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.

Category: Machine Shop

Mechanical widgetry

MPCNC: DeWalt DW660 Collet Grip Removal

The MPCNC uses a DW660 Cutout tool as a low-cost spindle for tools with 1/8 and 1/4 inch shanks. It features a tool-free “collet grip” to twist the collet nut against the shaft lock, which is convenient for a hand tool and not so much for a CNC spindle: I find it difficult to get two hands into the MPCNC setup with the proper orientation to push-and-hold two locking buttons, while applying enough torque to twist the collet nut:

DW660 – collet grip

Fortunately, it’s easy enough to remove the collet grip. Remove the collet nut, unscrew the four screws holding the yellow snout in place, then pull the snout straight off to reveal the spindle lock plate:

DW660 – nose cap interior

Capture the spring, slide the spindle lock plate out to expose the snap ring (a.k.a. Jesus clip) holding the collet grip in place:

DW660 – collet grip snap ring

Remove the snap ring, make the appropriate remark, pull the collet grip out of the snout, reassemble the snout in its One Correct Orientation, and you’re done:

DW660 – collet grip removed

The retroreflective tape snippet let my laser tachometer report a top speed over 29 k rpm, pretty close to the advertised 30 k rpm.

If one were fussy, one would 3D print a thing to cover the snout’s open end:

DW660 – snout cover

The original snap ring holds it in place and the fancy pattern comes from octogram spiral infill on the bottom.

The collet nut fits either a 5/8 inch or 16 mm wrench, both of which stick out to the side far enough for a convenient hold while pressing the shaft lock button.

2018-01-22
Low Budget Bench Power Supply
The idea behind this gadget surfaced while I was looking for something else and, although the front panel makes my skin crawl, it’s just an adjustable DC power supply:

Tattoo power supply – original front panel

This is apparently the cheapnified version of the item appearing in the eBay listing:

Tattoo Power Supply – eBay listing photo

Let’s say it has the potential to be a DC power supply, although we might quibble about the “Precision” part.

As delivered, it’s a deathtrap. Of course, it’s not UL listed and I didn’t expect it to be.

How many lethal problems do you see?

Tattoo power supply – original AC wiring

For starters, it has a three-wire AC line cord with the green-and-yellow conductor chopped off flush with the outer insulation inside the heatshrink tubing just behind the transformer:

Tattoo power supply – ungrounded AC line

The blue wire is AC neutral, but it really shouldn’t be connected to the finger-reachable outer fuse terminal.

The brown wire is AC line, which goes directly to one power switch terminal. In the event of a hot wiring fault, an unfused conductor touching the case will test the GFI you should have on your bench wiring.

The AC line cord uses some mysterious copper-colored metallic substance that’s about as stiff as music wire:

Tattoo power supply – stiff AC wire

The strands cannot be twisted together like ordinary copper wire, although they can be soldered. They may be copper-plated aluminum, because a magnet ignores them.

After soldering the strands together, they snap when bent:

Tattoo power supply – soldered broken AC wire

Generous strain relief is not just a good idea, it’s mandatory.

After some Quality Shop Time, the ground wire now connects to the case through the transformer’s rear mounting screw, the neutral AC wire connects to the transformer, the hot AC wire goes to the tip of the line fuse, and the fuse cap terminal goes to the switch:

Tattoo power supply – AC line rewiring

I relocated the white LED to the middle of the meter, where it looks a bit less weird:

Tattoo power supply – revised front panel

I have no idea what “Porket indicate” might mean. Perhaps “Precision indicator”?

The right 1/4 inch jack, labeled “Foot”, normally goes to a foot switch you don’t need for a bench power supply, so I converted a length of drill rod into a dummy plug to short the jack contacts:

Tattoo power supply – dummy switch plug

The tip comes from a bit of lathe and file work and the white cap comes from a bag of wire shelf hardware.

A genuine hologram sticker (!) on the back panel proclaims “1.5 – 15 VDC 2 A”, which seemed optimistic. Some fiddling with power resistors suggests tattoo liners (I learned a new word!) don’t draw much current:
- 4 V @ 1 A
- 8 V @ 800 mA
- 10 V @ 600 mA
It can reach a bit over 18 V (pegging the meter) at lower current, so it’s Good Enough for small projects with un-fussy power requirements.

