RepRap: Blog

I've been looking at a better microscope and found a 4K USB/WiFi one on Amazon AU for NZ$63 https://www.amazon.com.au/Bysameyee-3840x2160P-Microscope-Inspection-Magnification/dp/B09NBY6G9S . It just had to be better than my "Z Axis" one (less than 1MP and ancient) so I got one to try out. There goes a week's beer fund. Here's how my better microscopes stack up excluding aforesaid crappy one. The 4x4 square is 50μm per division and I have manipulated the images to give a pixel-per-pixel comparison at maximum real zoom:

On the left, the trinocular port on my Konus Crystal 45/90 with an 8MP Svbony SV205 image sensor. Quite sensibly, this does not claim a magnification factor (see previous rants on why USB microscopes lie). That can easily make out the 10μm subdivisions, and can resolve down to a micron. It is, however, a great lumbering beast and cost a few thou. 

Middle is the $63 Amazon special. It's quite nice and actually has proper focusing: When you turn focus, it actually focuses the image on the sensor plane rather than shuffling the entire imaging assembly back and forth to hit a fixed focus.

It also has a detachable transparent endcap, so one can get it closer in. 

On the right, the original "decent" Digitech microscope I bought from Jaycar. A reasonable device when I bought it for $300, but now outclassed by the 4K technology. Came with a very nice stand for bench use though.

So why isn't maximum magnification all the time the best thing? Well, two reasons:

 1. With great magnification comes lousy depth of focus, and μRepRap is making 3D structures, not flat microscope sample slides.

Note that I have experimental implants in my eyes with infinite focal depth on the macro scale. This means that when using a binocular microscope I get a radically better depth of simultaneous focus than most people, but I can't take pictures of exactly what I see, and few others can see what I do. It also means my Svbony imager focus almost always needs tweaking before I take a photo.

2. Doubling the resolution quarters the amount of available light. Adding more light only works up to a certain point, then you have a small sun on your workbench and your samples melt. 

Next step is to try the 4K out on imaging the probe as it closes in on the glass slide, and see if I can use that image to get the probe within a few microns of it. The old <1MP microscope was obviously not capable of doing that. If it works out, I'll get another. 

# posted by vik-olliver @ 10:23 AM 0 comments

 The GRBL stepper setup is as follows:

CNCjs 1.10.3 [Grbl]
Connected to /dev/ttyACM0 with a baud rate of 115200
Grbl 1.1g ['$' for help]
client> $$
[MSG:'$H'|'$X' to unlock]
$0=10 (Step pulse time, microseconds)
$1=255 (Step idle delay, milliseconds)
$2=4 (Step pulse invert, mask)
$3=3 (Step direction invert, mask)
$4=0 (Invert step enable pin, boolean)
$5=0 (Invert limit pins, boolean)
$6=0 (Invert probe pin, boolean)
$10=17 (Status report options, mask)
$11=0.100 (Junction deviation, millimeters)
$12=0.200 (Arc tolerance, millimeters)
$13=0 (Report in inches, boolean)
$20=0 (Soft limits enable, boolean)
$21=1 (Hard limits enable, boolean)
$22=1 (Homing cycle enable, boolean)
$23=3 (Homing direction invert, mask)
$24=5000.000 (Homing locate feed rate, mm/min)
$25=8000.000 (Homing search seek rate, mm/min)
$26=10 (Homing switch debounce delay, milliseconds)
$27=1000.000 (Homing switch pull-off distance, millimeters)
$30=1000 (Maximum spindle speed, RPM)
$31=0 (Minimum spindle speed, RPM)
$32=0 (Laser-mode enable, boolean)
$100=31.000 (X-axis travel resolution, step/mm)
$101=33.642 (Y-axis travel resolution, step/mm)
$102=32.000 (Z-axis travel resolution, step/mm)
$110=15000.000 (X-axis maximum rate, mm/min)
$111=15000.000 (Y-axis maximum rate, mm/min)
$112=15000.000 (Z-axis maximum rate, mm/min)
$120=200.000 (X-axis acceleration, mm/sec^2)
$121=200.000 (Y-axis acceleration, mm/sec^2)
$122=900.000 (Z-axis acceleration, mm/sec^2)
$130=6500.000 (X-axis maximum travel, millimeters)
$131=6500.000 (Y-axis maximum travel, millimeters)
$132=6500.000 (Z-axis maximum travel, millimeters)
ok

# posted by vik-olliver @ 1:34 AM 0 comments

Paul asked if NEMA14 steppers could be used in a μRepRap. Well, I guess. 80:1 mechanical advantage will do a lot if your motor hasn't got much torque. So I've split the PIKA version of the Axis Driver away from the MAUS version, tidied it a bit, and made the screw holes into slots that should take NEMA14 or NEMA17:

The motor shaft and boss are (I think) the same size on both, and the slots should self-centre the motor. As this is gloriously untested there are no STLs, but you can download and build from here

https://github.com/VikOlliver/RepRapMicron/blob/main/pika/pika_axis_driver.scad

Let me know how it goes. 

# posted by vik-olliver @ 9:38 AM 0 comments

The guide to automated etching of RepRapMicron Probe Tips and their integration/assembly is now on the Github wiki: 

https://github.com/VikOlliver/RepRapMicron/wiki/Probe-Tip-Fabrication-And-Assembly

Comments and suggestions welcome.

# posted by vik-olliver @ 1:26 AM 0 comments

I have now posted the results of FPath Experiment 012 which is part of the FPath project. 

Experiment 012 builds on the Graphical Stigmergy control techniques discussed in earlier experiments and embeds commands into the virtual path. These commands can automatically trigger actuators when the device under control traverses that section of the path.

Also, which may be of some interest, is a brief discussion of a new Subsumption Architecture which has been implemented in the controlling software. It has proven to be quite versatile in operation.

I just thought that some of you might be interested in how all this is done. The video explains all: https://youtu.be/7SanmrL5zJI

Labels: FPath, Graphical Stigmergy, Image Recognition, Sub-millimeter Control, Subsumption Control Architecture

# posted by OfItselfSo @ 1:09 PM 0 comments

If you want a preview, here's a link to the Probe making documentation:

https://github.com/VikOlliver/RepRapMicron/wiki/Probe-Tip-Fabrication-And-Assembly

I've only covered the etching part so far, but I'll write proper docs for putting the etched tip on the Probe Arm later.

As an aside, I tried using the automated probe dipping with a variety of over- and under-etch roughened wires (by time and acid strength) and they generally end up with pretty much the same shape on the last 100μm:

As far as I can tell at this point, the upper profile is preferred.
 

# posted by vik-olliver @ 7:58 AM 0 comments