Home on Robot Daycare

 Gremlins eradicated - USB hubs are  bad, don't use them: "Only" ~3.3 meters in this test - not maxing out the motor/mechanism yet, there's still some motor control tuning to do.

A robot-weight steel puck: Test setup outside, before being beset by electrical gremlins:

Not done yet, but almost ready for some high-power testing.

 Now controlled over CAN and USB, using a gui based on the espresso machine software The the USB communication plus Python GUI gives me nice live-plots and logs.

 

Putting the lathe to work:

 Austin and I turned on Mike's tesla coil in the parking lot outside MITERS, for MIT's Campus Preview Weekend.

 I've been keeping my eye out on craiglist and machinery auctions for a small (but not that small) lathe for a while now, but small lathes (other than import mini-lathes) are pretty uncommon.

Lathe restoration has gone much more smoothly than anticipated:

Lathe backstory and move post to come, but here's a sneak-peak.

  Needs a cam handle, but it works.

Lots of progress on the jumping robot based on this mechanism.

Turning off the fixturing boss from milling: Undercut boss machining:

 Quick and dirty prototype of a passive foot pitch mechanism: CAD cross section: To make a return spring I flattened the end of a 1mm spring steel rod and drilled a 1mm hole through the end for a dowel pin axle: A drilled out screw acts as a guide bu…

I was inspired by my friend Ethan to finally start organizing my fasteners and other little bits of hardware: Ethan designed these 3d-printable stacking sub-bins - I have a lot of small fasteners, so these were really helpful: Beginning of the stack:

It spins!

I needed an undercutting tool for the part in the last post, so I made one from an old HSS end mill.

 Machining the rotor/cam nut for the screw mechanism: Turned on a manual lathe to this point, then milled on the 5-axis: Mid-finishing passes:

The astute reader can probably figure out what this is and what it's a test setup for: Oh how I missed you, MITERS Hardinge

 

I've made a lot of progress on the software and control side of the espresso machine, and learned some good lessons about designing the real version of the machine.

 Testing a mostly-functional espresso machine gui.

Needle valve + basket with the bottom cut out + aluminum "puck" with an o-ring = adjustable coffee puck simulator.

 

 Last Sunday I whipped up an enclosure design for the mill to replace the shipping crate.

One section done, one section half machined.

The most recent attempt was so close.

I've just done 3+2 machining up until now, and haven't tried any simultaneous 5-axis toolpaths.

 Making a stainless shaft.

I didn't forget about this!

 Over a year ago I started porting my motor control firmware away from mbed.

PI+Lead pressure control with ~30 hz bandwidth (probably will get it's own thorough post soon), native USB data transfer either way (logging at a little over 1 kHz, sending commands at ~15 hz from the GUI), python/QT gui running the show.

 First experiments using native USB CDC (communications device class) on STM32's, using the CubeMX libraries: It's been surprisingly straightforward to get working.

It's been a while since I did any system id for fun: Pretty darn 2nd order (as expected from motor inertia and magnetic coupling stiffness).

Even before getting a lever espresso machine, I've been thinking about how I might design one if I were to do it from scratch.

 It works!

   The click at 0:41 is very satisfying Questionable workholding stack: Fancy "morphed spiral" profiling toolpath came out well: Inlet and outlet visible With fittings, shower screen and seal installed, and portafilter locked in.

 More like "heap" at the moment, but it's getting there.

The eventual goal is to have these for all my tools so I can preset tool lengths and never swap ER collets.

 A quick experiment in doing some turning on the mill.

Using the super glue and blue tape trick to fixture some large (relative to the mill), thin parts.

Finished making some long overdue fixes to the gourd ukulele.

  Using a leftover pendulum motor controller, Moog brushless motor scavenged from the Media Lab years ago, and gear pump from ebay to play with closed-loop pressure control.

2 parts in one operation, for a dial thermometer holder on the espresso machine grouphead.

 You'll now notice that I added a Feed tab to the top of the page.

I've had a La Pavoni Professional lever espresso machine for a couple years now, which I got on ebay and fixed up.

 Getting back to this mechanism.