Questions regarding tuning move for StealthChop2

ÖrjanE

Background: I'm using a Duet 2 Maestro for a normal cartesian printer and just switched to firmware 3.4rc1 where the drivers are now by default starting in SpreadCycle mode. This prompted me to configure the system to perform the necessary tuning sequences for StealthChop2, primarily to make the machine quiet. When doing this, I realized that there are several things that are unclear to me.

Q1: Is it necessary to repeat the tuning sequence when the motors have been idle? My testing seems to indicate that it is sufficient to do the tuning only after the whole system has been powered down. Is that correct?

Q2: The examples I've seen suggest doing the tuning in connection with homing, but this may not work for the extruder motor. It there any reason for not using StealthChop2 for the extruder?

Q3: The tuning sequence seems to be that one should energize the motor (M17), then wait at least 130ms before doing a "normal" move. Is there an upper limit for how long to wait? Specifically, is is possible/advisable to wait until the normal printing starts, possibly several minutes later?

Q4: There does not seem to be any information in the Object Model about the driver mode. It this planned/possible/irrelevant?

My idea is to use conditional g-code to do the tuning sequence only when needed; in the homeall.g for X, Y, and Z, and in the start sequence for E (after the nozzle has been heated). I guess global variables can be used to remember if the tuning has already been done since power-up/reset.

dc42

@örjane said in Questions regarding tuning move for StealthChop2:

Background: I'm using a Duet 2 Maestro for a normal cartesian printer and just switched to firmware 3.4rc1 where the drivers are now by default starting in SpreadCycle mode. This prompted me to configure the system to perform the necessary tuning sequences for StealthChop2, primarily to make the machine quiet. When doing this, I realized that there are several things that are unclear to me.

Q1: Is it necessary to repeat the tuning sequence when the motors have been idle? My testing seems to indicate that it is sufficient to do the tuning only after the whole system has been powered down. Is that correct?

You should not need to repeat the tuning moves when the motors have been idle. However, if you remove VIN power from the Duet (with separate 5V power supplied to the Duet), then after restoring VIN power you will need to tune them again.

Q2: The examples I've seen suggest doing the tuning in connection with homing, but this may not work for the extruder motor. It there any reason for not using StealthChop2 for the extruder?

The extruder doesn't usually make much noise anyway.

Q3: The tuning sequence seems to be that one should energize the motor (M17), then wait at least 130ms before doing a "normal" move. Is there an upper limit for how long to wait? Specifically, is is possible/advisable to wait until the normal printing starts, possibly several minutes later?

You could wait if you wanted too, but do you really want the motors to be consuming power before you move them? Also it is important that the first move is at reasonable speed. If you do the tuning in the homing files then you can control that.

Q4: There does not seem to be any information in the Object Model about the driver mode. It this planned/possible/irrelevant?

Yes we plan to add it.

ÖrjanE

@dc42 Perfect. Thanks!