Because the rear running light will have a higher duty cycle than the front light, I made the (admittedly too small) heatsink slightly longer, with a deeper recess to protect the lens from cargo on the rear rack:
Boring that nice flat bottom is tedious; I must lay in a stock of aluminum tubing to simplify the process.
Drilling the holes went smoothly:
Those two holes fit a pair of pins aligning the circuit plate, with a screw and brass insert holding it to the heatsink. Scuffing a strip across the aluminum might give the urethane adhesive (you can see uncured globs on the pins) a better grip:
The screw / insert /pins are glued into the plate to permanently bond it to the heatsink. The screw occupies only half of the insert, with the longer screw from the end cap pulling the whole affair together.
The Micro-Mark bandsaw has a metal blade guide below the table that contributes to the awful noise it makes while running, even when it’s not cutting anything. Having recently touched the Delrin = acetal rod stash, a simple project came to mind.
A doodle with the original metal guide dimensions:
The 10 mm dimension is non-critical, so I started with a 1/2 inch acetal rod and turned the stub end to match.
A doodle suggested how to carve the slot with a 20.5 mil = 0.52 mm slitting saw, with the offset from a Z touchoff at the top:
The V block setup required swapping out the overly long OEM screw for a shorter 5 mm SHCS to clear the Sherline’s motor:
The end result looked pretty good:
And it looks like it pretty much belongs in the saw:
The 6 mm stud goes into a hole in the frame, where a setscrew holds it in place. You must remove the blade to extract / replace the guide, with the correct position having the end of the slot just touching the back of the blade.
The foam ring apparently keeps crud away from the stud on the backside; I doubt it’s mission-critical.
The saw became somewhat quieter; the ball bearing guides above the table now generate most of the racket. At some point I’ll try replacing them with a block, probably made from UHMW, with a simple slit to guide the blade.
Plastic guides may not last as long as the steel ones, but occasional replacements will be worth it if the saw runs quieter.
The groove holds a length of 4 mm OD (actually 5/32 inch, but don’t tell anybody) brass tubing:
The M3 button head screws are an admission of defeat, as I could see no way of controlling the width + thickness of the aluminum slabs to get a firm push fit in the PVC tube. The screws let me tune for best picture after everything else settled out.
A little more machining opened up the top of the groove:
A short M3 button head screw (with its head turned down to 4 mm) drops into the slot and holds the slab to the threaded hole in the LED heatsink. The long screw is holding the threaded insert in place for this dry fit.
I doodled a single long screw through the whole thing, but having it fall off the heatsink when taking the rear cover off seemed like a Bad Idea™. An M3 button head screw uses a 2 mm hex key that fits neatly through the threaded insert, thereby making it work.
Butter it up with epoxy, scrape off the excess, and let things cure:
The need to gnaw a V groove into the side of two 60 mm aluminum bars led to this Sherline CNC mill setup:
Milling the near end of the bars put the angle plate’s rear lock screw within a millimeter of the column; the vise fits in exactly one spot on the angle plate and that’s where the jaws must be.
While controlling the mill with the Joggy Thing and some manual command entry, because it’s easier than real CNC programming, I overshot the near end and rammed the column with enough enthusiasm to dislodge the Y-axis leadscrew nut. An interlude of utter confusion ended with the backlash preload nut firmly jammed against the leadscrew coupler on the other end of travel:
The paper shreds show where the bellows formerly stuck on the Y axis stage.
The backlash nut chewed off a few star lock gear teeth on its way out, as seen here just above where they mesh:
It’s been quite a few years since I took the thing apart to replace the nuts, so I used the opportunity to lube the otherwise inacessible X axis leadscrew inside its table upside down on the bench.
The setscrew locking the Y axis leadscrew nut in place heaves into view with the X axis table off:
I thought about jamming it in place with a second 10-32 setscrew, but the ones on hand were just an itsy too long and collided with the X-axis table:
The thought of having the additional setscrew work loose, grind into the underside of the table, and require major surgery for recovery persuaded me to drop it back in the drawer.
With everything in place, I adjusted the backlash (on both axes) down to a few mils:
Tweaking the X axis preload nut under the table is not my idea of a good time, but it’s been quite a while since I had to do that.
Folding the new paper bellows and installing them took about as long as repairing the mill.
Milling the second V groove worked fine; all is right with the Sherline again.
A pleasant evening at a virtual Squidwrench meeting produced the raw shape of the front end from a 1 inch aluminum rod:
Trace the outline of the LED’s PCB inside the cylinder just for comfort, align to the center, and drill two holes with a little bit of clearance:
For the 24 AWG silicone wire I used, a pair of 2 mm holes 8.75 mm out from the center suffice:
Gnaw some wire clearance in the lens holder:
Tap the central hole for an M3×0.5 screw, which may come in handy to pull the entire affair together.
Epoxy the PCB onto the heatsink with the lens holder keeping it aligned in the middle:
Then see how hot it gets dissipating 900 mW with 360 mA of current from a 2.2 Ω resistor:
As you might expect, it gets uncomfortably warm sitting on the bench, so it lacks surface area. The first pass will use a PVC cylinder for easy machining, but a full aluminum shell would eventually be a nice touch.
A doodle with some dimensions and aspirational features:
Even without a lens and blinkiness, it’s attention-getting!
This requires drilling holes through the extrusions:
Running the center drill down until it just nicks the sides produces enough of a pilot hole through the center section to capture the 3 mm drill. If I had to drill enough holes to make a fixture worthwhile, I could probably eliminate the divots.
Two more holes + epoxied M3 brass inserts attached the 60 mm beam directly to the Z Axis stage, thereby eliminating the vertical beam and a steel bracket:
The M3 SHCS attaching the 100 mm beam goes through both beams. I think you could get the same result with a Tee Nut or a 12 mm Square Head bolt, should you have those lying around and don’t want to drill another hole. The Corner Cube screwed into both beams prevents rotation and helps ensure perpendicularity.
The Y stage now attaches directly to the beam, rather than through a pair of Corner Cubes, because I realized I wasn’t ever going to adjust its position.
The Z Axis stage stands on the plastic plate through a hellish mixture of metric and USA-ian screws. Basically, the 6-40 screws into the stage were long enough, the 6-32 screws through the plate fit the existing holes, and M3 screws are for MakerBeam:
To my utter astonishment, the threads in the end of the vertical beam had the proper alignment to let a Square Head bolt snug the beam against the 40 mm beam on the plate. As a result, the L Bracket just prevents the vertical beam from turning on the screw and the combination is as rigid as you (well, I) could want.
The 40 mm beam has two spurious holes, because I thought I could avoid drilling another hole in the baseplate. Nobody will ever notice.
After squaring and tightening everything, the 100 mm beam along the Y Axis is now horizontal within 0.2 mm and the X Axis is horizontal to better than I can measure.