Posts Tagged M2

Makergear M2: Heating Times

With the platform and extruder starting at the 19.5 °C = 67 °F Basement Laboratory ambient …

The extruder takes 1 minute to reach 175 °C, overshoots to about 180 °C, crosses 175 °C going downward at 1:30, then gets up to 174 °C again at 3:15. I ran a PID tuning session quite a while ago with inconclusive results. Reducing the initial overshoot would probably increase the time-to-get-ready, with no net improvement.

The platform, which isn’t the stock Makergear hardware, requires 3:30 to reach 69 °C, just under the 70 °C target, at which point it’s ready to start. There’s no insulation under the PCB-trace heater, but some previous tinkering implies that running bare doesn’t make much difference, particularly with a fan blowing on the top surface of the glass.

M2 - Improved HBP - bottom view

M2 – Improved HBP – bottom view

The modified platform runs from a 40 V supply with an initial power of 250-ish W at ambient. A quick measurement at 75 °C during a print:

  • 40 V @ 5.8 A = 230 W peak
  • 10 s on / 30 s off = 25% duty cycle
  • 230 W × 0.25 = 58 W average

Remember that’s with an outboard SSR to unload the RAMBo’s MOSFET.

By and large, the M2 is ready to print in under 5 minutes from a standing start, which is just about enough time to spritz hair spray on the platform, load the G-Code into Pronterface, and so forth and so on.

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Fit Test Blocks for 3D Printers: OpenSCAD Version

During one of my recent presentations, somebody asked about the accuracy of 3D printed parts, which reminded me of another member of Coasterman’s Essential Calibration Set: the perimeter width/thickness test block. Back in the day, calibrating the extruder meant getting the actual ratio of the thread width to its thickness to match the ideal value you told Skeinforge to use; being a bit off meant that the final dimensions weren’t quite right.

But when I got it right, the Thing-O-Matic printed a test block with considerable success, despite the horrible retraction zittage:

Perimeter Calibration Block - yellow 1.10 rpm 0.33 0.66 mm

Perimeter Calibration Block – yellow 1.10 rpm 0.33 0.66 mm

Alas, feeding the STL to Slic3r showed that it was grossly non-manifold, and none of the automated repair programs produced good results. Turns out it’s an STL created from a Sketchup model, no surprise there, and the newer slicers seem less tolerant of crappy models.

Sooo, here’s a new version built with OpenSCAD:

Fit Test Blocks - build view

Fit Test Blocks – build view

You get three blocks-and-plugs at once, arranged in all the useful orientations, so you can test all the fits at the same time. They come off the platform about like you’d expect:

Fit test blocks

Fit test blocks

I tweaked the code to make the plugs longer than you see there; the short ones were mighty tough to pry out of those slots.

I ran the plugs across a fine file to clean the sides, without removing any base material, and the plugs fit into the slots with a firm push. I’d do exactly the same thing for a CNC milled part from the Sherline, plus breaking the edges & corners.

The plugs doesn’t fit exactly flush in the recesses for the two models on the right side of that first image, because the edges and corners aren’t beveled to match each other. It’s pretty close and, if it had to fit exactly, you could make it work with a few more licks of the file. The left one, printed with the slot on the top surface, fits exactly as flush as the one from the Thing-O-Matic.

Of course, there’s a cheat: the model allows 0.1 mm of internal clearance on all sides of the plug:

Fit Test Block - show view

Fit Test Block – show view

The outside dimensions of all the blocks and plugs are dead on, within ±0.1 mm of nominal. You’d want to knock off the slight flange at the base and bevel the corners a bit, but unless it must fit inside something else, each object comes off the platform ready to use.

Feel free to dial that clearance up or down to suit your printer’s tolerances.

