A4988 driver help needed

I built my MP3DP out of spare parts I had from other projects. One key difference I have is I am using A4988 stepper drivers. I read through everything I could locate on the Ramps 1.4 and the A4988 drivers and all I did was get more confused. I made the edits to the firmware change from the DRV8825 to the A4988 but something is still not right. Do I still use all three jumpers or do I use less? Or can I make a change in Marlin to correct things? I am trying to print a small 3/4" end cap and the printer starts to print a MUCH larger circle

You should be using all three jumpers and only need to change the steps per mm in the firmware to half of what they currently are.

I’d recommend to go for 1/16th step, so only one jumper.

1/32th step doesn’t bring anything in terms of actual real life precision, lowers the torque and also lowers the possible speeds a lot. I used to have all my machines set to 1/32, but after I changed to 1/16th I don’t think I could ever go back.

Hey Dui, I think you have something mixed up, all three jumpers are 1/16th step with A4988 drivers :slight_smile:

[attachment file=77209]
A4988 is not capable of 1/32.

Unbenannt.png

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Oh, sorry, I thought you were having the DRV8825, my apologies!

I got mixed up, indeed

So if I change from

#define DEFAULT_AXIS_STEPS_PER_UNIT { 200, 200, 800, 200 }

to

#define DEFAULT_AXIS_STEPS_PER_UNIT { 100, 100, 400, 100 }

things should work?

Should, super easy to test, manually move it 10mm with repetier and make sure it moves 10mm. If it does not let us know exact what it moves.

You all are great! I was finally able to get back to the printer after getting all my Christmas lights going. I was able to get the printer and the quality is GREAT! The issue I am having is the steppers are noisy. They vibrate or buzz and I am wondering if this is caused by the vref not being set right on my a4988 drivers? Any suggestions?

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Set your drivers for 70-80 your steppers max amp rating and that will be about as quiet as they get. Some of the imports do buzz for some reason, it does not seem to a a functional problem but some are more noisy than others.

I have this set up, not quite finalized yet but getting close. The thing I noticed is the x axis vibrating a lot, making an annoying noise. I tested stuff and it’s definitively not coming from the steppers. Something is causing the horizontal steel rods to vibrate, it’s really annoying. If I apply some pressure on them with my hand, it cuts down the vibration by half. The 2 screws holding them in are as I tight as I dare them to be, don’t know what else I could do to minimize the sound.

J, I am unclear to what you are referring. It would be best to start a new thread and maybe add some pictures of what you built and what you are using.

I ended up increasing my vref to 1.0 and most of the vibration disappeared