Steps Per MM Adjustment Assistance Required

[spencyg]

Good afternoon internet people.

I just purchased my first FFF printer, a Wanhao duplicator 4S. Initial impressions of the hardware is pretty good. I have run into a couple typical Chinese hardware issues which I'm resolving with the manufacturer, but overall it is pretty good. I am running the latest release of Simplify3D and upgraded my firmware to the latest Sailfish through ReplicatorG 40R30. The prints look very good, most likely due to the seemingly high quality of the S3D code output. One issue I am having which seems to come up on the web frequently without a thorough explanation is how to set Steps Per MM for my Cartesian axis? I have been into the firmware settings within both RepG as well as S3D, and it is clear that this is NOT how you actually change the hard settings of steps per MM within the hardware. I came across some reference to GPX this and .ini that....none of it makes a whole lot of sense, and there doesn't seem to be enough documentation out there to actually self-teach some of these more complicated settings. I require the very best dimensional accuracy possible out of this printer as I'll be using it for prototyping machine/product parts which must precisely mate with each other. It is clear that some tuning is required, but no clear path to accomplish said tuning.

I am currently printing a 25mm cube with all faces coming in at around 24.65-24.7. I have done this same print multiple times with the same result each time. The print material is PLA, and I'm printing on a heated glass bed. Any assistance getting to the information precisely explaining the axis steps calibration process would be greatly appreciated.

SG

[JoeJ]

You should do a search for "steps per mm". There are MANY topics that answer this already. For example, they just posted a tip of the week about it (http://forum.simplify3d.com/viewtopic.php?f=8&t=1937)

[KeyboardWarrior]

Good afternoon internet people.

I just purchased my first FFF printer, a Wanhao duplicator 4S. Initial impressions of the hardware is pretty good. I have run into a couple typical Chinese hardware issues which I'm resolving with the manufacturer, but overall it is pretty good. I am running the latest release of Simplify3D and upgraded my firmware to the latest Sailfish through ReplicatorG 40R30. The prints look very good, most likely due to the seemingly high quality of the S3D code output. One issue I am having which seems to come up on the web frequently without a thorough explanation is how to set Steps Per MM for my Cartesian axis? I have been into the firmware settings within both RepG as well as S3D, and it is clear that this is NOT how you actually change the hard settings of steps per MM within the hardware. I came across some reference to GPX this and .ini that....none of it makes a whole lot of sense, and there doesn't seem to be enough documentation out there to actually self-teach some of these more complicated settings. I require the very best dimensional accuracy possible out of this printer as I'll be using it for prototyping machine/product parts which must precisely mate with each other. It is clear that some tuning is required, but no clear path to accomplish said tuning.

I am currently printing a 25mm cube with all faces coming in at around 24.65-24.7. I have done this same print multiple times with the same result each time. The print material is PLA, and I'm printing on a heated glass bed. Any assistance getting to the information precisely explaining the axis steps calibration process would be greatly appreciated.

SG

You could use the horizontal size compensation if your tolerances are off by a fixed value. If you print a 50 mm cube, does it come out .3 mm small or does it double to .6 mm small. If it's .6 mm, then I'd recommend steps per mm, however if it's still only .3 mm off, then that means you are off by a fixed value.

http://forum.simplify3d.com/viewtopic.php?f=8&t=2042

[BaronWilliams]

This is a useful feature to add.

All of the printers that I've used so far are off to some degree on the X, Y, and Z axis. Each printer I used has an inaccuracy that's unique and consistent to it on each axis. Ranges of inaccuracies I've seen are from about 0.05-1.05%. That's a lot when the object you're printing is large.

For example, one MakerBot Replicator 2 I use shows these inaccuracies

Y axis print size 99.775280898876%
Z axis print size 98.95855382922%
X axis print size 99.832813315301%

I would like to see these steps per mm adjustment profiles values stored by printer name (i.e., "MakerBot 2X on Floor 1", "MakerBot 2X in Lab B", etc.) rather than stored in a process or factory file. For example, two MakerBot Replicator machines I have used have slightly different inaccuracies from each other. This is probably because they have slightly different stepper motors in them. FlashForge printers also have these kinds of issues where an older version of a specific printer will have slightly different parts than a newer version of the same printer, and so the inaccuracies do not match.

Currently, if I need a completely accurate size from a specific physical printer, I have to scale the X, Y, and Z axis values according to the inaccuracies found for that specific psychical printer I'm currently printing on. I can't rely on all printers of a certain model to have the same inaccuracies. This means I need to keep inaccuracy notes for every single physical printer I use and scale the job before making the G-code. I also need to make sure I don't accidentally save the factory file after making the size adjusted G-code, or the adjustments become part of the models, and I can't revert back without reloading the STL models.

[AndersE]

Better to do a real firmware calibration..

new steps/mm = (expected move length/actual move length) * old steps/mm

Just print a known calibration cube ( as big as possible) and measure with a caliper.

if firmware settings is for example 50 steps/mm and a 100mm cube is measured 98mm:

100/98*50=51.02

The new firmware setting should be 51 instead of 50step/mm.

Then redo the same procedure until you get as close as you need.
Do it for all axes.

[spencyg]

You should do a search for "steps per mm". There are MANY topics that answer this already. For example, they just posted a tip of the week about it (http://forum.simplify3d.com/viewtopic.php?f=8&t=1937)

Believe me...I have done LOTS of searches and still I'm left confused. The answer to all of these topics is "do a custom GPX file", which I know nothing about. Then I do a search for custom GPX file and get nothing. Basically, people are answering these questions with a level of assumption that those reading it are already super-users. I'd like to see a STEP BY STEP on doing the GPX file modifications for sailfish, right from opening it up to modifying it, to updating the physical machine with the new settings. If there is something like this level of explanation already out there, I would love to be directed to it.

I have not attempted to print a 50x50x50 to see if the consistent 1.25% error I have been experiencing. I'll try that tonight. I have played around with extruder parameters which has helped with some surface finish stuff but not with my dimensional tolerances. It seems I'm somewhere around 1% error in the X axis, and 1.25% error in the Y axis. I have constructed many CNC machines using Mach3 software, and steps per unit are always requiring very specific tuning beyond what the mathematical "ideal" steps per unit would suggest. This is also using ballscrews which are far more precise than Chinese timing belts and cast timing pulleys.

SG

[JoeJ]

http://forum.simplify3d.com/viewtopic.p ... +gpx#p5991

[BaronWilliams]

Better to do a real firmware calibration..

If you have this option in your printer's firmware, good for you. You can set it there and you're all done.

However, not all printers have such settings in their firmware that the user can change, otherwise we wouldn't be requesting it in Simplify3D. Some of the printers I use support this in the firmware, others do not.

[spencyg]

So I've got the GPX file working with a custom .ini file. Unfortunately, modifications to the .ini settings for steps per mm don't seem to effect my print. I disabled the default create .x3g setting in S3D and put the correct file path in the additional terminal commands box.

This line is exactly what I've got:

c:\S3DGPX\gpx -p -m r1d "[output_filepath]"

It creates an x3g file in the same directory as the gcode file is being directed towards. The x3g file runs on my printer, but the settings don't seen to effect anything. I'm running the latest sailfish and version 2.2.2 for S3D. This is driving me insane.

SG

[spencyg]

Oh, and the .ini file is basically a copy from the link above. The gpx executable and ini file are in their own folder on the harddrive. It didn't work at all with the gpx executable in the S3D folder, presumably due to path character size limitations.

SG