<p>As alluded to in <a href="https://3dprinting.stackexchange.com/questions/23182/using-dual-y-stepper-drivers-on-marlin-ramps-1-4#comment41779_23182">this comment</a>, under the question, <a href="https://3dprinting.stackexchange.com/q/23182/4762">Using dual Y stepper drivers on Marlin / RAMPS 1.4</a>, there is a concept of an A4988 &quot;twinner&quot;:</p>
<blockquote>
<p>I am rather building an A4988 &quot;twinner&quot;</p>
</blockquote>
<p>The question itself also mentions:</p>
<blockquote>
<p>... add-on nanocard hosting a couple of twin A4988 drivers</p>
</blockquote>
<p>Can anyone explain what this is, and/or how it works? Are there any schematics, design guides, PCB board designs that can be used, or pre-built versions available?</p>

CC BY-SA 4.0
2024-04-08T08:27:11.337Z
Surely it's just driving the steppers in series (like you're supposed to when driving multiple steppers on a single driver)? Though from what he wrote ("not daring to drive both with one") maybe he's mirroring the EN, DIR, STEP pins to a second driver.
towe
CC BY-SA 4.0
2024-04-08T08:40:52.727Z
@towe - In series? That's interesting. I had assumed in parallel. After a quick google I found : *A series connection provides a high inductance and therefore greater torque at low speeds. A parallel connection will lower the inductance which results in increased torque at faster speeds.* So is in series preferable? However, it is the drivers that are doubled up, not the steppers (Quote from the question: `add-on nanocard hosting a couple of twin A4988 drivers`) I presume that the stepper drivers themselves would need to be in parallel (for electrically/electronically logical reasons).
Greenonline
CC BY-SA 4.0
2024-04-08T11:03:24.927Z
Usually driving two steppers with one driver is done for controlling dual Z axis steppers would have to stay in sync to prevent the bed from tilting - though the same would apply on a Y axis I suppose. Connecting the steppers in series ensures that they both have the same current applied through their coils are are being driven at equal strength -> less risk of one side losing steps while the other doesn't. The downside is the higher inductance, i.e. at the same drive voltage, you'll need to drive the coils longer to reach the set current, which reduces the potential top speed of the stepper.
towe
CC BY-SA 4.0
2024-04-08T11:07:03.760Z
That's not much of an issue on the (always-slow) Z-axis, but could be an issue for Y. Results of driving steppers in parallel depends on how well matched their inductances (and loads) are. The overall inductance is reduced, which means you're now limited by the current the driver can produce w.r.t. speed and torque. Since an A4988 is already pretty weak compared to what most NEMA17s can handle, I don't see much advantage to parallel connections.
towe
CC BY-SA 4.0
2024-04-08T11:09:18.720Z
Actually putting the drivers in parallel... uhhh. I assume for sharing current requirements between both? Not sure how well you'd be able to synchronize them when microstepping and how they would handle that at all. It'd be much more reasonable to just use a more powerful driver (i.e. TMC5160 or external ones) than that.
towe
CC BY-SA 4.0
2024-04-10T00:03:38.913Z
As someone running an AWD delta with pairs of motors on shared drivers, you absolutely want them in parallel, not series. Running them series is effectively halving the voltage and thereby the max speed before pullout. Running them in parallel halves the available current, but modern drivers support much more current than your motors will use, while nothing has as much voltage as you'd like. Mine are each running at 650 mA on a driver putting out 1.3A that can handle a max of 3A, with 48V.
R.. GitHub STOP HELPING ICE
<diy-3d-printer><stepper-driver><ramps>
What is an A4988 "twinner"?
Greenonline
# What is an A4988 "twinner"?

(Asked by: username_0 on 2024-04-05)

As alluded to in [this comment](https://3dprinting.stackexchange.com/questions/23182/using-dual-y-stepper-drivers-on-marlin-ramps-1-4#comment41779_23182), under the question, [Using dual Y stepper drivers on Marlin / RAMPS 1.4](https://3dprinting.stackexchange.com/q/23182/4762), there is a concept of an A4988 "twinner":

> I am rather building an A4988 "twinner"

The question itself also mentions:

> ... add-on nanocard hosting a couple of twin A4988 drivers

Can anyone explain what this is, and/or how it works? Are there any schematics, design guides, PCB board designs that can be used, or pre-built versions available?

**Tags:** diy-3d-printer, stepper-driver, ramps

> **Comments:**
> **username_1**: Surely it's just driving the steppers in series (like you're supposed to when driving multiple steppers on a single driver)? Though from what he wrote ("not daring to drive both with one") maybe he's mirroring the EN, DIR, STEP pins to a second driver.  
> **username_0**: @username_1 - In series? That's interesting. I had assumed in parallel. After a quick google I found : *A series connection provides a high inductance and therefore greater torque at low speeds. A parallel connection will lower the inductance which results in increased torque at faster speeds.* So is in series preferable? However, it is the drivers that are doubled up, not the steppers (Quote from the question: `add-on nanocard hosting a couple of twin A4988 drivers`) I presume that the stepper drivers themselves would need to be in parallel (for electrically/electronically logical reasons).  
> **username_1**: Usually driving two steppers with one driver is done for controlling dual Z axis steppers would have to stay in sync to prevent the bed from tilting - though the same would apply on a Y axis I suppose. Connecting the steppers in series ensures that they both have the same current applied through their coils are are being driven at equal strength -> less risk of one side losing steps while the other doesn't. The downside is the higher inductance, i.e. at the same drive voltage, you'll need to drive the coils longer to reach the set current, which reduces the potential top speed of the stepper.  
> **username_1**: That's not much of an issue on the (always-slow) Z-axis, but could be an issue for Y. Results of driving steppers in parallel depends on how well matched their inductances (and loads) are. The overall inductance is reduced, which means you're now limited by the current the driver can produce w.r.t. speed and torque. Since an A4988 is already pretty weak compared to what most NEMA17s can handle, I don't see much advantage to parallel connections.  
> **username_1**: Actually putting the drivers in parallel... uhhh. I assume for sharing current requirements between both? Not sure how well you'd be able to synchronize them when microstepping and how they would handle that at all. It'd be much more reasonable to just use a more powerful driver (i.e. TMC5160 or external ones) than that.  
> **username_2**: As someone running an AWD delta with pairs of motors on shared drivers, you absolutely want them in parallel, not series. Running them series is effectively halving the voltage and thereby the max speed before pullout. Running them in parallel halves the available current, but modern drivers support much more current than your motors will use, while nothing has as much voltage as you'd like. Mine are each running at 650 mA on a driver putting out 1.3A that can handle a max of 3A, with 48V.  

---

## 0 answers

