Hi all, I’m getting ready to build my own MPCNC. Currently in the research/planning phase and just trying to wrap my head around everything. One question that I have right now is does the base kit use endstops? I would imagine that it would have to have at least one limit switch on each axis. However, I don’t see any limit switches listed in the parts or included in the Primo kit from the V1 Store. So with one limit switch on each axis, that allows you to home the machine. And then with the dual kit that adds another switch onto each axis for a max position. Am I missing something here? There has to be at least one limit switch on each axis, right? Thanks.
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Dylan,
The endstops are nice if you really want an electrical process to square the rails. But as many here have said, if you put the rails to the hard stops, then jog the machine to the 0,0 location of the intended cut, you can then set the “origin” for the current gcode and the rails should remain square until you turn off the power.
It’s not like many 3D printers where you need to home everything before you start cutting. You do want to “square” the rails against the stops, but then after you power it on you can move the core around via the control box and it should remain square.
Mike
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The base kit does not come with with end stop switches and wiring…and end stops are not needed for most CNC use. It is recommended you wire your machine without end stops and in a series configuration and run the machine for awhile to understand things before considering dual endstops. As Mike mentions, the primary reason for a dual end stop setup is to square the axes. So with dual end stops, there are no max end stops. There are two min X end stops for X1 and X2 steppers, and two min Y end stops for Y1 and Y2 steppers. When homing, each stepper is run independently so that when each end of each axis is at min its position that axis is square with the machine.
Having run my machine without end stops for awhile, having added end stops, having read the many topics on this forum on end stop troubles, and having to troubleshoot wiring problems with my end stops, I’m pretty ambivalent about them. For most people, everything that can be accomplished with a dual end stop setup can be accomplished by having calibrated physical end stops to push against before powering up the machine.
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Thank you both for the great info! I have been using my Printrbot Simple Metal w/Heated Bed for many years, and assumed that a CNC Router would also need endstops. I will take your advice and hold off on adding the endstops for now (and maybe never add them since it seems like it works just as well without them). Thanks again!
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I built my Primo with dual endstops out of the gate, because I am quite comfortable with the wiring, and having an automated process to square the machine seems easier to me.
That said, once the machine has been squared, I hardly ever use the endstops for cutting reference, since the endstops are necessarily the minimums for X and Y, and EstlCAM tends to use the 0,0 as an origin for the final job. As such, if 0,0 is the hard stop limit for the machine, it can’t move to a negative position in order to cut an edge to 0 in either the X or Y dimensions. Since the tool has a finite width, and it has to move to x=-1/2w in order to cut an edge at x=0, if 0 is already the hard limit of the tool, it can’t do it.
Things that I do use the endstops for is to have a hard zero for the machine, as a reference, so that I then jog the machine over to X=50, Y=50, then re-zero the machine’s workspace coordinates. This way, if something goes wrong, I can restart the machine with a reasonably high degree of precision. This allows me to restart jobs, where something has gone wrong, provided that it does not ruin the workpiece. It might spend a few minutes cutting air, but the toolpath will end up being the same, which has saved me a few times.
I’ve had the wiring come loose to a switch as well, one of mine likes to do that. When that happens I’ll probably manually square the machine, and use it without the endstops for a while, until I have time to fix the wiring. It’s really not a big deal most of the time.
If you are comfortable with wiring, then the endstops are nice to have, but by no means at all a necessity. The dual endstop wiring is more work, and it is one more thing that can go wrong with the machine that isn’t needed for regular operation.
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@SupraGuy I would definitely be comfortable with the wiring part. But what else makes it complicated? Is it straightforward to “add in” the endstops into the firmware to then be able to use CAM to square it on startup?
Differences/potential issues:
- Dual end stops uses different firmware for many boards, so you need to be comfortable flashing firmware to your board.
- Dual end stops require five drivers, so you need to have each stepper use its own driver. Serial wiring pairs steppers in a serial configuration and only uses three drivers. If you are ordering from Ryan, you have to select your wiring choice at the time of the order. And regardless of which wiring you select, I don’t believe the switches are part of the kit.
- Common issue is that the switches need to be wired normally closed.
- You need to be setup with some thing like Repetier-Host to be able to send a M119 and get the data back to debug end stop issues. You cannot just run headless.
- For the Rambo board, extra focus needs to be placed on the end stop pinouts on the control board in order to avoid shorting 5V to ground.
Not all that complicated, but there are enough gotchas here that end up generating questions for the forum.
P.S. Complications are all in the initial setup. They are not complicated to use.
Other than the wiring… There’s nothing complicated. You do need a board with 5 drivers on it. Most 3D printer boards for Marlin already have that. You need to keep straight 2 sets of wires each for the X and Y motors, and the associated endstops… But that’s wiring. If you’re making your own harness, the dual endstop version is actually considerably simpler, since it’s just the 4 wires for the motor and 2 for the stop, and no having to figure out anything for the series wiring.
The provisions for bolting the endstops to the truck is already there. The stop blocks have already been created. The firmware version for the endstops is already created and configured.
I’ll add that setting the endstop position and offset requires some careful, tedious, repetitive cutting/drawing and measuring.
I would say that you want to purchase a board that has the ability to do use the dual end stops and build your wiring with the extra wires that are needed. It is easier to build your wiring with the stops than to come back an add it at a later time. I find the dual end stops very useful on my projects that use multiple bits.
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Thank you all for the great info. I have learned a lot! I was thinking the same thing as @1629dill; I will buy a Rambo board with 5 drivers but not wire up the endstops right away - that will be a future project once I learn the basics.
I ran without end stops for over a year. I set aside projects that I thought benefited highly or required end stops like repeated milling using a fixture. After I installed end stops and became active in this forum, I realized that everything I though I needed electronic end stops for could have been accomplished using physical stops that I could push the axes against before powering on or zeroing X & Y. In theory, there are some things that can only be accomplished using electronic end stops, but I say “in theory” since they are talked about on this forum, but I have yet to see someone implement them…things like automatic bit changes using multiple workspaces.
With that said, electronic end stops work well. If you strongly plan on having them someday, then, as Dan mentions, you will be a step ahead by wiring the steppers as if dual end stop and using the dual end stop firmware. If purchasing from Ryan, this means buying dual end stop cables with your kit. Ryan should put the dual end stop firmware on the board based on the cables. You do not have to have end stops wired in to use dual end stop wiring.