Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
The case for this gadget slides into the back of the ICOM IC-Z1A HT and powers the radio through its usual battery contacts. I reshaped 5/16″ 4-40 brass machine screws into flat-top studs, then soldered 8-mil tin strips to their tops.
Grab a screw in a pin vise, brace it on the bench vise, and file off everything that doesn’t fit:
Reshaped 4-40 screws
The result should fit neatly into the flatted recess, with the top flush in the rectangular slot:
Studs in their recesses
Cut an oversized strip of 8-mil tin and solder it to the stud. I tinned both pieces to get nice solder coverage, although the notion of tinning a piece of pure tin with silver-tin solder did give me pause. It’s all in the flux, I suppose.
Anyhow, put the two tinned sides together and hit the combo with a half-second pulse at 100% duty cycle from my resistance soldering gadget. Perfect:
Tin strip soldered in place
Then snip off whatever doesn’t fit into the slot with an ordinary (albeit shop-only) scissors, making it just slightly shorter than the slot so the end doesn’t snag on anything. File the sides and corners so they’re easy on the fingers, flatten the strip so it fits neatly into the slot, buff it up a bit, and it’s all good.
Contacts in place
Takes longer to describe than to do it, at least the second time you do it…
The plastic-ball-in-plastic-socket joint found in bicycle mirrors seems to fail after a year or two of constant use. These are some doodles & thoughts about building a small, robust, adjustable joint.
A bike mirror needs two ball joints:
at the helmet mount to put the mirror in the proper spot
at the mirror to align the image
A flexy boom can replace the helmet joint, although rotation around X (pitch) is still handy.
A flexy mirror mount can replace the mirror joint, but it must also be compact.
Without heroic measures, the range of travel for a ball joint isn’t all that much.
How to make a ball? Anneal & drill a standard ball bearing for a wire shaft? Solder onto chrome steel? CNC mill the end of a bar in a rotary table?
How to make a socket? Some of that low-temperature themoplastic might be useful. Mold it around the ball, slit radially, and squash it in a circ clamp?
How to adjust? Circumferential clamp around the socket or pull the whole socket into a wedge? Radial cuts through the socket to allow compression or depend on plastic/elastic deformation?
How much friction? You want it stiff enough to hold position in a strong wind and easy enough to reposition. You definitely don’t want grub screws or fiddly knobs!
The doodles are all far too complex, some are absurd, one can’t be built (at least by me), and I’ll probably end up using some bendy wire anyway.
Something of this may be useful in another project … and now I can throw out that scrap of paper.
As described there, I made a fixture and a small plate to hold 2.5 mm and 3.5 mm plugs in the proper alignment for the mic & speaker jacks on our ICOM IC-Z1A HTs. Knowing I was going to rebuild the interface boxes, I made several spare plates and tucked them into a small bag against future need.
Jack Plates – Oblique
Time passes.
Come to find out that the new gratuitously gold-plated 2.5 mm plugs in my stash have a slightly thicker front plate that doesn’t quite fit into the recess I milled in the plates for the old nickel-plated plugs. So I set up a little nest in on the Sherline’s table, snuggled each plate into the corner, and poked a 9/32-inch end mill 1 mm down into the plate. The net change was a 0.5 mm deeper recess. Sheesh.
Milling the plug plate recess
I’d originally create the recess with helical milling, but I recently uncovered a stash of shiny-new end mills in a box: 9/32 is 7.31 mm, just about exactly what you want for a 7-mm dia plug front plate surrounded by a blob of fast-curing epoxy.
Plugs epoxied into plate
This epoxy just holds the plugs in the right position for wiring and initial testing. After the cable checks out, I’ll smoosh a blob of epoxy putty around the whole thing as before.
The circuit board is 30-mil, double-sided, half-ounce (I think) copper on glass-fiber stock, direct-etched by rubbing ferric chloride solution onto it with a sponge.
The top copper image (on the left) is reversed so it comes out correctly when you’re doing toner-transfer etching.
I didn’t bother with a silkscreen, because I don’t have a soldermask and there’s no room for text around the parts anyway.
