Posts Tagged Sherline

Bandsaw Worklight

Having hacked back the end of the USB gooseneck extension, a tweak of the COB LED heatsink mount for my desk lamp produces a smaller version for a 1.8 W LED:

Chip On Board Heatsink Mount - Bandsaw Lamp - solid model

Chip On Board Heatsink Mount – Bandsaw Lamp – solid model

That fits half of a random heatsink, bandsawed just to the far side of the middle fin and milled flat.

Ream out the 5 mm hole with a #8 drill for a snug fit around the gooseneck, jam gooseneck in place, dab epoxy on the corners of the recess, mash the heatsink in place, solder wires to LED, smear epoxy on the aluminum backplate, clamp while curing:

USB Gooseneck - LED assembly

USB Gooseneck – LED assembly

And it looks pretty good, if I do say so myself:

USB Gooseneck - on bandsaw

USB Gooseneck – on bandsaw

The hook-n-loop tape holding the cable to the bandsaw gotta go, but should suffice until I conjure a better mount.

The alert reader may wonder how a 9 V COB LED runs from a 5 V USB cable with nary a trace of a voltage booster to be seen. Well, that’s not really a USB cable any more; I paralleled the red+white and black+green wires for lower resistance, then hacked a 9 VDC power supply into an old USB hub:

Hacked USB hub - PCB mods

Hacked USB hub – PCB mods

I ripped out the upstream USB plug, hotwired the 9 V supply where the 5 V USB wires used to be, soldered jumpers on the downstream sockets to short the outer two pin pairs together, razor-knifed the power leads going into the epoxy-blobbed USB controller, and declared victory:

Hacked USB hub - in use

Hacked USB hub – in use

Admittedly, that “In Use” LED runs a bit brighter now.

I have a few other tools on that bench in need of LED lights; when I build ’em, they can all plug into this hub. No reason to invent new connectors & cables & all that. It may need a power switch.

Turns your stomach, eh?

The OpenSCAD source code as a GitHub Gist:

 

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Pot Lid Repair

For reasons not relevant here, we (temporarily) have a set of pots with glass lids. One of lids had a remarkable amount of crud between the glass and the trim ring under the knob, which turned out to be corrosion falling off the screw. Trying to remove the screw produced the expected result:

CKC Pot Lid - broken screw in handle

CKC Pot Lid – broken screw in handle

For whatever reason, they used an ordinary, not stainless, steel screw:

CKC Pot Lid - corroded screw

CKC Pot Lid – corroded screw

I figured I could mill the stub flat, drill out the remainder, install a new insert, and be done with it. The knob has a convex surface and, even though this looked stupid, I tried clamping it atop a wood pad:

CKC Pot Lid - precarious clamping

CKC Pot Lid – precarious clamping

Two gentle cutter passes convinced me it was, in fact, a lethally stupid setup.

Soooo, I poured some ShapeLock pellets into a defunct (and very small) loaf pan, melted them in near-boiling water, and pressed the knob into the middle, atop some stretchy film to prevent gluing the knob in place:

CKC Pot Lid - ShapeLock bedding

CKC Pot Lid – ShapeLock bedding

That’s eyeballometrically level, which is good enough, and the knob sits mechanically locked into the room-temperature plastic slab. Clamping everything down again makes for a much more secure operation:

CKC Pot Lid - clamped ShapeLock fixture

CKC Pot Lid – clamped ShapeLock fixture

A few minutes of manual milling exposes the original brass insert molded into the knob, with the steel screw firmly corroded in the middle:

CKC Pot Lid - screw stub milled flat

CKC Pot Lid – screw stub milled flat

Center-drill, drill small-medium-large, and eventually the entire insert vanishes in  a maelstrom of chips and dust:

CKC Pot Lid - OEM insert removed

CKC Pot Lid – OEM insert removed

Run a 10-32 stud into an insert, grab in drill chuck, dab JB Kwik around the knurls, press in place while everything’s still aligned in the Sherline, pause for curing, re-melt the ShapeLock, and the insert looks like it grew there:

CKC Pot Lid - new insert installed

CKC Pot Lid – new insert installed

Wonder to tell, a 1 inch 10-32 screw fit perfectly through the pot lid into the knob, with a dab of low-strength Loctite securing it. Reassemble everything in reverse order, and it’s all good:

CKC Pot Lid - repaired knob

CKC Pot Lid – repaired knob

Well, apart from those cracks. I decided I will not borrow trouble from the future: we’ll let those problems surface on their own and, if I’m still in the loop, I can fix them.

