Search Results for: 3018

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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CNC 3018XL: Pilot V5RT Pen Holder

It turns out my all-time favorite Pilot Precise V5 Extra Fine stick pen also comes in a clicky-top retractable version:

Pilot V5 and V5RT pens
Pilot V5 and V5RT pens

The cartridge is a nice 6 mm cylinder, eminently transformable into a plotter pen:

Pilot V5RT holder - installed
Pilot V5RT holder – installed

A few minutes with a caliper provides key measurements for a snout surrounding the business end:

Pilot V5RT Pen Holder - snout dimension doodle
Pilot V5RT Pen Holder – snout dimension doodle

The green letters & numbers give the nearest drill sizes. The “T” values along the bottom are the tailstock turns (at 1.5 mm/turn) required to poke the drills to the indicated depths, eyeballed when the body just enters the hole.

Having recently decomissioned the Thing-O-Matic and harvested its organs parts, I have a vast collection of 3/8 inch = 9.52 mm shafts and matching bronze bushings:

9.52 mm shaft and bushings
9.52 mm shaft and bushings

Bronze bushings have low stiction, at least when they’re co-axial, and are much shorter than linear ball bearings.

I chopped off a 70 mm length of shaft and faced the raw end:

Pilot V5RT holder - facing shaft
Pilot V5RT holder – facing shaft

The other end had a maker’s logo, but I don’t recognize it:

Pilot V5RT holder - center drill
Pilot V5RT holder – center drill

I really wanted an 8 mm bore around the snout, but it just didn’t work out. The ring around the 7.5 mm counterbore shows where the larger drill just … stopped:

Pilot V5RT holder - drilled shaft
Pilot V5RT holder – drilled shaft

A trial fit with the pen cartridge:

Pilot V5RT holder - pen in shaft
Pilot V5RT holder – pen in shaft

The top of the shaft gets a somewhat longer knurled ring for the 3 mm SHCS holding the cartridge in place:

Pilot V5RT holder - knurling pen clamp
Pilot V5RT holder – knurling pen clamp

The screw bears on a split collar turned and drilled from a Delrin rod:

Pilot V5RT holder - drilling Delrin clamp
Pilot V5RT holder – drilling Delrin clamp

The “split” came from a simple saw cut across one side and I milled a flat spot in the knurling to seat the screw. As usual, the knurled ring got epoxied to the shaft.

The snout started as a 3/8 inch aluminum rod, drilled as shown in the sketch, with a (scant) 7.5 mm section to fit the shaft. The carbide insert left a nicely rounded shoulder that required trimming to fit snugly into the shaft:

Pilot V5RT holder - shaping snout seat
Pilot V5RT holder – shaping snout seat

The compound can handle the shallow angle required to shape the snout:

Pilot V5RT holder - tapering snout
Pilot V5RT holder – tapering snout

A trial fit showed the snout was a bit too long for comfort:

Pilot V5RT holder - snout test fit
Pilot V5RT holder – snout test fit

Making something shorter doesn’t pose much of a challenge:

Pilot V5RT holder - trimming snout
Pilot V5RT holder – trimming snout

Another trial fit shows it’s spot on:

Pilot V5RT holder - shaft snout pen test fit
Pilot V5RT holder – shaft snout pen test fit

The critical part is having the snout support the plastic around the pen tip to prevent wobbulation.

Epoxy the whole thing together, add a suitable spring, tighten the screws & nuts for the reaction plate, and it’s all good. I write with about 50 g of force for these pens, so a light preload seemed in order:

Pilot V5RT Pen Holder - initial downforce measurement
Pilot V5RT Pen Holder – initial downforce measurement

If I’d weighed the full-up shaft + snout + collar + cartridge, I’d know if the Y intercept matches that weight. It seems a little lighter, but I’m not taking the thing apart to find out.

The first version of the 3D printed holder (shown above) is a straightforward modification of the LM12UU diamond drag bit holder, but, after building enough of these things, I realized the circular reaction plate should be triangular to get more clearance in front of the Z-axis stepper motor when installing & removing the holder:

Pilot V5RT Pen Holder - solid model - show view
Pilot V5RT Pen Holder – solid model – show view

It also has a recess for the serrated top of the bearing, to prevent the knurled collar from clicking annoyingly as the Z-axis rises at the end of each stroke.

Now, to see how well it draws!

The OpenSCAD source code as a GitHub Gist:

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CNC 3018-ProXL: Y-axis Extension

The CNC 3018-Pro uses cheap & readily available parts, so extending the Y axis went smoothly:

CNC 3018-34 - overview
CNC 3018-34 – overview

The 2040 side rails are now 450 mm long, as is the 8 mm leadscrew. I ordered 500 mm guide rods to forestall small length mismatches, then marked them to match the rails:

CNC 3018-ProXL - marking guide rods
CNC 3018-ProXL – marking guide rods

Cut them off slightly beyond the mark, face the raw ends to length, drill-and-tap for M5 screws, then put a pair of just-under-50-mm stubs in the bar stockpile. They ought to come in handy for something, right?

