GoPro to NERF gun connector

Status: Project finished!

I designed a mount for a GoPro camera to the picatinny  rail of a NERF foam dart gun.
The NERF part is identical to my "NERF dual gun connector" connector and thus should fit perfectly.
I obviously coult not test how well the GoPro part fits.
It should be a very tight (0.1mm allowance) fit and follow the curve of the housing. So the camera will not shake loose and will always film straight ahead.
Both sides for the NERF rail and the GoPro M6 bolt are tapered to make insertion easier.

Update: perfect fit!

Update 2: improved version with trapped nut

NSECT Arduino Anti Aircraft

Just some notes on a possible new project.
Just collecting links and notes and testing the concept at this point.


  • Android based computer vision test works.
  • NSECT not yet recabled to be controlled by an Arduino.
  • NSECT foam dart gun not yet modified to add more degrees of movement.


Take my old N.S.E.C.T. toy and have an Arduino run it with 2 H-bridges.
Redesign the turret to turn in 2 dimensions.
Then add camera and distance meassuring and computer vision to target low flying quadcopters.

Step 1

Attach 2 H-bridges to an Arduino to control the 2 DC motors for movement.
Then also attach turrent, LED and gripper -controls.
Trying to copy the work of Jeremy Parton here.

  • Jeremy unsoldered the receiver chip and connected the Arduino to the (now free) pads.
  • "Keep in mind I used resistors (I suspect it was 100 ohm) between the Arduino and the NSECT board.
  • "I also strongly support converting to an H Bridge instead of the existing relays. As far as I could tell the biggest killer of NSECTs was the start-stop motion and the motors shredding the gears. A soft start would go a long was to extending the life of the gears in the legs."

Step 2

Redesign the foam-dart turrent with 3D printed parts to move in both dimensions.

Step 3

Add an old Android phone with a camera that can speak ADK with the Arduino.
Run OpenCV or similar to detect and track flying objects with the blank sky in the background.
Tell the Arduino the heading. Have the Arduino meassure distance via ultrasound, look up the balistic curve and fire away.

The "OpenCV Sample - color-blob-detection" works well and seems to do the trick!


  1. official download and official documentation
  2. Android OpenCV 
  3. also OpenCV 
  4. object tracking on Android 
  5. Android ViewerCV

2012-11-29 N.S.E.C.T.


Rant about Google Now

My comment on a posting about Google Now got somewhat lengthy, so I'm turning it into a Blog posting:

Would be more amazing if Google Now actually worked.
  • Completely oblivious to train schedules in my calendar.
  • Not offering non-local trains to reach my destinations.
  • Not offering bus schedules in all places I was ever at.
  • "Leave now" notifications not leading to the corresponding cards (but instead to Google Now in general with a completely unrelated set of cards).
  • Constant, annoying routes to places I've never heard about, let alone having any intent on going there and to meet people I've never gone to meet in the past (they just happen to be in a village less then 100Km away at the moment).
  • Oblivious to airplane reservations in calendar, email and the Lufthansa App.
  • It's a glorified weather app that is limited to the weather where I am instead of where I'm going.

And why is that website  insisting on scaling up to be 2x2048px, 2x18" wide? I takes forever to scroll over even one of these giant, multiple screen height photos. The text is practically unreadable that  way.

"Google’s going to know when my flight is, whether my package has gotten here yet and where my wife is"
It was completely oblivious of my flight even though flight number, locations and time zones on calender entries,... where there.
It never found out about any of the packages I got standardized tracking emails for. (DHL, DHL-Express, USPS, FedEx, Amazon emails with tracking numbers,... in German and in English.)
It can't even figure out where I live, where I live during weekdays and where I work (despite having Latitude active),
let along who I'm affiliated with. (Even though it probably knows about my Google Accounts and thus the Google+ circles.)


Thing-o-Matic upgrade to Sailfish/Jetty Firmware

While waiting for my new extruder (because the one I printed myself physically broke before I was able to print my improved, stronger one), I'm upgrading my Thing-o-Matic to the Sailfish firmware everyone is talking about.

First step was to solder the Interface Kit that is collecting dust since at least 2 years.
I did solder some buttons 180° reversed but they work nonetheless.
Interesting fact: The display is black while USB is connected but fine without USB.

