Friday, August 30, 2013

BeBoPr Boards Available Online!

After about a year (or an eternity in the 3D printer world), the BeBoPr board is FINALLY available for purchase through the folks at Circuitco via their site:

With any luck, vendors who have had the BeBoPr listed but unavailable for ages (like Mouser and DigiKey) will also have stock soon.

Note that this is the version of the BeBoPr designed for the BeableBone White (remember that year or so I mentioned?), but these boards will work just fine with the newer BeagleBone Black with a few minor tweaks.  If you don't need the on-board HDMI, you can get the BeBoPr working with a BBB by cutting two pins and soldering two wires.  If you need HDMI or plan to attach an LCD cape, you have to move a bunch of pins around.  The easiest way to do this is to get a bridge-board and build it up with some wire and connectors.  You can order a set of boards directly from OSH Park, or I will probably be getting a quantity made since you probably won't need all three, and lead time on OSH Park PCBs is a couple weeks.  Contact me directly via e-mail: charles (at) steinkuehler (dot) net if you're interested in a set of boards, but note that it will be at least 2-3 weeks until I have any in-hand.

Bas (the BeBoPr designer) has more details on both of these options on his wiki, along with a bunch of other useful information.

The boards from Circuitco  should be exactly the same as the board I got directly from Bas (from an early prototype run) and have been using to drive my 3D printer, so it should work just fine with my MachineKit image.

Bas has a new version of the BeBoPr, the BeBoPr+, which is a BeBoPr with the bridge board directly soldered on.  These boards are not yet available through BoardZoo or other online retailers, but Bas has a supply available for EUR 117 each.  Contact him directly via e-mail if you're interested:

Oh, you might think the bridge board looks a little funny and I agree.  It looks kind of funny...but when I'm hooking all the wires to my 3D printer, I REALLY appreciate the extra space between the BeBoPr and the BeagleBone.  Not only does it allow me to keep my serial terminal connected, but it keeps the HDMI, USB, and micro-SD cards away from all the wires going to the printer.  Having used the BeBoPr both ways, the extra space provided by the bridge board really helps to keep all the connections more accessible.

Saturday, August 17, 2013

Check Your Temperature

Printing vases is hard, but I finally managed to get it right:

I kept getting gaps in my vases, which looked for all the world like the motors were skipping during the print.  This wasn't simply loosing steps, however, as later layers were still aligned correctly, so something strange was going on.  I spent MANY hours over several days trying to see if I could get LinuxCNC to cause one of the goofs while I was watching, to no avail (each print takes almost 4 hours).

Finally, I thought I found a reliable way to cause the glitching by using the Mini gui and enabling the back-plot display.  Except it turns out that for some unknown reason, when you enable the back-plot the Mini gui actually pauses real-time motion ON PURPOSE until the plot is generated, then starts things back up again, which was causing the glitch I was seeing.  <sigh>

Anyway, since some of the goofs had a bit of the "burned plastic" look about them (brownish discoloration of the normally translucent plastic), I figured I'd try reducing the temperature a bit.  Dropping from 180 degrees to 170 helped a LOT, and resulted in only a few errors in a 3+ hour vase print (vs. at least 20-30 usually).  Another ten degrees lower, and printing at 160 degrees completely cleared up the glitches, and I  got my first clean printed spiral vase (above).  Here's a close-up:

I had been happily printing more 'normal' objects (with infill) at 180 degrees without issue both with LinuxCNC and with my earlier Ardunio/RAMPS combination.  I never printed a vase with my Ardunio, so I'm not sure yet if the reduced temperature is required because of a difference between the temperature readings on the Arduino/RAMPS board and the BeBoPr with LinuxCNC, or because when printing a vase there's not enough plastic going through the extruder fast enough to keep the hot-end from heat-soaking and causing "mini-jams" or cooking the plastic a bit.  Probably a little of both.

Wednesday, August 7, 2013

K9 SmorgasBoard

A new toy:

While I was on vacation, the great folks over at Practical Micro Design sent me a geeky new toy to play with, the K9 SmorgasBoard!  This awesome board has just about every sort of I/O you might want if you're working on machine control using a BeagleBone.  There are Pololu sockets for the 3D printer crowd, more traditional DB25/LPT connectors for "legacy" motor drivers as used in LinuxCNC, analog inputs and outputs (including support for thermocouples), RS422/differential encoder inputs, and lots more.

I saw one of these at the LinuxCNC dev-fest in Wichita, but it's a lot more fun having one to play with!  Not to worry if you have a BeBoPr, however...I am keeping my BeBoPr and bridge board setup as the controller for my MendelMax printer, and I'm going to use the K9 for experiments.  I'm currently planning on building a slightly modified Mini-Kossel, but I'll have to see how it turns out.  It may wind up being more than just slightly modified.  :)

If you're not completely living on the bleeding edge and trying to drive all your machine control applications with a BeagleBone, checkout the other products from the PMDX folks.  They have a lot of stuff that might help you move motors and make some chips.  Also, drop them a line if there's something you REALLY want to see in a BeagleBone expansion cape, or if you'd like to have them make a BeagleBone product at all.  The K9 is mostly a proof of concept and test platform, so pipe up and let them know if you want to see a real product or it may never happen!

Oh, and if you want to get geeks writing code for you for free, send them some nifty new hardware to play with (hint-hint!).  Let's see, I could use a...  ;-)