The OpenSCAD source code:

// Fit test block based on Coasterman's perimeter-wt.stl
// Ed Nisley - KE4ZNU - May 2014

Layout = "Show";

//- Extrusion parameters must match reality!
//  Print with 2 shells and 3 solid layers

ThreadThick = 0.20;
ThreadWidth = 0.40;

Protrusion = 0.1;			// make holes end cleanly

function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

// Dimensions

Clearance = 0.1;

PlugSize = [10.0,10.0,25.0];
BlockSize = [25.0,13.0,20.0];

PlugOffset = 10.0;

// Useful routines

module ShowPegGrid(Space = 10.0,Size = 1.0) {

  RangeX = floor(100 / Space);
  RangeY = floor(125 / Space);

	for (x=[-RangeX:RangeX])
	  for (y=[-RangeY:RangeY])


module Block() {
	difference() {
		translate([0,PlugSize[1] - PlugSize[1]/2 - BlockSize[1]/2,-PlugOffset])

module Plug(Clear = 0.0) {
	minkowski() {
		if (Clear > 0.0)

// Build it


if (Layout == "Block")

if (Layout == "Plug")

if (Layout == "Show") {
	translate([0,PlugSize[1] - PlugSize[1]/2 - BlockSize[1]/2,-PlugOffset])

if (Layout == "Build") {

	translate([-30,0,0]) {

	translate([30,0,0]) {


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Boneheads Raven Skull: Extruder Contamination, Continued

The Boneheads Raven Skull demo came out reasonably well, albeit in a reduced size, on the Squidwrench Frank-o-Squid:

TOM286 - Raven Skull on platform

TOM286 – Raven Skull on platform

So I ran off a full-size version on the M2 for comparison:

Raven Skull - on M2 platform

Raven Skull – on M2 platform

The extruder apparently contained a gobbet of black PLA, left over from the Pink Panther Woman, that managed to hang on inside until the very tip of the beak:

Raven Skull - beak contamination

Raven Skull – beak contamination

Close inspection found two black strands closer to the base of the printed parts:

Raven Skull - black contamination

Raven Skull – black contamination

The rear of the skull joins the front just behind the eye sockets, where the solid bottom layers make a visible contrast with the air behind the perimeter threads elsewhere. Refraction darkens some of the threads, but the two black patches stand out clearly.

If it weren’t natural PLA, those flaws wouldn’t be nearly so noticeable.

Were I doing this stuff for a living, I might dedicate a hot end (or an entire extruder) to each color and be done with it.

All in all, the printed quality is about as good as I could expect from a glorified glue gun.

The extreme slowdown while printing the tip of the beak pushed Pronterface’s remaining time estimate over the edge:

Boneheads - Raven - Pronterface time estimate

Boneheads – Raven – Pronterface time estimate

I’m not sure what the correct value should be …


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Pink Panther Woman: Extruder Contamination

The Pink Panther Woman is my reference standard (*) for smooth perimeters and zitless filament retraction:

Pink Panther Woman - left

Pink Panther Woman – left

That’s vastly improved since the Thing-O-Matic’s last attempt:

PPW - outie zits

PPW – outie zits

Done in natural PLA, as it seems the previous version also walked off:

Pink Panther Woman - natural PLA

Pink Panther Woman – natural PLA

The attentive reader will note an odd red stripe on the left leg of the black PLA version. Here’s a closer look:

Pink Panther Woman - black with red contamination - detail

Pink Panther Woman – black with red contamination – detailPink Panther Woman – black with red contamination – detail

I had recently changed from red to black PLA and, as usual, purged the extruder with a few hundred millimeters of black filament, until it emerged pure black. Alas, I forgot to wipe the outside of the nozzle:

Pink Panther Woman - black - contaminated nozzle

Pink Panther Woman – black – contaminated nozzle

That red blob produced the red tab on the neck, as you can see if you look carefully at the first picture.

There are very few visible imperfections in either object: the state of DIY 3D printing is pretty good.

(*) Does anyone know of similar male figures suitable for this purpose? That torso seems to be about the extent of Thingiverse’s offerings.

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Makergear M2 Build Platform: Moah Powah!

A surplus Mean Well PSP-600-48 48 V 12.5 A power supply just arrived, I dialed it back to 40 V, and swapped it with the 36 V brick I’d been using to drive the M2’s improved heated build platform.

