Why Kapton rocks

I have never been a big believer in using kapton tape as a heated bed surface. I never saw much benefit, and whenever I used it I ended up cutting it or scratching it very easily trying to get the parts off.

When I use blue tape I generally heat the bed up to 90-110. I print the part, and then as soon as it is finished I pry it off with a chisel. This ends up with a lot of damage to the blue tape, but it is pretty cheap to replace, and easy to pull up a single strip at a time.

The turning point for me came when I tried to do the same procedure on my kapton bed. The adhesive simply wasn’t strong enough to keep the tape on the bed and it ended up bending and lifting and tearing. I knew that was not supposed to happen, so I stopped and looked at what I was doing, and realized that the point of kapton is that it loses grip as it cools. That means you need to cool the bed in order to get the part off! I feel silly admitting that it took me so long to see I was being impatient.

Now that I have that figured out I print, cool, and then generally I can snap the piece off fairly easily. I wipe the surface down with nail polish remover on a cotton ball before every print. Sometimes I still need to get the chisel out and put the tip under one edge of the piece, but once one corner pops free, the whole piece is free. No more prying from every corner.

My one complaint is that I only have 1″ wide kapton. 2 or 3″ would be much nicer. I’ve also been meaning to get some PET tape with a high temp adhesive to test against.

Ways i have messed up reprap prints

This is a running list of all of the ways I have broken a print. This doesn’t have anything to do with my machine calibration. That’s a whole other post in itself!

-I got a snag in the filament feed which stopped extrusion.
-My heated bed shorted out on a bulldog clip.
-With the print not centered on bed it hit the endstop a few hours into the print.
-I have tried to print from stls not positioned at z-0.
-My cooling fan for extruder unplugged midway through and then the extruder jammed up.
-With the firmware z speed not limited properly, i have lost steps due to rapid z moves.
-Filament strips and stops extruding.
-I have run out of filament.
-On a multi part bed, one part became loose and then slowly caused blobs to build up on other parts. It eventually knocked most of the other parts loose.
-Before I had my heated bed fully figured out I had a LOT of parts curl and then come loose from the bed midway through a print.
-I didn’t check the scale of one stl I downloaded from thingiverse and it ended up being about 4mmx4mm.

Got any more to add? post them below in the comments! I’m sure I’ll keep discovering more.

Hardware store fix for prusa belt tensioner

On my self sourced prusa I have been going back and forth on how best to tension the belts lately. I had a zip tie hack that actually worked out fairly well, but it had a fair bit of slop in it, and I think that helped set up some vibrations and Generally keep it from being the best it can be.
I love my local hardware store. I went there (twice) today and on the first walk there I remembered this piece of hardware that is generally used to tension screen doors to keep them square. I checked one out and I think it will be perfect for my y belt. I may even throw one on my x axis, but I’m not sure if I need it.
Here’s a pic

As you can see in the pic I have been experimenting with a very light y stage. It is perforated hardboard that they sell for hanging tools. The actual bed will go on top of there with 4, 5mm bolts and have the glass and hbp clipped to it.

I have also gone with a double wide skate bearing for the idler end of the x and y axis. If the two ends are aligned, then you don’t need anything else keeping the belt “on” the pulleys. Simple tension holds them there. This has made things much smoother and simpler compared to using fender washers.

Advice needed for Makerbot rebuild

To be honest: I posted this to the makerbot forums. I have had limited luck on those forums before so I am also posting here. I’d like to be able to get input from reprappers as well as makerbotters.

I’m rebuilding a late-model cupcake for fablab Boston. It has had some parts stolen, and I’m looking for advice on what route to go.

The two issues are that the motherboard has been stolen and it has a mk4 extruder. I know that the simplest thing to do would be to buy a new motherboard but the direct replacement (1.2) seems to be perennially out of stock.

Then we get to the fact that it still has a mk4 extruder. Since this will be used to teach kids how to print and do 3d design, I would really prefer if it had a bulletproof hot end. I think that generally means stepper-based, either mk6, mk7, or a wades style printed one.