Next step: Download and unzip the software.
...takes ages on an old Atom based EeePC despite my flash disk upgrade.

After updating to "MakerBot Motherboard v2.X(Gen4) with Mega 2560" the interface reacts extremely slow and I can't connect via USB anymore. (Solved, see next issue below)
Serveral seconds to register a single key press on the interface kit.
Rebooted the PC, now I can connect but it can't find Toolhead #0 and the console is full of "timeout" messages.
Consequently I can jog but not turn the ABP gelt or move/heat the extruder.
My versions:
  • Thing-O-Matic with an MK6 extruder (no MK6+), ABP and Gen4 interface kit.
  • ReplicatorG-0040-windows-r003
  • "MakerBot Motherboard v2.X(Gen4) with Mega 2560"
  • Sailfish Firmware v4.1 (r720) 
  • Extruder Controller v3.6, AtMega168 (was way too small to read at first.)
  • Update: Extruder control firmware now 3.1
Update: Forgot to open cable hell, dismount the extruder control board, so my angled USB plug would fit and upgrade the extruder firmware. The step was not mentioned in the installation manual.
Much faster now, toolhead can be manipulated.
The firmware of the stepper controller is not updated through it's connection to the main board.

New issue: Display width smaller then firmware thinks it is. Extruder and bed do not heat. (solved)
...this is going to be a loooong night.
There is also a problem with ReplicatorG that luckily is of no consequences here. The list of machine types is longer then the display and does not scroll.
  • Update: Found a setting "onboard prefs"->Motherboard->Misc where the display is set to "20x4" while it is "16x4" 
  • Problem: That dialog is smaller then the screen(1024x600) but the "OK" button is outside the window (I can barely see it's upper corner) and the window cannot be expanded in height. Only in width. 
  • Update: I was able to create a virtual display 768px high and the upper 4-5 pixel rows of the button became visible.

New issue: Display blank when USB plugged it while switching on ToM. Can I move the extruder stepper forward/backward, Belt and jogging controls on the PC now failing.(mostly solved)
Jogging works find on the interface kit, without the PC.
Control Panel in replicatorG suddenly also stopped to display the target temperatures in the graph. Only the current+past temperatures are graphed.
I can move all axes and heat up via the interface kit but not move the extruder stepper forward/reverse.
power-cycled the ToM. Display now stayed on while USB but the offset display ha returned! (Aren't onboard preferenced saved in flash?) ReplicatorG hangs when trying to disconnect to connect anew.
Set display size again, rebooted the ToM. Now all except the extruder forward/revers is working. Why?
After trying to extrude with 1,89 RPM jogging is failing again.
Then jogging resumed, and failed again. It looks like axis-jogging is disabled while it thinks it is moving the extruder (wich is not moving at all).

Last issue: Extruder stepper not moving.
One of the extruder cables had come loose while checking the print on the ATMega168 (to make sure it's not a 368). No changes. Extruder stepper still unresponsive.
Flashing the extruder firmware 3.1 again. Failed. Powering down. Unplugging USB. Trying again. Flashind succeeded.
Issue persists. Extruder stepper does not move and machine has forgotten it's onboard preferences yet again.
Checked the extruder cables. Everything connected correctly.
Tried to uncheck "volumetric 5D extruder" but it did not help.
The DIR LED is glowing but the STEP LED on the extruder controller is constantly off. So this may be a software issue.The fan of the extruder is also off.
I can hear a very faind "thud" noise when pressing "stop" after forward or reverse. So something is happening.
I found this but there is no "extruder hold" in the "misc" tab. for "ThingOMatic w/ABP and Extruder MK6 (Accelerated)".
With "ThingOMatic w/HBP and Steptruder MK7 (Sailfish)" I can disable "extruder hold" and get at least a high pitched sound when the extruder stepper is supposed to be running. However still no movement.
I mistook the heater cables for the extruder stepper cables.
Will test extruder stepper cables and switch axis A=extruder with X and jog on Monday.
If that works, it's clearly a software fault. Question is...what to do if it is?
Solved! It turned out to be a hardware issue.

