, absolutely nothing happened other than maybe burning off a coating with a little discoloration on either side of the path.
However, the circle lifted out with zero drama:
And was a perfect fit in the worm bin.
Color me surprised!
I have no pictures of the happy results, as all this happened in the few minutes between “We should try a screen”, dropping the cut screen in place, and reassembling the bin.
I think the screen would cut just as well with a higher speed. If the screen works and we need another, I’ll run a few tests first.
With the set of Dremel collets organized, I made a quartet of handles for them:
The idea came from the June/July 2026 Machinist’s Workshop, wherein I learned Dremel nuts / chucks fit on a 0.275 inch = 9/32 inch 40 TPI threaded body, drilled through 11/64 inch.
Making such a thing involved some pleasant lathe time:
The business end of the body has a slight taper to (ideally) match the collets:
However, the collets have tapers ranging from 20° to 35°, so I defined a 60° center drill to be Good Enough™ and got a free taper while drilling the central hole.
The collets sit in the taper:
Tightening the nut closes the collet:
The article described a nicely turned wooden handle, but a somewhat uglier 3D printed handle is fine with me:
Which comes from a few lines of OpenSCAD code:
difference() {
cyl(h=HandleLength,d=HandleOD,anchor=BOTTOM,texture=Knurling,tex_size=[3.0,6.0],tex_taper=0.08) position(TOP)
cyl(h=3.0,d=HandleOD,circum=false,rounding2=2.0,anchor=BOTTOM);
down(Protrusion) {
cyl(h=15.0,d=ShaftOD + HoleWindage,chamfer2=2.0,circum=true,anchor=BOTTOM);
cyl(h=2*HandleLength,d=ShaftID + HoleWindage,circum=true,anchor=BOTTOM);
}
}
The variables match the threaded body to my fingers:
Protrusion = 0.1; // make holes end cleanly
HoleWindage = 0.2; // make holes large enough to fit
ShaftOD = 6.9; // collet closer thread - 40 TPI 0.275 OD
ShaftID = 4.3; // … internal clearance
HandleOD = 15.0;
HandleLength = 45.0;
Knurling = "trunc_diamonds";
The motivation for all this was to put the smallest taps in a holder suitable for delicate jobs. The smallest chuck on my real tap driver bottoms out on an M3 tap and can’t grip the M2 tap:
I try very hard to not tap small holes, but sometimes you gotta do what you gotta do and now I’m better prepared.
Incidentally, the first threaded body I made absolutely did not fit the Dremel nuts. After eliminating everything else, I discovered I’d set up the lathe change gears with a 20-65-45 train, rather than the 20-65-50 train required for 40 TPI with the lathe’s 16 TPI leadscrew.
Protip: Even the best threading job (which I didn’t do on any of those things) can’t make a 36 TPI screw fit into a 40 TPI nut.
A new Gorilla Grip shower mat defeated the spring-loaded clip its predecessor dangled on between showers, so I applied a contour gauge to the shower stall, copied the shapes to paper, scanned them, then fit some curves:
Combine the two to get a model of the shelf, subtract it from a rectangle, and produce a cardboard test piece:
Put a hook on the bottom, a small bump on the top, and round the corners:
Function-test a cardboard pair:
They clear the hump along the edge and fit snugly across the front and sloping underside, so make an MVP from 6 mm acrylic:
Laser-cut acrylic may be too brittle for the job, but it gets the mat off the floor for drying and we’ll see how this works before doing anything more complex.
With the Sherline CNC mill once again able to move under its own power, an hour or so of tweakage got the laser aligner settled in its new home:
It’s (still) an upcycled laser line projector, minus the cylindrical lens stretching the dot into a line, running from a pair of AA alkaline cells:
The three small screws provide simpleminded angle adjustment, with the disadvantage of simultaneously moving the lens in the XY plane.
The upper bubble level shows it’s not at all vertical:
That’s because the beam must fall down the middle of the Sherline’s spindle bore:
Getting the alignment right requires a mirror on the tooling plate, which I will not attempt to photograph again, reflecting the beam upward through the spindle, where it will light up the bottom of the no-longer-a-line projector’s lens mount. When that happens, the projector is boresighted on the spindle, regardless of whether the tooling plate is perpendicular to the local gravitational field.