Option 1_ I can get a motherboard v2.4, stepstruder mk7 complete kit, and an arduino mega 2560 from Makerbot for $85+$229+$65=$379

Option 2_ I can get a motherboard v2.4, another stepper driver, a stepper motor, arduino mega 2560 from Makerbot and some printed wades extruder parts for $85+$92+$65+free=$242

Option 3_ I can just get the motherboard v2.4 and an arduino from Makerbot and fight with the old dc extruder for $85+$65=$150

Option 4_ I can get a full reprap-style ramps board from reprapworld.com with stepper drivers, an arduino mega, a stepper motor and printed parts for a wade extruder for $130+$16+free=$146

Am I missing any better options? I’m leaning towards option 4 currently, but I could be persuaded. Am I correct in assuming that I can’t use repg on a RAMPS setup? That would basically be a full reprap toolchain conversion.

I’m honestly fairly excited about moving to a slic3r / pronterface toolchain because repG has always been fairly buggy and I feel like the cupcake is not that well supported in recent versions.

Direct drive Extruder gear

I’ve been on the lookout for the same kind of gear that makergear uses on their extruder for quite a while. Not the gearhead for the motor, but the actual part that bites into the filament.

I found cornwall model boats this morning, and I ordered a few from England. It appears to be a fitted end for a model boat u-joint, but it looks like it could easily work and they are available in both 5mm and 1/4″. I have a vague idea of using two of those on the shaft of this motor to make a dual filament bowden extruder.

The point of that would be to print the same part on the same machine twice at the same time. RAMPS has support for three thermistors and three outputs, so I could effectively double my print speed for parts that occupy less than half of the bed! An alternate idea is to use one RAMPS to control two machines, by either getting more powerful motor drivers or by getting twice as many. The only issue with that would be the 4 thermistor issue. Either printing PLA or some external circuitry could be fix that. I’ve been meaning to build up a bang-bang heated bed for some time now…

Boston Reprap User group meeting

I’m trying to put together a meeting of people interested in 3d printing. It’s called reprap because I think most of the people will come from there, but makerbotters and professional printers alike are more than welcome!

I’ve got a post over on the reprap forums trying to get an idea of how many people are interested and when we should do it. If you want to come out, then post a little bit about yourself over there and hopefully we can meet up!

weird z behavior on prusa reprap- FIXED

EDIT: over on the #reprap irc Rhys-jones and a few other helpful folks figured this out for me. Since the endstops aren’t working on my machine yet, the 0,0,0 position was based on wherever it was when it started up. I guess the x and y were similar to that same position, but the z wasn’t. The fix was to add “G92 X0 Y0 Z0;” to the beginning of the gcode. That sets the current position to 0,0,0 on the printer. This can be done in the Start/End Gcode tab in Slic3r. Thanks again all who helped!

I have something weird going on with my reprap where it will take the first z move and scale it dramatically. Then all of the others will behave normally. I made a video to illustrate it.

Machine will jog correctly through pronterface. when it encounters the first .4mm z move it ends up moving significantly farther. It ended up moving around 1 cm.

This is the code for that abrupt z move “G1 Z0.400 F7800.000”

at the end of the video you see it begin the second layer, and it moves the correct amount! This is the code for that z move “G1 Z0.800 F7800.000”

I am very confused.

For those interested, this is a gen6 board running sprinter and controlled by pronterface on my mac. The gcode was a single walled box sliced by slic3r 5.5. The config.h for sprinter is below.

Continue reading “weird z behavior on prusa reprap- FIXED”

gen 6 and sprinter homing issue

I’m at the point of troubleshooting where I either give up and go for a bike ride, or seek help. So I’m seeking help, and then I will go for a bike ride!

I am having an issue where I can’t get the gen 6 board to properly home. I have tried to home it by sending gcode (G28 X0) through slic3r and through the slicer home buttons. It recognizes the x end stop when jogging and refuses me to push past the limit, but it will not home for me.

