What is the reason to use 24v with the jackpot and LR4? I have a 12v 30a meanwell power supply I used on my mpcnc, and was hoping to use it on my LR4. Any issues with that? The board looks to support the range, just not sure what I would be giving up going lower. Thanks
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12 V can do fine. I used 12 V on my LowRider v2 and on my LowRider v3. I did finally start using 24 V when I built LowRider v4. I think the only advantage with 24 V is that you can do faster Rapids with the machine. But to get those faster rapids, you have to tweak a parameter or two. If you don’t change the Gcode travel / jog parameters in your CAM software and tweak your kinematics regarding inertia in your Jackpot config, then you won’t see really any difference between 12 V and 24 V.
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12v should be fine, based on the jackpot page it says 19 watts for the board and gives the example of 24v at 0.8amp, 19 watts for 12v should be 1.58amp for the board (someone correct me if I’m wrong please) don’t forget you’ll still need the power for the steppers as that would be just the board and esp alone
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The steppers get powered from the board though right? You just mean I need enough amperage for the board and steppers both? That can all run on the 12v input on the board right? Figured surely 12v 30a would be enough for the steppers as well.
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Yea, that’s way more than needed. The power supply sold in the V1 store is 24v @ 2.5 amps, so 60 watts. You’ve got 300 watts more than that.
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Thanks, I wasn’t seeing an amp or wattage of the one sold, so couldn’t really come up with solid answers. Appreciate everyone’s help! Rather stick with 12v so I can use LEDs and fans in 12v without having to step down.
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The stepper drivers are constant current. And the resistance isn’t constant. So total power isn’t the only consideration. But 12V will be just as rigid as 24V at low speeds.
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That’s what I wasn’t to sure if it included or not when the page said 19 watts or not, based on its minimum stated, thanks!
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So I’ll start out with the 12v supply, and if I need more speed, I can upgrade it later. Thanks for helping me figure out what the higher voltage is used for.
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That probably would have been my next question.
Thank you @jeyeager for giving the specs of the V1 solution.
I recall reading the specs, which I think indicated 36W, and it seemed to have too little overhead. So, I opted for 150W (24V), since I already have it. If I find it, I might also use the 105W that I should also have, somewhere.
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So for those who arent into electrical engineering there is a fundamental equation
Voltage (V) = Current (I) x Resistance (R)
Whilst I agree with Jeff’s comment that resistance isnt strickly constant for understanding this it is for all intents and purposes the same… and you will see with higher voltage that you will be able to drive a higher current which drives the stepper motor - if it is required.
I’m very aware of Ohms law (I have a MS in EE). But stepper motor drivers are very dynamic. They are closed loop control around driving a constant current in each coil by adjusting the duty cycle in a PWM signal. A higher voltage does effectively nothing until the PWM signal is at 100% duty cycle. That happens when the steppers are moving fast, and the back emf fights the current. This is an inductive load, not a basic resistive load.
So you don’t see any difference at low RPMs. A lower voltage works fine until that PWM reaches 100%. After that, the driver can’t deliver the rated current, and the torque goes down. Only in those speeds is the higher voltage psu able to push more current, and provide more torque.
The only effective different is more torque at high speeds. It has the same torque at lower rpms.
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So I have my LR4 running with the jackpot and default values from the v1 config. I am noticing, that randomly, when moving the Z, with the toolhead all the way at X0, the left Z will snag or stepper grind. If I help it move, it will go up and zero.
Is this possibly due to my 12v power supply, and might I need to up the stepper amperage in the config to compensate?
Things will be fine most the time, but randomly this occurs. Just looking for suggestions what to check.
Just finished cutting my struts out, guess I’ll just take it apart put them on and then re calibrate and see if that clears it up. Something might be in bind somewhere
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I suggest starting a new thread, as your issue isn’t really the same as the OP.
Sounds like there is too much resistance/friction on the Z lead screws.
Start by cleaning and lubing the lead screw threads.
Then check the lead screw nut for alignment. I think on the LR4 that Ryan is suggesting to not use the retaining screws on the lead nut to allow it to self align.
Does the gantry drop down when power is removed? That is a sign that everything is moving properly. If it stays up when power is removed, that indicates that there is excessive friction in the system.
Yea it wasn’t dropping without power. I’m still working on reassembly after struts, so need to check for square and all. If it still has issues I’ll start new new post. Thanks, I wondered if something got in a bind before. Makes sense. Appreciate the reply!
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