Evolution of a Blog

This blog has evolved as you can tell by comparing the title with most of my recent posts. The title should really be something like "The Physical Interface Side of Computing". It will still feature Raspberry Pi and Arduino from time to time but my current hardware of choice is a BeagleBone Black with JavaScript and Node.js providing the development environment.

Thursday, March 20, 2014

3D Printer - Some Lessons Learned

I am sure that I am no where near done having my printer learn me lessons but thought that I would take a minute to capture some of those learning's to date:
  • Seems obvious, but, turn things off when making hardware changes!   As in unplug the power and the USB connection!
  • Probably obvious to someone that knows electricity, but, unplug the printer before soldering something (like a control or power lead) that is connected to the printers electronics!
  • When doing calibration prints keep a careful record of each print and the conditions for that print.   You might even want to go so far as to save individual config files for the slicer you are using.
  • Don't mix PLA and ABS in the same nozzle.  I am not completely sure this is backed by any one else but I am convinced that I had a mega clog as the result of this practice.
  • "ABS Goop", which is some ABS dissolved in acetone, makes a good bed prep for printing PLA.
  • A clean bed results in a clean printed surface!
  • PLA is a lot easier to work with than ABS.  In my case I had much less issue with warping, adhesion, and as a bonus everything was faster given a lower bed temperature.
  • Printer enhancements for ease of adjusting the level of the bed early is highly advised!
  • Once you have done the above you can do a rough adjustment of height using the piece of paper method and then print a bed leveling exercise to get the rest of the way.  I print this file pausing to adjust the overall bed height then resuming while often adjusting corners with the printer running.
  • Timing belts should be tight.  This is another thing that might seem obvious but I ran for quite a while with belts that were a lot looser than they should have been.
It feels like I am missing some things ... which I will come back and add as I remember them.

Thursday, March 13, 2014

Random / Occasional Axis Slips

My printer is in it's terrible twos.   It went through a period of printing stability and still has its moments.....until an axis decides to randomly slip or skip.  I have been working on this for weeks and have tried everything that I can find on this board (at least I think)!  As I said, the printer will have moments of stability where it will print for hours with no issue and pretty good quality.  The X-axis is the favorite to slip but the Y and Z will occasional join the fun.  It does not always happen on a long print as it has been known to happen early in a print as well. 

Here are the things that I have tried and/or ruled out:

I have adjusted the trim pots from just over stall to a quarter or more turn past stallI have swapped stepper drivers
I have moved the x-axis to the second extruder slot
I have upgraded power supplies
I have added a big cooling fan to the electronic stack
I have ensured that my timing belts are not slipping
I have made sure that the carriages move with minimum resistance
I have slowed everything down when I slice the part

 What else is left to try?!?!?   Could it be the Ramp board ... or the Arduino?  They are the only things that I have not replaced or been able to rule out!   Frustrating!

One thing that occurs to me, that is easier to remedy than a swap out of electronics, is connecting the printer to a cleaner power supply.   I just happen to have one (that also converts from 220V to 120 and offers filtered power at 220V) so that is in the circuit now.

Someone on the RepRap Forum has suggested possible EMI issues, if not in power, then I don't know how I would solve!?!?

[Update] I have gone ahead and replaced the Ramps board and the printer has been behaving since including finishing a seven hour print with no hiccups.   Fingers crossed.  

[Final Update] Printer has been stable.  It was either the Ramps board, or possibly, a wiring fault that got corrected when I replaced the Ramps board.   Not sure if I will ever know!

Friday, February 28, 2014

Calibration, calibration, calibration

equals iteration, iteration iteration.

The most extreme of the overhangs was the most challenging, and in fact, is still not perfect.  Interestingly the only way I was able to get it as far as it is gotten was to print it sideways and have another object printing above it so the fan plays on it more than if it were printed alone.






Tuesday, February 25, 2014

It was all going so well

Until the stepper gremlins showed up.   My printer is eating Pololu Stepper Drivers.  At 8 quid each.

I got a new stepper yesterday and after carefully plugging it in and doing an initial test everything was hunky dory. It was running at .4v as measured between ground and the trimpot. My other steppers are all at .5v but I thought I would start lower as opposed to higher. So I print some calibration objects and everything is still hunky dory. I print a fan holder in white cause the one I am using does not match the rest of my parts. It prints fine. So I print some more calbration parts as I am iterating iterating iterating. Everything fine. I go to bed. The printer does as well.

