February 25, 2019 at 6:37 pm #90836
I see that my mini-Rambo ahs max and min connections for x y and z. Is it possible to auto square with this board and just use one end stop (a home position at the bottom left corner of my machine)?
Has anyone tried this?
Would be great to be able to send the thing to a home position for a tool change and square up check all at once.
I see that the dual end stop auto square is available on the big board, just wondering if a less complicated system is possible.
LeighFebruary 25, 2019 at 10:34 pm #90846
Dual endstops allow you to measure the travel of each motor during homing, and then move each of them independently to adjust for the error. The other requirement is dual motor drivers, since you need to be able to move each side independently during homing.
So the reason you need the bigger board is for the extra drivers. 2X, 2Y, and 1Z driver, so 5 drivers total.February 26, 2019 at 7:30 am #90868
I was thinking that each microswitch (one at the end of travel for x and Y. 4 total all at one end of travel) would simply set a start point which is a known square point.
How much error can creep in over say 40″ of travel?
Isn’t placement of the microswitches likely to introduce error in a dual end stop system? If each side is adjusted for travel but the actual distance between making the switches is different? How accurate and repeatable is microswitch cut off possible?
LeighFebruary 26, 2019 at 9:05 am #90891
After everything is running, both sides move in lock step. If they start square, they will stay square. The dual endstop can start a little out of square and then adjust one end a little. The dual endstop software can set an offset between the two microswitches to account for mounting differences.
On a long axis (40″), it’s much easier to get lower errors (in angle). The normal way to set up the machine is to just start the machine while holding it as close to square as possible. If you’re off by even 1/8″, thats 1/8″ over 40″. But it’s easy to get even closer than that manually.
Dual endstops are great, but they are definitely an advanced set up. I would recommend starting without any endstops first. When you have a dozen projects under your belt, you can decide if it’s worth it.
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