My machine does the homing routine fine when homing federate is set @ 1000mm/min but when I double homing feed rate to 2000mm/ min the machine crashes past limit switch on X & Y Axis. the limit switches on my machine are both @ the origin end of the machine. Inputs for all axis work fine as indicated on the F1 Screen. Soft limits for min distances are set as when I use the mpg the machine will not move when rotating the wheel. any ideas why this is might be happening?
HOMING QUERY
- Thread starter supman
- Start date
stevefrisby
SteveFrisby
Homing Has to be done slower then normal feed as the machine doesn't have a clue where it is when powered on. So the homing process is all about the machine finding reference points so it knows the limits of the axis for instance.
Homing has to be done slowly as the time from activating the sensor to actually stopping the travel is dependent on how fast the axis is traveling, Think stopping distance in a car the faster you are going the further it will take to stop, its basically the same for homing
Once the machine has been homed you will notice it will actually start to decelerate prior to reaching the sensor as it knows where the end point is it also knows to slow down so it doesn't crash into the end stop
Homing has to be done slowly as the time from activating the sensor to actually stopping the travel is dependent on how fast the axis is traveling, Think stopping distance in a car the faster you are going the further it will take to stop, its basically the same for homing
Once the machine has been homed you will notice it will actually start to decelerate prior to reaching the sensor as it knows where the end point is it also knows to slow down so it doesn't crash into the end stop
yes I understand Steve's analogy that makes perfect sense. my point is AFTER I have done homing at one speed successfully on start up, then I decide to increase homing speed, should the machine not apply the braking earlier for the increased speed to allow for the now known points or have i missed something.
it makes perfect sense for me to do a home routine on start-up just to make sure the machine knows where XYZ origin is for the machine and working coordinates. also to set Z axis to o on surface of stock.
it makes perfect sense for me to do a home routine on start-up just to make sure the machine knows where XYZ origin is for the machine and working coordinates. also to set Z axis to o on surface of stock.
Attachments
breezy
Moderator
@supman,
Consider the situation as, when you switch the machine on all the memory locations that store the details concerning the position the machine is at, are filled with garbage (each memory bit could come up as a 1 or 0, totally random) or the machine may have been moved manually from the last position it through it was. ie Estop.
So the homing sequence assumes that all data it has on the position the machine is at is wrong, so it CAN'T apply braking as it approaches it's homing position because it DOESN'T know where the home position is!!!
Regards,
Arie.
Consider the situation as, when you switch the machine on all the memory locations that store the details concerning the position the machine is at, are filled with garbage (each memory bit could come up as a 1 or 0, totally random) or the machine may have been moved manually from the last position it through it was. ie Estop.
So the homing sequence assumes that all data it has on the position the machine is at is wrong, so it CAN'T apply braking as it approaches it's homing position because it DOESN'T know where the home position is!!!
Regards,
Arie.
breezy
Moderator
@supman,
Any reason why you have the minimum axis travel set to a negative value? Is the maximum travel the full length of your axes? Or is the sum of the positive values of those two figures the true length of each axes.
What setting do you have in regards to home position against the physical position of the homing switches?
Usually the minimum travel is zero and the home position is at the homing point of homing switches. (minus the backoff value)
I can't see how those setting can affect the operation of the MPG but strange things can happen with axis and homing settings being different from the norm, MASSO firmware may not take into account that situation.
Regards,
Arie.
Any reason why you have the minimum axis travel set to a negative value? Is the maximum travel the full length of your axes? Or is the sum of the positive values of those two figures the true length of each axes.
What setting do you have in regards to home position against the physical position of the homing switches?
Usually the minimum travel is zero and the home position is at the homing point of homing switches. (minus the backoff value)
I can't see how those setting can affect the operation of the MPG but strange things can happen with axis and homing settings being different from the norm, MASSO firmware may not take into account that situation.
Regards,
Arie.
i was doing a ctrl+alt+home as a means to return to origin.as it turns out bad move by my part. doh my bad. after some thought I tried G28 instead to return to origin. increased max feed rate from 4000mm/min as posted in pic to 10000mm/min. works a treat. speeds up and slows down in time as it should.
The min negative values are the distance from the inductive sensor pick up to the end stops (XY Axis)so to speak. the machine extremities . do I not need to worry about this? I'm sure I saw in one of Peter's video somewhere about allowing a little extra just in case (machine coordinates versus working coordinates), maybe I was wrong or misinterpreted it.
the max values are close to their respective physical limits yes. (the soft limits as their are no limit switch's at other end of XY Axis).
as my table is of a reasonable size a little faster will help. this is all new to us so learning fast hopefully(thanks to all at this forum).I use artcam for my design work to create tool path nc file. Old controller was supplied with toolpath for windows software for interface to machine. from nc file. Certainly different that's for sure.
Homing speed at 1000mm/min was no problem for sensors but was quite slow.
