Tour Easy Daytime Running Light: Flashlight Ball
Posted by Ed in Machine Shop, Recumbent Bicycling on 2017-07-20
A flashlight used as a daytime running light must point generally forward and an actual bike headlight must light up the road, so it must sit on an az-el mount. My old bike helmet mirror mount had actual vertical and horizontal joints:
Helmet mirror mount – El slide in place
Every doodle along those lines seemed too big, too fragile, too fiddly, or all at once.
Living here in the future, though, we can produce (crude) ball joints to order:
Flashlight Ball Mount
That’s an early version of the outer mount using threaded brass inserts.
The ball around the flashlight separates along the obvious plane of symmetry, with a 2 mm socket-head cap screw and brass insert on each side. I tried printing the hemispheres convex-side-up with hand-hewn support structures inside:
Flashlight Ball Mount – support structure – on platform
The huge overhanging sections parallel to the axis didn’t bond to the supports, curled upward, and began nudging the dangling Z-axis homing switch actuator. This wasn’t a completely wasted effort, though, as similar support structures came in handy for the outer clamp ring.
Flipping the hemispheres over so they printed U-channel upward didn’t work much better, even sitting on a flat section to eliminate the absurd part of the overhang. This view shows one hemisphere with the missing cap:
Fairing Flashlight Mount – Ball – solid model
Flipped over, the flat surface bonded perfectly to the platform, but the overhang still warped as the upper layers cooled and pulled the perimeter upward:
Flashlight Ball Mount – warped section
Because normal support structures don’t contact the outer surface, I added fins to the model to hold the perimeter (almost) flat until the outer walls became sufficiently vertical to stop warping:
Fairing Flashlight Mount – Ball – build view – solid model
They’re fearsome hedgehogs in person:
Flashlight Ball Mount – flattening fins
The grip diameter determines the sphere diameter, as the sphere must have enough meat next to the grip to hold the screws and inserts. Rather than have the diameter different for every flashlight, I set it to the maximum of 45 mm or the actual diameter, which means all the flashlights in my collection have a common ball size. The hemispheres on the right have flattened ends to accommodate flashlight grips shorter than the sphere’s final diameter, achieved with a pair of intersection() operations lopping off the protruding bits:
Because the fins extend from resolutely convex surfaces, I snipped them off with flush-cutting pliers, reamed out the holes, epoxied the inserts in place, assembled the ball, and introduced it to Mr Belt Sander.
Protip: don’t hold the ball with your finger through the hole. It will eventually fly off under the workbench and it’s better if it doesn’t break your finger in the process.
A somewhat rough outer surface turns out to be an advantage, not a liability, as the clamp ring around the ball must hold it against the normal (and unusually severe) vibrations found on a bike.
The inner cylindrical section is smooth enough to require a wrap of tape around the flashlight grip to anchor it in position. The tape adheres to the flashlight and squishes into the ball’s layer lines, even under mild pressure from the 2 mm screws. The outer clamp ring applies compression to the ball, so the tiny screws need not withstand much force at all, which is a good thing.
Tour Easy Daytime Running Light: Fairing Clamp Plates
Posted by Ed in Machine Shop, Recumbent Bicycling on 2017-07-19
For reasons obvious to any cyclist, we must improve the forward conspicuity of our Tour Easy recumbents with a white daytime running light; a near-miss boosted this to the front of the project queue. While you can outfit a standard bike with a handlebar-mounted headlight (*), at any price from the sublime to the ridiculous, the smooth snout of a fully faired recumbent covers all the usual attachment points.
A small LED flashlight tacked onto the fairing support bracket seems workable enough to make up for a significant case of ugly:
Tour Easy – J5 Tactical V2 – front
That’s a J5 Tactical V2 flashlight on my bike.
Mary’s bike has a tidier Anker LC40 in an earlier mount version:
Tour Easy – Anker LC40 – front
The Anker required an adapter to hold an 18650 cell in its 3xAAA-size body. The J5 V2 is resolutely 18650-only, which is fine with me.
The intent here is to find out whether this works, figure out the proper aiming point(s), then de-bulk the mount.
The next few posts will cover various bits & pieces of the design, because I must remember why I did things the way they turned out: sometimes the obvious choices didn’t work.
