Maybe I am blind, but i don’t see instructions for regular end stops in the build instructions.
I have them with the kit I bought, but not sure how to wire or use them
There are only dual end stops. AFAIK they are only used for squaring the x/y axes before cutting begins. They don’t work during cutting unless you change the firmware. To install them 1 end stop is placed on each 0 end of the X axis and 1 end stop is placed on each 0 end of the Y axis. (2 on X and 2 on Y). Each stop is then wired directly to the board – the location depends on the board.
Regular end stops are probably not necessary. The dual ones are used to square the machine, but without that functionality, they’re not so much needed for a CNC. They would, however be needed for a 3D printer, so if you want to mount an extruder, you’ll want them.
There are holes in the trucks to mount them, and the stops. clamp on the bars. IIRC, it’s a pair of M2.5X10 screws to mount them to the trucks.
If I only wanted endstop functionality (single) I would probably wire them normally closed and then in serial, so that either one triggering on an axis would serve to stop the machine.
1 Like
I would have loved to have had “normal” end stops on my Burly rig. I upgraded to dual end stops with my Primo not so much because I wanted better squareness of the rig, but because I wanted the ability to return to specific positions on my spoil board. And this ability has been very helpful in three projects so far.
I have a theory on how you can add these end stops, but it should be reviewed by someone who knows more about the firmware than I do.
-
Wire up the two end stops, one for each axis. Plug the switches into where X1 and Y1 are indicated in the dual end stop instructions. Make sure you wire them up normally closed as indicated in the instructions.
-
Maybe you will need to upgrade your firmware with changes to configuration.h or change to the dual end stop firmware. Jeff or Ryan will know. I seem to remember hitting the home menu item on my Burly (series wiring and firmware), and it beginning the homing sequence.
For homing is where I thought they’d be useful, so I could more easily do bit changes and return to the same zero. Just have to figure out how.
There are no “regular end stops”, you’ve got dual. They are used for homing and racking square. Otherwise you would put hard stops on the rails somewhere where you could physically push the x/y rails up against before starting in order to start from a consistant zero, you’d manually tweak and set the stop blocks to square the rails.
Conceptually, there is no reason why a “regular” end stop wouldn’t work. It is just a matter of figuring out the recipe.
Can you define regular end stops?
Yes. Regular to me is having the motors wired in series and using a single end stop switch for each axis. It does not give you the squareness of a dual end stop setup, but it gives you a home position that you can use to find positions on the spoil board. And yes hard blocks might be a solution also, but you could also ask why have dual end stops if hard stops accomplish the same thing.
I could more easily do bit changes and return to the same zero. Just have to figure out how.
For bit changes, just don’t turn off the steppers and the zero of you work piece remains the same. The problem with end stops is that they reset your zero point. So after homing you have to record the coordinates of the home position wrt your work piece, move back to that position, and then zero again. In my CAD authoring tools there is the concept of global and local coordinates, but I don’t see anyone using them with the MPCNC (at least with Marlin). I don’t even know if Marlin implements them.
I find knowing positions valuable for various “fixture-ing” stragegies.
1 Like
Yup!
I’m thumbing through the (non-dual) firmware and it looks there is provision for limit switches in the code. @caffgeek, plug a limit switch into your board, issue a homing gcode command (ie G28 X to home x axis) , and see what happens? Find the x1 or y1 pin per the dual endstop instructions for your board. You don’t have to install it on the machine, just see what happens when you click it with your thumb after you issue the homing command.
1 Like
I should have said, I don’t know if our version of Marlin enables them. I vaguely remembered that something had to be defined in Marlin for these to be enabled. Just checked and it is “CNC_Coordinate_Systems,” and I just checked the code for the dual end stop version I’m running, and it is defined.
This is bad advice. Check with M119 first. It will save you a heart attack.
The series firmware should have the endstops set up (they have to be turned off, they are on by default). The questions is, are the NC or NO. I think they are NC, so you should connect (-) and (s) on the xmin port to the (C) and (NC) spades on the endstop. Then send an M119 and see if it shows triggered when pressed and open when not. Make sure they are installed on the negative X side, and you can then try homing with G28 X
It’s your machine, you can do what you want, but there are fewer use cases for endstops on a CNC machine, which is why it isn’t documented well.
You said you want to be able to have repeatable cuts after tool changes, well, if you power off the machine, and you don’t power it back up with hard endstops, it will likely not be at the same square. So you’ll need dual endstops or hardstops, at least. I start with hard endstops, and I’m careful to not skip steps when I change bits. Although that is easier in a LR, because I can take the whole router out.
2 Likes
I’m very friendly with my estop.
2 Likes
Regular endstops work by default in the non-dual firmware. But check with M119 like Jeffe said because at a minimum you will need to check the wiring.
I used non-dual endstops for this a while ago. No special firmware tweaks were needed.
1 Like