Posts Tagged 3018 CNC

ACM Poughkeepsie Presentation: Algorithmic Art

In the unlikely event you’re in Poughkeepsie this evening, I’ll be doing a talk on my Algorithmic Art for the Poughkeepsie ACM chapter, with a look at the HPGL and G-Code transforming math into motion:

Superformula - triangle burst - detail
Superformula – triangle burst – detail

The PDF of the “slides” lacks my patter, but the embedded linkies will carry you to the blog posts & background information:

See you there! [grin]

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CNC 3018XL: Pilot V5RT Pen Holder Lock Screw

Flushed with success about the MPCNC drag knife locking screw, I installed a similar screw on the V5RT pen holder for the CNC 3018:

Pilot V5RT holder - lock screw insert - assembled
Pilot V5RT holder – lock screw insert – assembled

A dark ring of epoxy around the screw holds a shortened M3 brass insert in place:

Pilot V5RT holder - lock screw insert
Pilot V5RT holder – lock screw insert

As it turned out, the original recess left only a few threads for the M3 SHCS, so the much longer screw wobbulated alarmingly. I drilled out the threads, turned the knurls off the insert, shortened it a bit, masked the pretty knurls on the aluminum ring, then glopped the insert in place while the Sherline held the screw vertical:

Pilot V5RT holder - insert epoxy
Pilot V5RT holder – insert epoxy

While I was at it, I added a thin ring of foam rubber under the knurled ring to keep it from clacking against the upper bushing.

Now I can’t lose the hex wrench when I take the thing out for Show-n-Tell sessions …

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Monthly Image: Digital Machinist 14.4 Cover

I ain’t getting richer, but I did get mah pitcher onna cover of th’ Digital Machinist:

Digital Machinist Cover DM14.4 - Winter 2019
Digital Machinist Cover DM14.4 – Winter 2019

I just caught George Bulliss in a weak moment. [grin]

It’s the diamond drag holder on the CNC 3018-Pro, before the XL axis extension hackage., with the probe camera stuck to the left side.

You can say you knew me before …

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Homage Tektronix Circuit Computer: Colored Scales

Although the original Tektronix Circuit Computer had relentlessly monochrome scales, a dash of color added a festive holiday look:

Tek CC - Pilot V5 - color test overview
Tek CC – Pilot V5 – color test overview

Well, OK, that’s excessive.

The intent was to see how the pens behaved, with an eye toward accenting general-purpose circular slide rule scales with a few colored characters.

The green pen shows how I built the arrows by drawing a line through vertical arrow characters:

Tek CC - Pilot V5 - plain paper - letters
Tek CC – Pilot V5 – plain paper – letters

I like blue ink entirely too much, having used a blue pen as my daily writer for most of my adult life:

Tek CC - Pilot V5 - plain paper - red blue
Tek CC – Pilot V5 – plain paper – red blue

Red ink for “backwards” scales and suchlike would work well, even if it’s too vivid for the tick marks:

Tek CC - Pilot V5 - plain paper - red green
Tek CC – Pilot V5 – plain paper – red green

Those are all on unlaminated plain paper, with plenty of room for improvement.

Seeing as how I’d be doing all the “tool changes” manually, optimizing the plotting sequence would be mandatory: one pen change per color per deck!

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CNC 3018XL: Pen Variations

Cheap 1 mm pens produce scratchy lines:

CNC 3018 - Cheap pen - plain paper
CNC 3018 – Cheap pen – plain paper

More expensive 0.5 mm Pilot Precise V5RT pens produce well-filled lines:

CNC 3018 - Pilot V5RT - plain paper
CNC 3018 – Pilot V5RT – plain paper

Both of those are on plain paper. Better paper would surely improve the results, while moving the cheap pen further into sow’s ear territory.

For reference, the cheap pens use a collet holder:

CNC3018 - Collet pen holder - assembled
CNC3018 – Collet pen holder – assembled

The Pilot V5RT pens use a custom holder:

Pilot V5RT holder - installed
Pilot V5RT holder – installed

A 3D printer really simplifies making things!

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CNC 3018XL: Adding Run-Hold Switches

Although the bCNC GUI has conspicuous Run / Hold buttons, it’s easier to poke a physical switch when you really really need a pause in the action or have finished a (manual) tool change. Rather than the separate button box I built for the frameless MPCNC, I designed a chunky switch holder for the CNC 3018XL’s gantry plate:

CNC 3018-Pro - Run Hold Switches - installed
CNC 3018-Pro – Run Hold Switches – installed

The original 15 mm screws were just slightly too short, so those are 20 mm stainless SHCS with washers.

The switches come from a long-ago surplus deal and have internal green and red LEDs. Their transparent cap shows what might be white plastic underneath:

CNC 3018-Pro - Run Hold Switches - top unlit
CNC 3018-Pro – Run Hold Switches – top unlit

I think you could pry the cap off and tuck a printed legend inside, but appropriate coloration should suffice:

CNC 3018-Pro - Run Hold Switches - lit
CNC 3018-Pro – Run Hold Switches – lit

Making yellow from red and green LEDs always seems like magic; in these buttons, red + green produces a creamy white. Separately, the light looks like what you get from red & green LEDs.

