Tuning your printer instructions help reprappro

Hi all

I'm following the instructions for the reprappro mendel at [reprap.org] and find the instructions hard to follow for Tuning your printer

1. With the machine off remove the tongue from the extruder drive;
2. Wind filament through by turning the gear by hand; the end of the PTFE tube will come out of the drive;
3. Wind through about 50mm of filament and cut it with sharp sidecutters about 5mm downstream of the drive;
4. Carefully mark where the stub of filament is flush with the drive exit with a fine felt-tipped pen;
5. Turn on the machine, send it an M302 command (allows for cold extrusion), and extrude 100mm of filament;
6. Mark again with the felt-tipped pen;
7. Extrude another 10mm and cut off your measured sample;
8. If the sample is L mm long and your current steps/mm is e, then change e to be e*100/L; (using M92 Ee, where e is the new E steps/mm value, eg M92 E650)
9. Run the test again to check you now get 100mm;
10. To make the change permanent send an M500 command to store the values in EEPROM
11. Heat the hot end up to temperature;
12. Push a little filament through by hand from the 50mm you left sticking out, then pull the filament out to leave the path free;
13. Reload the machine in the usual way.

I'm stuck on number 8. If the sample is L mm long and your current steps/mm is e, then change e to be e*100/L; (using M92 Ee, where e is the new E steps/mm value, eg M92 E650)

My measurement for extruding 100mm is 109mm, but can't understand the calculation, I'd really like to improve the instructions with a worked example for other people new to 3d printing.

Many thanks

Edited 1 time(s). Last edit at 10/01/2013 04:28PM by Fordangerous.

What is your current steps/mm?

hi Jo

how do I find this out?

Thanks

Hi Fordangerous

The most up-to-date instructions are on the reprappro.com website, [www.reprappro.com] though in this case there isn't much difference.

The bit you are missing is knowing what your e-steps are currently set to. If you followed the commissioning instructions, you may remember the M503 shows the current EEPROM settings, and includes the M92 X... Y... Z... E... response, which shows the steps per mm for each axis. Here: [www.reprappro.com]

Knowing the current setting will allow you to calculate the new setting. If the current setting of 650 is giving you 109mm, your new setting should be e*100/L = 650*100/109 = 596.33
Set this by sending: M92 E596.33
Followed by: M500
to save the setting to EEPROM.

No real need to set it in firmware and up load it, just so long as you save your new setting with M500, it will survive resetting and turning the power off.

I have written a number of guides for other problems you may have; see the troubleshooting section here (useful for any/everyone with a reprap): [www.reprappro.com]

Ian
RepRapPro tech support

Yes, you will need to send the M503 command. See RepRapPro Wiki:

Quote

Confirm settings
----------------------------------

The Melzi controller runs RepRapPro's version of Marlin firmware. This allows many machine specific settings to be adjusted from Pronterface, without having to upload new firmware. To check current settings, send an M503 command to the machine. The log window should show something like this:

>>>M503
SENDING:M503
echo: Steps per unit:
echo: M92 X91.429 Y91.429 Z4000.000 E945.000
echo: Maximum feedrates (mm/s):
echo: M203 X500.000 Y500.000 Z3.400 E45.000
echo: Maximum Acceleration (mm/s2):
echo: M201 X2500 Y2500 Z50 E2500

Any settings updated from pronterface will take immediate effect, however they will not be saved to EEPROM (non-volatile memory) until you send an M500 command. Following this, the settings will persist following a power off.

*This is your current E steps/mm. In this case it's 945.000.


So in your case is would be:

(Your current E steps/mm) * 100 / 109 = New E steps/mm


Then you must send:

M92 (Your new steps/mm)


Lastly, you'll need to send the M500 command.



Hope this helps .

Edited 3 time(s). Last edit at 10/01/2013 10:11PM by Jo1212.

Thanks very much, it's definitely improved the print quality (which was already good), I may fine tune some more when I work out how to make the filament completely straight when measuring it.

Cheers

Your welcome. Glad I could help.

Is this doable with a rapman? Seems like there is NO documentation on it, but I don't want to have to buy a new board and convert it to RAMPS or similar if I don't have to. Just trying to get better print quality.