RacOutlaw
Posts: 3
Joined: Tue Feb 12, 2019 9:20 pm

Z OffSet

Wed Feb 13, 2019 5:47 am

Ok this is what i am seeing here.. On the g-code tab if i set my z offset to -0.80 the first layer of the print is right where it should be as far as the first layer thickness and also on the wipe pillar. If i look at the live preview however to see what the unit is doing there the layers are not seen on top but are actually being drawn below under the build area. This would be fine if it did not mess with the layer height,as it keeps on laying down the next layer and the next it gets to the point where the print head is plowing threw the first 2-3 layers that it has put down. The print nozzle is not raising up in respect to the layers it is putting down..
This is not a hardware issue but is something in the software.If i take the z offset of -0.80 out and put it back to level 0.00 start a print and then jog the print head down to -0.80 the print works fine layer height increases and the print head goes up with it..but i do not want to have to keep moving the head down to where it needs to be every time i go to print something. which is why i bought this software.

And while it is trying to print the layers the software shows the z is at -0.80 and is increasing with every 0.20 layer it prints to -0.60 -0.40 and then it gets too much built up and is plowing threw the printed layers but the print is still showing z=0..

nerys
Posts: 138
Joined: Tue Mar 29, 2016 8:47 pm

Re: Z OffSet

Fri Feb 15, 2019 12:23 am

this is PURELY MY GUESS

but the output you describe is logical and make sense.

the printer can not goto -0.80

but you "defined" -0.80

so what happens if you are at 0.00 but define -0.80 and tell it to go up .2mm?

it won't move at all because +0.2 is -0.6 which is still impossible you are still at 0.00 lowest so it just sits their and does the next layer.

it will keep doing this until layer 6 which will be the first software defined layer at something above 0.00 ie 0.2mm

so your first 6 layers will all be smooshed together because you defined a start point of less than 0.00 equal to 6 layers before a net postive.

at least that is how I read your description and it does make sense for the software to do that in a mathematical sort of way.

ie can't set your offset to a negative "absolute" value. use the first layer height option under the layers tab to do a less than full layer height adjustment (ie less than 100%)

unless I am totally reading that wrong and a more knowledgeable user chimes in ?

RacOutlaw
Posts: 3
Joined: Tue Feb 12, 2019 9:20 pm

Re: Z OffSet

Fri Feb 15, 2019 7:23 pm

Yes that is what is going on but i thought that the z-offset in simplyfi3d was or would be the same thing as the z-offset that you use in the menu of the A20m to set a - offset to compensate for the bed height. That is what it does in the z-offset of the menu atleast.. IE: if i start a print and it tries to start printing a 0.10 first layer but is 1.0 above the bed in the menu of the A20M you can set the z-offset to -0.9. Then when it goes to start the first layer again it would be at the needed 0.10 and the screen will show the z height as such ie 0.10. But the software sets the height right but the display on the A20M shows z=0 and the software shows it as a - number of what the offset was so the print head does not come up with each layer.. I would think that the software would need to be fixed so that when a - offset is set that the software will still show like the menu the layer height of the first layer and not the - number of the offset...

Thanks for the input however and i will try to use what you said in the layer menu and see how that works... just seems to be a software glitch too me :)

Thanks again for the info to try

nerys
Posts: 138
Joined: Tue Mar 29, 2016 8:47 pm

Re: Z OffSet

Mon Feb 18, 2019 12:52 pm

Not a software glitch remember you have hardware and you have software Hardware can do whatever it's programmed for software can only instruct Hardware within is programming limits

So when the software says go down it can only go down to zero because the hardware won't permit it to go less than zero so basically it's a software bumping into Hardware limit thing.

In all cases no matter what you command simplify3d to do the hardware most likely won't permit you to command below zero the end stop switch

In reality what you want is in Altered value of first layer height so if the nozzle is too high you want to squish a little more

But you can't go below zero so in order for that to work you are a zero point must be as low as you desire to go because that is the lowest the software is able to command

I suspect as noted the reason it did not lift up was because the hardware was interpreting the software's commands as absolute values and not relative values

The same thing will happen in a properly set up printer if you command the slicer to draw a portion outside of the build volume the printer will move to its program limit and then simply stop while continuing to execute and dismiss the slicer commands at that limit it was to move left and right as long as it does not hit that limit and then resume wants least like to come in and re-enters the permitted volume of the printer the result is you'll have a flat spot in your print at that location where the hardware reinterpreted the slice command based on its volume limitations

So we both cases your Hardware we interpreted the slice based on its built-in limits 4 build volume which is why you got a strange result

RacOutlaw
Posts: 3
Joined: Tue Feb 12, 2019 9:20 pm

Re: Z OffSet

Mon Feb 18, 2019 9:19 pm

Yes that makes since but i must bow my head in shame as i did not think to put that in my reply.. All this is done above the limit switch.. That is how i can jog it down to the height i need before each print is going into the menu and going to z jog and running it down.. Sorry for not thinking about putting that in here as that does as you have said just then would be the you cant go no lower than this.. I apologize for that very important section of the replay.. I am still new and wet behind the ears.. But from alot of reading and your help and channel i have came along way :) but yes i have not hit the limit switch for the Z height.. As to why i said its a software...

Again sorry for the lack of that info and the help you are giving.. All as to which is very much welcomed

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