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.

Monday, March 30, 2015

The Danger of Having a Nice Hammer...

...is that everything starts to look like a nail.   My hammer of choice, as you can tell from this blog, is the Arduino microprocessor integrated with various electronic sensors and relays and packaged in something 3D printed.

In this case it was a mod for my new 3D printer.  The new printer is an enclosure which makes it particularily nice for handling ABS which I have not been successful in doing with my open Prusa I3.  What this enclosure does is trap heat inside it which is what you want for ABS...just not for PLA.

Now I can take the cover off the printer, and leave the door open, when I print PLA but I wanted something a little easier than popping the cover on and off.   So enter the below configuration:

Two fans connected to a relay that will turn them on and off but also connected to an Arduino Nano for speed control.   Relay driven by the Arduino Nano, however, if the Nano is not present then the fans will run controlled by the on/off switch. DHT-11 temperature sensor also connected to the Nano.  Arduino Nano enclosed in my Projects Platform.   All of this gear wrapped into a custom designed chunk of 3D printed panel that replaces one of the side panels in my printer.  This panel features cutouts for the fans, power outlet, on/off switch, and a place where the Arduino Nano/LCD Projects Platform can be slotted.  The panel also as a little electronics bay for the relay, a power regulator  (12v to 5v), and the various connections.   You may be able to see this but there are also wire tie downs printed on the panel.

I had all the hardware assembled and had started on the software.  It would function in either a simple on/off mode but more importantly in a mode that would trigger on a certain temperature threshold being hit.   Fans would run at different speeds depending on the temperature deviation.

Somewhere in the process of putting all of this together it occurred to me that all I really needed was some positive airflow while printing PLA or while cooling ABS down for removal from the build platform.   In other words, all that was needed was this simple panel and a cheap fan:

Not nearly as much fun!   Bit it meets the requirement just fine! 

In the end I did decide that the least that I could do was to use one of the fans that I had already bought so the final cofiguration has the below insert as the cooling option:

Friday, March 27, 2015

Items For Sale from this Blog

Item Link to Article Buy
Duplicator 4S Build Platform Clips LINK
Available Configurations

Arduino Nano/LCD Projects Platform LINK
Available Configurations

RepRap Environmental Monitor
(Alarm and Kill Switch)
Prices / Terms and Conditions

Price includes shipping to destinations within the UK.  For shipping outside of the UK please contact me.

Sunday, March 22, 2015

Super Cool Active Fan Mount and Duct

It has become clear that to achieve the speeds and level of detail that I desire a fan is required.  I experimented with a duct that uses the extruder fans in a reversed mode and had issues that I now feel were a result of cheap fans.  I think with better fans that duct would satisfy a lot of people requirements.

But I want to be able to do active cooling controlled for each print if desired.  I found this fan mount and duct on Thingiverse and was intrigued.   Unfortunately I was not able to get it printed before I gave up on the ducts that I mentioned above so I resorted to using Nicks Hub on 3D Hubs.  I had it in two days though it did cost me a few quid. 

Here is Nick's version mounted on my printer and the one that I was then able to print.

That duct is a work of art both in how it works and how it looks.  It even printed nicely once I had a copy of it mounted.

Vapor Bath for ABS Print

Now that I am printing ABS at pretty high resolution I wanted to try an acetone bath. 

Obviously the Marvin on the right has been in the bath.   Both Marvins were printed at 0.1mm resolution and once the acetone bath was done the layers had completely disappeared.

My batch consisted of a jam jar with a very small amount of acetone, a wire stretched across the top for a hanger, and the heated build plate of my Prusa I3 set to 80c.  Marvin was in the bath for about 10-15 minutes.

Shiny Marvin was hung with a paper clip which explains the boo-boo in key ring attachment.

There were a couple little imperfections that completely went away in the bath.  Pretty cool.

Friday, March 20, 2015

Calibrating for Dimensional Accuracy

Next phase of calibration ... making sure that parts fit!   First test was the 20mm cube.  I think it looks great on the bed.   This is an ABS print and you can see how stuck it is on the DR-4.  In fairness I have probably smushed the first layer a little more than is needed and may adjust the build platform down a smidge.   One of the nice things about FR-4 is that it seems to be forgiving on the first layer being overly tight.   Of course this leaves a ridge of plastic that is not always appropriate!