The four vias at the corners mark the edge of the board. Trim it with tinsnips (or a shear if you have one), then introduce it to Mr Belt Sander until the edges pass directly through the middle of those via holes. Round the corners a bit so they fit into the case recess atop the mounting shoulder.
Put Z-wires in the small round vias (the ones that don’t have any other traces) to connect the top and bottom ground planes.
Put Z-wires in the other round vias to connect a top-side signal to the corresponding bottom-side trace.
There are three jumper wires across the bottom; with only two layers I don’t get all bothered about embedding the last few. Those vias are square.
I don’t have any way to do plated-through holes, so solder the wires to both sides of any vias with traces on both planes. I admit I missed two of them on the TT3 ribbon cable.
The big empty space around the positive power terminal prevents the ring-lug connector from shorting to the ground plane. Now that I think of it, there’s no need for an empty space on the bottom copper, but it doesn’t do any harm.
The boards fit in the two halves of the enclosure, which is held together by four 7/8-inch 2-56 machine screws. The blind holes in the lower (right) half are tapped for the screws. The clearance holes in the upper (left) half are a bit too close to the interior; if the setup isn’t perfect, they break through.
The right half slides into the HT’s battery pack grooves. The two tin plates match up with the HT’s power input contact springs.
Interface – top and bottom surfaces
The oval mark around the four LEDs is actually a 1 mm deep recess in the cover; the LEDs are the tallest things on the board and I sort of ran out of room. The GPS connector is essentially flush against the back of the HT, so the board can’t get any lower. Even though the case halves are milled from a hulking 3/4-inch plastic plate, the top surface is only 1 mm thick above the LEDs, so the board can’t get any higher.
The interior view:
Interface box – interior
The DB-9 serial connector mounting screws hold the TinyTrak3 board in place. The GPS receiver and PC serial port (used for configuration) plug into that connector.
The four external cables connected to the circuit board:
power from external battery pack
helmet mic + earbud
PTT switch
HT speaker + mic + mic power
A closeup of the audio PCB in its natural habitat:
GPS + Audio circuit board
The two nuts on the right fit on 4-40 brass screws that I converted into studs under those tin battery pack strips, about which more later. The nuts hold the circuit board in place atop a shoulder around the interior of the compartment.
The OEM battery packs have nice tabs that engage the HT’s clever pushbutton latching mechanism. I spent a lot of time staring at them: they’re easy to do in an injection mold and impossible to machine at my skill level. So I punted: two strips of tape hold the enclosure in place on the HT. Works fine.
You’ve seen bits & pieces of this in the previous weeks and months: now it’s up and running!
Admittedly, this is brassboard hardware; I must now build three final versions for our bikes incorporating all the tweaks & adjustments. But it’s time to write this stuff down so I can find it again … and perhaps you can use some chunks, too.
I don’t have an instruction manual to go along with this, nor is there a parts kit available. You’ll certainly want to modify everything for your own purposes; the circuit board and case certainly won’t fit whatever HT you’re using!
Over the next several days, I’ll be describing & documenting the tricky parts… in no particular order, because I’m not going to sort my notes & photos ahead of time.
One of our nice aluminum water bottles hit the floor and, of course, the tiny little hinge shattered. It’s some wonderful engineering plastic, but just look at the leverage you can apply to those few millimeters of material. This is the sort of repair that can’t possibly be economically justified, but it pisses me right off when something that should be rugged turns out to be this fragile.
The 2 mm steel hinge pin snapped the molded plastic center post of the hinge off the cap; we found the larger fragment, but the smaller one may lurk under the refrigerator for quite some time. Nothing bonds to this plastic and, if the post broke in the first place, adhesive isn’t going to help.
Broken hinge
Some doodling showed that a replacement hinge post should be machineable. The general idea was to square up the remaining chunk of the post, then attach a replacement hinge pivot with a screw. The post is almost exactly 1/4-inch thick, call it 6.2 mm, which means the right-angle feature under the pivot ought to keep the whole affair from twisting.
