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antiklesys

Feeder Mod & Marlin

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If I modify the dimension of the bolt of the feeder from 8 mm to 20 mm what has to be changed in the configuration of Marlin?

I did change the steps ratio to 314 in buildmemarlin (I'm trying this mod here

http://www.thingiverse.com/thing:15897

) but it doesn't seem to go well...also with the new Marlin I'm forced to put in G92 E14, is there any other parameter I should put in instead?

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Wait, that's not G92, that should be M92.

M92 sets the number of step motor steps per 1 "unit". For X/Y/Z a unit is 1 mm. For E the unit changed. In NetFabb, the E value represents... no idea, I've heard it represents the amount of mm filament coming out of the nozzle.

For Cura/RepG34 it represents the amount of filament entering the extruder in mm. For Cura the default M92 E865.888 is used. However, this value can be tuned. This type is called "volumetric", which has 2 values that are easy to calibrate. One is the filament diameter (measurable), and one is the M92 Exxx, also called "steps per E". Which can be calibrated.

Now that you have changed your extruder bolt, the amount of steps it needs to take for 1 mm of filament has changed. For the old way (NetFabb) you need about M92 E5. For the new volumetric way, you need the M92 E314.

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Nope.

Standard bolt - old way: M92 E14

Standard bolt - new way: M92 E865.888

20mm bolt - old way: M92 E5

20mm bolt - new way: M92 E314

There is no G92 command.

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Nope.

Standard bolt - old way: M92 E14

Standard bolt - new way: M92 E865.888

20mm bolt - old way: M92 E5

20mm bolt - new way: M92 E314

There is no G92 command.

Thanks Daid :)

So I'll just throw in the standard Marlin and change these parameters and do a M500 to save everything.

Why's 314 and 5?

I did some math and accordingly to my results should be 346.3552 for the old one and 5.6 for the new one, but I think I'm missing something. Can anyone double check this out?

Here's my calculations:

8 (diameter of the small screw) divided by 20 (diameter of the big screw), multiplied by 865.888 = 346.3552

and

8 (diameter of the small screw) divided by 20 (diameter of the big screw), multiplied by 14 = 5.6

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M92 E5.092 worked for me in NetFabb.

865.88/315 = 14/5.092 is where I came up with that number.

Kyle

I came up with it the same way.

The 6/20 factor might be wrong because the filament digs into the bolt a bit, so the actual diameter at which the filament is pushed is different.

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Slightly OT, Be sure to print 50bearingblock.stl either solid or with a tight fill. My first set had maybe a 1.0 or 1.5mm fill (netfabb-speak, so 25-30%) and the bearing pins sheared/crushed a bit. It wasn't obvious initially, but i couldn't put any real pressure through the bearing on the filament and it slipped a lot. Second set I printed with a much tighter fill.

Kyle

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