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trouble adjusting E steps per mm

Posted by koenejet 
trouble adjusting E steps per mm
April 11, 2016 11:49PM
I need help again. So I replaced the clone extruder on my FolgerTech prusa i3 with a geared extruder using an e3d V6 (and not a clone either). I am very pleased with the new set up. Some of you may remember I had to water cool my old extruder or it wouldn't print any more than 4 hours.

Anyhow, I'm trying to set up the E steps per mm and I'm having much difficulty with this simple task. Doing the math tells me that I should put in about 900. So I started with that. I connected the printer to my computer, and using Repetier Host commanded to extrude 10mm. It extruded 18. I adjusted the steps down to 825 on the controller mounted to the printer (not configuration h), retried, and it extruded 12. Getting closer. But from that point on, no matter what I put in, it would always extrude about 14mm on the second run. For example: if I put in a low number like 700, it would extrude 5mm, but the next time it would extrude 14. Without changing anything. It seemed like no matter what I put in, it would always revert back to extruding 14mm.

So I though maybe I should use the configuration h file. The default was 90 (for direct drive), so I put in 900, saved it, uploaded it, and then re-commanded to extrude 10mm from Repetier Host, and it extruded about 14mm. I put in a smaller value, and it still extruded about 14mm.

After messing around with it forever, I got it to extrude 11.5mm. I said screw it, it's good enough for now. But obviously I'm doing something wrong. Now when I first set it up with the original extruder, I got it right at 10mm with no problems. Why is it giving me such a hard time now?

It seems like when I adjust it using the controller mounted to the printer, it tries to do it, but then reverts back to some other setting for the next command.

If anyone can point out what I may be doing wrong, I would greatly appreciate it.
Re: trouble adjusting E steps per mm
April 12, 2016 09:50AM
Sounds like you have eeprom enabled no longer use Marlin or repetier but you may have to flush the eeprom and reload it for your config.h to take effect sure someone will be along to tell you exactly how soon enough
Re: trouble adjusting E steps per mm
April 12, 2016 12:11PM
When i first got the machine, I set it up with no problems. I dont know when I could have changed any EEPROM settings. As far as I can remember Im doing it the same way I have in the past.

Just to clarify one thing though. When I change the steps per mm using the controller mounted to the printer, that does 'override' the value in the configuration h file, correct? So it shoukd work fine the way i'm doing it.? The only thing I dont like about that controller is that it does not let me run the extruder. I have to connect it to my computer and use Repetier host to drive the extruder.

Is it possible that Repetier host is telling it how many steps to move? Or does it not work that way? I dont think it does, but if so that may explain it.

Thanks again for any input.
Re: trouble adjusting E steps per mm
April 12, 2016 01:17PM
If you saved anything to eeprom, it will persist even when flashing fresh firmware to the board. I found this out the hardway. I disabled eeprom as it's just as easy to just change the settings in Configuration.h and re-flash and not worry about stale settings getting in the way.
Re: trouble adjusting E steps per mm
April 12, 2016 05:27PM
Not an expert, but I think the way it works is you have the values hardcoded in your firmware, that are overwritten by the settings in your EEPROM (if enabled), which are overwritten by your printers "RAM". When you turn on your printer board, the settings from your firmware or the EEPROM are copied over to the printers "RAM". Any changes you make to the printer through g-code commands or the LCD panel are stored in "RAM" and lost if the board loses power or is reset. If EEPROM is enabled, you can save the "RAM" settings to EEPROM, reload the settings from EEPROM, or reload the settings from the firmware using the M500 to M503 commands.

Most people disable EEPROM while configuring / calibrating their printer because they will make changes to their configuration.h files but then they have no effect after reflashing the firmware because the printer "RAM" defaults to the EEPROM settings if enabled.

I am a little lost reading your OP however. Are you using 900 steps per mm for your extruder or 90? Are you extruding 100mm of filament or 10mm (and getting 14mm)?

EDIT: Can you link your configuration.h file as an attachment so we can take a quick peak at your settings?

Edited 1 time(s). Last edit at 04/12/2016 05:28PM by Kurzaa.
Re: trouble adjusting E steps per mm
April 12, 2016 08:44PM
Maybe I should have started out by stating that I am a little bit computer challenged. I may not be using the correct wording when describing my problem. I'll try to clarify.

Since I changed from a direct drive extruder to a geared extruder, I have to change the steps per mm. I'm using Repetier host manual controls to command a 10mm extrusion. I measure how much it extruded, and I get about 14mm. I use the SD card controller mounted on my printer to adjust it (I started out with 900 steps per mm), and then re-command a 10mm extrusion.