The min negative values are the distance from the inductive sensor pick up to the end stops (XY Axis)so to speak. the machine extremities . do I not need to worry about this? I'm sure I saw in one of Peter's video somewhere about allowing a little extra just in case (machine coordinates versus working coordinates), maybe I was wrong or misinterpreted it.
the max values are close to their respective physical limits yes. (the soft limits as their are no limit switch's at other end of XY Axis).
as my table is of a reasonable size a little faster will help. this is all new to us so learning fast hopefully(thanks to all at this forum).I use artcam for my design work to create tool path nc file. Old controller was supplied with toolpath for windows software for interface to machine. from nc file. Certainly different that's for sure.
Homing speed at 1000mm/min was no problem for sensors but was quite slow.
@supman
The reason for the overshoot on your homing is the acceleration setting on your drives.
30mm is very slow to start and slow to stop. When The homing sensor triggers the axis starts to decelerate and because the deceleration is slow it overshoots. If the sensor cannot be cleared in 10mm it will alarm. Worse still if it travels out the other side of the sensor then the problems are even worse.
For a drive running at 10000mm per minute try acceleration of 280mm. I think you will be able to increase your homing to 3000mm/m or maybe faster. you will hear a big difference when your axis start moving.
If it helps mine is 15000mm/min with acceleration of 400mm/sec. Homing speed 4000mm/min which will give you some idea.
When Masso starts the X, Y position is half the Soft limit travel. Soft limits are overridden when homing and you will see that as soon as you start homing the DROs changes to a bit more than maximum allowed travel to ensure it can get from one end of the machine to the other.
Hope this helps
Cheers Peter
The reason for the overshoot on your homing is the acceleration setting on your drives.
30mm is very slow to start and slow to stop. When The homing sensor triggers the axis starts to decelerate and because the deceleration is slow it overshoots. If the sensor cannot be cleared in 10mm it will alarm. Worse still if it travels out the other side of the sensor then the problems are even worse.
For a drive running at 10000mm per minute try acceleration of 280mm. I think you will be able to increase your homing to 3000mm/m or maybe faster. you will hear a big difference when your axis start moving.
If it helps mine is 15000mm/min with acceleration of 400mm/sec. Homing speed 4000mm/min which will give you some idea.
When Masso starts the X, Y position is half the Soft limit travel. Soft limits are overridden when homing and you will see that as soon as you start homing the DROs changes to a bit more than maximum allowed travel to ensure it can get from one end of the machine to the other.
Hope this helps
Cheers Peter
breezy
Moderator
@supman,
Super BAD!!!!! No wonder you were asking about the homing speed!
X0Y0 in MDI will return to MCS origin. G28 actually is a return to home position which can be a different location to the MCS origin.
So you are saying that the machine can travel further on both axes after it homes. Because you have the max set close to the physical length, with the min values you have set, MASSO will see your axes lengths longer than they are, this could see you running into the end stops before the soft limits are triggered. MASSO calculates the the instructed move for soft limit overrun before it moves the axis. So if you issue a command either in Gcode or MDI that MASSO sees as moving beyond the soft limits it throws an soft limit alarm and doesn't move.
I'm assuming you have hard limits turned OFF, because the homing sensors are also the hard limit sensors, in this case you can reconfigure to a more standard configuration.
Set the Home position values in the X & Y boxes (attached photo) to the distance the sensors are from the end of the axes and in the axes setup set min to zero and max to true length of each axis. From MASSO documentation homing page.
What Peter was saying at start of setting up axes set the min to a large negative min value until you have tuned the distance travelled per pulse correctly, then set to the correct values for your axes. Soft limit values should be a little shorter than the physical length.
Regards,
Arie.
Super BAD!!!!! No wonder you were asking about the homing speed!
X0Y0 in MDI will return to MCS origin. G28 actually is a return to home position which can be a different location to the MCS origin.
So you are saying that the machine can travel further on both axes after it homes. Because you have the max set close to the physical length, with the min values you have set, MASSO will see your axes lengths longer than they are, this could see you running into the end stops before the soft limits are triggered. MASSO calculates the the instructed move for soft limit overrun before it moves the axis. So if you issue a command either in Gcode or MDI that MASSO sees as moving beyond the soft limits it throws an soft limit alarm and doesn't move.
I'm assuming you have hard limits turned OFF, because the homing sensors are also the hard limit sensors, in this case you can reconfigure to a more standard configuration.
Set the Home position values in the X & Y boxes (attached photo) to the distance the sensors are from the end of the axes and in the axes setup set min to zero and max to true length of each axis. From MASSO documentation homing page.
Step 5: Specifying homing location
As the homing sensors/switches can be mounted on either side of the axis, the position of the homing sensor/switch needs to be entered. If the sensor/switch is mounted on the 0.00 location as per the above axample then enter Home Position as 0.00. If the sensor/switch is mounted on the other side, for example the axis travel is 400mm and the sensor/switch is mounted at 400mm location then set Home Position as 400.0
What Peter was saying at start of setting up axes set the min to a large negative min value until you have tuned the distance travelled per pulse correctly, then set to the correct values for your axes. Soft limit values should be a little shorter than the physical length.
Regards,
Arie.
