Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
The Gizo spider’s eight legs built right up to the top without incident:
Gizo spider – nearly complete
The Articulated Spider assembled from many flat pieces distributed over the sheet, with no excitement at all:
Articulated and Gizo spiders
The orange parts printed in a separate operation (the eyes push in and glue on, respectively), because multi-material printing doesn’t make sense unless there’s no other way.
Those were test cases of joint fit without any model adjustments. The Gizo prints fully assembled and, as with the Steamopus, all eight joints worked smoothly after a few careful break-in motions. Each of the Articulated Spider’s many joints snapped together without incident, but benefited from a dot of silicone grease apiece.
Long years ago, the Bakelite (or some such) lid on our rarely used teapot disintegrated, whereupon I replaced it with an aluminum sheet and metal knob. Admittedly, a metal knob was not the brightest idea I ever had, but it sufficed for a few uses over the intervening decades.
Mary hosted this month’s quilting bee and, after having someone else bring a larger teapot for the occasion, suggested I Make. A. Better. Knob. After a bit of searching, this statue seemed appropriate for the season:
Skull teapot knob
It’s printed with PETG filament that should easily withstand the no-more-than-boiling-water temperatures found atop a teapot.
I imported the original model into PrusaSlicer, shrank it to 50 mm tall and simplified the mesh, exported it as an OBJ file, imported it into OpenSCAD, mashed it together with a 1/4-20 threaded_nut from BOSL2, added the finger protector, and got a suitable model:
Teapot Knob – solid model bottom view
The as-printed threads were a bit snug with $slop=0, but running the screw in with a dot of silicone grease to ease the way worked fine.
I should rebuild the whole lid in PETG-CF sometime.
The Ruida KT332N controller on my OMTech laser cutter has two settings affecting the final position of the U axis (which controls the platform’s position) after pushing the Focus button on the machine console:
KT332N Laser Controller display
After turning the machine on or pressing the Reset button, the U axis does not automatically home and reports its position as 1000 mm. This allows manual control in either direction with the U↑ and U↓ buttons.
Pushing the Focus button (then confirming the action by pressing the Ent⏎ button) causes the controller to raise the platform until the focus “pen” (which is really a switch) trips, presumably on the material you intend to cut / engrave. This picture shows the pen and its attachment to the laser nozzle:
OMTech laser focus pen-switch
The pen’s position in its clamp has no relation to the laser beam focal point below the nozzle: loosening either of the clamp screws lets you move the pen vertically. You must tell the controller how much to move the platform after the switch trips to properly set the focus, which means you must measure that distance. More on that later.
The vertical position of the platform when the “pen” switch trips is its Home position. The controller then lowers the platform by the distance in the Home Offset setting and defines that position as U = 0.0 mm.
The Home Offset can be zero:
KT332N Home Offset Setting
In which case the platform does not move after the switch trips:
Focus step gauge – 3 mm
The step gauge shows the nozzle is 3.0 mm above the material (the first step is 2 mm, because a 1 mm acrylic tab is crazy talk) when the switch trips. Although you can’t quite see the switch plunger through the gauge, it has about 5 mm of travel before tripping, which means it’s firmly pressed against the material and you must not move the nozzle in X or Y to avoid scraping the plunger across the material.
Setting Home Offset to 15.0 mm lowers the platform by 15 mm after the switch trips, putting the nozzle 18 mm above the material:
Focus step gauge – 18 mm
You can (and I have) set the Home Offset so the platform lowers by exactly enough to put the focused beam at the top of the material: push the Focus button and the machine automatically focuses on the material and sets U=0.0 mm at that level.
Unfortunately, the controller will subsequently not move the platform above that position, corresponding to U axis coordinates below zero. That means you (well, I) cannot move the platform upward to put the focus point into the material, as is sometimes required for a good cut through thicker material.
The Focus Distance setting defines an additional distance from wherever the Home Offset leaves the platform:
KT332N Focus Distance Setting
It’s not 15 mm, because I was fiddling with the focus.
That value will position the platform 16 mm below the switch trip point. Because Home Offset = 0.0 sets the U axis coordinate to zero at the trip point, the U axis will be at 16 mm when the platform stops moving.
The key difference is that the controller will now allow the platform to move upward, with decreasing U axis coordinates, until it reaches the switch trip position at U=0. The last 5 mm of travel will occur with the switch actuator pressing against the material, so it’s pretty much useless for actual cutting or engraving.
So I think the way to go involves setting:
Home Offset to the 5-ish mm required for full switch release
Focus Distance to the remaining 10-ish mm with the focal point on the material surface
I hadn’t done that before, because I hadn’t thought this through.
The Home Offset depends only on the switch travel before it actuates and won’t change when (not if) the pen position changes with respect to the nozzle.
The Focus Distance defines the additional travel for proper focus at the material surface, so that’s where all the variations due to pen position will go. Unfortunately, that distance cannot be directly measured, because it corresponds to the difference between two positions.
Although the total capacity remains about the same as before, the voltage depression causes the camera (which expects to run from a high-voltage lithium cell) to crash immediately after the car’s USB power jack shuts off, preventing it from properly closing the video file.
Another Batmax battery from the same batch works fine, so we’ll see if it can survive for another year.
NYS DOT installed rows of street lamp foundations along both sides of Rt 376 as part of the intersection reconstruction that will eventually put a fourth traffic circle along Raymond Avenue. Until the intersection of Rombout House Lane with Rt 376 vanishes, this lamp base at the corner sits well within the turning radius of the heavy trucks entering & exiting the contractor’s material dump & equipment marshalling yard:
Street Lamp Base – A
The fluorescent paint appeared after something heavy ran over the base and bent two of the bolts that should secure the lamp post.
A few days and a few more passes killed those bolts dead:
Street Lamp Base – A – more destruction
The barrier barrel in the background sat atop the base for a few days, but obviously didn’t affect the outcome.
A few hundred feet south, a heavy metallic mass sheared off another pair of bolts and bent the survivors:
Street Lamp Base – B
Someone eventually moved the sheared bolt atop the base, so perhaps the damage has been noted where that note will have some effect.
The “bolts” are the threaded end of long rods embedded in the three or four feet of pre-cast concrete forming the lamp base. The concave concrete mass to the right in the first picture is residue from the poured concrete in the hole anchoring the base to the ground.
A four foot deep trench along the row of lamps holds electrical conduit between them for the wiring that will eventually surface through the conduit covered by the duct tape. The white-and-blue cord hauls the pull tape from one base to the next to pull the conductors through the conduit.
Replacing those cast-in-place bases won’t be a trivial (pronounced “inexpensive”) operation and I suspect a powerful motivation to just un-bend the wounded bolts and pretend they’re not severely weakened. I doubt a base with just two bolts will pass final inspection, but maybe the inspector won’t look inside the lamp pole covers.
As before, the sole & lugs on Mary’s new Specialized cycling shoes requires too much torque to release the cleat, so I once again carved off everything that got in the way:
Cycling shoe sole carving
A field test prompted a little more carving, but you get the general idea.
This surely affects the shoes’ lateral stability, but getting her feet out of the cleats when & where needed outweighs everything else.
The Smell of Molten Projects in the Morning 