Nice! But, as a laser builder, I can see some things.
Those are open loop motors. Change to closed loop, and make a little Arduino or whatever to make it stop (open the door interlock) if any motor trips its ALARM signal.
Open loop was fine in its day. But closed loop is not pricey at all, and offers higher speeds/torques for the same type of motor. They run smoother. They cannot “lose steps”, if you exceed the motor’s max speed it will let it get a few step behind but then shut down that axis and express ALARM if it gets more than a few steps. It will stay there until you cycle power or the drive reset pin. It’s just more reliable.
Spoken from a builder of a 220W RF laser with obviously deep pockets… lol
I’ve been watching these for a couple of years and the prices are dropping. However, even the minimum cost open loop type NEMA motor appear to be at least twice the price of an equivalent open loop type.
That’s just the motor, the motor driver is also somewhat more expensive than the price of a regular driver. The lowest cost I found on-line was about $50 or higher for the driver, I paid $12 for my open loop driver.
–
There is clearly an advantage to closed loop – just from the specifications, I’d love to have a pair.
When it comes down to it there are other things I’d rather have for the machine than to spend money on something I’ve never needed and hasn’t given me a lick of trouble… I find very few ‘users’ having trouble with motors and drivers.
Maybe @Dannym can enlighten us on how he connects the error output of the open loop motor drivers to the Ruida? I’ve been meaning to ask him for quite a while…
They have a couple of ‘error’ outputs, brake and alarm, each has +/- (inverted?).
The Ruida has error input only via the limit switch (LMT +/-), coolant (WP) and door open (DrPro)and there is no real way to use them effectively to recover, that I can see.
If it gives you a failure, can you recover or are you in the same boat as if it’s a open loop failure… except you know about it quicker…?
Since they already have the motors and I assume the drivers, they would basically have to throw that out to replace them at a higher cost… and realistically end up with the same machine…
As soon as the cost of these gets low enough I’m will try them, but when it’s working, I have trouble substantiating more money for little perceptible gain.
I would move them and re-purpose them as home switches. You will probably never use limit switches if you have home switches.
Limits require 4 switches and won’t set 0, 0… and home only require 2 … are you sure about this?
I’m thinking you’re not aware of the difference… If you do, I apologize for the following dissertation …
Home switches allow the Ruida to designate a 0, 0 or ‘home’ location during initialization. Once that operation is complete they are no longer ‘active’, the Ruida ignores them… You can reach in with a screwdriver and trigger the home switch while it’s cutting and nothing happens…
Limit switches exist ‘outside’ the work area to tell the Ruida that the head has gone outside of it’s ‘limit’ or work area.
The nomenclature of the Ruida, doesn’t help … for the X axes the LmtX- is the home input where the LmtX+ is the limit input. The same pairs exists for the Y and Z axes inputs.
You need a pair of$44.33 CL57T and like a 425oz-in $39.57 for the gantry. Gantry motor is static and there’s no drawbacks to being longer or heavier, so get the biggest.
The X axis motor has a cost associated with the extra weight, and usually space limitations. Closed loop steppers need extra clearance for the encoder on the end, so if you run into a hard limit on how long the motor can be, the closed loop will have to be a shorter, lower torque nema23 stepper there.
My dear fellow Newton would likely disagree with you here, giving this whole “inertia” business and whatnot.
Moving a larger and/or heavier item takes more effort and/or time. A heavier motor has more inertia, and thus doesn’t like to change speeds/directions as much.
So, yes, there are drawback to “bigger is better”. The right tool for the job is the best choice, not just the biggest one you can fit
I’m referring to the motor on a static mount, that drives the Y axis. It doesn’t move. Doesn’t matter how heavy that one is.
Larger motors do have larger rotor inertia, but for a given NEMA face spec (23, 34, etc) it generally scales with torque. A motor twice as long has twice the torque and twice the inertia. Bottom line is the max accel a larger unloaded motor can do is about the same as a smaller motor.
Of course, with more load added, you bring down the max accel of the rotor. The larger motors will be less affected by the load.
so i treid to add my Ruida controller to lightBurn but it says i need to add dsp to my lisense key but i realy don’t understand why i must pay 60$ again to add this to light burn can any one help. i dont have R1000 to do this again
It’s a more complex product, it cost more to develop, thus it costs more to purchase. That’s true for pretty much everything. Both a ferarri and a fiat get you to the same place, yet one is significantly more expensive. You want a more premium product, you pay a more premium price, that’s how the world works.
To turn it around, you didn’t offer to pay the “full price” when you had to pay $60 less for the GRBL version only. You were more than happy to not pay the ‘full’ price. Why now expect to not have to pay the full price if you want the full product?
You may want to consider using RDWorks until funds are available. You could potentially do all your design and layout in LightBurn if that’s easier and then transfer the design in AI, DXF, or SVG format.
Well, it’s $60 for the GRBL version, $120 for the GRBL+DSP. If you bought the wrong GRBL version by mistake, there’s no harm, you just pay $60 for the upgrade to the GRBL+DSP version. It’s not a dime more than buying GRBL+DSP to begin with. Same price.