Water Bottle Hinge
I planned to leave the left side unmachined and cut it to fit by hand, but then figured, eh, just make it happen. I also expected to leave the area around the screw a lot thicker, with a neat counterbore around the head.
This being a bash-to-fit, file-to-hide kind of project, I wrote a snippet of G-Code (at the bottom of the post) to chew out the part from a sheet of Lexan, then did the perpendicular hole & countersinking with manual CNC.
No pix of that; I was working in a white-hot fury. Basically, I double-sticky-taped a slab of Lexan to a sacrificial sheet, clamped it to the tooling plate, and had at it with a 2 mm end mill. Cutting a 6.4 mm sheet with a 2 mm end mill is a bit iffy, as the flutes are just barely that long; the mill was armpit-deep in swarf and I was dribbling water into the cut to keep it cool.
By the time I stopped for a picture, the situation looked like this.
Replacement hinge part
For what it’s worth, that’s the second part. I had to lower the screw head below the top of the half-round feature on the left end in order to clear the cap. That’s what CNC is really good for in my shop: make another one, just like the other one, only different exactly like that.
I drilled a #50 (2-56 tap) hole in the cap pretty much by eye, using laser targeting to touch off.
Laser aligning to hinge stub
The hole wound up minutely too far inboard, but some filing cleaned up the stub edge and it was all good. I started the tap in the mill, held loosely in the chuck and turning it with my fingers, then finished up on the bench.
The screw hole goes all the way through the cap. I filed the screw down so the end sits flush at the bottom of the cap, where the silicone rubber gasket should seal firmly against it.
Here’s what the hinge looks like with all the bits assembled. The spring bears on the screw head, which makes the cap open with more snap than before. I put a little counterbore under the screw head, even after lowering it, to reduce the spring tension.
Rebuilt hinge
The cap has a spring-loaded latch that never worked very well in the first place and this repair didn’t improve it. As nearly as I can tell, the molded ledge on the cap has a rounded edge that the latch simply cannot engage. This is beyond even my level of interest; Mary was accustomed to using the wire snap to hold the cap closed and that practice will continue.
Works well enough for us and I got some Quality Shop Time on a rainy afternoon.
The G-Code uses a slightly modified & simplified version of the tool length probe routines. I’m not convinced that using the G59.3 coordinate system is the right way to go, but everything else seems worse.
(Water bottle hinge repair)
(Ed Nisley - KE4ZNU - June 2010)
(Rough-cut 1/4-inch plate with clamp at +Y)
(Sacrificial plate below, double-stick tape to secure)
(Tool change @ G30 position above length probe)
(-- Global dimensions & locations)
#<_Stock_Thick> = 6.5 (overall thickness)
#<_Traverse_Z> = 1.0
#<_Safe_Z> = 30.0 (clamp clearance)
(-- Section controls)
#<_Do_Outline> = 1
#<_Do_Drill> = 1
(-------------------)
(-- Initialize new tool length at probe switch)
( Assumes G59.3 is still in machine units, returns in G54)
#<_Probe_Speed> = 250 (set for something sensible in mm or inch)
#<_Probe_Retract> = 1 (ditto)
O<Probe_Tool> SUB
G49 (clear tool length compensation)
G30 (to probe switch)
G59.3 (coord system 9)
G38.2 Z0 F#<_Probe_Speed> (trip switch on the way down)
G91
G0 Z#<_Probe_Retract> (back off the switch)
G90
G38.2 Z0 F[#<_Probe_Speed> / 10] (trip switch slowly)
#<_ToolZ> = #5063 (save new tool length)
G43.1 Z[#<_ToolZ> - #<_ToolRefZ>] (set new length)
G54
G30 (return to safe level)
O<Probe_Tool> ENDSUB
(-------------------)
(-- Initialize first tool length at probe switch)
O<Probe_Init> SUB
#<_ToolRefZ> = 0.0 (set up for first call)
O<Probe_Tool> CALL
#<_ToolRefZ> = #5063 (save trip point)
G43.1 Z0 (tool entered at Z=0, so set it there)
O<Probe_Init> ENDSUB
(-------------------)
(-- Get started ...)
