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Vacuum Tube LEDs: Hard Drive Platter Base

Stainless steel socket head and button head screws add a certain techie charm to the hard drive platter mirroring the Noval tube:

Noval - Black PETG base - magenta phase

Noval – Black PETG base – magenta phase

Black PETG, rather than cyan or natural filament, suppresses the socket’s glow and emphasizes the tube’s internal lighting:

Noval tube on platter - button-head screws

Noval tube on platter – button-head screws

The base puts the USB-to-serial adapter on the floor and stands the Pro Mini against a flat on the far wall:

Noval tube socket and base - interior layout

Noval tube socket and base – interior layout

A notch for the cable seems like a useful addition subtraction to the socket, because that cable tie just doesn’t look right. I used 4 mm threaded inserts, as those button head screws looked better.

The solid model looks like you’d expect:

Vacuum Tube Lights - hard drive platter base - solid model

Vacuum Tube Lights – hard drive platter base – solid model

Those are 3 mm threaded inserts, again to get the right head size screw on the platter.

The height of the base depends on the size of the socket, with the model maintaining a bit of clearance above the USB adapter. The OD depends on the platter OD, with a fixed overhang, and the insert BCD depends on the OD / insert OD / base wall thickness.

Although I’m using an Arduino Pro Mini and a separate USB-to-serial adapter, a (knockoff) Arduino Nano would be better and cheaper, although the SMD parts on the Nano’s bottom surface make it a bit thicker and less suitable for foam-tape mounting.

I drilled the platter using manual CNC:

Hard drive platter - Noval base drilling

Hard drive platter – Noval base drilling

After centering the origin on the platter hole, the hole positions (for a 71 mm BCD) use LinuxCNC’s polar notation:

g0 @[71/2]^45
g0 @[71/2]^[45+90]
g0 @[71/2]^[45+180]
g0 @[71/2]^-45

I used the Joggy Thing for manual drilling after each move; that’s easier than figuring out the appropriate g81 feed & speed.

The 3D printed base still looks a bit chintzy compared with the platter, but it’s coming along.

The OpenSCAD source code as a GitHub Gist:

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  1. #1 by rkward on 2016-09-13 - 08:11

    “manual CNC” = cerebral numerical control?

    • #2 by Ed on 2016-09-13 - 12:28

      Would that it were so!

      I type G-Code directly into the MDI panel and use the Joggy Thing for alignment & touchoff. That process neatly combines the accuracy of CNC positioning with the impromptu “Oh, shit!” of manual milling… [sigh]

  2. #3 by Vedran on 2016-09-13 - 08:56

    How about chucking the base in the lathe and giving it a light finishing cut to get rid of layer transitions? Afterwards you could finish it with a coat of black paint from a spray can.

    • #4 by Ed on 2016-09-13 - 12:25

      I’ve never been satisfied with machining 3D printed objects, probably because I don’t make them rigid enough to withstand much in the way of external force. Perhaps a mandrel to support / clamp the inside?

      I should do a couple of test pieces just to see how it works, now that I have nice sharp carbide inserts…

  3. #5 by madbodger on 2016-09-13 - 09:52

    I’m unclear what that cable tie is wrapped around, it looks like it’s just floating on the wire. You could, theoretically, print the socket and the base together, in which case you’d only need one set of screws to hold the platter on as well.

    • #6 by Ed on 2016-09-13 - 13:44

      Half a dozen screw threads stick out beyond the brass insert: just enough for the cable tie to not quite fall off. It’s sooo half-assed that the socket model now has two slots bracketing the LED.

      I haven’t figured out how to slide the LED into the middle of a socket that grows out of the base: a slot would (probably) require impossible-to-remove support. Plus, the USB adapter sits in the air gap under the socket; the soon-to-arrive Nano boards may suggest a different arrangement.

      That poor platter has way too many screw holes, fer shure…

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