Hooking up a closed loop driver is the same as open. STEP and DIR signal. BRAKE is a thing you probably don’t need- it’s for a braking resistor which you might need if you’re running a crane or elevator somehow, something with massive potential energy that pulls on the rotor as it goes down. This actually generates current out of the drive, which can overvolt the power supply. A normal horizontal XY laser cutter does not need this.
Closed loop uses (most commonly) 2000 counts/rev encoders that provide more accurate rotor placement than open. If you briefly demand too high of an acceleration and the rotor cannot keep up, the drive will allow it to go slightly out of sync (less than a full rotation) without stalling. Open-loop ends up blinding stepping the stalled (unsynchronized) rotor at the wrong freq until the STEP command goes to zero, then can recover from the stall. Closed-loop always delivers the correct phase of current for the actual rotor speed and velocity and maintains torque, even if it’s “behind”. It will catch up as soon as the speed or accel fall enough to allow it to step faster and get the rotor in position. It is not common to need to do this but it does make it more robust.
If an open loop stepper stalls, it will likely later crash into an axis limit since it doesn’t know where it is, and stall the other way.
If a closed loop stalls or jams and gets out of sync beyond that small tolerance, it will express the ALM signal and halt motion on that axis until power is cycled (or there may be a RESET input to cycle).
All stepper drive (closed or open) signals are fully isolated optos, and typically designed for 5V input. The + and - wires on an input go to an LED and series resistor (sized for 5V) that light up an optocoupler that drives an internal phototransistor that switches current with that light. So it doesn’t matter where your ground is. Commonly, we tie all the input + to 5V power and the Ruida pulls the - side down when it wants to step. But also you could tie the input - to ground and pulse 5v to the +, that’s not commonly done though.
This makes the input fully differential. If you don’t tie the + to 5V at the supply, just run a twisted pair from +/- to the Ruida or whatever controller, it is totally immune to RF interference as that induces current in both wires and they cancel out.
It is impossible for a power surge on the controller to damage the Ruida, as there is no connection from power to the +/- opto inputs.
Drive outputs are isolated the other way. There is an optoisolator with an NPN phototransistor that acts like a switch that closes when it drives the LED inside it. Again, it is NOT tied to any ground or power inside the drive, but it will only conduct current from + to -. It does have a voltage limit but it should be over 24V. Most commonly this is connected to a device as a pull-down switch, to something like a 5V input with a 10k ohm pullup resistor. The phototransistor usually does not have a series resistor to limit current and you must be sure not to tie it to 5v and ground directly, as that would draw high current.
These drive inputs are usually NOT sized for 3.3v operation due to the series resistor on the input’s LED.
I built a system with a 5V Arduino. It reads a number of signals including all the drives’ ALM pin. Also my water flow sensor is a Hall effect that creates pulses when running, whereas the Ruida requires a simple ON to function. It can also take in the chiller’s ALARM pin.
If the Arduino counts enough water flow pulses, it pulls the Ruida WP input low (low=ok to go) which makes it ready. If not, it drives the Ruida WP pin to 5V and the Ruida will throw a WP error.
The lid can be an “and” of coolant-flow-ok, chiller ok, power supply ok, all 3 motor drive ALM pins reading OK, and anything else- oh hey, AIR ASSIST PRESSURE SENSOR! And water temp sensor! Let’s put that in too!
But best to NOT send this signal to DrProt directly. Rather, the Arduino drives a small relay or transistor output that goes in series with the door switch. So both must be closed for DrProt to enable running the laser. In this config, it is impossible for a malfunction in the Arduino to enable the machine to run with the door open.
However, I don’t actually do that, because I have a command-line interface on a USB-to-UART FTDI cable to the PC. It does lots of things, and I can type in an override command so the door lock CAN be overridden there. It will always reset everything including the door lock override when power is cycled. To do this, the machine’s door interlock has to be just another input to the Arduino, not the series-switch I described in the prior paragraph. The CLI also reads out the problem if it occurs so you don’t need to go in back and inspect the drives’ “alarm” LEDs.
Really, the best part of closed-loop is that ALM pin that is guaranteed to detect the drive not moving correctly. It can’t detect a skipping belt, but it will always detect a loose stepper wire, jam, high accel stall, or a high speed stall. Yes, it has saved things several times.
Thank you so much i showed my husband and he fixed it so its working. And burning. Now. May i ask im working on rd works v8 57 but im strugling to turn of my laser when it is framing so it start burning when framing how can i turn it of so its just framing.
And then what will be the best setting for engraving and cutting i treid to setup my co2 so it wil ing grave but it engraves to deep i did try to set up a test file but it is still to deep…
I know we have cheap safety glasses im wearing it when im playing, its a learning curve, i had a small diode and everything is new. But we piece of plexiglass 3mm is here so i will be putting on this week with the lid.
I know i will do it as sson as the money is there. As soon as i get the small clientelle back up i will pay it… is will work on lightburn and save dfx file and then work on rd works its just easier straight from lightburn.