The improved platform was designed for a 30 V supply that would run it at about 150 W, which took slightly less than forever to reach operating temperature.

With the 36 V supply set to 38.6 V, the platform drew 6.2 A at room temperature, which worked out to 6.2 Ω and 240 W. It was a tad pokey getting up to temperature

At 40 V, the platform starts at 6.3 A / 6.3 Ω / 250 W from a bit over room temperature and drops to 5.8 A / 6.9 Ω / 232 W at 70 °C.

At about 250 W, the platform takes about three times longer to reach operating temperature than the extruder, but it doesn’t require calling down to the engine room for more coal before maneuvering. I must run some numbers on it, now that I have a power supply with a useful range.

There’s obviously an upper limit to the peak power the PCB traces under the glass can handle, but it runs at the same average power (to produce the same average temperature) and, at least so far, hasn’t shown any signs of distress. The few additional watts at 40 V won’t make any difference.

Note that you must use an external DC-to-DC solid state relay, because the Rambo controller board can’t handle anything over 24 VDC and high current loads tend to melt its Phoenix-style connectors. When you add the SSR, replace the HBP connectors with Anderson Powerpoles, use fat wires, and be done with it.

M2 HBP SSR Wiring

M2 HBP SSR Wiring

The M2’s Marlin firmware uses bang-bang control and tends to overshoot the setpoint; I’m not sure a few degrees makes all that much difference, particularly because it’s not measuring the temperature at the top of the glass plate.



Knurled Planetary Gear Bearing: Show-n-Tell Stockup

Having had the only two working knurled planetary gear bearings “roll away” at a recent show-n-tell session, I made a few more:

Planetary Gear Bearing - black red natural

Planetary Gear Bearing – black red natural

The top looks slightly understuffed, but it’s solid:

Planetary Gear Bearing - Red - top detail

Planetary Gear Bearing – Red – top detail

They’re a nearly perfect fondletoy, so I can understand why they rolled away…

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Makergear M2: Platform Leveling with Cart Coins

It turns out that an array of Cart Coins and Cart Releasers make a fine thickness test pattern and become useful tchotchkes when you’re done:

Cart Coins - printing

Cart Coins – printing

They’re a bit easier to see in the digital realm:

Cart Coins - platform layout - layer 1

Cart Coins – platform layout – layer 1

The trick is that they’re both eight layers thick at 0.20 mm/layer. With the platform aligned exactly right, all the objects should measure exactly 1.60 mm thick.

The blue numbers give the thickness measured across the stem, just above the hole, on each object:

Platform Leveling - Initial

Platform Leveling – Initial

The green numbers are the skirt thickness: 22 = 0.22 mm.

The platform has a tilt of 0.20 mm from +Y to -Y and is just about perfect from -X to +X.

The M3x0.5 adjusting screws under the (improved) platform, seen from the front (-Y) end of the platform:

M2 - Improved HBP - bottom view

M2 – Improved HBP – bottom view

The silicone plugs inside the springs are slightly compressed, so the springs are only decorative. The platform is rigidly mounted on the plugs, with only very slight compliance, and I haven’t leveled the platform in a few months.

Tightening the “north” adjusting screw by 1/6 turn lowered the +Y end of the plate by about 0.05 mm and tilted the +X side slightly higher:

Platform Leveling - Adjustment 1

Platform Leveling – Adjustment 1

The skirt thicknesses are now in blue, too.

Tightening the “north” screw an additional 1/6 turn and tightening the “east” screw 1/6 turn produced an almost perfect result:

Platform Leveling - Adjustment 2

Platform Leveling – Adjustment 2

The thicknesses don’t vary quite randomly, but I think further adjustments won’t make much difference: the total range is only 0.12 mm = 1.53 to 1.65 mm. That’s pretty close to the limit of my measurement ability on the plastic pieces.

Notice that the skirt thread, which should be exactly 0.2 mm thick all around, really isn’t. I’m going to see whether a two-layer-thick skirt measures a more consistent 0.40 mm.

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