The Zzipper fairing originally mounted to the strut across the handlebars with a single 1/4-20 nylon screw on each side. Even with a nylon washer on the outside, the stress concentration cracked the polycarbonate sheet around the screws and brackets, so I designed & printed flat ABS plates to spread the stress over a larger area:
Fairing mount – inside
The tapered edges were supposed to be flexible, but the foam sheets sandwiched on both sides of the fairing actually provided most of the compliance. There’s another screw in the open hole binding the inner & outer plates together.
The mounts worked perfectly, even as they faded over the years. The fairings became quite scuffed during the course of our near-daily rides, but, heck, we’re also a bit scuffed and it’s still all good.
The new PETG inner plates seat on the bracket to nearly its full thickness:
Tour Easy – Zipper fairing plate – inside
The flashlight on the outer plate applies torque around the bolt which (I hope) the sides of the recess can resist. This is the absolutely key part of the design and, I’m somewhat ashamed to admit, took me far too long to figure out. What you don’t want: weird & fragile gimcrackery clamped onto the strut extending under the fairing’s edge, with the flashlight hanging far off to the side.
I modeled the fairing strut’s aluminum bracket as a 2D rectangle, plus a pair of chords, embiggened by a thread around the outside edge, minus the hole, then extruded to the proper height:
The hole isn’t strictly necessary, as I punch out both screw holes as part of the plate assemblies.
The overall plate shape comes from the top half of a hull() wrapped around four squashed spheres:
Then the inner plate is just a plate blank stamped with the bracket:
You’ll need a set for the side of the fairing without the running light:
Fairing Flashlight Mount – Plates – solid model
The outer plate looks reasonably sleek in real life, although that’s not the primary consideration:
Tour Easy – Zipper fairing plate – outside
You could replace the squared-off ends with simple half-circles, maybe stretched into stylin’ ellipse shapes, without too much effort.
I got out the screws, set up to cut them with a pull saw and miter box, then realized they are plastic. Put away the saw, got out the utility knife, and cut them to length with one firm push. No distorted threads, no dust, no muss, no fuss.
(*) Opinion: any headlight with non-replaceable, USB-chargeable cells is a toy. I can replace a discharged (or failed) 18650 cell in the middle of a ride, where a dead battery inside a spendy headlight would leave me in the dark. Might not matter for a DRL, but seems absolutely critical on night rides. ‘Nuff said.
Layout Pen For Black Objects
Posted by Ed in Home Ec, Machine Shop, Recumbent Bicycling on 2017-07-18
This worked surprisingly well to lay out black foam gaskets for new fairing mounting plates:
Black foam layout with ceramic fabric pen
Mary uses the Fons & Porter Mechanical Pencil to mark quilting patterns on fabric. It has, they say, a “strong ceramic 0.9MM white lead” with “water-soluble dyes” capable of both laying down a durable mark and washing out without leaving a trace. I don’t care about the latter, of course, but it did brush off reasonably well.
The next step involved running an X-Acto knife around the perimeter of the plate and punching the holes.
You can get colored ceramic leads (for small values of color) for use on other backgrounds.
HP 7475A Plotter: Rebuilt Carousel Drive
Posted by Ed in Machine Shop on 2017-07-17
A followup to the saga of the HP 7475A plotter with a broken carousel drive:
With the information you shared, we were able to successfully model and reconstruct the drive wheel in only a couple of days.
One useful thing we discovered is there’s a lot of room for error – so long as the pin catches and the wheel isn’t slipping on the motor shaft, the mechanism will work. The grooves and the interior radius of the original part aren’t critical.
Because of your heads up about Geneva wheels, I found this excellent website – https://newgottland.com/2012/01/08/make-geneva-wheels-of-any-size/ – which includes a link to a Geneva wheel calculator. With the measurements you sent and a measurement off of the pen carousel, the calculator generated near perfect dimensions for a replacement. There was a little sanding and rounding to fit but it was certainly within tolerance.
Interestingly, the pieces of the drive wheel that I pulled out of the case revealed a small hidden detail. On the underside, there’s a collar around the motor shaft that gives the cam an extra ~.03″ thickness. Presumably this is to help reduce friction during travel. Our prototype doesn’t take this detail into consideration – we’ve had no issues with friction, and we compensated for the thickness by making the pin a little longer – but it’s meaningful to note.
HP7475A Carousel Drive – cam1
The broken pieces also confirmed the thicknesses and radii of the original part, and so my partner was able to build an accurate technical drawing of the drive wheel for future fabrication.