Anyway.   The important thing about the 20mm cube is whether it has been printed as a 20mm cude.   Measuring this one shows 19.90 and 19.96 with a height of 9.94.   I think that I am pretty happy with those dimensions.

On to the thin wall test.   First pass not looking so hot as I think that a .4mm thin wall test should measure at 0.4mm!

Tried "outline/perimiter shell" setting of one (in Simplify 3D) and things got worse!

I have paused on this task for a while.   My printer is producing output that is dimensionally stable to itself and I am happy with that for now.

Wednesday, March 18, 2015

More on Print Bonding - Use of FR-4

I have printed a lot of PLA onto glass with my Prusa I3 but for some reason I could not get good adhesion with the new printer.  In fairness I never tried hair spray which I had success with previously but I was out.   The reason that I was out was that I had used some ABS goop when I ran out and it worked fine.   Had been using it ever since.  No bonding problems what so ever on the Prusa I3.

Alas, not the case now.   I have some hair spray on order and will try it when it gets here for both PLA and ABS.   In the meantime I decided to experiment with a new material for my build platform.  I had read good things about FR-4 and so decided to buy some from eBay.  FR-4 is one of the materials used for circuit boards and is a very stiff, very rigid, fiberglass composite.    The one that I bought did not have copper on it though I understand that some people print on the copper side as well?

The sheet that I bought was 1.6mm thick and 8"x6" which is just about a perfect width for the Duplicator 4S though a little long.   Enter the Dremel.   This stuff is not easy to cut.   The first tool that I used just about burnt up.  I did get it cut using a little circular saw but not as nicely as I would have liked.  But it fits.  I made some little clips to fasten my glass build plate and had to modify them a little given that the FR-4 is thinner.

What you see in the pictures to the right is the FR-4 on the build platform with the platform being held by version one of my clips printed on my Prusa I3.   Version 2 of the clips, or the insert anyway, are what is being printed on the platform now.

The first couple prints that I did were right onto the Fr-4.   After the first couple I cleaned it with acetone and then added a little ABS goop.   It seemed to help with the bonding so that is my process now.

I also printed a little spatula as the last thing that I want to do is use a metal knife and scratch the FR-4.

Once things were dialed in it was pretty much like printing on glass.  Except that it is harder to see white PLA on yellowish FR-4!   A minor issue.  I will say, however, that what I had read about it being a good platform for bonding is true.   Here is a short video that illustrates both the bonding, and the release once the platform has cooled.

I love the way stuff sticks to the point of madness but when the FR-4 has cooled it just about slides off.

I have read that some folks have had FR-4 lose adhesion over time.  Obviously I will have to wait and see.     I find it hard to believe that a little steel wool, some very fine emery paper, and then some ABS goop will not remedy any stickage issues.

I will update as needed.  I also have to try ABS but as that is what most people have used with FR-4 I suspect it will be fine.


Printed some ABS and as expected it worked well.  If possible even better than the PLA!  I let the build plate completely cool and the part I printed, which had been firmly attached, was completely loose when I came back to it.

An interesting observation when printing ABS right after PLA.   The build platform seems to be higher?  As in the ABS is more smushed onto it?   Could it be that the higher heat has the FR4, and maybe even the build plate under it, to expand that much?   It makes sense that it would but I was not expecting as much of a variation.


I can not imagine printing on anything else at this point.  

Tuesday, March 17, 2015

Wireless Connection to 3D Printer

I can now send files to be printed on my new 3D Printer wirelessly!   All that was needed was a Toshiba Flash Air SD Card, some instructions on setup, and a pointer to those instructions from MadMike on the RepRap Forum.

This is really the Cats Meow.   Setup requires that you be comfortable with modifying hidden files using a Unix friendly text editor but was pretty straight forward.   The technique should work on any printer that prints from an SD Card.

Ironically I had the Flash Air card as I was being cheap and did not want to fork out for an Eye-Fi card after an old one died.  I did not like the Flash Air card as a photo device and broke down and got the Eye-Fi card instead.   I am glad to now have a use for the Flash Air card.