To the Sprinter committers,

Please consider including the following lines in Configuration.h as a convenience for your users...
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// X, Y, Z, E steps per unit - SAE Prusa Mendel with Wade extruder:
//float axis_steps_per_unit[] = {63, 63, 2268, 510};

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I based these numbers on these calculations: [reprap.org]
I have verified that these numbers work by printing out the 20mm box and the 50mm tower from this calibration set: [www.thingiverse.com]
I used Skeinforge to generate GCode, with a flow rate and feed rate of 35mm/s.


Thanks for your work on Sprinter, my excursion into the world of 3D printing has been very rewarding.

-ted stockwell

Thanks, hopefully they will add it to the config file comments.

clarification: you have 2268 for Z axis, but that value depends on how many threads per inch you have on your Z axis rods (i.e., whether you are using 5/16-18 or 5/16-24 rods) and whether your stepping 1/8 or 1/16:

Pre-calculated #define z_steps_per_mm:
- For 5/16-18 rod lead screws set it to 1133.858 for 1/8 and 2267.716 for 1/16 stepping.
- For 5/16-24 rod lead screws set it to 1512.287 for 1/8 and 3024.575 for 1/16 stepping.

source: wiki

Edited 3 time(s). Last edit at 01/02/2012 10:59PM by thewaterengine.

The reason these haven't been included are because they won't be the same as everyone. What pulleys/belts you use affects it, my prusa has >200 steps/mm for X and Y because I'm using tiny belts and pulleys. Also, you need to get the steps/mm for e for your particular hobbed bolt, as they all vary in diameter.

OK... but settings for 'Metric Prusa Mendel with Wade extruder' are already included in Configuration.h.
Naturally, those setting will need to be adjusted if you are using 'non-standard' parts.
The settings I propose are just for a 'standard' Prusa that uses SAE parts instead of Metric parts.

My machine was built with SAE Prusa parts and XL drive belts I bought from Colin Farrer on EBay, electronics and motors from Ultimachine, hotend and Wades Extruder from MakerGear, hobbed bolt from eckertech, and 5/16-18 threaded rod from Home Depot.
As a newbie I would have appreciated having 'standard' settings in Configuration.h for this setup since it took me several weekends and many hours of Googling before I figured out how to properly calibrate my machine.
I had a difficult time until I figured out the proper settings for axis_steps_per_unit, then everything fell into place very nicely.

Since I bought all my parts from popular vendors and have no custom-made parts I would make the argument that this configuration is a 'standard' configuration that would be worth including in Configuration.h (or maybe in some file included in your distribution where folks can document the settings used for various builds).


best regards,
-ted

james glanville Wrote:
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> The reason these haven't been included are because
> they won't be the same as everyone. What
> pulleys/belts you use affects it, my prusa has
> >200 steps/mm for X and Y because I'm using tiny
> belts and pulleys. Also, you need to get the
> steps/mm for e for your particular hobbed bolt, as
> they all vary in diameter.

The calculation for Z steps per mm does not involve pulley/belts, so they can add it. On the flip side, the X and Y calculation for both SAE and M8 involve belt pitch and pully teeth values. If they have ballpark precalculation examples for M8 X and Y, why not SAE X and Y?

Bottom line, however, is that regardless of whether you use M8 or SAE hardware, your absolutly right that people needed take into account their specific specs for calculations per the forumlas. In addition to the forumulas, they also should check by measurement actual movement to ensure accuracy.

* The SAE prusa build is sort of a fork - the official/base build is metric so example values in firmware tend to be only for the metric version. I think that is why you do not and likely will not see SAE values in some of the firmware. Europeans also tend to look down on SAE as a standard (perhaps with good reason, but that's an off-topic matter - hey, the Brits still refer to how many stone a person weighs!).

I'm with you Ted about firmware including standard SAE values, but I don't see it happening. I am biased, however, because I also bought my threaded rods from Home Deport :-)

and i thought i had a high step count at 200 per mm! what kind of belts, pulleys, stepper motors, & microstepping is that? 1mm pitch?