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TCRT5000 Proximity Sensor Mount

Having a few TCRT5000 proximity sensors lying around, I used one for the Color Mixer so folks could just wave a finger to flip the LED colors, rather than pound relentlessly on the top plate:

Color mixer - controls

Color mixer – controls

The stem fits into a slot made with a 3/8 inch end mill:

Prox Sensor Bezel - Slic3r preview

Prox Sensor Bezel – Slic3r preview

You move the cutter by the length of the sensor (10.0 mm will work) to make the slot. In practical terms, drill a hole at the midpoint, insert the cutter, then move ±5.0 mm from the center:

Prox sensor panel cut

Prox sensor panel cut

A bead of epoxy around the stem on the bottom of the panel should hold it in place forevermore.

The rectangular inner hole came out a tight push fit for the TCRT5000 sensor, so I didn’t bother gluing it in place and, surprisingly, it survived the day unscathed!

The OpenSCAD source code as a GitHub Gist:

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Vacuum Tube LEDs: 6H6GT Dual Diode

Having accumulated a set of octal tube base clamps, it’s now a matter of selecting the proper clamp for each tube:

Octal tube base V-block clamps

Octal tube base V-block clamps

The process of shell-drilling the tube base, drilling the hard drive platter, printing a tube socket and case, wiring up the Arduino and base LED, then assembling the whole thing requires a bit of manual labor, assisted by some moderately exotic shop machinery.

The getter flash atop this small 6H6GT dual diode tube rules out a cap and there’s not enough space for a side light:

6H6GT - on platter

6H6GT – on platter

Fortunately, the base LED completely lights the internal glass:

6H6GT - purple phase

6H6GT – purple phase

The slowly changing color would make a fine night light:

6H6GT - cyan phase

6H6GT – cyan phase

It must be Art!

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Vacuum Tube LEDs: 5U4GB Vacuum Rectifier with Sidelight

A larger version of the V-block clamp accommodates the 35 mm = 1-3/8 inch octal base of a 5U4GB Full-Wave Vacuum Rectifier tube:

5U4GB - spigot milling

5U4GB – spigot milling

The evacuation tip nearly touched the inside end of the base spigot!

I had to cut the shaft and half the body off the shell drill in order to fit it into the space above the tube base and below the chuck:

5U4GB - base shell drilling

5U4GB – base shell drilling

A slightly larger shell drill would still fit within the pin circle, but the maximum possible hole diameter in the base really isn’t all that much larger:

5U4GB - base opening

5U4GB – base opening

The getter flash covers the entire top of this tube, so I conjured a side light for a rectangular knockoff Neopixel:

Vacuum Tube Lights - side light - solid model

Vacuum Tube Lights – side light – solid model

There’s no orientation that doesn’t require support:

Vacuum Tube Lights - side light support - Slic3r preview

Vacuum Tube Lights – side light support – Slic3r preview

A little prying with a small screwdriver and some pulling with a needlenose pliers extracted those blobs. All the visible surfaces remained undamaged and I cleaned up the curved side with a big rat-tail file.

I wired the Arduino and Neopixels, masked a spot on the side of the tube (to improve both alignment and provide protection from slobbered epoxy), applied epoxy, and taped it in place until it cured:

5U4GB - sidelight epoxy curing

5U4GB – sidelight epoxy curing

The end result looks great:

5U4GB Full-wave vacuum rectifier - side and base illumination

5U4GB Full-wave vacuum rectifier – side and base illumination

 

It currently sends Morse code through the base LED, but it’s much too stately for that.

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Vacuum Tube LEDs: Milling a 0D3 Spigot the Right Way

Now, with the 0D3 tube properly clamped and aligned in the Sherline mill:

OD3 Octal - V-block clamp

OD3 Octal – V-block clamp

I can slowly run an end mill down onto the spigot:

0D3 Octal - milling spigot

0D3 Octal – milling spigot

Eventually converting the whole post into black dust in the vacuum cleaner:

0D3 Octal - milled spigot

0D3 Octal – milled spigot

That was completely uneventful, which is pretty much the whole point of good fixturing, isn’t it?

Applying the vacuum cleaner while milling seems to have kept the dust out of the base, although I’m not sure I can pull that trick off every time.

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Improved Octal Tube Base Clamp

In order to clamp the tube in a V-block, the clamp must position the tube’s centerline so the envelope will clear the V groove, thusly:

OD3 Octal - V-block clamp

OD3 Octal – V-block clamp

The clamp now extends into the V-block and surrounds the entire Bakelite tube base:

Octal base compression clamp - Slic3r preview

Octal base compression clamp – Slic3r preview

The little divot captures the clamp screw and the slot lets the whole affair compress just enough to firmly squeeze the entire tube base.

The tube data table now includes columns for the envelope OD and the base OD, although only the 0D3 (and similar) Octal tubes in my collection have a bulging envelope and a smaller base. You can build clamps for cylindrical glass tubes if you like; I don’t vouch for the accuracy of the table contents.

For whatever it’s worth, the 6SN7GTB tube I started with has a 32 mm Bakelite base and the 0D3 tube has a 29 mm base. That should probably justify two separate entries in the table, but I’m making this up as I go along.

The OpenSCAD source code as a GitHub Gist:

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