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#1 2018-12-25 15:16:10

macdarren
Member
Registered: 2017-03-20
Posts: 140

Is there a way to set a Z offset?

My issue is with a phrozen shuffle XL..

When I print directly on the bed, prints come out shorter than expected.  (ie a 10x10,x10 cube will be 10x10x8.75)

With same orientation (flat face to the bed), just lifting the item onto supports will result in 10x10x10. (I presume the supports are reduced)
Not sure why this happens and it has been suggested I am zeroing too low which seems possible.
Maybe I am not getting good resin flow on lowest layers or something?

It is hard to make minor changes in zero height (I have tried using sheets of paper as spacers with little change)
Is it possible to add some fixed z offset to just see if this problem can be fixed?
If I could insert a parameter to add .05 or .1 to all z positions just to see if it helps?

Thanks
Darren

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#2 2018-12-27 15:36:19

elshad66
Member
Registered: 2017-03-31
Posts: 85

Re: Is there a way to set a Z offset?

the motor loses steps, try to raise the current
try to pause after raising Wait After Lift 1sec

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#3 2018-12-28 06:10:02

macdarren
Member
Registered: 2017-03-20
Posts: 140

Re: Is there a way to set a Z offset?

Thanks,

I will try changing the wait time...since this is a new supposedly calibrated system not one I have built I am loath to open and start changing things in the box or the firmware.

Not sure what drivers it uses or how they are adjusted.

I suspect however that this is not the actual issue since printing things on supports yields proper Z for objects...and these tests are hardly large so the peel forces should not be too much for the motor.

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#4 2019-01-01 18:28:01

macdarren
Member
Registered: 2017-03-20
Posts: 140

Re: Is there a way to set a Z offset?

I found a mechanical problem that caused my Z to very...I fixed this but I still have a fixed amount of Z error.
I would still like a way to set the zero position via software either positive or negative with respect to the end stop switch.
There is probably a way in the firmware but I read don't have easy access to that and think a nanoDLP solution would be more helpful.

Thanks

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#5 2019-01-02 14:27:24

Shahin
Administrator
Registered: 2016-02-17
Posts: 2,305

Re: Is there a way to set a Z offset?

What are the support/normal layer height?

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#6 2019-01-02 19:16:45

macdarren
Member
Registered: 2017-03-20
Posts: 140

Re: Is there a way to set a Z offset?

I see the problem with all layer thicknesses I have tested....05 to .2
I usually use supports 5mm high, however the problem only occurred when I print directly on the bed.
This leads me to think it is a first few layer issue..now that I have corrected the play in the Z axis.

I even think I know where the issue is coming from....I think the way my printer is built the FEP can stretch down a bit from the platform zero point.
If I set the zero position below the actual floor of the vat then run the printer to that point causing the motor to skip just a couple steps as it presses the FEP into
the LCD then I get good results....

What I would like to do is be able to adjust how on either side of the zero sensor want to set the actual print zero point.
I guess you can think of it like the mechanical zero is not really the print zero.  It is in reality just a 'known position sensor' so the printer can reset to a point before
or after a print or at powerup etc.  IN pay case it happens to be close to the print zero point but not right on it...my FDM printer has a similar situation where
you can adjust print zero in very tiny amounts.

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#7 2019-01-03 05:23:32

Shahin
Administrator
Registered: 2016-02-17
Posts: 2,305

Re: Is there a way to set a Z offset?

Objects get sliced using normal layer thickness but for support section you can move z-axis with different height. Maybe you should try use more support layers with thicker than normal layers  so you can counter effect of shorter prints

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