Here is the problem. A value of 900 gave me (originally 18mm, now it gives me 14mm), so I changed the number to 800. It then extruded about 5mm, but when I immediately re-commanded another 10mm, it then extruded 14mm. So any change I make will affect the first try, but then on the next try, it reverts back to 14mm.

I was under the impression that in order to use the add-on SD controller, EEPROM had to be enabled. When I installed it, I was following instructions I found online, and I believe that one of the steps was to enable the EEPROM. If I disable it, won't that kill the controller?

Also, (and this question has been bugging me for a while), All of the steps per mm for all of the axis's that I adjusted using the add-on controller, are different from what is in the configuration h file, because I fine tuned it using the controller and not the computer (many months ago). If I under stand Kurzaa correctly, basically whatever I put into the add-on controller will override what ever is from the configuration h file?

Or maybe let's try a different approach. Forget all my problems. Pretend I just came here stating "I have a Reprap Prusa i3, with an add-on controller, and I need to adjust the extruder steps per mm, because it's pushing out too much filament. Can someone tell me step by step how to do it." Because I'm sure I'm just missing a step, or doing something wrong.

I was able to do this last year with no problems and I really don't think I changed anything that would affect it now. I'm also not positive the best way to copy my configuration h file to here.

I'll keep playing with it, but any other ideas would be good.
Thanks again for all the input.
Re: trouble adjusting E steps per mm
April 13, 2016 07:07AM
It might help to know which Firmware you are useing as they behave slightly differently if you Have Repetier FW then you can adjust the EEPROM Setting's from within RepHost (I can't remember how now as I haven't used in in over 12 months)

Re: trouble adjusting E steps per mm
April 13, 2016 08:04AM
I am using Repetier. I actually did stumble across the page last night within Repetier that allows me to do just as you said.

After much trial and error, I got it to extrude fairly close to the correct amount. I'll do a print tonight and see how it looks.

Thanks again for everyone's input.
Re: trouble adjusting E steps per mm
April 13, 2016 08:10AM
One other thing. My next project is to replace the z axis end stop with an optical stop. I will need to invert the end stops input. I think I have an idea of how to do it, but if someone could tell me specifically how, so I don't screw something up, would be great.

Thanks again
Re: trouble adjusting E steps per mm
April 13, 2016 08:16AM
I don't know about Repetier, but the later versions of Marlin (I'm using 1.1.0_RC3) have a double-home functionality which is nice. It homes the axis, then backs off and homes it again at a much lower speed. I've found that this eliminates any over/under homing that I was experiencing with the prior firmware. I bought an optical stop for my Z axis, but while waiting for it to arrive, I updated the firmware and so never installed it.
Re: trouble adjusting E steps per mm
April 13, 2016 12:21PM
For me, I don't really care much about exact accuracy for x and y home. If it stops in the corner, it's close enough to home for me. I have noticed though, that with the mechanical end stop, the z home isn't perfectly the same every time and I find myself leveling the bed more often than I should have to. I read that this is a common problem, and an optical end stop would be better.

The parts I will be printing tonight are an adjustable target, and a mount for the stop. Once that's done and installed, I just need to invert the signal.

I got three of the optical units, but until I need to print a part that reaches the edge of the glass, I'm not going to worry about x and y home. (Actually, I did have to print a part a while ago that was touching both ends of the x axis and one end of the y, with no problems.)

So again, if any one has info on inverting end stop signals, I would appreciate it.

Thanks again all,
Re: trouble adjusting E steps per mm
April 16, 2016 10:20PM
Well I got it printing pretty good now. I basically just multiplied the gear ratio by the original steps per mm of the direct drive unit and came up with 440 (way off from the 900 I originally tried), put that into the smart controller and printed a part. It came out almost perfect.

And, just in case anybody needs to know: If you install an optical endstop, you will need to go into the configuration h file and change the axis endstop inversion from 'true' to 'false'. That's the only change needed. I only did the z axis for now, and it works great. I never did like the mechanical one for the z axis.

Anyway, hope this helps someone.

Oh and by the way, the new geared extruder I'm using is the Toranado I downloaded from thingiverse. This thing is a work of art. It took a little bit of effort from start to finish to get going, (my issues, not the design of the extruder), but I just got to say that the guys who designed this did an awesome job. I highly recommend it to anyone looking into making a geared extruder. And if you are going to go to the trouble to build this, buy a real e3d v6. Don't put a clone of anything on this work of art, and you will be happy with it.

thanks again,
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