EXTRUDER MOTOR NOT WORKIG FOR E-VALUE LESS THAN 10

At school we are building a reprap mono. We are using Melzi electronics.
A couple of days ago we had a problem with microstepping and you guys solved it right away.
We now have all the motors microstepping at 1/16 step. X , Y , and Z motors are moving the correct distance. _ THANK YOU

The problem we are having is with the extruder motor. The commissioning instructions say to send a "M302" command ( to allow cold extrusion) and then to send "G1 E5 F500". When we do this , the extruder does not move. However If we send a command with the "E" value 10 or greater, then it works fine.
For example if we send "G1 E10 F500" then it works fine.

Our STEPS_PER_UNIT parameters are set at "M92 X100.000 Y100.000 Z4000.000 E660.000"
Our MAXIMUM_FEED_RATE parameters are "M203 X300.000 Y300.000 Z3.000 E45.000"

When we calculated our M92 we got 633.6 , so we changed "M92 Z636.6" but that didn't help.
We also tryed playing with our M203 settings for Z but that didn't work either

We have the extruder motor microstepping at 1/16 steps - Is this alright or should it be set different?
Are there any other parameters , besides the M92 and the M203, that might affect this?

Any help would be greatly appreciated,
Thank You

Did you change Z or E?

Sorry for the confusion, I should have proof read my post better

We changed the 'E"

the line that read:
When we calculated our M92 we got 633.6 , so we changed "M92 Z636.6" but that didn't help.
should have read:
When we calculated our M92 we got 633.6 , so we changed "M92 E636.6" but that didn't help.

and the line that read:
We also tryed playing with our M203 settings for Z but that didn't work either
should have read:
We also tryed playing with our M203 settings for E but that didn't work either

Have you tried slowing the feedrate down? Try G1 E5 F200 instead of F500.

Thanks for the input, 3dkarms

Already tried that, We tried slowing the feed rate down to as low as 100, and speeding up to as fast as 900 , and everything inbetween. It didn't do anything. The extruder doesn't even make a noise. The only thing that works is making the "E" value 10 or greater. Then the extruder seems to work fine.

Here's an update.
Using Pronterface (Printrun 2014.03.10.)
When we use the graphical button for extrude, and set the length(amount) to 5mm and the speed to 500 mm/min then it works fine on both "Extrude" and "Reverse" buttons.

But - when we send a "G1 E5 F500" it does nothing
---------when we send a "G1 E0 F500" it does nothing

------when we send a "G1 E15 F500" it works fine
------when we send a "G1 E0 F500" it returns to start point

Shouldn't sending the G1 command do the same as the graphical user interface?

Sounds like your extruder is using absolute positions instead of relative. Try sending M83 before any of the G1 commands.

I tried sending the M83 command before the G1 command as you suggested and here are the results

M302
M83
G1 E5 F500 (Extruder didnt turn)
G1 E12 F500 (Extruder ran forward)
G1 E-5 F500 (Extruder ran reverse) NOTE"E" NEGITIVE VALUE
G1 E-8 F500 (Extruder ran reverse) NOTE"E" NEGITIVE VALUE
G1 E-6 F500 (Extruder ran reverse) NOTE"E" NEGITIVE VALUE
G1 E3 F500 (Extruder didnt turn)
G1 E9 F500 (Extruder didnt turn)
G1 E10 F500 (Extruder ran forward)

So it would appear that if the extruder will work if the "E" value is less than 0 or greater than or equal to 10. But if the "E" value is between 0 and 10 then the extruder will not run.

However it sill runs fine at any value if I use the GUI Extrude or Reverse buttons

I was just wondering if it works with a print job? as any of the values for in with in the Gcode is going to be less then 5 and more likely less then 1.
Have you tried reflashing the firmware?

Quote
ricym66721
However it sill runs fine at any value if I use the GUI Extrude or Reverse buttons

Can you post the gcode that's sent to the printer by the GUI? If it's sending gcode that works for values less than 5mm then you should be able to copy what it sends and send it to the printer directly.

Sorry to take so long to get back to you guys.
No school over the weekend so we just got back to it today.
To answer your questions:
We tried reflashing the firmware today - It didn't seem to change anything

We have not tried Printing anything because we are still commissioning the printer, however we talked it over today and decided to go ahead and finish the commissioning and try printing. It will probably be a few days before we get to try the printing - we will keep you posted.

When we use the Extrude button , In the window it just says "Extruding 5.0000 mm"
When we use the Reverse button it jus says "Reversing 5.0000 mm"
So we don't know what gcode is being sent to the printer.
Is there some way to find out what gcode is being sent to the printer?

Thank you guys for all your help and suggestions.
We very much appreciate all of the help

have you tried the G0 E5 ?
I see all G1 commands in the tread.

I don't really know why you're playing with G-codes.
Have you set the v ref for the stepper?
I assume you have no filament in the extruder?
If you click "Extrude 50mm" at 300mm/m in Pronterface, does it move ok? In both directions?

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Waitaki 3D Printer