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#1 2019-03-12 05:42:56

fcollingwood
Member
Registered: 2017-07-11
Posts: 26

Using direct control for a bottom up printer

Seeing some really really strange behaviour using direct control and max and min endstops.

nanoDLP thinks the top is position 0. because I don't really want to crash the LCD, I would much prefer the bottom to be position 0, and I would like to be able to hit the floor button and for nanoDLP to move the carriage to the bottom position and set position 0. However, there is no option to have zero at the bottom in direct control like there is for a RAMPS board. I also want any attempt to move the carriage down when the bottom endstop is triggered to be ignored.

Shahin, please could you add the following options in for direct control:

1. Zero at bottom
2. Do not permit downwards movement of carriage when bottom endstop is triggered

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#2 2019-03-12 05:54:46

Shahin
Administrator
Registered: 2016-02-17
Posts: 2,644

Re: Using direct control for a bottom up printer

Item two should work. It does not check bottom limit?

Zero at bottom rarely used, issue is that if for any reason limit does not work well, motor will try to reach lower and crashes LCD. But for zero on top, software side would not even try to reach lower than floor except in case of human errors.

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#3 2019-03-12 06:00:34

fcollingwood
Member
Registered: 2017-07-11
Posts: 26

Re: Using direct control for a bottom up printer

For item 1, if it thinks it is at position 0, but the carriage is actually lower, if it is given the start print command, it will ignore the endstop and carry on going past the trigger point of the bottom endstop.

For item 2, I'm finding that often I can't floor if the carriage has been moved manualy, it will go to where it *think* the floor is.

My datum point is the bottom, that's where I need to measure from - My machine is a converted D7, and that's how it was for the original board.

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#4 2019-03-13 14:24:46

fcollingwood
Member
Registered: 2017-07-11
Posts: 26

Re: Using direct control for a bottom up printer

@Shahin - Is there any chance of at least getting 1 as an option when using direct control? I really don't want to have to add a limit switch at the top of the Z of the D7 I've converted.

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#5 2019-03-14 05:12:33

Shahin
Administrator
Registered: 2016-02-17
Posts: 2,644

Re: Using direct control for a bottom up printer

Will check and try to fix the issue.

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#6 2019-03-29 08:18:29

Shahin
Administrator
Registered: 2016-02-17
Posts: 2,644

Re: Using direct control for a bottom up printer

Due to performance reasons we only check limits during calibration and manual movements, for limit on top, it does not cause any issue as flow is complete. After each power on it calibrate itself and etc. But for limit at bottom it is a risky as some issues on hardware part could cause broken LCD.

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