....(still updating this blog post)


A fast and foldable 3D printer


A fast 3d printer that can be folded up for transport.
  • fast -> don't move the object, move the head
  • fast -> no bowden extruder (stop/reversal issues)
  • transport -> include 1 roll of filament inside the case


Based on the Type A Machines "Series 1" design.
Better to base directly off the ToM to Series upgrade.

The glass plate could get a joint to fold up, flat onto the Z rods.
Use a reprap heated bed instead of the glass plate.
The top XY-assembly be taken off and attached to the backside including the Z rods, now vertical glass plate and the 2 electronics boxes.
The front would become either
  • just 3 L shaped pylons to support the front of the XY-stage or
  • a cover for the front that would in transport cover the open XY-stage
Get away with the bottom entirely. One of the electronics boxes would need a hole
for the hot end poking out of the XY-stage.
Since your XY-stage is so thick, the space could be enough to transport a spindle
of filament right inside the case.
(What good is a printer without filament.)

*** Blog posting will be constantly updated as this idea matures.***

Upgrade path

Start with the Thing-O-Matic electronics, Z stepper+spindle, small X+Y steppers.
Upgrade later with a reprap sized heated conveyor belt (running left to right) instead of the glass plate/heated bed.


  • 21.11.2012 - idea formulated, asked Type A about the license of their laser cut files, searching for people willing to help
  • get my Thing-o-Matic extruder working again first. 
  • Start by creating parts in Alibre Design for the X/Y-stage and an assembly from the Series 1 drawings.
  • give proper named/part numbers to all existing and new parts to efficiently discuss changes.
  • (planned) 23.11.2012 - design the new laser cut parts needed during a train ride
  1. build tray with joint to folt it 90° up.
  2. detachable top
  3. new front side to act as a cover for the top
  4. right electronics box with hole for the extruder
  5. shorter bottom plate
  6. Makerbot compatible extruder+hot end mount to reuse them until an upgrade to the Series 1 extruder is feasable
  • (planned) ??? - CNC mill the plywood parts (instead of laser cutting)

Update: I'll postpone this project and do the "regular" ToM to Series1 upgrade first to determine the mechanical load the moving toolhead imposes at high speeds.



Type A 3d printers as an upgrade path for the ToM

Found an interesting upgrade path from my Thing-O-Matic to a Type A 3d printer.
I planned to sell by ToM and get an Ultimaker. But now the quote from Jetguy made me think about it's bowden concept:
"I've had the vision of creating a fast bot. I've gone the bowden route
in a real Ultimaker frame. The results were less than stellar and
there is a reason why I've abandoned it. It frequently jams or chews
the filament. It is was very dificult to tune any kind of anti-ooze or
stringing and never met my expectations.
While of cause the major plus for a bowden design is the limited mass to be moved and thus the speeds and mechanical stress.

Here is the quote from Jetguy about a possible upgrade path for me:
And, as far as bots go, If I had a T-O-M and was shopping for upgrades, you could get someone to cut this frame in plywood for less than $100 (1 sheet of 1/4 inch plywood), then you only need about $100 in parts (8 each LM8UUs 8*$1.75, a smooth rod kit for a mendel $30, 2 5.5kg.cm torque motors 2*$20, 2 608 skate bearings, the Cupcake Y belt, 3 Cupcake Z belts, the 5 36t Gt2 *mm bore pulleys, and finally, a Reprap heated bed. I also used a 360watt 12 volt supply but you could use a PC supply mounted on the back. I call this  the ultimate T- O-M upgrade. ...
No need to spend thousands on a new bot, upgrade what you have into a new frame. There were lots of good things about the T-O-M, but now with Sailfish, you can take advantage of a larger build area and different frame for peenies on the dollar compared to buying a new machine.

I'll post every single edited DXF and part up on Thingiverse soon.
I basically gave the BOM above. If I had a T-O-M, this is going to be
a stellar upgrade for those willing to take the leap!!!!


Let's see...

