WolfStrap, Unable to get motors to move

Hello, I have spent the past year building a WolfStrap model 3D printer using threaded rods and captive nuts to drive the axes. The control board I am using is the RAMPS 1.4 board, with Repetier Host, and Marlin firmware. The drive motors are standard NEMA 17 motors driven with the DRV8825 motor drivers. I do not own an LCD for this printer. Upon issuing a command to the motors, they produce a sound that is either buzzing or sounds like the motor is skipping. The things that I have tested are as follows:

- Made sure my endstops work and are correctly configured
- My power supply outputs 12.65 volts and I believe that this is still in the safe range
- My hotend heats up and my thermistor gives back a proper temperature reading
- Tested a second RAMPS board
- Tested multiple types of motors
- Tried running the motors with no load and they did not move
- Ran both the Marlin and Repetier framework on my printer
- Ran the RAMPS test firmware with the same motor issues
- I can move the motors with a separate motor driver and arduino
- My RAMPS board has all 3 jumpers inputted into it
- I spent an hour or two reading and editing the configurations.h file

Edited 2 time(s). Last edit at 11/08/2018 01:47PM by StormZillaa.

Buzzing motors meant hat the motor doesn't have enough power to move. You may need to set the current on the A4988 stepper drivers. Information can be found here: [www.pololu.com]

You will need to check the specifications for the motors that you are using. For 12V operation, it's probably best that they have less than 30 ohms/phase. you should also make sure that you have the phases wired correctly, but if they run with no load, this is probably okay.

Next check that the axes move fairly easily, and that there is not excess drag. It sounds like you are using threaded rod or lead screws to move the axes. This places fairly high speed requirements on the motors, which might cause issues if you are trying to move or accelerate too quickly. I am using T8*8 leadscrews on my printer, and this means that I need high current, and I'm running my printer from a 24V supply to make sure that I can do it. If you are using regular threaded rod, your printer is only going to be capable of slow movement. This is particularly true with a 12V supply and a RAMPS 1.4 controller.

Though my printer is lead screw based, this is not the normally recommended method of driving your axes. Maybe for Z movement, but for X and Y movement, most people use a belt drive in order to achieve higher speeds at lower motor RPM.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

I made a typo in my original post, I had meant to say that the motors would not move without any load on them as well. I also posted the wrong motor drivers because I'm terrible at reading which kind I ordered vs which kind I had initially thought about purchasing.

Edited 1 time(s). Last edit at 11/08/2018 01:48PM by StormZillaa.

This is pretty common if you are scratch building. There is no standard wiring of stepper motors, no standard colors, nothing. If you are first firing up a printer where you bought parts without a kit, then your wires are wrong.

Look on your RAMPS board at the stepper connectors. You should see "2B 2A 1A 1B" above the pins of the connectors on the board. These define the windings 1 and 2.
Dig out your DVM and set it to measure resistance (use the 100 ohm range). Use the meter to find the two windings. when you have two wires that go to the same winding, you will register (usually) around 5-10 ohms, some steppers measure higher. Attach one pair to the "2B 2A" and the other pair to the "1A 1B". Do this for all the steppers the exact same way so that they will all work the same. Set your mechanics to about the middle so you have room to move each way. Put your finger on the reset button of the board so you can stop it all when they go the wrong way. Now issue G28 (home) to the board, stuff will start moving. Because you are guessing which pair to put where, your steppers will all either go the direction you expect, or they will all go the opposite direction. If they move in reverse you can mod your firmware to swap directions or simply swap the order of one of the windings.

WARNING WARNING WARNING Make sure that your endstops are correct before you home. Use the gcode M119 (report end stops) to see what is going on there and when you home they will stop.

That should do it. After this you will want to tune the winding current on your drivers, but you need to get the steppers moving before you do that.

have fun,
DLC

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Kits: Folgertech Kossel 2020 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head, TronXY X5SA Pro(E3DHemera).
Scratch: Maker-Beam XL Micro Delta, 220x220CoreXY.
Actually bought: Bambu Labs X1 Carbon