With the Z axis / spindle near the top of its travel, screwing the lens (mounted in a toolholder) onto the spindle produces a defocused beam on the tooling plate:
If the spot doesn’t look similarly round-ish, then the beam isn’t completely filling the entrance pupil of the lens and you must twiddle the projector’s angle / position until it does.
With that done, running the Z axis to put the lens about 30 mm above the plate produces a suitably teeny spot:
The Sherline’s previous home atop that same gray countertop had been firmly affixed to the basement wall, with the gantry and laser projector screwed to the floor joists: everything immovable. The countertop now sits atop a workbench not firmly affixed to anything: a good solid bump will likely knock the Sherline out of alignment with the beam.
How often that happens and how awful recovery will be remains to be seen. For now, It Just Works™ again.
Feeding Sherline aligner into the search box will reveal much of the backstory.
I extracted an XZ positioner from the Box o’ Optics Lab Stuff before coming to my senses: this is not nearly such a critical application.
Notes on finally getting the Sherline CNC mill operating in its new home, with a suitable Axis startup image:
The gray countertop from its former home sits on foam strips soaking up a slight warp with enough isolation to keep things quiet.
The gantry required the usual fiddling to make the cable hoist the Z axis directly upward, with the orange flag on the counterweight barely visible below the monitor.
I recently touched the box of precision XYZ positioners and there might be something useful, albeit grossly overqualified, in there to simplify dropping the laser pointer beam directly through the spindle bore.
A clean installation of LinuxCNC 2.9.8 on an ancient Dell Optiplex 9020 proceeded smoothly. Installing x11vnc let the rest of the proceedings happen from upstairs in the Comfy Chair. For unknown reasons, vinagre works better than Reminna as a VNC client, after recalling F11 enters / exits fullscreen mode.
The mesaflash utility accompanying LinuxCNC 2.9.8 did not recognize the Mesa 6i25 card. Fetching & compiling the most recent version (3.5.17) cleared that hump and flashed the bitmap:
sudo mesaflash --verbose --device 5i25 --write 5i25/configs/hostmot2/5i25_prob_rfx2.bit
The 6i25 wants to be known as a 5i25, with its jumpers in their default positions:
For unknown reasons, the button originally known as btn-trigger became btn-joystick for a while and has now reverted to btn-trigger. It’s labeled 1 in the four-button cluster:
Which required changing the pin name in the Kicad library component:
Which required converting the old Kicad library format into the new Kicad library format, a completely automatic process without, AFAICT, any unpleasant side effects.
The new name fed into the schematic as expected, after minor fumbling while re-adding the modified component and setting its annotation number:
The X axis home microswitch has (apparently) become more bouncy while it was idle, so I increased the number of samples before HAL sees a change in that GPIO input:
The dbounce block runs in the servo thread at 1 m per tick, so those 20 samples take all of 20 ms while the X axis moves 0.15 mm. At some point I should apply a scope to that switch, but for now It Just Works™.
Considerably to my surprise, compiling the modified Kicad schematic into a HAL file proceeded without incident, despite various Python updates in the last five years.
Kicad produces an “intermediate XML file” containing the netlist data intended for a conversion / export program, which is basically what my Kicad-to-HAL lashup does. I told Kicad to use Bash’s true command as a converter:
So I can run the Kicad-to-HAL converter manually:
python ../Kicad\ Conversion/Kicad-to-HAL.py Sherline\ HAL\ -\ Logitech\ Gamepad\ jogging.xml Sherline.hal
You could tell Kicad to run it and it would probably Just Work™, but I’m used to peering at the results and dinking with my program.
Which produced a new Sherline.hal file that Just Worked™ with the existing Sherline.ini file containing the configuration constants.
The Sherline has cut only air so far, but, as the man said, “E pur si muove.”
You don’t have one of these, but your bench needs something like it:
Tiny Bandsaw perches just above it and now I have a place to drop the scraps you see collecting in its tray.
The can hangs by its rim from a completely kludged two-layered MDF hook stuck to the metal table frame with good 3M foam tape:
It’s not in the way of Tiny Bandsaw, because I stand at the left end of the bench, and it’s not in the way of the Sherline / LinuxCNC keyboard, because I stand to its right. So far, so good.
Should it fall off, I’ll think of something better.
The Smell of Molten Projects in the Morning 