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.

Tag: Sherline

Sherline CNC mill

  • Kenwood / Wouxun Headset Jack Spacing

    Wouxun plug mounting plate - overview
    Wouxun plug mounting plate – overview

    Try as I might, I cannot uncover a definitive answer to this simple question: What’s the center-to-center spacing of the mic and earphone jacks on the side of Kenwood and Wouxun HTs?

    The usual searches produce answers like 11 and 12 mm, both of which are obviously wrong, as can be determined eyeballometrically just by holding a scale against the plugs.

    Based on measurements I made on a Wouxun headset, the yellow plug mounting plate put the plugs on 11.2 mm centers and they fit into the KG-UV3D radio; it’s been working fine ever since.

    However, having just measured a speaker/mic and a headset, both from Kenwood, I come up with 11.5 mm. Frankly, I trust the Kenwood hardware a bit more: the plugs seem more rugged and the overall production values are higher.

    The calculation is simple: measure the pin diameters, then subtract half their sum from the outside distance across the pins. Cross-check by adding half the sum to the inside distance between the pins, which should give the same answer. It helps if the pins are actually round.

    The jacks in the Kenwood and Wouxun radios have enough compliance to accept either a Wouxun or a Kenwood headset plug without complaint. Maybe it doesn’t matter?

    Despite that, I made another gluing fixture with 11.5 mm spacing:

    Plug alignment plate - 11.5 mm spacing
    Plug alignment plate – 11.5 mm spacing

    Those are 0.1 inch grids; it’s a little bitty block of smoke-gray polycarbonate from the scrap heap. The plugs are nominally 3.5 mm (which is not 1/8 inch in this universe) and 2.5 mm, with clearance drills #28 and #39.

    Then I tried poking those 11.2 mm spaced plugs, now firmly epoxied in place in the yellow plate, and guess what: they don’t fit, no how no way. That’s not surprising, because there’s no compliance on either side of the joint and the plugs aren’t on the right centers for the fixture. Makes for a good No-Go gauge, I suppose.

    However, I think I’ll tweak the solid model spacing to 11.5 mm and run off another plug mounting plate for the next radio.

    FWIW, our ICOM IC-Z1A HTs use a sensible 10.0 mm spacing and that old fixture worked fine.

  • HT GPS+Voice: Battery Contacts

    For this version of the contacts (the old version is there) that make the GPS interface look like a standard Wouxun lithium battery, I left a bit more of the slot on the brass screw heads and increased the recess depth to compensate:

    HT-GPS Case - Battery contacts
    HT-GPS Case – Battery contacts

    The nuts all have fancy nickel plating, with washers & ring lugs silver-soldered in place:

    HT-GPS PCB - battery contact parts
    HT-GPS PCB – battery contact parts

    The trial fit looks OK:

    HT-GPS Case - PCB and battery contacts - end view
    HT-GPS Case – PCB and battery contacts – end view

    I even found the cutest little flat 1/4 inch wrench that fits 4-40 nuts, so I can do a better job of crunching the PCB between the nuts. That excess screw length has got to go, too…

  • HT GPS+Voice Circuitry: Bare PCB

    Drilling the PCB went fine, as did the etching & silver plating:

    PCB with edge wrap - front
    PCB with edge wrap – front

    The rear side has a fine ground plane:

    PCB with edge wrap - rear
    PCB with edge wrap – rear

    The small spots scattered over the rear mark vias that stitch the front and back planes together; lacking plated-through holes, I solder nippets of 24 AWG wires to both sides. The wrinkly edge comes from solder on the copper foil binding the entire perimeter.

    While I have no hard evidence that all of the fuss & bother matters, the most recent version of this circuit is the quietest yet: the machine noise from the TinyTrak3+ that plagued the first iteration has pretty much vanished.

    I’ll grant you that the silver plating doesn’t look very silvery in these pix, but it’s quite different from the bare copper in person. Here’s the front just after rubbing it in with a vigorous circular motion:

    HT-GPS PCB - raw plated - top
    HT-GPS PCB – raw plated – top

  • Storing Sherline CNC Mill Leadscrews

    After replacing the Y axis leadscrew, I decided that the X axis leadscrew was in fine shape, because it’s tucked under the table and not exposed to the swarf and grit that fell on the Y axis screw before I installed the bellows. Being that sort of bear, I couldn’t throw out the worn Y axis leadscrew, so I had two rather delicate rods that really needed more protection than a twist of paper.

    So I sawed off a length of 1 inch PVC pipe, faced the ends in the lathe, and added two rubbery endcaps from the heap:

    Sherline leadscrews stored in PVC pipe
    Sherline leadscrews stored in PVC pipe

    That fits neatly into the big box alongside the rotary table, with the bag of assorted nuts so they’re all together.

