Sunday, March 25, 2012

Extruders and Hot Ends

When I initially started building my Prusa Mendel, I decided to go with the standard  Wade's Extruder (Thing:1794 from thingiverse.com) and a hot end called the Budaschnozzle 1.0 from  Lulzbot.com. Because it was my first setup, I  spent a lot of my learning curve with it. 

Wade's Extruder and Budaschnozzle


The second setup I acquired was the Bruthead filament drive and hot end from MakerGear.com. 

MakerGear


The third setup I've used is Greg's Accessible Extruder (Thing: 6713 from Thingiverse.com) and the J Head MKIV-B Hot-End from hotends.com.

Greg's Accessible Extruder and J Head



Here are my impressions:

First, I should clarify that I am using 3mm ABS filament. I haven't used 1.75mm or PLA.  I don't have plans to until later and then, only when I experiment with a dual extruder system using PLA as a support material.
    
(1)
Wade's Extruder:  I don't like it. I have spent more time removing the larger gear so that I could remove the motor and get to the screws that attaches the extruder on the x-carriage.  This is not fun when calibrating a machine for the first time.  Also,  I am not a fan of the hobbed bolt as a means of gripping the filament.  It easily becomes filled with filament particles and slips.

The Budaschnozzle 1.0 is no longer available and is now 1.1 (the difference being that the nozzle is more accessible for removal). I have version 1.0 and overall it is a good hot end. I have successfully used the .35mm and .5mm nozzles and questionable results with the .25mm and .75mm nozzles. My only dislike for the hot end is that the heater block and nozzles are made of aluminum and because of this they are fragile when cleaning glassified ABS (I recently had to re-tap the heater block because I over heated it while cleaning).

(2)
The Bruthead filament drive is the best! The geared stepper (with a 5:1 reduction) is easily dismantled for clearing jams.  The filament drive gear grips the filament well without tearing into it.  This is the most expensive of all three setups, but well worth it.

The MakerGear hot end uses a nichrome wire heat core, unlike the other two hot ends which use heat resistors. I find this to be fine. I personally have had less serious jams in the hot end system than the others ( I have been able to run it at a lower temperature).  Both the .35mm and .5mm have been equally successful.

(3)
Greg's Accessible Extruder is a vast improvement over Wade's. Getting to the motor mount screws without having to remove the larger gear saves considerable time.  But the hobbed bolt kills it for me.

The J Head MKIV-B hot end is still intriguing to me and deserves more experimenting.  Initially, I ordered the .35mm setup and couldn't ever get a print started with it.  I could extrude a very fine thread and that's it.  I don't have any way of accurately measuring it,  but I think the nozzle is bored incorrectly and is much smaller than .35mm. I have printed a number of successful prints with the .5mm nozzle.  My main dislike is the shape of the nozzle end.  It's not blunt or flat like the MakerGear or Budaschnozzle nozzles, but has a sharp nose.  I think this digs into the filament layer rather than pressing it to the required depth.


.35mm J Head Nozzle

.5mm MakerGear Nozzle

I don't have any similar print samples from each hot end to compare.  I don't have the time or the interest.  I think all three basically would give equal results.  What I am concerned about is longevity.  I need a trustworthy system that will give me a 2 day print time without jamming.  From my experiences to date, I feel only the MakerGear setup will be able to accomplish this.  And because of my confidence in it,  I plan to adapt it for dual extrusion in the future.




Thursday, March 15, 2012

3d Printer in Action

Friday, March 9, 2012

Calibrating a RepRap 3d Printer

Calibrating a machine like this is a true test of patience and perseverance. Many hours I have spent trying to get the myriad of software to work together before I could even make the printer move, let alone extrude plastic. Being an open source project, there are frequent updates and hybrid versions of the operating software available for this printer and they don't always work well together or even at all.
Once I got a working package together, then the actual calibration took place. Fine tuning the movement of the axes and the extruder with the delicate flow of material at just the right temperature in order not to extrude a mess or even worse a jam in the hotend, took weeks to to accomplish.
Now with a somewhat decent setup, I was ready to find out what this printer could do. The following pieces are my more interesting results. They are straight from the printer with no cleaning or reaming.


X-carriage for the printer. The linear bearings snap nicely in place.

I was curious about bridging and ran a test of an open cube in order to see how well my setup would do.

Calibration cube from Thingiverse. If you look closely, there is only a little drooping from the bridge.

Next, I wanted to run a test of a tall and slender form that has some complexity.

Vica Illusion Sculpture from Thingiverse. Created by chylid.



Last, I needed a good idea what to expect for an organic form.


Devil Head from Thingiverse. Created by yzorg.




All of the above were printed with the MakerGear Brutstruder and hotend. All except the devil head were printed with a .35mm nozzle, the head was printed with
a .5mm nozzle. I started my initial testing with the Wades Extruder and Budaschnozzle hotend, but after frequent jams while doing my initial calibrations, I was unsure whether my problems were my settings or a hardware design of my extruder system. I then began shopping for other solutions. A later blog entry will cover 3 different hotends and extruder systems that I now have.




I'm going to end this entry with some basic information which may help others who are trying to calibrate there own machines.

Not all systems are compatable it seems, so I will start with a basic breakdown.
I'm running Windows 7 32bit OS on an AMD Dual Core System
My choice of printer software is Printrun/Pronterface with Skeinforge

The following is the stream of programs, drivers, and dependencies needed for the software to work. Please make note that all is 32bit and some versions are not up to date because the newer version is not compatible with the "core group" (this especially holds true for the Arduino program! I could not get the latest version to upload my firmware).

arduino0023.zip install the program and accompanied driver
upload the Kiliment-Sprinter-a352585 firmware  (included in the Renosis package that's listed later down this list)  to the Arduino Mega

Download the following, and install in this order:
pyglet-1.1.4.zip  For this one, you will need to unpack it, open a command terminal, and navigate in DOS in order to install.

Install the following programs:
kliment-Printrun-7a1ccb8 
MakerGear-Prusa-Skeinforge-Settings-a0ee1e7
entire contents of Renosis package is dumped into kliment-Printrun-7a1ccb8 folder
psyco-1.6.win32-py25.exe this addition will supposedly make Skeinforge run faster

The rest depends on the intricate nuances of your own machine and how well you can tune it with the software and firmware.
The best 5 sites I found to be the most useful:
http://reprap.org/wiki/Printrun
http://buggerit.blogspot.com/2011/08/hains-prusa-mendel-reprap-calibration.html
http://www.renosis.net/Skeinforge-41-guide.html
http://www.thingiverse.com/
http://www.google.com/  A full sentence describing your problem and a world of information retrieved (just make sure the word reprap is in there somewhere). I wouldn't have made it this far without it.


Next up is input. I'll begin exploring different means of creating my own content.

Addendum Aug 13, 2013:

A lot has changed since I set up my first printer. New profiles and updated software has helped tremendously. The latest version of Skeinforge is an example. If you come across this entry and would like to set up your printer, the easiest method now is to download Repetier Host here http://www.repetier.com/download/ and install. This will install all the python scripts and other dependencies for you. Also it gives you Slic3r which is an easier slicer to use, but still offers the option of using Skeinforge as well. The included profiles Durbie Normal and Fine are included which are the best profiles I've seen to date.

If you are up and running, but don't have the Durbie profiles, they can be found here
https://github.com/romscraj/Skeinforge41in the .Skeinforge folder of the software.

With this software and the Durbie profiles and the mechanical calibration information here http://www.renosis.net/Skeinforge-41-guide.html, it's a much easier road to getting a new printer commissioned when building from scratch.