Here is a pic of my printer. On the x axis the endstop is on the far left side.

Here is my configuration.h file

To boil down my problem into one bite: if the x axis endstop is defined on the correct side, homing does nothing. If it is defined on the wrong side, homing does a few mm shutter and then resets to the original position.

Continue reading “gen 6 and sprinter homing issue”

marlin, slic3r, pronterface and me

Ok. A recent move has kept me away from my prusa for a few months now. In that time all of the “cool kid” software has changed. Naturally I want to be running a similar setup with all of the new bells and whistles, so off I go.

I am going to go about uploading marlin onto my gen6 mendel-parts.com board. Installing pronterface on my Macbook running lion, and eventually get to using slicer to generate the stl files.

Step 1: Get marlin on my gen6 main board

I downloaded the most recent version of marlin from github.
I got the newest version of arduino (23) from here
I got the sanguino arduino add-ons from here (Updated to arduino core 0023)

Ok, enough downloading for now. Install the arduino first. There is a driver included with the download called the ftdi driver. Install that as well. That enables usb connectivity for some boards.
Now go here and follow the directions for installing the sanguino add-on. What you are doing is adding support for the specific chipset included in many main boards.

Now your mac side should be set for marlin. Go into the marlin folder you downloaded and open marlin.pde with arduino. It should open up a sketch with a bunch of other tabs behind it. The main one you will need to play around with is configuration.h. In there you should comment out or in the specific hardware and features you have/want.

Here is an example:

This is from the top of configuration.h

#define BAUDRATE 250000
//#define BAUDRATE 115200
//#define BAUDRATE 230400

The // that starts most lines tells the arduino to ignore it. These three lines represent a multiple choice for you. In the above example the first line is the one that is currently setting the baud rate. This is an important change. The default marlin firmware has the baud rate set to 250000 for some reason. I don’t think that will work out very well. Change it to 115200 and you ought to see better results.

Some other lines that I changed are:
//#define ULTIPANEL

Feel free to look around and get a grip of all of the options available. There are a lot. Don’t play with the pid settings unless you really know what you are doing, though.

Now you should be ready to upload the firmware to your board. Before you connect your board to your computer, select the board from the pulldown menu in the arduino app. Mine was “Sanguino with atmega 644p” Hit the verify button and wait for it to verify. If it fails, then you need to determine if it is a software issue, or a config issue. Look at the error message and do what it tells you to do. The firmware will check to see if your board in arduino matches the board that you defined. If it doesn’t then it will throw an error.

With a valid verification under your belt, plug your reprap in to the wall, connect it to your computer and turn it on. In the arduino app go to tools / serial port and select your machine. It should begin with /dev/tty.usbserial and not have anything to do with bluetooth in the middle. Once that is successfully uploaded you are done flashing marlin!

Step 2: installing Pronterface on osx Lion

I basically followed the directions here https://github.com/kliment/Printrun and I only had one hiccup. I will paste them below.

Download and install [wxPython2.8-osx-unicode] matching to your python version (most likely 2.7 on Lion, check with: python –version) from: http://wxpython.org/download.php#stable

Download and unpack pyserial from http://pypi.python.org/packages/source/p/pyserial/pyserial-2.5.tar.gz
In a terminal, change to the folder you unzipped to, then type in: sudo python setup.py install

I then tried to run it by typing “python ” (including the space) and then dragging in the pronterface.py file. It gave me an error about not finding any 64 bit resources, so I scrolled down a bit on the github page and found the answer. I typed “export VERSIONER_PYTHON_PREFER_32_BIT=yes” into terminal.

That’s it! Pronterface is installed. Select your port and your speed and hit connect. Now you have the firmware and the front end gui set up. I did a bunch of little tweaks to the firmware because my board was reporting really high temps. I had the thermistor set incorrectly in the firmware, so I would disconnect the machine in pronterface, change the setting in arduino, upload it, and then reconnect in pronterface. That is going to be your loop whenever you change something from here on out.