Hello All, I am new here and new to 3D Printing I acquired a QU-BD Two Up Budget Printer from a friend and it was missing a few parts. I was able to get all the missing parts except the exact same lead screw for the z axis. I purchased a Drillpro 400mm 8mm 2mm Pitch lead screw. I am assuming I need to change the steps per mm in the firmware. I am wanting to double check that I am doing the correct thing.
I have nema 17 stepper motors so I thinks with my research I use the formula below to figure the correct steps. My stepper board is set at 1/16 microstepping.
(200 * 16) / 2 = 1600Then I can flash this via the eeprom settings in reperter host. Right now the marlin firmware has 1511.81 in the z axis and what I am running into is that the z is raising to much per step of the z.
I hope that my thinking is correct by going to 1600 that the movement of the z will actually be less.
Hi,
Your calculation seems correct.
Here is an online calculator just for reference: http://prusaprinters.org/calculator/#stepspermmlead
In the EEPROM send the command M92 Z1600 then save it with a M500 command (are you sure the eeprom is switched on in the firmware?). Then just power cycle the machine and check again with M501 command if the printer is accepted it.
After this just move the Z axis by 100mm and measure it with a ruler or caliper. If the move was not correct just dive the 100mm with the measured move value, and multiply the step/mm value.
So if you move the Z axis by 100mm but is moves 123mm the calculation is the following: 100/123 = 0.813 (requested / measured value) then
1600 step/mm X 0.813 = 1300.813 step/mm.
This calculation also applies to the extruder calibration, so I highly recommend to check that also with a 100mm value. (To allow the extruder motor move without heating up the hotend just send m302 command, make sure the filament is removed from the hotend to not damage it )
Regards,
Tamas
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Great that is the information I was needing. I believe eeprom is enabled but I will double check.
Hope it helps 
Do you have the original arduino firmware for the printer, witch you can open and edit in the Arduino IDE?
T.
Yes I do and I did not have the eeprom enabled so I just did enabled it and ran a test. 1600 it is not the correct setting. I can not find my calibers I will have to look in the morning and do a manual measurement. thanks for the help.
Adam
Ok, you can use a ruler also. Just for a hint a 8mm lead screws usually have 1.25mm pitch so 2560 steps/mm.
But with a ruler also you can get quite a good measurement if using 100mm travel.
If found the correct setting please modify it also in the firmware:
In Marlin just look for this around line 680 : the numbers are X Y Z E (extruder).
#define DEFAULT_AXIS_STEPS_PER_UNIT {200,200,640,155}
Then upload and check the EEPROM Z steps settings also again.
T.
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Thanks for the additional information with my calipers I was able to get it worked out and changed in the frimware now I have exactly 1mm movements on the z.
Great!
What was the correct steps/mm setting?
T.
