New stepper drivers messing up print scale Hey guys (and girls?) I recently replaced the DRV A4988 stepper drivers on the x and y axes of my printer (sort of a prusa i3 running on ramps) with DRV8825 drivers. I put them the right way around and all, but now if I tell either of those axes to move say 50 mm, then it only moves 25 mm. I haven't changed any of the firmware settings . . . I have all 3 jumpers under each driver so it should be running with 1/16 micro stepping right? Do I need to change micro stepping or steps per unit settings? Any help would be appreciated. Thanks Dan https://reprap.org/forum/read.php?4,841878,841878#msg-841878 Sun, 12 Apr 2026 15:15:24 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,841878,841942#msg-841942 Re: New stepper drivers messing up print scale https://reprap.org/forum/read.php?4,841878,841942#msg-841942 calculate Vref

I_TripMax = Vref × 2 
or 
Vref = I_TripMax / 2
]]> o_lampe Reprappers Wed, 19 Dec 2018 23:09:09 -0500 https://reprap.org/forum/read.php?4,841878,841941#msg-841941 Re: New stepper drivers messing up print scale https://reprap.org/forum/read.php?4,841878,841941#msg-841941
I tried doubling the steps per unit and was struggling to find a balance between the motors getting really hot (current too high?) and the motors losing synchronization when I decreased the voltage on the trim pot. Do the motors tend to run hotter at 1/32 micro stepping, or are the DRV8825 drivers just harder to tune than the A4988 ones?]]> GingerNinja Reprappers Wed, 19 Dec 2018 22:59:55 -0500 https://reprap.org/forum/read.php?4,841878,841936#msg-841936 Re: New stepper drivers messing up print scale https://reprap.org/forum/read.php?4,841878,841936#msg-841936
Micro stepping jumpers for DRV8825 (Jumper on == High)

]]> Dust Reprappers Wed, 19 Dec 2018 18:38:38 -0500 https://reprap.org/forum/read.php?4,841878,841903#msg-841903 Re: New stepper drivers messing up print scale https://reprap.org/forum/read.php?4,841878,841903#msg-841903
Are you aware of the low speed step-skipping problem with the DRV8825s?]]> the_digital_dentist Reprappers Wed, 19 Dec 2018 10:25:25 -0500 https://reprap.org/forum/read.php?4,841878,841900#msg-841900 Re: New stepper drivers messing up print scale https://reprap.org/forum/read.php?4,841878,841900#msg-841900 So in that case I double the steps per unit for the X and Y axes right? Or keep it as 1/16 and remove a jumper?]]> GingerNinja Reprappers Wed, 19 Dec 2018 10:21:11 -0500 https://reprap.org/forum/read.php?4,841878,841899#msg-841899 Re: New stepper drivers messing up print scale https://reprap.org/forum/read.php?4,841878,841899#msg-841899 obewan Reprappers Wed, 19 Dec 2018 09:55:10 -0500 https://reprap.org/forum/read.php?4,841878,841881#msg-841881 Re: New stepper drivers messing up print scale https://reprap.org/forum/read.php?4,841878,841881#msg-841881
* Specify Stepper Driver types
* The options are used to determine driver pulse timings as well as more advanced functionality.
* Stepper timing options can be overridden in Configuration_adv.h
*
* Options: A4988, DRV8825, LV8729, L6470, TB6560, TB6600, TMC2100,
* TMC2130, TMC2130_STANDALONE, TMC2208, TMC2208_STANDALONE,
* TMC26X, TMC26X_STANDALONE, TMC2660, TMC2660_STANDALONE,
* TMC5130, TMC5130_STANDALONE]]> Roberts_Clif Reprappers Wed, 19 Dec 2018 08:18:08 -0500 https://reprap.org/forum/read.php?4,841878,841878#msg-841878 New stepper drivers messing up print scale https://reprap.org/forum/read.php?4,841878,841878#msg-841878 I recently replaced the DRV A4988 stepper drivers on the x and y axes of my printer (sort of a prusa i3 running on ramps) with DRV8825 drivers. I put them the right way around and all, but now if I tell either of those axes to move say 50 mm, then it only moves 25 mm. I haven't changed any of the firmware settings . . .
I have all 3 jumpers under each driver so it should be running with 1/16 micro stepping right?
Do I need to change micro stepping or steps per unit settings?
Any help would be appreciated.

Thanks
Dan]]> GingerNinja Reprappers Wed, 19 Dec 2018 08:01:30 -0500