G40 G49 G54 G80 G90 G92.1 G94 G97 G98 (reset many things)
M5
(msg,Verify clamp to +Y, stock taped down)
M0
(msg,Verify X=0 at left edge, Y=0 on finished centerline)
M0
(msg,Verify tool touched off at Z=0 on surface)
M0
O<Probe_Init> CALL
T0 M6 (ensure first tool change pauses)
(-- Drill the hinge pin hole)
#<Pin_X> = 7.0
#<Pin_Y> = 0.0
#<Drill_Dia> = 2.06 (Drill diameter)
#<Drill_Num> = 46 (Drill number)
#<Tool_Num> = 146 (Tool number)
#<Drill_Radius> = [#<Drill_Dia> / 2]
#<Drill_RPM> = 3000
#<Drill_Feed> = [#<Drill_Dia> * 100]
#<Drill_Depth> = [#<_Stock_Thick> + 2 * #<Drill_Dia>]
O<Doing_Drill> IF [#<_Do_Drill>]
(debug,Insert Num #<Drill_Num> drill)
T#<Tool_Num> M6
O<Probe_Tool> CALL
(debug,Set spindle to #<Drill_RPM>)
M0
F#<Drill_Feed>
G0 Z#<_Traverse_Z>
G83 X#<Pin_X> Y#<Pin_Y> Z[0 - #<Drill_Depth>] R#<_Traverse_Z> Q[2 * #<Drill_Dia>]
O<Doing_Drill> ENDIF
(-- Mill outline)
#<Hinge_Radius> = 3.75 (half-width of hinge body)
#<Cutout_Base> = 2.75
#<Cutout_Screw> = 1.50
#<Cutout_Screw_Y> = [#<Hinge_Radius> - #<Cutout_Screw>]
#<Cutout_Screw_A> = ASIN [#<Cutout_Screw_Y> / #<Hinge_Radius>]
#<Cutout_Screw_X> = [#<Hinge_Radius> * COS [#<Cutout_Screw_A>]]
#<Passes> = 3
#<Mill_Dia> = 1.98 (end mill diameter)
#<Tool_Num> = 20
#<Mill_Radius> = [#<Mill_Dia> / 2]
#<Mill_RPM> = 3000
#<Mill_Feed> = 100
#<Entry_XL> = [0 - #<Mill_Dia>]
#<Entry_YL> = [0 - 2 * #<Hinge_Radius>]
O<Doing_Outline> IF [#<_Do_Outline>]
(debug,Insert #<Mill_Dia> mm end mill)
T#<Tool_Num> M6
O<Probe_Tool> CALL
(debug,Set spindle to #<Mill_RPM>)
M0
F#<Mill_Feed>
G0 X0 Y[0 - 2 * #<Hinge_Radius>] (get to comp entry point)
G0 Z#<_Traverse_Z>
G42.1 D#<Mill_Dia> (cutter comp right)
G1 X#<Pin_X> Y[0 - #<Hinge_Radius>]
#<Step_Z> = [#<_Stock_Thick> / #<Passes>]
#<Current_Z> = [0 - #<Step_Z>]
O<Outline_Passes> REPEAT [#<Passes>]
G2 J[0 - #<Hinge_Radius>] Z#<Current_Z> (ramp down to cutting level)
G3 Y#<Hinge_Radius> J#<Hinge_Radius>
G3 X[#<Pin_X> - #<Cutout_Screw_X>] Y#<Cutout_Screw_Y> J[0 - #<Hinge_Radius>]
G1 X0
G1 Y[0 - [#<Hinge_Radius> - #<Cutout_Base>]]
G1 X#<Pin_X>
G1 Y[0 - #<Hinge_Radius>]
#<Current_Z> = [#<Current_Z> - #<Step_Z>]
O<Outline_Passes> ENDREPEAT
G0 Z#<_Safe_Z>
G40
O<Doing_Outline> ENDIF
G30 (back to tool change position)
(msg,Done!)
M2
The Smell of Molten Projects in the Morning 