We both wake up this morning and I go to print another calibration test. The printer gets a short way into the print and the x-axis skips. I checked the voltages again and every thing was as I had left it. I have adjusted the voltage up on the x-axis and am reprinting and everything was working for the first 60 or so layers then the x-axis slipped again...though not nearly as much as above (2 cm versus 2mm).

...BUT...

Nothing changed between last night on the x-axis. I did tighten the y-axis timing belt but that is the only change. Could that have caused enough additional current pull from the y-axis to cause the x-axis a problem given my lower amperage adjustment there? I am concerned because, as stated above, I seem to be eating steppers and this working, not working behaviour, has been observed before!


I am calibrating for layer consistency on x-y axis. Looking great on the Y-axis and all but two layers of the X-axis. Then I can work on the whiskers.

Tuesday, February 18, 2014

3D Printer - Some Improvements


Here is a photo of my printer as it stands today.  I have integrated a number of customizations that I will talk about a little below.   One of the distinct advantages of going the RepRap route, as opposed to buying a packaged printer, is this ability.

One of the first 'useful' things that I printed.  I decided that the filament was dragging on the top of the printer so figured this would help reduce friction.  It seems to help.
Not exactly an improvement that I came up with since the printer shipped with the fan.   I did have to print the mount though!  Yes, those are cable ties instead of bolts.   Not the best print job on the slanted bit of the mount either.   That aspect of printing is still eluding us.
This is an improvement that I found on Thingiverse.  It makes it dramatically easier to level the bed.   Rather than fumbling with a wrench or pliers and a socket driver.  There are a number of designs out there so take a look.
There are two improvements shown by this photo.   The spring cord is for the x-endstop and it is also helping to keep the x-servo control lines out of the way as the z-axis descends.  The other improvement is the easy adjustment for the bed height.   This may actually have been the way the printer was supposed to be assembled as there was a hole in the x-servo mount that I was able to exploit.   It makes it very easy to raise or lower the build platform...single spin of the grey thingy.
I will write more about this later, but, this is the biggest addition to the printer.   I want to offload printing and am going to use a Beaglebone Black attached to a 7-inch LCD.  The BBB can run Slic3r and Pronterface in their graphical forms but too slowly for my patience.   I am going to continue to slice my prints on my iMac and use a custom app running on the BBB to drive the Printrun command line printer controller.   The app is not quite done but is written in Javascript and Node.  It automatically picks up files from the iMac and queues them for printing.  The interface allows access to the same functionality as Pronterface but on a touch screen with a remote control (which you can see in front of the printer on the first image).   The web interface can also be run from anywhere else on the network, including from my iPad.  The app is at the 80% point now but needs some cleaning up.   Once it is functionally complete to a first version I am going to add a couple features including a webcam to watch the print bed.   The case and mounts are, of course, prints!

A recent change to make it easier to change hot ends.   Not as eloquent as some implementations that use a plug but easy.

New Hot End - WRONG SIZE!

Decided that a spare hot end should be on hand so ordered one from China.   Takes a while to get by which time my current hot end has become clogged.   I need that spare.   I go to install it so I can clean the original and ALAS it is a 3mm hot end not a 1.75mm!  Doop.   Have had great luck working with vendors in China so am sure I will get this resolved but the timing is a challenge.

Tuesday, February 11, 2014

3D Printer - Calibration

This is part of a series of posts describing my adventures with 3D printing, and specifically, with a Prusa I3 RepRap Kit.   The first of the series is here. This post will talk briefly about calibration.   Briefly because I don't have much to say on the topic other than a) it is important, b) it is a pain in the ass, and c) it seems never ending (to me at least)!

I am still not done calibrating though I am happy enough with where I am that I have printed some reasonably large parts.  I think that I can still get more even layers (I think that stability of the build area is my problem here) and I still can not print steep overhangs as well as I think the printer is capable of.

My primary resources for this task are from the RepRap wiki and are as follows:

Calibration

and

...to here
Print Troubleshooting Pictorial Guide

From here...












In a zillion adjustments with more to come!