I'm new to electronics and Arduino but basically I want to build a router lift. It's supposed to be controlled by a stepper motor. The router motor will weigh 1.7 kg. The total weight on the lead screw should be around 2kg.
I'm looking at this stepper motor (or similar): Schrittmotor, NEMA17, Flansch 42mm, 1A, 26,5Ncm, 16,90 €.
From reading here it seems people recommend 24V power supply. But it's unclear to me what current I need to feed to the stepper. Let's say it needs 1A. But my power supply outputs 2A. Do I need to pass the current through some part that takes it down to 1A? Or can I feed 2A into it anyway?
I want to convert the 24V to 5V so that I can drive the stepper and Uno with the same power supply.
Can I use this R-78E5.0-0.5 component? To me it seems reasonable because 5V @ 500mA is the same as USB.
The internet told me that TMC2209 is a quiet and good stepper driver. So I'm looking at that one.
I will need to figure out the emergency stop button and power on switch. As well as a screen that shows current router/cutting depth.
At one point I considered a time-of-flight sensor to get the router/cutting depth and a button to zero it but now I'm more inclined to rely on the stepper by just counting revolutions.
You need a propper stepper driver, a stepper + leadscrew that is up to the task and a decent power supply. 24 or better 36 V, 5A. You can use the R-78E5.0-0.5 if you like. time-of-flight sensor for cutter depth won't work. Use a closed loop stepper instead. And endswitches/limitswitches and home switch. Oh, an overall plan on what you try to do would be great
The plan is a lift for a router table. As such, it will only go up and down. Probably in the range of 0-70mm.
It clearly does not have the same requirements as a CNC.
A tof sensor for cutting depth works in theory - it would be mounted below the spindle and read the spindle's offset. In practice, that's another story. And maybe you know something I don't?
About open vs closed-loop. I read quite a few posts on this forum that open-loop steppers are used for CNCs and if that's true I believe it should be enough for a router lift.
When you say I need a proper stepper driver, are you implying that the TMC2209 is not up for the job?
Ah, ok. You should go for a wormgear, it's selflocking and you can go with that small stepper. You can use any stepper driver for that - won't hear the stepper anyway. Endswitch is a must for homing - TOF is ... well, there is a reason why it's not used.
I don't understand how homing would work on a table router. Isn't what I need just a zeroing button or a Z probe? Every time I change router bit the "home" would be different, right? So I don't care that much about absolute position. Just the distance from the router bit tip to some known point, eg zero.
Limits: when you hit them, it indicates something bad is happening. Overshooting limits will damage the machine - or make you some extra work. Usually these are travel limits.
Home: this is a dedicated position in your machines world coordinate system. It has a known position in respect to the limits - or the other way around.
Tool length offset (table): that's when you have different tools. It's usually measured upftont when you load the tools and not probed on the workpiece (as that would damage the tool).
soft limits: tool length changes your travel length, so soft limits (limits in software) are used to prevent the tools damaging your machine.
work coordinate system: usually the surface of your work piece has Z=0. Tool length offsets may be different, but when the tool touches your work piece you have Z=0. Also when your workpiece has an undefined Z, probing for the surface gives Z=0.
The last one is what you address with with a Z-probe or touchoff button. It has (almost) nothing to do with machine limits.
When you have a tool changer (whatever it may be) that ensures your tools all have the same height or an individual known height then you don't need to probe, especially when your work piece surface is fixed and only the tool height change.
In your case you always need at least one limit switch so you know your machines hardware limits. And a known toollength. You can just measure that when load a tool or make some fancy rotating touchplate
My understanding of a table router is that the lift is done under user control, the user can see where the tool is. So I don't think you need any homing or limit switches.
However, you would need some way to "home" the position. This could be simply done by measuring the offset and inputting to the control system. This would need to be done each time you power up or change tool.
I figured as much as well. But I realized that my small kids might push the up/down button for too long and for that scenario limit switches might be a good idea. Or if the button is pressed by mistake for some other reason.
I have a cheap CNC router with no limit switches, the carriage just hits the stop and the motor skips steps. The noise is disconcerting but no damage ensues.
However, limit switches are not a bad idea, depending on how much torque the motor develops and certainly if there is a possibility of "misuse". If you have a geared motor then limit switches are definitely recommended.