    Despite what you see there, the screws are wrapped in paper with a bit of oil, so it’s all good.

  • Harbor Freight Slitting Saw Arbor

    A three-pack of 100-tooth 2 inch cutoff saw blades followed me home from Harbor Freight a while ago. Although they’re intended for a craptastic HF tabletop saw, I thought they might come in handy on the Sherline for slicing lengths of brass tubing. The reviews for the saw indicate the blades are no good for steel, barely adequate for brass, and dandy for wood; they have nowhere near enough teeth for a screw cutoff blade.

    None of the arbors in my collection fit a blade with a 3/8 inch hole, so a bit of lathe work produced one while the 3D printer cranked out a GPS+audio case:

    Cutoff saw arbor in Sherline toolholder
    Cutoff saw arbor in Sherline toolholder

    The shaft is 3/8 inch drill rod and the collars are 3/4 inch drill rod, both of O1 oil-hardening steel that will remain forever unhardened, fitting into a Sherline endmill toolholder. I drilled-and-bored the collars to a slip fit on the shaft, then epoxied the rear one in place:

    img_2156 - Cutoff saw arbor - parts
    img_2156 – Cutoff saw arbor – parts

    I drilled a 0.6 inch deep blind hole in the shaft and tapped it 10-32 all the way down for a 1/2 inch SHCS. A bag of assorted 10-32 taps produced a bottoming tap that came in handy, but I put tapping in the same category as parallel parking: I’ll walk half a mile to not parallel park the van. Couldn’t avoid it this time.

    The flat on the shaft came from a bit of hand filing, which was easier than setting up the mill.

    The front collar’s undercut ensures just the rim contacts the blade. The photo shows the vanishingly thin layer of epoxy on the rear collar that mooshed out as I clamped the stack together:

    • Fixed (rear) collar
    • Waxed paper with a 3/8 inch hole punched in the middle
    • Cutoff blade
    • Split lockwasher for a bit of space
    • Loose (front) collar
    • Socket head cap screw

    After the epoxy cured, a pass through the lathe skimmed off that thin epoxy layer and trued up the fixed collar face to eliminate the last bit of wobble. The radial runout remains just enough so that one tooth tings before the others engage, but I’m not entirely convinced that’s due to the (minimal) shaft-to-blade clearance.

    In use, putting the split lockwasher between the loose collar and the SHCS provides a little clamping compliance.

    At some point, I’m sure this thing will come in handy…

  • Sherline Z-Axis Home Switch Spacer

    Sherline Z Axis home switch spacer
    Sherline Z Axis home switch spacer

    After drilling that PCB, I noticed that the Z axis saddle locking lever (which also functions as the backlash adjustment) had come loose. It turns out that if you don’t tighten the thumbscrew or it works loose, then the locking lever can turn with the leadscrew and, at the very top of the Z axis travel, can walk off the leadscrew thread.

    A snippet of rectangular brass tubing epoxied to the top of the Z axis saddle solves that problem by removing 3/32 inch of precious travel. A slip of brown waxed paper (yes, harvested from the new Y axis leadscrew wrapper) kept the epoxy off the dovetail.

    Just for consistency, I removed 0.09 inch from the Z axis home offset, but that really won’t make any difference.

    HOME_OFFSET = 6.84
HOME = 6.5

    Now, I’d put the switch in that position because the saddle jams against the preload nut exactly at the end of the switch button travel. Now I can crush the switch by manually running the Z axis beyond its Home position …

  • Maximum PCB Platen: Hold-Down Screws

    The whole point of tweaking the Sherline was to get it ready to drill the Wouxun KG-UV3D GPS+voice PCB. While setting up for that, I drilled two #5 holes in the maximum-size PCB platen for 10-32 socket head cap screws to hold it to the tooling plate:

    Sherline with maximum PCB platen
    Sherline with maximum PCB platen

    The sloppy hole fit lets the platen align to the tooling plate with the outer two 6-32 screws on the back edge.

    Most of the PCB boards I make aren’t nearly as wide as the platen, which means the new SHCS won’t get in the way. The screws require a nut (as a spacer) to keep them from bottoming out on the Sherline’s table underneath the tooling plate and the washers are just because I can’t do it any other way; I should just shorten the screws and store them with the platen.

    Masking tape holds small PCBs to the platen reasonably well, probably because I use an unreasonably high 50 mil travel clearance. I have a defunct dehumidifier that might make a dandy low-volume vacuum pump to eliminate any lifting in the middle: a project that has been on the to-do list for far too long…