  1. Cut the plywood myself on my CNC
  2. I already have LM8UUs and 608 skateboard bearings en masse
  3. I already have a Reprap heated bed (I wanted to use it on my Repman)
  4. get two heavy NEMA17 stepper motors
  5. add *good* smooth rods (consistent diameter, straight)
  6. add a Cupcake Y belt and 3 Z belts (where to source them?)
  7. add 5 pulleys (source?)
  8. a >=360W PC power supply should be easy.
  9. finally: do my own Reprap-sized ABP design with leveling and tightening adjustment bolts.
  • Staying on the Thing-O-Matic and just designing a better ABP is less work
  • Less that can go wrong.
  • The larger build volume is intriguing.
  • I already have many of the parts
  • Extruder, Hotend, Firmware and host-software won't be touched.
  • When designing my own ABP anyway, I can build a Reprap sized heated titanium conveyor belt.
  • Update: I found collapsible Type A!!! (The space in the upper part could be designed to hole a spool of PLA when collapsed.)

Sounds possible.

Thinking about it....I think I can design a modified Type A case where
  • In the Z=max position, the Z-spindle and smooth Z rods can be collapsed into the horizontal plane.
  • The 4 edges can be collapsed down
  • The build-surface has a hole for the extruder in the back-left corner
  • So in the end everything can be collapsed to be as high as the height below the build surface plus the height of the Y-stage.

Improving Gaerisls Extruder

The issue

In my first 2 attempty the mounting of the ball bearing simply broke...on both sides.

The solution

I guess I'll design a stronger lever-arm before trying this extruder to replace the unreliable(at least with PLA) in my .
I should also try to print it with 80% infill instead of my usual 25%.

The original is only posted as an STL. Gaerisl didn't post his source files.
So I need to take meassurements and design mine from scratch using Alibre Design 2012. :(
Why do so few people publish their source files to be modified and why don't we still have an interoperable file format for parametric CAD?

Update: Gaerisl based his design on one by Jag and he not only published his source files but even published them as Alibre Design files!!! Life is great!

Update II My strong version is printed. First try worked but I was not perfectly satisfied. So I changed a few meassurements and printed a second time. Uploaded the final version to Thingiverse of cause.

Update III The extruder is working but I found one side of the idler-arm axis to be weak. Also  a few smaller issues.  Fixed them and am currently generating the G-Code to print a new body. ..it will be a pain to insert the mounting bolts yet again. :(  So far the new extruder is working. Only longer prints like this extruder body will show how well it performs regarding manual tension adjustment.

Problem!!! The front part of the extruder main body, holding the axis to the idler arm, broke before I was able to print my improved version. Can't print at the moment. :(

Update IV: testing and  how to mount the extruder without going crazy.

Future plans

If the NEMA17 turns out to be too weak, I can still gear it down using this. ;)
When the extruder finally becomes reliable, I can turn to making a proper (tensioned and leveled) Quick-Change ABP belt out of the Quick Change HBP.


New Extruder

One of the issues I have with the Thing-o-Matic and PLA is that Makerbot Industries uses a bolt pushing a Delrin plunger onto the filament to press it against the rotating drive shaft.
There is no spring involved.
My guess is that this leads to my issues of the filament pressure requiring constant human observation and adjustment as the filament diameter never stays perfectly constant.
So here I am, trying to replace the extruder with a spring loaded design (for the second time).
I tried this once in 2011. Back then I used a geared down design and the gears as downloaded where too small by 1-2mm and would not mesh properly.
This time I'll try a more simple, direct drive design first.
This also has the benefit of not requiring me to reverse the stepper motor as there are no gears to change it's direction of rotation.


Nexus 7 fails

(I'm not at all unsatisfied with the device. I'm just pointing out where it can be improved. Much needed to have a contrast to all the hype.)

I just got my Nexus 7 32GB 3G.
I wanted a Nexus10 with 3G to have the resolution for camera remote control in FullHD but such a device is not sold.

These are the first few minutes of unpacking:

No SD Slot

We knew about this missing, important feature all along.
Still  a huge disapointment.
A tablet is a really nice device to show photos around.
Photos you just took.
But for that you need to get the SD card out of your camera and into the tablet.

Since there is no regular sized USB slot, I cannot attach a card reader.


Ripped the case in tryin to open it using the obvious finger-hole.
This could have been a much smoother experience.
Have a look at the clever packaging HTC always did for their models.
(My last one was the HTC "diamond" Touch Pro.)

"Sim Ejection Device"

supplied SIM ejection device....
Looks like a paper clip to me.

