Almost printing!!!

Hello all, I have finished assembling my first reprap, a Prusa. Ive got two major things to figure out before printing starts. One, is the temperature of the hot end. I set it starting at 200, going up in increments. The last one I tried was 280, somewhere around 260, my software reading jumps to around 330, my question is how do I get the most accurate results? I have no programming knowledge whatsoever, im more mechanically inclined.

Now for the problem that has put me at a standstill. One of my motors, and I just noticed a second one, is getting extremely hot, without moving. Sometimes it clicks or jerks when its supposed to stand still, and almost always gives off a whirring sound, that changes pitch based on trimpot setting. The other motor gives no warning when it overheats. Ive tried turning the trimpot down, but then its unable to move the reprap. The controller on the arduino (im running ramps 1.3 assembled kit) doesn't get warm to the touch. Ive taken the wires off the controller and inspected them, they look like a sturdy connection with no shorting. Think I might have a controller or motor problem? The X axis is the main concern, but the Y axis was the one that surprised me by getting hotter without any warning.
The first time I noticed the heat, it was almost too hot to hold, but after letting it cool down, and powering up the reprap again, the motors all moved great again.

Have you made sure the wires on the thermistor are not touching each other? 280C is incredibly hot, I extrude PLA on my Mendel at 175C just fine

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Experimenting in 3D in New Zealand

I'm fairly certain the wires aren't touching, Ive got kapton tape separating them, and if they were, the temp would show crazy values for a short. Anyway, the actual temperatures definitely aren't 300C, im using a free abs sample from makerbot i think, and its still not extruding. My meat thermometer (worst possible way to measure the hot end temp) says the nozzle gets to 160C when its set to 280. I haven't gone through any settings, just plugged a 100k thermistor into the ramps, figuring that's what it was designed for.

you should check if you have the right thermistor table in your firmware. You can also check the resistance of the thermistor (unplugged from RAMPS). If it is a 100k thermistor, it should read 100ohm at room temperature.
The motor getting hot without moving and humping directs to too much current. Try adjusting the pot on the pololu driver board.

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regards,
Tom

There are many types of 10k or 100k thermistors with different beta's so just measuring the resistance at room temperature is not enough. It would limit the possibilities though. You have to ask your source what type it is. Then you can pick the right thermistor table. It sounds like you definitely have the wrong table loaded in the firmware.

The sudden change in reading from 260 to 330 is probably because you have loaded a table with only 20 points in it, probably for a 100k thermistor. In my experience, there are not enough points in a 20 point table to get accurate reading in the 180-250C range where we need it. I use a 30 point table that was extracted from a 50 point table to give more points in the range of interest.

As far as the stepper motors, you need to tell people here what type of electronics you have. As Tom wrote, you need to adjust the trimpots in the stepper motor controller board. You should be able to get it to a point where it's able to turn but the motor is cool enough to be touched. If not, you might want to make sure that your axis is moving smoothly and not binding.

Electronics, Opto endstops: [ultimachine.com]
Thermistor : [ultimachine.com]

The electronics says it comes loaded with the software needed to make a reprap, and since I do not yet know how to do those things myself, I just took Ultimachine for their word and hooked it up to my computer. Is the temperature table part of the computer side of software, or in the arduino?

All my axis's work great (issues with Z, but works when I fiddle with it), I have used lithium grease to help with friction and the corrosive properties of having brass and stainless steel touching. The action along the smooth rods is very smooth.

The overheating problem can occur when I ask for no movement of the axis, the motors just sit there, doing nothing, and get very hot. When I turn down the trimpots on the controller boards, the motors are no longer able to move the axis's. Ive got it dialed in to the minimum voltage required for movement. My question is, do I have shorts in 2 of my 5 motors? Since my controller boards arent even getting warm, I assume they arent overvolting.

Edit: also, if I needed to build my own table, is it just a matter of putting my hotend in my oven at 20 different temperatures, throwing that into a spreadsheet and getting the equation for resistance to temp?

Edited 1 time(s). Last edit at 07/14/2011 07:06PM by alnmike.

There's probably nothing wrong with your motors. The x and y stepper motors are set to hold the position of the steppers while idle. If it doesn't hold it, then the x-carriage or the bed can wander. That would be bad as the layers won't line up to each other. Because of this, the x and y motors are drawing current even when not doing anything and they get warm or hot depending on your trimpot setting. I have my trimpot set between 1/4 and 1/2 turn.

I didn't buy the complete kit from Ultimachine so I don't know if the thermistor table that's loaded is consistent with what they're selling. One would expect that to be the case but your test seems to indicate that it's not. Have you tried extruding plastic, either PLA or ABS, to see at what temperature they'll extrude. If you disconnect the wires to your extruder motor, you can push the filament or turn the driven gear by hand. It shouldn't need too much to extrude plastic.

Anyway, I recommend the Sprinter firmware along with Pronterface to control the printer and send gcodes. To load the firmware, you need to use Arduino.

I'll follow this up with my thermistor table for the thermistor from ultimachine.

Here is a video of my problem axis. The motor overheats because it fights itself or something, the printbed moves smoothly quietly and overheat-free. I have sanded the smooth rods some and added lithium grease. The two axis's have about the same tension on them from the motors point of view. I use my hand to turn the wheels when its off, and they feel about the same. I tried pronterface, but repsnapper just seems more intuitive to use, at least for my purposes of just getting it running. All of the home buttons work (z axis needs help, but w/e), optos are working great, still need to calibrate the temp sensor, it does read 100 Ohms at room temp. Reading the sprinter documentation, its for a different setup than mine, and I dont have the knowledge to tweak the settings yet.