The solid model shows off the recesses around the LED caps, making their tops flush with the surface to prevent inadvertent pokery:

Run Hold Switch Mount - Slic3r
Run Hold Switch Mount – Slic3r

The smaller square holes through the block may require a bit of filing, particularly in the slightly rounded corners common to 3D printing, to get a firm press fit on the switch body. The model now has slightly larger holes which may require a dab of epoxy.

A multi-pack of RepRap-style printer wiring produced the cable, intended for a stepper motor and complete with a 4-pin Dupont socket housing installed on one end. I chopped the housing down to three pins, tucked the fourth wire into a single-pin housing, and plugged them into the CAMtool V3.3 board:

CNC 3018-Pro - Run Hold Switches - CAMtool V3.3 header
CNC 3018-Pro – Run Hold Switches – CAMtool V3.3 header

The CAMtool schematic matches the default GRBL pinout, which comes as no surprise:

CAMtool schematic - Start Hold pinout
CAMtool schematic – Start Hold pinout

The color code, such as it is:

  • Black = common
  • Red = +5 V
  • Green = Run / Start (to match the LED)
  • Blue = Hold (because it’s the only color left)

The cable goes into 4 mm spiral wrap for protection & neatness, with the end hot-melt glued into the block:

CNC 3018-Pro - Run Hold Switches - bottom
CNC 3018-Pro – Run Hold Switches – bottom

The model now includes the wiring channel between the two switches, which is so obviously necessary I can’t imagine why I didn’t include it. The recess on the top edge clears the leadscrew sticking slightly out of the gantry plate.

The LEDs require ballast resistors: 120 Ω for red and 100 Ω for green, producing about 15 mA in each LED. Those are 1/8 W film resistors; I briefly considered SMD resistors, but came to my senses just in time.

A layer of black duct tape finishes the bottom sufficiently for my simple needs.

Note: the CAMtool board doesn’t have enough +5 V pins, so add a row of +5 V pins just below the standard header. If you’ve been following along, you needed them when you installed the home switches:

3018 CNC CAMTool - Endstop power mod
3018 CNC CAMTool – Endstop power mod

A doodle giving relevant dimensions and layouts:

Run Hold Switch Mount - Layout Doodles
Run Hold Switch Mount – Layout Doodles

I originally planned to mount the switches on the other gantry plate and sketched them accordingly, but (fortunately) realized the stepper motor was in the way before actually printing anything.

The OpenSCAD source code as a GitHub Gist:

It seems bCNC doesn’t update its “Restart Spindle” message after a tool change when you poke the green button (instead of the GUI button), but that’s definitely in the nature of fine tuning.

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CNC 3018XL: Rotating the Axes

After extending the CNC 3018-Pro platform to 340 mm along the Y axis, I tweaked the Spirograph demo to work with 8-1/2×11 paper:

Spirograph - 3018XL Platform - Portrait Mode
Spirograph – 3018XL Platform – Portrait Mode

Yeah, a Portrait mode plot kinda squinches the annotations into the corners.

Rotating the coordinates to put the X axis along the length of the new platform is, of course, a simple matter of mathematics, but it’s just a whole lot easier to rearrange the hardware to make the answer come out right without fancy reprogramming.

The first step is to affix an MBI-style endstop switch to the left end of the gantry upright:

3018XL - endstop - left gantry
3018XL – endstop – left gantry

The gantry carriage sits at the 1 mm pulloff position, with the switch lever just kissing the (fixed) lower carriage plate. As before, good double-sticky foam tape holds everything in place.

The probe camera hovers just over the switch and the Pilot V5RT pen holder is ready for action.

Shut down the Raspberry Pi and turn off the power!

At the CAMtool V3.3 board:

  • Swap the X and Y motor cables
  • Move the former Y endstop switch to the X axis input
  • Plug the new endstop switch into the Y axis input, routing its cable across the top of the gantry
  • Abandon the former X axis switch and its cable in place

Modify the GRBL configuration:

  • $3=4 – +Y home @ gantry left, +X home @ frame front
  • $130=338 – X axis travel along new frame
  • $131=299 – Y axis travel across gantry

Tweak the bCNC config similarly, if that’s what you’re into.

Verify the new home position!

I reset the G54 coordinate system to put XY = 0 at the (new!) center of the platform, redefined G28 as the “park” position at the (new!) home pulloff position, and set G30 as the “tool change” position at the -X -Y (front right) corner of the platform, with bCNC icons to simplify moving to those points.

And then It Just Worked™:

3018XL - rotated axes
3018XL – rotated axes

The Spirograph patterns definitely look better in landscape mode:

Spirograph - 3018XL Platform - Landscape Mode
Spirograph – 3018XL Platform – Landscape Mode

I eventually turned the whole machine 90° clockwise to align the axes with the monitor, because I couldn’t handle having the X axis move front-to-back on the table and left-to-right on the screen.

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