Micro SIM fuckup!!!

Dear Google, what about telling me before that this giant tablet needs a fucking *MICRO SIM CARD*????
Inside a slot large enough to fit a regular Mini SIM card and artificially made smaller by an inserted plastic tray.


As a company this much under scrunity for having access to way too much data, this leaves a very bad taste.
Of cause it's nice that the device is already personalised to the account that purchased it but this would be much nicer to be in the form of a question asked uppon purchas and/or a personalised engraved name in the case like with the Nexus One.

Wrong translation of the question below "Sie sind nicht *me*?" = "You are not me"?

No Telephony/SMS

There is no telephony app (headset or bluetooth car set) nor an SMS app.


It takes some getting used to, that the keys now change orientation too and are no longer hardware keys at the left side, where the hand is in landscape.

Free books

It's nice of Google to give me some books for free....but *why are they all in english*? This is a German device with a German power plug shipped to Germany and aparently already customized with a German account.
So why would you gift me books in English?

Missing updates

Google took the time to customize this device with my account...but I still *have to install updates* to the supplied, basic Google apps 24h after it was shipped?
And not "install all updates now" but I have to *open and install each single update* with multiple taps!
Google? These are YOUR apps!

Also: The *update button jumps* as soon as the icon next to it finishes loading.
One more example of how *Google consistently fails to test in slow, unreliable, real world networks* all the time.

There is also a *system update* waiting while it's still busy updating and intalling all the apps.
Why wasn't this shipped with Android 4.2 right away if the software was already customised to my account uppon purchase?


At maximum the speaker is not very lound.
Barely enough for a movie in a quiet room. Certainly not enough for a room that is not quiet.


It's very strange to not get the notifications when pulling down at the top-center like you are used to on a phone. Instead you have to pull down at the top, left edge.


Firefox has one major issue. Every time I close a tab or navigate "back", the browser closes. (And the tab stays open)
Seems to be Androiud 4.2 or tablet -specific.


The swiping is nice...but worthless  without a good dictionary.
I want my device in German but I type in German and English and sometimes (e.g. quoting or translating or simply using english technical jargon) both.
"Language&Input" has an obvious way to select your second and third language.
(A typical american oversight, one meight say.)
It's hidden in the settings of the specific keyboard even though these dictionaries affect all keyboards.
After installing british and american english, the space bar still the current language but doesn't react to any long press, flinging, dragging or similar to change it. (missing hint)
You have to search the internet to find that after already selecting the additional languages in the settings, you still need to long-press the & key to get a menu, there disable "system language" and select the languages you want to actually use.
(I don't know why you would install keyboard languages you don't want to actually use.)
It also still doesn't support multiple languages at the same time. Bigger issue then a native english speaker may think it is.

Play Store/Android Market

No longer has a menu entry "my apps". (I'm looking for an app I once had installed but that didn't fit onto the phone anymore.)
Screen jitters and freezes during an ap update.
Does not show the app description in widescreen, only in portrait when an update is offered.

Developer options

The developer menu is well hidden now. You need to tap the build-number 7 times to get it to show.
The crash log menu can be activated then to show under "battery status" of all places.

The USB-driver for ADB is the one of the Nexus Galaxy. But that driver doesn't know the USB device ID of the Nexus 7 and has not been updated. So you need to manually select that driver (after becoming or calling an administrator) and ignore the warning that the driver is not compatible with this device.
Who would think of using a Samsung driver for an Asus device?


workshop vacuum cleaner attachment for CNC - v1.6

I still did not find the time to test the Sailfish firmware for the Thing-O-Matic by Jetty.
Simply because I have to assemble the Interface Kit first and that requires a ton of soldering.

So here I am with the original firmware and all the issues I've come to known, printing my latest version of the workshop vacuum clean attachment.
The last version I tested was V1.3 and I found a number of mistakes in my meassurements.
So I made a number of changes:
The top half is still split into 2 parts, small enough to fit into the tiny Thing-O-Matic build volume.
Left and right half are however now not (only) glued together but also attached using 2 M3 grub screws and have a more complex divider that aligns and interlocks them.
Additional camfers and roundings make the part stronger at little expense in terms of plastic.
I did not change the lower half yet but instead want to fit the upper half first.
Only if it fits well will I 3d print the lower half.
By then I may have found a source for bristles to attach to help in getting all that suction down to the milled part and brush over the blank to dislodge more shavings to be sucked off.