Caveat emptor, indeed.
2018-01-17
MPCNC: Epoxy-filled Connector

When I wired up the MPCNC’s tool length probe, I planned to reinforce the wiring with a dab of epoxy. What I didn’t notice in my enthusiasm, alas, was the opening from the rear to the front in each pin slot:

Epoxied connector – rear

Which let the epoxy flow completely through the connector:

Epoxied connector – front

So I cut the mess off and applied heatstink tubing on each wire, just like I should have in the first place.

Now you know the rest of the story …

I really dislike pin headers as cable connectors, but that’s what the Protoneer CNC board uses:

MPCNC – Protoneer Wiring – SSR

It’ll be Good Enough if I don’t do anything ~~else~~ particularly stupid.

2018-01-16
Stainless Steel Water Bottle: FAIL

Although I repaired the spout a while ago, those water bottles were never satisfactory and saw very little use. A recent cabinet cleanout showed the “stainless steel” has passed beyond its best-used-by date:

Stainless steel water bottle – rust

With no regard for whether the patient would survive the operation, I peeled off its rubber foot and applied the Lesser Hammer:

Stainless steel water bottle – insulation

The “insulation” seems to be a rigid urethane-like foam disk few millimeters thick on the bottom of the interior flask, with good old air around the sides.

The bottles never worked very well and now we know why.

Gone!

2018-01-14
Eyeglass Temple Re-re-repair

After three years, the temple screw on Mary’s oldest and most-battered “reading” glasses worked loose. A dab of low-strength Loctite should hold it in place forever more:

Reading glasses temple repair

That brass ~~stake~~ pin certainly adds a Steampunk flair to the proceedings …

2018-01-13
MPCNC: Z Height Probe vs. Tempered Glass Sheet

Sliding the tempered glass sheet I used for the initial trials and B-size Spirograph plots under the Z height probe eliminated the plywood benchtop’s small-scale irregularities:

MPCNC – Z-probing glass plate

The first height map looks like a mountain sproinged right up through the glass:

ProbeArray-Glass-50

More red-ish means increasing height, more blue-ish means increasing depth, although you can only see the negative signs along the left edge.

The Z axis leadscrew produces 400 step/mm for a “resolution” of 0.0025 mm. The bCNC map rounds to three places, which makes perfect sense to me; I doubt the absolute accuracy is any better than 0.1 mm on a good day with fair skies and a tailwind.

The peak of the mountain rises 0.35 mm above the terrain around it, so it barely counts as a minor distortion in the glass sheet. Overall, however, there’s a 0.6 mm difference from peak to valley, which would be enough to mess up a rigidly held pen tip pretty badly if you assumed the glass was perfectly flat and precisely aligned.

Rotating the glass around the X axis shows a matching, albeit shallower, dent on the other side:

ProbeArray-Glass-flip-50-2018-01-05

For all its crudity, the probe seems to be returning reasonable results.

The obvious question: does it return consistent results?

2018-01-12
MPCNC: Z Height Probe

A little support pillar makes a printable holder for a small tactile pushbutton:

Z Axis Height Probe – solid model

A(n) 0-80 brass washer epoxied atop the butt end of a P100-B1 pogo pin keeps the pin from falling out and provides a flat button pusher:

MPCNC – Simple Z probe – push plate

With the epoxy mostly cured, ease the pin off the tape, flip the whole affair over, shove the switch into position, realign vertically with point down, then let the epoxy finish curing with the washer held in place against the switch to ensure good alignment:

MPCNC – Simple Z probe – epoxy curing

The brass tube ID is a sloppy fit around the pogo pin, but it’s also many pin diameters long and the position error isn’t worth worrying about.

Solder a cable, clamp it in the pen holder, attach to tool holder:

MPCNC – Simple Z probe – installed

The pogo pin provides half a dozen millimeters of compliance, letting the initial probe speed be much higher than the tactile pushbutton’s overshoot could survive, after which a low-speed probe produces a consistent result.

Unleashing bCNC’s Autolevel probe cycle:

MPCNC – Z-probing glass plate

Although the picture shows the MPCNC probing a glass plate, here’s the first height map taken from the bare workbench top with 100 mm grid spacing:

ProbeArray-100-2018-01-04

The ridge along the right side comes from a visible irregularity in the wood grain, so the numbers actually represent a physical reality.

Doing it with a 50 mm grid after re-probing the Z=0 level:

ProbeArray-50-2018-01-04

Eyeballometrically, the second plot is 0.2 mm higher than the first, but this requires a bit more study.

All in all, not bad for a first pass.

2018-01-11