The trimpot on the axis that is acting jumpy is at halfway, any less and it just jumps without moving the printhead, any more and it still jumps, but moves it fine, and overheats quicker.

Here is a short video showing my problem.
Notice the noise when its connected, a few mouse clicks and the noise changes when the reprap is connected with my computer. Also, notice the screw holding the smooth rod move a little bit, I tried loosening them all on 1 side to see if the axis was binding because it wasnt parallel perfectly.

Edit, I took off the problem axis to start troubleshooting the temperature problem, which I solved, my own stupidity. Anyway, when I just did my test, my extruder motor started doing the same symptoms as the axis motor. I felt the ramps controller board and it burned my thumb (sensation, not actual damage). I immediately turned it all off. Unplugged the extruder motor, I can feed the plastic through manually just fine now.

Another edit:
I just plugged the Y axis (works perfectly) into the X axis controller, and it does the same jerking motion/sound that the x axis does. Now im thinking I have 2 out of 4 bad controllers, and the motors are fine.

Edited 3 time(s). Last edit at 07/31/2011 05:35PM by alnmike.

Yeah. You've fried two. The trim pot setting will never need Moe than 30%.

Bleh, well at least its not the motors. Anything I can do to see if they might have been made faulty and switch em out with ultimachine?

Update with another video.
I ordered 3 more controllers, so I have one extra, My reprap now moves and extrudes as its supposed to, my temperature does have a big swing range though.

My new problem is in this video, when I hit print, everything goes to home, the extruder counter resets to zero (I did have the reversing problem, but fixed it), and it sits there for a number of seconds doing nothing, when it does start printing, the extruder make a fast ticking noise, and when the print motion stops, the extruder goes into crazy mode, then stops when the printhead starts moving again.

Hi, sorry can't help with your current problem, but wanted to mention the white smoke on your video looks like you're overheating something. When I had this the last time I broke my hotend (ptfe thermal barrier cylinder creeping and dropping the barrel).
Usually I believe a hotend shouldn't smoke at all (never tried ABS yet then, only PLA).

Yeah, my kapton tape that i have right on top of my nichrome wire is smoking pretty bad, I think somehow the wire isnt as tight as it could be against the metal to drain the heat away. I know its getting a bit hot to burn kapton tape... But it should be serviceable enough for me to get it up and running so I can make new versions of all the pieces that are sub-par with what I got off ebay, then I can go around and start the upgrades.

Your extruder tip is too hot. You have to fix that first before trying to print.

The pause is probably due to a M109 command to set the tip temperature and wait in your g-code. It's a good idea to look at the g-code and understand the commands. It's not really that complicate and everyone should really learn what they mean.

I took a long look at the Gcode to figure out the reversal process and to just understand whats going on. But I dont understand why the extruder motor isnt turning during print and goes into overdrive at pauses, or even why it pauses. Every youtube ive seen shows smooth transitions of motion. Before I fixed one of my extruder problems (It wasnt turning at all), I watched my printer go through a few layers of motion seemlessly. But now that I 'fixed' my extruder, it doesnt work

Anyone have ideas?
Edit: Ive tried changing the flow and feed rate in skeinforge (re-slicing the test each time) both up and down, changed the e_feedrate setting in Pronterface both up and down, and all combinations of those 3 parameters.
Here is the Gcode thats im trying to print:

G28
G92 E0
G90
G21
G28
M103
M105
M106
M140 S60.0
M141 S30.0
M142 S0.0
M113 S1.0
M108 S255.0
M104 S200.0
G1 X-25.92 Y-23.11 Z0.72 F60.0
G1 F1200.0
G1 E0.0
G1 F60.0
G92 E0
M101
G1 X-25.92 Y23.11 Z0.72 F240.0 E2946.78
G1 X-23.04 Y23.11 Z0.72 F240.0 E3130.38
G1 X-23.04 Y-23.11 Z0.72 F240.0 E6077.16
G1 X-20.16 Y-23.11 Z0.72 F240.0 E6260.76
G1 X-20.16 Y23.11 Z0.72 F240.0 E9207.54
G1 X-17.28 Y23.11 Z0.72 F240.0 E9391.14

And it goes on, if theres a problem, it should be in the first part.

Edited 1 time(s). Last edit at 08/22/2011 10:17PM by alnmike.

I dont know what the M103 and M101 settings are, its not on the Wiki, the M108 value looks like the setting in skeinforge that I kept changing from 10-255, flow rate. Right about where the M101 is, the extruder goes crazy. Ive got a .5mm nozzle, and a wades extruder with a NEMA 17, if anyone could give me their settings. Its a SAE prusa, but uses the metric belts and allthread, so the settings from a metric prusa should suffice.

... it's not well documented and not interpreted in the same manor by different firmwaes

The code M101 (or M3) means "extruder ON", M103 (or M5) means "extruder OFF" ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Are you using Skeinforge 39? I would have thought so judging by those very large extruder numbers.

Use the gcode dictionary to check what your gcodes are doing: [reprap.org]
This is an older version of the dictionary and shows the codes that are deprecated: [reprap.org]

If you're using a stepper extruder (rather than a DC motor), a bunch of those gcodes need commenting out, using replace.csv in Skeinforge, along with some settings in the 'Dimension' tab. See this post for how to do it [forums.reprap.org]
However, if you are using Skeinforge 39 there are quite a few other settings that could be causing some other problems in your gcode, like the use of negative numbers; most people use absolute numbers. Skeinforge 41 is the latest version, but you might be better off using ahmetcemturan's SFACT, which is a simplified version of Skeinforge 41 - [forums.reprap.org] It's standard settings are close to what most people need, and is reorganised a little for reprap and clarity. However, you need to make sure your extruder is calibrated for it. See PrusaJr's post here: [josefprusa.cz]