The original side rails & guide rods were 290 (not 300!) mm long, so the table gained another 160 mm of travel for a total of 340 mm; I suppose it’s now a CNC 3034-Pro. Seeing as how it’s the only one and I don’t want to kill my snicker SEO, let’s call it a CNC 3018-ProXL or a maybe 3018-Pro34. Whatever.

The embiggened 300×340 mm platform dates back to the original 1955 kitchen: genuine Formica over plywood. It sits atop the previous 300×180 mm table, now demoted to being a riser, and a sheet of closed-cell foam, with the same 50 mm long M6 screws holding everything to T-nuts in the 3018’s original aluminum platform.

And, yes, the identical Formica underneath the machine originally covered a freestanding kitchen cabinet; I knew I kept it around for some good reason. Kinda disorienting to see a piece of the pattern moving against the same background, though.

The GRBL setup now extends the Y-axis length ($131=338) and puts the G54 coordinate at the new middle, with the Z-axis origin kissing the ball-point pen on the new surface:

 G10 L2 P1 X-145 Y-169 Z-24.6

While I was at it, I set the G28 position at the far left side of the gantry, with the table sticking out to the front, and the Z axis at the top:

 G28.1 X-298 Y-1 Z-1

Those are absolute machine coordinates, with Y and Z pulled off home by 1 mm. I set one of bCNC’s buttons to emit G28 and park the tool carrier over there, out of the way.

With all that prepared, a full-size Tek Circuit Computer disk plots the way it should on a sheet of Letter-size paper:

CNC 3018-34 - first light
CNC 3018-34 – first light

I suspect the longer rods wouldn’t work quite so well for actual milling / machining any material tougher than, say, rigid foam blocks. For engraving and pen plotting, they’re all good.

Some measurements show this countertop isn’t quite as flat as the previous one, but a pair of tweaks got it within -0.15 / +0.1 mm:

CNC 3018-ProXL - table flatness - 2019-11-09
CNC 3018-ProXL – table flatness – 2019-11-09

Which I defined to be Good Enough™ for use with spring-loaded implements of cutting & drawing.

Your mileage will certainly vary.

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CNC 3018-Pro: Collet Pen Holder

Along the same lines as the MPCNC pen holder, I now have one for the 3018:

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

The body happened to be slightly longer than two LM12UU linear bearings stacked end-to-end, which I didn’t realize must be a constraint until I was pressing them into place:

CNC 3018-Pro Collet Holder - LM12UU - solid model
CNC 3018-Pro Collet Holder – LM12UU – solid model

In the unlikely event I need another one, the code will sprout a max() function in the appropriate spot.

Drilling the aluminum rod for the knurled ring produced a really nice chip:

CNC3018 - Collet pen holder - drilling knurled ring
CNC3018 – Collet pen holder – drilling knurled ring

Yeah, a good drill will produce two chips, but I’ll take what I can get.

There’s not much left of the original holder after turning it down to 8 mm so it fits inside the 12 mm rod:

CNC3018 - Collet pen holder - turning collet OD
CNC3018 – Collet pen holder – turning collet OD

Confronted by so much shiny aluminum, I realized I didn’t need an 8 mm hole through the rod, so I cut off the collet shaft and drilled out the back end to clear the flanges on the ink tubes:

CNC3018 - Collet pen holder - drilling out collet
CNC3018 – Collet pen holder – drilling out collet

I figured things would eventually go badly if I trimmed enough ink-filled crimps:

Collet holder - pen cartridge locating flanges
Collet holder – pen cartridge locating flanges

The OpenSCAD source code as a GitHub Gist:

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CNC 3018-Pro: HD and CD Fixtures

I actually had this in mind when I laid out the hard drive and CD engraving fixtures:

CNC 3018-Pro - HD and CD fixtures
CNC 3018-Pro – HD and CD fixtures

The fixtures are centered at X±70.0 mm / Y=0.0 from the G54 workspace coordinate origin dead-center in the middle of the platform, with G55 centered on the HD fixture to the left and G56 on the CD fixture to the right.

So the engraving workflow amounts to homing the CNC 3018 when I turn it on, taping a platter in a fixture, selecting the corresponding WCS, loading a suitable G-Code file, and firing it off. It seems bCNC returns to G54 after completing the file, so verifying the WCS selection every time is Very Good Practice.

The friable lacquer coating on some CDs fills my world with glitter whenever I engrave a pattern on their label side. I didn’t plan on a dust shoe for this thing!

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