Hello everyone.
I’m set to start building the LowRider 3 and have almost all parts required. I have however one question on the Ramps 1.4 + Arduino Mega 2560 main board I’m planning to use.
Can I use the E0 and E1 in this setup for the Y2 and Z2 steppers? If yes, what changes do I need to make in the firmware? Or is the firmware available on the v1e firmware page ([V1CNC_Ramps_DualLR]) is all I need? My plan is to have a dual end stop for auto squaring.
Note: I have no coding experience.
That firmware is the right one.
You don’t need any coding experience. It should flash with XLoader, so you don’t even need to compile it.
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Thanks for the quick response, Jeff. I was a bit concerned because this firmware is in the ‘untested’ category.
The V1 firmware for this board is setup for the DRV8825 stepper drivers. If you have A4988 stepper drivers (common in Ramps kits), I believe you will need to make a simple source code change and recompile. You will find instructions for compiling the firmware in Ryan’s PlatformIO instructions. Or you could avoid the issue and replace your A4988 drivers with DR8825 drivers.
Both drivers require you to set the vref voltage manually. The vref voltage set the max current the driver will output.
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Hi Robert. I won’t be using the A4988 drivers that came with the kit. I got the DRV8825 already but thanks for the tip.
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You dpon’t need a recompile for the A4988 drivers though. You will need to change the steps/mm but that can be done from the LCD. (It can also be done from a connected PC via Gcode, but I don’t remember the codes to do so.)
The A4988 drivers have a max of 16x microstepping, so the steps/mm will be 100 (This is what we use for almost all of hte other boards, too.) The DRV8825 drivers support 32X microsteppuing, so the steps/mm is 200.
The biggest thing though is that many A4988 drivers support a maximum of 1A (1000mA) driver current. Some support more, but you don’t know without checking. 1A is probably enough, really, (V1 firmware defaults to 900mA) in most cases) but I like running mine a bit hotter. I have my Primo on 1000mA for all, and my LR3 runs 1300mA for the X axis, and 1000mA for the Y and Z axes.
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So is this 1.0 on the stepper instead of the .7, or are yiu speaking of something else?
Thanks for that info on the A4988, Dan.
My motors are rated at 2A; so, the DRV8825 would be a better fit, I guess.
Can anyone tell me how long the Xloader takes to upload the firmware? It’s been about 30 mins and got me wondering.
It takes 30 to 45 seconds.
Got it figured out. Got the port wrong.
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So, I got the firmware uploaded. I’m trying to test the motions on the table, so connected the steppers to the controller. X-stepper is ok, Y1 and Y2 steppers are also ok. But only Z1 stepper is working. What could be wrong with the Z2?
Start by verifying the v-ref for the E1 (Z2) stepper driver. If that check out, swap the stepper driver between E0 and E1 and see if the problem stays with the socket or moves with the stepper driver.
And plug the Z2 stepper into E0 to verify the wiring and the stepper.
The vref is fine and I did exactly what you suggested and swapped the drivers on E0 and E1. To my surprise, all 5 steppers are working fine now. Whatever was wrong, no complaints now 
The other issue I’m facing now is on the limit switches. They’re not triggering. I set them up for a ‘NO’ connection and they do not stop the steppers when I close them.
I believe they should be set up NC. And not sure on the RAMPS board but on the SKR they have to be to signal and ground. Not positive
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I connected them ground to signal. Should the steppers be working with no limit switches installed if the setup is NC? Mine did, so I assumed the setup should be NO.
If memory serves correctly the limit switches will only stop the steppers during a homing cycle. So if your just jogging the machine around it will move just fine. But if you try to home it I would think yours wouldn’t move at all since you have them wired NO
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I just tried auto home and the steppers still move.
Confirming that the firmware is expecting NC connections. You will need to change either the switch connections or the firmware. The M119 g-code can be used to query Marlin about how its seeing the switches (open or triggered).
They need to be wired NC. I strongly suggest using M119 first, to verify the wiring and make sure you have the right endstops to the right motors.
They are ignored, except when homing. If you home and they are triggered, they should move away from the endstop to try to clear the endstop. Then you should get homing failed.
If that sounds counter intuitive to you, you are not alone. But we have learned through lots of user difficulties to configure them this way. If you’d like them on all the time, and you’d like them NO, you can change that in the firmware, but you need to compile the changes yourself.
In CNC, the workpiece determines the coordinate frame, not the machine. So endstops have limited utility. The exceptions are auto squaring and working with jigs on repeated jobs.
We choose to ignore them normally, and wire them NC because we want people to be able to work without endstops and then add them later. Plus, it is easier for the machine to just move 5mm when homing with bad endstop wiring, than crashing.
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