Making a printing using a scara arm concept

Dear users of this forum and tech wizards,

I am currently doing a project where I am making use of a SCARA arm in combination with an airbrush to create a regular printer. During this project I am making use of the following youtube videos as a guide:
[www.youtube.com] (end product will use an airbrush instead of laser module)
[www.youtube.com] (same ish project but making use of different control module)

The person in the video is driving nema 17 motors using an Arduino UNO + CNC shield V3 in combination with a4988 stepper drivers (or arduino mega + ramps board depending on the video). However for my project I would like to use 2 nema 23 stepper motors (24V DC 2A) (103H7123-5740) instead.

Now this is where my problem starts to take shape. When trying to control both nema 23 stepper motors (or for that matter 1) the steppers make A LOT of noise (The noise isn't a problem for this project) and the stepper driver modules (a4988) start heating up. When trying to run the motors the output torque is nowhere near where it should be and after 5 seconds or so the steppers stop running.

Things I have done to trouble shoot are:
- Set currentlimit to the correct value on each driver
- Test if the Stepper motors are broken (they aren't)

Now what I think is going on is that the current stepper drivers are just unable to handle the current needed to run the motors and as a result they heat up and the thermal switch turns the drivers off.

Now my question is, do you think I would get an improvement if I were to use the Arduino UNO + CNC shield V3 in combination with drv8825 drivers or should I move away from the CNC shield?

The reason I am using the shield is simply for the reason that I would like to change a minimal amount of code to make my system run and that would mean having to operate it from an Arduino UNO. I hope I summed up my problem and question clearly enough and that some of you may be able to help me. Thank you in advance!!!

P.S. Sorry if this question is posted in the wrong forum please (re)move it if that is the case.

... you'll best select proper drivers (and motors) -- you can easily control external (comercial) stepper-drivers - simply wire STEP+DIR+GND to the corresponding pins of the external driver ... I'm doing this regularly with "much beefier" steppers - up to 2Nm and up to 5:1 gearing

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Check your exact model, there are AC versions as well as DC for that motor.

[products.sanyodenki.com]

You might find RAMPs and an Arduino Mega has greater redundancy for blown up channels.

Viktor is quite right, the A4998 is a little spartan for that load. Beefier drivers with heatsinks and active cooling fan recommended.

Also, what's the rating of your power supply?

Checked the step value on the hardware matches the software? (Better drivers can give finer steps reducing noise)

Power supply of at least 6 amps @ 24V. More means it will run cooler.

(The motors can draw more than 2A, they do have multiple coils).

Having excess current available does no harm if it isn't drawn by a load, but not having enough (or pushing a marginal supply too hard) will not help make the thing move smoothly.

I don't know what the current / power limit of the shield is. I also don't know how thick your connecting wires are to the motors, or how long they are (this can impact drastically too).

For sure you need cooling on those drivers. My mini mill uses NEMA 23 motors (specs same as yours, not sure if same brand) with a4988 drivers. I have small heatsinks stuck to the driver chips, which get quite hot in ambient air, but with a 4010 fan blowing on them they stay nice and cool. I'm running on 12V, but I'm not sure if that matters since the drivers regulate the current. The sound of the steppers is about the same as my old Creality CR-10, not unpleasantly loud. Drowned out by the cutter noise most of the time.

... in one setup I'm using RAPS128 drivers with current set to around 1.2Amps and NEMA-23 steppers with 2Amps max coil current - the drivers gets a bit more than 30degC, the motors stay cold ... but enough power to move even heavy loads "fast enough" - here a video from testing a paste-dispenser-prototype (belts in XY, spindle in Z):

[www.youtube.com]


One of my next designs is a "parallel SCARA" - attached the "driving" base with 4 NEMA-23-steppers (2x Z-move and rotate), waiting on the joint arms, I have to design and mill ...

Edited 1 time(s). Last edit at 12/17/2021 03:31AM by VDX.

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]