Update: V1.5 of top-left is a bit thin walled and the overhang is quite steep. I should design an easier to print V1.6 .
Update 2: printed. LOTS of issues with the MK6 extruder on the Thing-O-Matic. As usual serveral hours of very careful hand holding was required to keep the filament pressure and still there are major defects.


CNC lessons learned

Having a great time with the CNC milling machine.
Getting that huge 6x10mm flat end cutter reduced the time from a day's work to a few hours.
Removing 2x2x4 times as much material in the same time.

Now I should look for 3mm flat cutters with rounded edges to replace the not really flat cutter that came with the #YOOCNC #CNC6040.
Currently my surface quality is just up to what my 3D printers produce while it could be so much better.

The biggest problem seems to be silently loosing some steps every now and then.
I should make it a habit to use that cheap mechanical edge finder when switching tools between roughing and details anyway.

The laptop is also too far away from the machine. I want to replace it with a touchscreen based machine mounted to the CNC on an articulated arm.

Attaching the shop vacuum cleaner was a great idea. Next up are an enclosure and bellows to protect the axes from dirt and dust. I'm also looking for a micrometer.


Selling my Thing-o-Matic

I'm selling my (heavily upgraded) Thing-o-Matic.
Anyone interested?
Interface kit, additional fans against the PTFE tube heating up,
Unicorn pen plotter, PCB milling vice,
automated build platform, Plastruder, ...


Alternative Thing-O-Matic firmware

After a rant on Google+ Craig Trader pointed out the Sailfish firmware to me.
It seems that a user named Jetty has created an alternative firmware for Thing-O-Matic, Replicator 1 and even the old Cupcake printers that Makerbot seems to have abandoned.
By his account it took 10 month and the prints he shows shure are impressive both in detail and speed.
 With my 16-32mm/s his 120mm/s sound just crazy fast!
It also has that pause feature I loved on the RepMan (I started writing it for the ToM firmware but never got to use it there,)

Gnucash Andoid app

Status: Brainstorming

An Android companion app to
  • enter expenses as they happen
  • expenses are stored templates involving multiple accounts and currencies
  • the actual values for each split are either to be enterd or a fixed percentage of an already entered value (e.g. 19% sales tax of a petrol purchase for the company car go to a different account)
  • look up existing transactions and invoices
  1. Gnucash (zipped XML) file is stored on a Dropbox or other network storage accessible from the phone
  2. After my first feature request for an official XML Schema was declined, wait for my second one to be accepted.
Possible Solutions:
  • jGnucash requires JWSDP. No idea on how to port that part of my code Android yet.
  • OFX import - does not allow split transactions at all
  • CSV import - does not allow split transactions at all
  • Gnucash API - C and desktop only. I don't do C anymore and idealy there is no desktop involved.Also: "Unfortunatly there doesn't exist any up-to-date coherent set of documentation."
  • Gnucash Android app (Sources) doesn't read or write Gnucash files. It only exports OFX.
  • Wait for the Gnucash team to come up with a network protocol or similar


Gnucash: "Provide an official XML schema" DECLINED

+1 vote

Provide an official XML schema

(No Status) → Declined
There is an informative RELAX NG schema that describes the current xml file format, which you can use to learn about the xml file format.
It is however impossible to code various accounting constraints in such an xml schema (eg to enforce each transaction has a zero balance). For this reason it is formally strongly discouraged to use any external tool to modify the xml data, unless it does so via the GnuCash api.
So there is no incentive for the GnuCash developers to spend more effort on a more elaborate xml schema.
Geert Janssens
Admin, GnuCash 

Yea...right....as if that API even existed for other languages (Java) or for platforms like Android or iOS.
I no longer have the time to maintain my unofficial XML schema that is the basis for a number of automated accounting tools. 
Since I can no longer maintain the XML schema, I fear my automatic PDF-invoice-parsing from IMAP-emails, HBCI/Paypal/Wirecard/CSV transaction syncronisation and the unfinished Android+iOS tools based on my jGnucashLib will vanish. :(