Yet another extruder problem... [Resolved!]

I've recently "inherited" an already-assembled Mendel, but have also inherited some of it's problems. Over the past week I've been reading the wiki and searching the forum for a solution, but haven't had any success.

I'm currently using TechZone electronics with a DC motor extuder, along with the most recent (stable) RepRap host software and firmware from the RepRap site. The problem is that I have no control over the extruder motor. Sometimes when I power-on the machine, the DC motor will start running on its own, and will not stop until the reset button is pressed. It will also randomly start running while the machine is powered on. When pressing the "Extrude" button in the RepRep console, nothing happens. The heat, however, will turn on and read the nozzle temperature (most of the time). I have also tried "making" and part from an .stl file, but the extruder does not run.

I have made the changes to the pins.h file, setting the STEP_ENABLE_PIN values to negative. I have also changed the extruder.h file to include "if (step_en_pin < 0 || step_en_pin == 255)". Still no success.

Previously I changed STEP_ENABLE_PIN from (byte) to (int) as described here, and set it to -1, but also no luck.

Any ideas on what to do here? Keep in mind I'm still relatively new to the RepRap machine and programming...

It seems to me like the best option might be to just buy Makerbot electronics and use a stepper motor for the extruder. Extruder problems aside, having to hold down reset buttons on the Techzone boards while uploading and turning the machine on is getting to be a nuisance...

- Kurtis
Ottawa, Canada

[RESOLVED]: DC motor is not compatible with latest RepRap firmware. Used stepper motor instead, no modification to code required. Still using Techzone boards. See [forums.reprap.org]

Edited 1 time(s). Last edit at 08/04/2010 01:13PM by kurtis.

I did not think that the Mendel had a DC Motor Extruder. The latest firmware assumes a Stepper Motor unless you change the firmware code to be a DC motor. The techzone and makerbot electronics are the same, just a different form factor. (There may be discussions about build quality etc, but they are the same design).

I would personally recommend following the instructions about configuring the firmware and review the build instructions on www.reprap.org for the mendel printer in order to ensure that every thing is actually setup correct. Start with the motorboard tests and on. The fact that you are using a mendel with a DC Motor does put it in the experimental side of things

David

Exactly which firmware do you have? Can you provide the link you downloaded it from?

The FiveD firmware does not support a DC motor extruder and it would be no small task to add support for it. You might have better luck with the MakerBot firmware (of which I am not very familiar.)

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Darwin clone, Gen 2 electronics, Arduino Duemilanove w/ AtMega328, 5D Firmware, Pinchwheel extruder
[www.codeerrors.com]

Well, that would certainly explain the problem. I'll take a look over at Makerbot.

I downloaded everything from here: [sourceforge.net]
I used the firmware included, which seems to run the the axes just fine. In the firmware, there are comments which explain what values to change if not using a stepper, which I assumed to imply a DC motor.

As I said, everything was sourced and built by someone else and was given to me to use for my graduate research, which means I unfortunately don't yet have that intimate knowledge one gains when building something from scratch.

I forgot to mention - the DC motor will randomly turn on even when the Extruder board is not connected to the main motherboard. I found that even by touching other connectors on the board, such as the thermistor, the motor will start. I'm no electrical engineer, but this seems strange, and leads me to believe there is possibly an electrical issue such as improper grounding...

In any case, I'll likely use a stepper extruder and replace the boards, but I'd still like to know what's going on.

> there are comments which explain what values to change if not using a stepper

I just double checked and those comments are still in the FiveD firmware, even though it will only work with a stepper. The comment was left in when the old GCode_Interpreter evolved into the FiveD_GCode_Interpreter. It looks like that is what you are trying to use.

It does sound like you have something else going on as well.

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Darwin clone, Gen 2 electronics, Arduino Duemilanove w/ AtMega328, 5D Firmware, Pinchwheel extruder
[www.codeerrors.com]

The stepper extruder still uses the extruder board, but drives the PWM in such a way that the stepper can be moved, so you should just be able to replace the DC Motor in the setup with a stepper motor.

Quick confirmation: It is the triangular shaped printer that you have been given and not the cube shaped one?

David

Yes, I have the triangular one. I plan to replace the motor with the stepper and go from there with the existing electronics.

As an aside, is the problem with holding the reset button while uploading firmware specific to TechZone boards, or is it independent of manufacturer?

Thanks again for all the help. I've been scratching my head over this for a few days.

On my board I don't have to help reset to to upload firmware, however this is a "feature" of some early techzone boards and Ardunio boards. There is a jumper near the serial port which when connected means that the reset should happen automatically. (That is as much as I know)

David

Auto-reset requires two things. The USB-Serial converter needs to bring the reset signal out to the connector. An over-the-counter USB-Serial cable probably doesn't do that.

The board also has to connect this line to the reset line of the through a capacitor. I have no idea if the techzone hardware does that.

The USB-Serial converter I use can be found here: [www.nkcelectronics.com]

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The major difference with this board is that it brings out the DTR pin as opposed to the RTS pin of the FTDI cable. The DTR pin allows an Arduino target to auto-reset when a new Sketch is downloaded.

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Darwin clone, Gen 2 electronics, Arduino Duemilanove w/ AtMega328, 5D Firmware, Pinchwheel extruder
[www.codeerrors.com]

The techzone USB-Serial board does do that, the only issue I was aware of was on the motherboard in older designs

David

Thanks. I'll try it out anyway.

While I wait for my new stepper motor, I decided to try uploading Gen3 firmware, which supports the DC motor extruder. After finally solving a persistent compiling error, I got the code uploaded, only to have the RepRap software freeze when I clicked any of the buttons, such as nudge or turn on heat.

I then decided to try the ReplicatorG software instead of the Reprap host. However, RepG could not connect to my motherboard. At first is was telling me I needed to upgrade firmware, so I tried uploading and it could not connect. Under the Machine tab, there are no RepRap machines, only cupcake. I assume I am supposed to select Cupcake here?

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kurtis
I assume I am supposed to select Cupcake here?

No, you must add a 'RepRap Mendel' to your machines.xml file.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

UPDATE:

I bought a Sparkfun stepper motor for the extruder and got rid of the big, bulky DC motor that never worked. Once I got that hooked up, I still had some problems getting it to work. It would buzz and whine, but no control. After lots of searching, I finally found this: [forums.reprap.org]

I had to add an additional wire to ground the extruder to the motherboard, and then the motherboard to the main power source ground. After I did that, everything started working! I'm back to using the RepRap Host software, with no madifications to the code, other than configuration changes (axis direction, steps/mm, etc).

Now, I'm trying to figure out if I can mount the stepper motor to the existing Plastruder Mk.4 without having to make new parts. I'd like to use the Geared (Wade's) extruder design, so I might just build that and scrap the Plastruder setup.