Extruder Steps per mm

My printer is an SAE Prusa, with Wade's Extruder, printing PLA at 220C. I am using a custom Gen6 electronics, the new Sprinter (the new Marlin FM from mendel-parts.com) and my current extruder steps per mm is 50.

Using Pronterface, I try to extrude 50mm and the filament moves about 1-2cm into the cold end, yet when I print using this setting it seems as if there is WAY too much plastic coming out of the extruder.

Can someone else with a similar setup post their value for extruder steps per mm? I am really at a loss here of what to do. Do I eyeball it based on print results? Any ideas?

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[wirelesslaunchpad.com] - My Prusa and Gen6 Electronics Blog

You need to calibrate e_steps_per_mm for your extruder.

1) Tell it to extrude 10mm
2) Measure how much went into the extruder
3) Do the math
4) Adjust the e_steps_per_mm in the firmware
5) Goto 1)

50 steps/mm seems very low compared to the base values on the wiki:http://reprap.org/wiki/Volumetric_Dimension_settings#Base_values_for_comparison

220C seems far too high for PLA btw. 185C is a good base reference point.

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-Nudel
Blog with RepRap Comic

How fast are you extruding when you calibrated using Pronterface? It's possible that you were extruding too fast when you did the calibration so that your pinch wheel was slipping or your motor was skipping steps. So, when you printed at a lower feed rate (also means lower flow rate), it didn't skip or slip (or did it less) so that you got more extruded filament. In pronterface, try do the calibration at slow flow rate like 40 mmm/m and watch the extruder carefully. You can also do it with the hot end removed from the extruder.

So, I took a step back and made sure that I had the E_STEPS_MM set correctly. It turned out that a value of 150 gave me good results. Then I hooked up the hot end and did a test print. The hobbed bolt is unable to push the filament anymore, and it just slips during the print. Even setting the Flow Rate Setting in Skeinforge to 160 from 210 or the Feed Rate to 12mm/s, doesn't seem to slow down the printer at all. When setting the mm/min setting low in Pronterface, it doesn't slip at all.

It also seems like my extruder is not consistent. During a print while the extruder is at the same (too fast) speed, I sometimes have so much plastic coming out it blobs and sometimes I don't seem to have any plastic coming out.

I'm starting to think there's something wrong with my extruder even though I have made many prints already (even though they are far from perfect).

Maybe I should just go back to the settings that kind of worked. Nothing seems to be working correctly at all anymore. :-(

Did you make your own hotend?

I have made all of mine and was able to print for months and months but it had to be hotter and faster than most people printed. It turns out the problem is heat rising up the thermal barrier and making for a much longer melt zone. This allowed me to print a low temperatures for half a print and then it would jam as the heat rose up. If I turned the temp up higher I could keep the entire thing molten thus the ability to print for many months.

To see if this is the problem try and touch the thermal barrier. If its hotter than you can handle touching, its to hot. Try adding a small fan across the thermal barrier and see if that helps. Most people find it helps even with a perfect hotend design.

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Sublime, I actually did! Before when it was working better I did have it at a higher temperature. I increased it back up to 215, and I seem to be extruding reliably again. Thank you!

Now I just need to figure out what to do about all this plastic coming out! There's way too much of it, something must be wrong. I'm going to keep playing with settings in Skeinforge hoping I find something that works. Anyone have any ideas?

Thanks again for all the help!

At this point start over or go back to an old profile. I had to do that myself after making a huge mess of my settings trying to fix what is actually a Hotend issue not a software issue.

And I strongly urge you to add a fan blowing across the top of the hotend. (not the heater block) You will be amazed at how much it helps.


NJC Wrote:
-------------------------------------------------------
> Sublime, I actually did! Before when it was
> working better I did have it at a higher
> temperature. I increased it back up to 215, and I
> seem to be extruding reliably again. Thank you!
>
> Now I just need to figure out what to do about all
> this plastic coming out! There's way too much of
> it, something must be wrong. I'm going to keep
> playing with settings in Skeinforge hoping I find
> something that works. Anyone have any ideas?
>
> Thanks again for all the help!

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Quote
NJC
...and it just slips during the print. Even setting the Flow Rate Setting in Skeinforge to 160 from 210 or the Feed Rate to 12mm/s, doesn't seem to slow down the printer at all. When setting the mm/min setting low in Pronterface, it doesn't slip at all.

160 is still too high. You should print with the feed and flow rate both set to less than 20 until you have some success before trying to push it. A flow rate of 160 with a feed rate of 12 with SF 40 and later is wrong. They should be equal. That's why you have too much plastic coming out.