Upgrades, mostly complete

Over the last weekend I've managed to install several new upgrades, centered around a new X-axis. The goal was to be able to run a dovetail bit through oak, and I'm happy to say it can.

X-Axis, front

X-Axis, back

The two 1800mm lengths of MakerSlide for the X-axis have been replaced with a single 80/20 25-5010 extrusion that is 100mm tall and 50mm wide (you can get an idea of big it is by looking at the X-Axis pictures). The V-Wheels for the X-axis ride on black OpenRails that are attached to the 25-5010 extrusion.
To mount the new 25-5010 X-axis I've milled new plates for the X-axis and the Y-axis. The plates are made out of 1/4" aluminum, and are considerably larger than the steel Shapeoko 2 plates I started with. The Y-axis plates sprout three V-Wheels on top instead of two. Since I knew exactly where all of my screws were going to be before I started, I replaced all of the slots in the original Shapeoko 2 plates with simple holes so I wouldn't have to make any adjustments. The holes were also faster to mill than slots.

Y-Axis

I've replaced the 1.8Nm NEMA 23 motor on the X-axis with a 13Nm NEMA 34 motor from omc-stepper online. The new motor required a new, larger pulley, and I upgraded the X-axis belt to a 15mm wide GT-3 belt. The new belt required custom clips milled out of acrylic to hold the belt. The new belt also needed custom 15mm wide idler wheels, which I ordered from Pulley-N-Wheel.

The X-Controller is driving the 13Nm NEMA 34 motor just fine, although the X-Controller can only put out 4 amps and the motor wants 5 amps. I'd rather have motors that can take down more current than the controller can put out than the other way around.
The design works pretty well, but the drag chain mounts remain a work in progress. I'd add a fourth wheel to the X-axis plates if I got a chance to mill them again. The X-Axis plates have holes to mount NEMA-34 motors, but I'll probably need the 4th wheels if I add the weight I'd get from two more NEMA-34 motors. My first attempt at mounting the X-axis ran into a collision between the screws holding the terminal block and the screws holding the OpenRails in place.
The only problem I've ran into so far was that I forgot to fully tighten the set screws for the X-axis, and debugging the backlash caused by the screw moving along the flat portion of the axel took a while.

X-Axis acrylic tabs

New milling strategy

Tonight I tried a new milling strategy for the final contour cut of my aluminum plate.
Instead of cutting the entire plate with .2mm depth cuts, I cut first 2mm at .2mm depth cuts, and then switched the depth cuts to .25mm

The cutting feed speed was set to 330mm/minute, but I suspect that GRBL is gating the feed speed.

Third successful aluminum run

I milled the third of four plates that I'll need for upgrading the CNC router to use the larger extrusions. I milled with the Niagara bit, 300 mm/minute feed rate, and .2mm per pass. At some point it lost a few steps doing the final contour cut. It also had to be cut down to 7.25mm, and even then didn't make it all the way through --- even though the aluminum is only 6.25mm thick.

This run was the first aluminum run with the X-Controller.

Upgrading to X-controller, GRBL values dump

$0=10 (step pulse, usec)

$1=25 (step idle delay, msec)

$2=0 (step port invert mask:00000000)

$3=3 (dir port invert mask:00000011)

$4=0 (step enable invert, bool)

$5=0 (limit pins invert, bool)

$6=0 (probe pin invert, bool)

$10=3 (status report mask:00000011)

$11=0.010 (junction deviation, mm)

$12=0.002 (arc tolerance, mm)

$13=0 (report inches, bool)

$20=0 (soft limits, bool)

$21=0 (hard limits, bool)

$22=0 (homing cycle, bool)

$23=0 (homing dir invert mask:00000000)

$24=25.000 (homing feed, mm/min)

$25=500.000 (homing seek, mm/min)

$26=250 (homing debounce, msec)

$27=1.000 (homing pull-off, mm)

$100=40.000 (x, step/mm)

$101=40.000 (y, step/mm)

$102=320.000 (z, step/mm)

$110=2000.000 (x max rate, mm/min)

$111=1000.000 (y max rate, mm/min)

$112=500.000 (z max rate, mm/min)

$120=10.000 (x accel, mm/sec^2)

$121=10.000 (y accel, mm/sec^2)

$122=10.000 (z accel, mm/sec^2)

$130=200.000 (x max travel, mm)

$131=200.000 (y max travel, mm)

$132=200.000 (z max travel, mm)

The jumper for the Z-axis is set to 2x microstepping.

You'd think I'd know by now to dump the values before switching to the X-controller, instead of looking them up after figuring out what my Z movement was wrong.

Nope.

Computing the delta for the Y-axis plates

Tip to tip, maker slide is, per this diagram, 43.9358mm.

The openrail distance is a little harder to find, because the image on the openbuild.net site is a raster image that's unreadable, but a PDF can be found here. The openrail adds 2.9679mm*2 to the 100mm 80/20 extrusion I'm using, for a total of 105.9358mm. This is a delta of 62mm.

The distance between the center of top and bottom holes for the deletion wheels mounted on maker slide is 64.60mm, or 20.6642mm to accommodate the wheels. The distance, center to center, for my plate will need to be 64.60mm + 62mm = 126.6mm

Successful second plate milled

I've milled the companion plate for the first X-axis plate. Along the way I tried changing the depth of cut to .24mm. This did not work, so I tried adding WD-40. This didn't help --- the machine would still skip steps.
Then I realized that after the last mill run I'd taken off one of the eccentric nuts to test the fit. I loosened that nut, and changed the depth of cut to .20mm.
Everything worked.

Good news, ok news

The good news: the Y-axis plate checks out fine. All 8 holes line up with the 80/20 50mm by 100mm extrusion, the holes for the motor mounts look aligned, the holes for the eccentric nuts fit exactly, and when the wheels are attached they are correctly spaced for the marker slide.

When the 11 year old was screwing in the screws for the 80/20 extrusion we both noticed that some of the screws were loose.

That's the ok news. The screws were loose because I tapped the axis with an M5 tap, and I should have used an M6 tap. Fortunately, a problem that is easily fixed.

Successful 5052 .25" aluminum milling run

Settings:

Feed rate: 300mm/minute
RPM: 30,000 RPM
Plunge rate: 60mm/minute
Depth of cut: .2mm
Lubrication: I used some WD40 at first, but it just seemed to make the aluminum flakes bunch up around the bit, so I stopped. I did run the ShopVac constantly.
Bit: Niagara Cutter N61442 Carbide Square Nose End Mill, Inch, TiCN Finish, Finishing Cut, 45 Degree Helix, 2 Flutes, 1.5" Overall Length, 0.125" Cutting Diameter, 0.125" Shank Diameter



I had to do a second pass where I went from -6.3 to -6.55.

Fans and pots

I've turned the potentiometers for the X and Y axis all the way up, and expanded the Lego case to include two fans.

So far everything looks good. 

Except that it turns out I have a 90 watt power supply, and when the potentiometers are turned all of the way up the power supply can't supply the full load.

Upgraded to x-carve z-axis

Last week the coupler on the z axis slipped during a run. 

I then ordered the x-carve z-axis plate, pulleys, and closed loop cable and swapped it in this week end. 

Grbl settings, for the next upgrade

I upgraded the firmware to 0.9, but forgot to save the Grbl settings.

Here are the input parameters used for the Grbl settings calculator:

X/Y belt pitch (inches): 0.0787402
X/Y motor (steps/rev) 200
X/Y pulley teeth 20
X/Y microsteps 8

Z threaded rod pitch (mm) 1.25
Z motor (steps/rev) 200
Z micro steps 2