New installation of Arduino won't allow change of default 'steps per unit'

Hello Everyone,
After my recent post I have been able to reinstall my old RAMPS board and uploaded Arduino /Marlin and everything looked fine until I tried to alter the ' DEFAULT_AXIS_STEPS_PER_UNIT ' values.

It seems that nothing I put into the Config h tab makes any difference to the actual movement of the X, Y and Z axes.
I am using 0.9 degree steppers with 2mm x 20 teeth pulleys. The IDE version is 1.6.7

I even uncommented the
'(XYZ_FULL_STEPS_PER_ROTATION * XYZ_MICROSTEPS / double(XYZ_BELT_PITCH) / double(XYZ_PULLEY_TEETH)' to see if it made any difference. Nope.

and I substituted it with:
XYZ_STEPS (400*16/4/40)

I have tried using different iterations of Arduino because I understand there are many minor differences which may be untraceable by newbies.

Here is the relevant section I am trying to get working.

// default settings

#define XYZ_BELT_PITCH 2

#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,100,80}
#define DEFAULT_MAX_FEEDRATE {50,50,50,50} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {3000,3000,3000,100} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

#define DEFAULT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 3000 // X, Y, Z and E max acceleration in mm/s^2 for retracts

I suspect I'm missing a basic step somewhere but I have no idea what it might be. Searching the forum has not brought this problem to my notice so any suggestions would be really appreciated.

Still puzzling my way back to operation :o


After you modified the value of DEFAULT_AXIS_STEPS_PER_UNIT, did you successfully upload Marlin to your RAMPS board again?

Hello Per and Everyone,
Yes, I successfully uploaded the Arduino sketch, with its now-visible white and red text ending in 'Thank You' (how polite!) and I then connect to my printer using Pronterface. All seems well.

I press the 'Home button and all three axes home perfectly.
They respond to my changes on 'Homing Feedrate' so this tells me that it's basically working fine.
Heaters and Fans and Extruders all work well.
My Motherboard is set as 33.

As for the Feedrate resultant, using the numbers in the first post we have:

When I put G1Z200 into the Pronterface 'send' window the effector moves from Home at approx. 245mm to 197mm.
When I put in 'G1Z150' into the Pronterface 'send' widow it runs from Home at about 245mm down to 172 mm.
When I put 'G1Z100', the effector travels from about 245mm above the bed to about 146 mm above the bed.
When I change to 'G1Z0' it goes to about 98mm above the bed.

To summarise:
Home = approx 245 mm above the bed.
Z250=220 above the bed
Z200=197. = 23
Z150=172. = 25
Z100=146. = 26
Z50 =122 = 24
Z0 = 98 = 24
Z-50 = 72 = 26

This is pretty good linearity, considering some parallax in my viewing of the ruler. It's roughly half the 'dialled in' amount one would expect prior to fine tuning the X, Y, Z Steps per Unit values. Of course this is useless if it cannot be changed at all.

I then changed just one number to test the upload. I disconnected from Pronterface and re-uploaded as follows;
I altered the #define 'XYZ_FULL_STEPS_PER_ROTATION 400' from 400 to 200, which would be normal for most steppers which are 1.8 degree units. I would expect the X,Y and Z motors to run at a different rate.

I reconnected to Pronterface. entered G1Z50 and the result was unchanged at 122mm above the bed.
This is the mystery!

I changed the Homing Feedrate again and it alters accordingly, i.e. 8060mm/min homes twice as fast as 4060mm/min. just as it should.

I am trying different versions of Arduino / Marlin 1.1 but no solution has appeared. I was thinking I may have made a bad change to a bracket or some other part of the text, but it all looks fine to me.

One thing I find strange is that I still never see the Arduino.ino symbol in Marlin, as it's shown in all the setup videos I've watched.
All I see is a 'File window' symbol and a lot of Adobe style symbols on the left hand side of the open folder. On checking the 'Properties' of the Marlin folder it clearly states it is a .ino file and my new computer settings has Arduino as the default program for .ino files. They seem to open and run but maybe there's a glitch in there somewhere.
Just desperately guessing.

I'll keep on trawling through all the options...

Thanks for your patience.


Hello Per and Everyone,
Not sure if My 'thank you' managed to get back to Per but your advice was exactly what I needed. I uncommented the EEPROM line which was preventing the required changes to upload and I have my printer up and running, all freshly calibrated and printing as before.

Many thanks for your kind help and for taking the time to put me on the right track.


Just in case it will be helpful to anyone else, here's the other thread where we resolved this issue:

I'm very glad to hear my advice was helpful.

I uncommented the EEPROM line which was preventing the required changes to upload and I have my printer up and running, all freshly calibrated and printing as before.

Do you mean that you commented Configuration.h, line 494 so that EEPROM_SETTINGS was not defined?