Low Steps Per mm - Cause, effect, solution?

Hello All,

I am building my own 3D Printer - Graber i3. I have followed all the necessary steps to configure the Marline firmware.

I am using the Ramps 1.4 controller board and the A4988 driver. The stepper motor I am using for X, Y and Z axis has 1.8-degree step angle.

I have used the Pursa Calculator to calculate the steps for X, Y, and Z axis - 80, 80, 1600 based on the GT2 pully-belt and 2mm threaded rod - screw system.

ISSUE:

* When I am using the calculated steps for the X, Y and Z axis I am observing higher movement (i.e 10-15 mm when I want to move 1mm)
* I have calibrated the movement by reducing down the calculated steps -
now the new steps are X=6.5, Y= 6.5 and Z = 26.66

1. My question is why I am getting such a lower steps per axis?
2. How can I get more accurate movement without skipping/slipping of the motor?

Please help

Thank you

Kunal

It sounds as though you don't have the microstepping jumpers fitted underneath the drivers.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

GT2 timing belt and pulleys should give you values near the 90 steps/mm point with motors that are 200 steps/revolution, and 16X microstepping.

As stated above, check that there are jumpers under the stepper motor drivers on your RAMPS board. Under each A4988 there will be a group of 3 jumpers. If they are all closed (Jumpers present) then you should have 16X microstepping, which will give you the kind of resolution that you're looking for.