While we intend to make a better replacement, our prototype was built with dense 1/8″ mat board, PVA glue, binder clips, and a short piece of wooden dowel from our bits box. Basically just stuff we had kicking around the studio. It’s held up shockingly well. A little dented around the edges from hitting the carousel, but there’s no slippage. I’m thinking I’ll use it until it falls apart, just to see how long it takes.
HP7475A Carousel Drive – repaired – cam2
Attached, find a technical drawing comparing the original drawing to our prototype (measured in good old fashioned 1980s inches); a photo of the retrieved piece, showing the collar on the reverse side; and a photo of the prototype in place. Feel free to share these – everyone deserves a working plotter!
7475a drive wheel
Once the carousel was working, my roommate – an electrical engineer – hooked me up with a custom serial cable, a Raspberry Pi, and a crash course in Python, so now that I can communicate with the plotter, the possibilities are staggering. I’m thrilled to add this machine to my print studio arsenal!
I love a happy ending …
For anyone with a new-to-you plotter, search the blog for 74754A to find info on replacing failed electrolytic capacitors, adapting Sakura Micron pens, refilling old plotter pens, building a serial cable, hacking Chiplotle to actually use hardware handshaking, and plotting Superformulas. Let me know how you got your plotter working!
Tour Easy: White ABS vs. Six Years of Sunlight
Posted by Ed in Machine Shop, Recumbent Bicycling on 2017-07-16
These white ABS fairing plates held the Zzipper fairing on my Tour Easy ‘bent since 2011:
ABS Fairing Plates – 6 years
Over the course of those six years I’ve ridden about 6 × 2500 = 15000 miles, maybe more, maybe less. I can ride at 15 mph for a while, but 12 mph seems a more reasonable overall estimate, making for a bit over 1000 hours. Figure the bike spends that much time sitting outdoors at the far end of the ride and you’re looking at what 2000+ hours of sunlight does to ABS.
In addition to discoloration, the plates have become brittle, as shown in the chips in third one down, and permanently deformed due to the pressure of the nylon bolts compressing the black foam against the fairing.
A closer look at the top plate:
ABS Fairing Plates – 6 years – detail
My 3D print quality has improved a lot since then.
New plates of a different design are, as NASA puts it, “in work”.
The pix come from the new LiDE 120 scanner. It does a good job with the color, but has (for good reason) an essentially zero depth of field: if it’s not on the glass, it’s out of focus.
Monthly Image: Mystery Lizard
Posted by Ed in Oddities, Photography & Images, Science on 2017-07-15
We found this critter keeping a watchful eye on the construction at Adams Fairacre Farms during our most recent grocery trip:
Mystery frilled lizard – detail
I think it’s an undocumented alien that entered the US stowed away in a tropical plant, because it was affixed to the array of ceramic pots outside their (open) greenhouse windows:
Mystery frilled lizard
To the best of my admittedly limited herpetological knowledge, none of our native lizards / geckos / whatever have such a distinctive dorsal frill / fin / ridge. I have no idea how to look the critter up, though.
We left it to seek its own destiny. Unless it’s a mated female (hard to tell with lizards), it’ll have a lonely life.
Perhaps it practices rishratha, which is entirely possible.
Cylindrical Cell Adapter: 18650 to 3xAAA
Posted by Ed in Electronics Workbench, Machine Shop, Software on 2017-07-14
Anker LC40 flashlights can use either one lithium 18650 cell or an adapter holding three AAA cells. I now prefer 18650 cells, but they’re nigh onto 4 mm smaller than the flashlight ID and rattle around something awful.
I can fix that:
Anker LC40 with 18650 cell adapter
Three new entries appear in the cell dimension table of my OpenSCAD inter-series battery adapter program:
NAME = 0; ID = 0; // for non-cell cylinders OD = 1; LENGTH = 2; Cells = [ ["AAAA",8.3,42.5], ["AAA",10.5,44.5], ["AA",14.5,50.5], ["C",26.2,50], ["D",34.2,61.5], ["A23",10.3,28.5], ["CR123A",17.0,34.5], ["18650",18.8,65.2], ["3xAAA",21.2,56.0], ["AnkerLC40",23.0,55.0] // Flashlight tube loose-fit for 3xAAA adapter ];
I took the opportunity of adding OpenSCAD Customizer comments, which means this now works:
OpenSCAD Customizer – dropdown selections
The model looks about the same as before, although with a few more sides just for pretty:
AnkerLC40 vs. 18650 Sleeve – Slic3r
That was easy …
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