Top Down Printer - How do I match default CW behavior?

Kiroe · 2017-03-09 03:50:28

Hello,

I have been running a top down DLP printer with CW for a few months now and I am wanting to switch over to NanoDLP to free up my laptop. Originally I was running RAMPS 1.4/Sprinter Firmware, but switched over to the patched Marlin as recommended. But unfortunately I cannot get my printer to behave like it does in CW. I've been messing with NanoDLP for a few nights now and just can't get it working. I've tried modifying the MuVE profiles, tried backXslash's top down settings, but nothing seems to work. All I am really trying to do is recreate the default behavior of CW. Any guides for this?

For my top down printer I need it to: Start at the position I set manually > expose for X seconds > dip (lift) into the resin 4mm > return to next layer height > repeat.

Any help would be awesome.

Thanks!

bigfilsing · 2017-03-09 05:40:24

I have never used a top down printer but i guess you set the start position manually according to the level of resin . So from that i guess you will need to "tell" the printer that that = Z home ( or zero)
CW just starts normally and relies on you having manually homed the printer ( or in your case manually set the start point
So if that logic is true then i guess in your start of print job G code, you need to set the Z to zero with the gcode command G92 Z0
You might also need to make sure the printer is using relative coordinates

Hope this helps

Kiroe · 2017-03-11 05:04:04

Thanks for the information bigfilsing!

I seem to have gotten movement finally, but it is in the wrong direction. I have my shield set to Zero at Bottom and if I manually click the z-axis adjust up, it moves up, down and it moves down. However, during the lift phase it is acting like a bottom up printer (moves up out of the resin, then back down). Here is what I have in the settings:

Before Each Layer:
G1 Z[[LayerPosition]]
[[WaitForDoneMessage]]
[[PositionSet [[LayerPosition]]]]

After Each Layer:
G1 Z{[[LayerPosition]]+[[ZLiftDistance]]}
[[WaitForDoneMessage]]
[[PositionChange [[ZLiftDistance]]]]

I want the printer to lower the build plate into the resin 4mm, the return to layer height. It is doing the opposite. I've even tried putting a -4 for the lift distance, but it causes the lift to barely move.

Sooo close, any help would be great!

Thanks!

bigfilsing · 2017-03-11 06:11:51

Always tricky when i haven't any experience with top down printing. What sheild are you using. Im intrigued by your statement " i have my shield set to Zero at Bottom" I presume you mean the bottom of your vat?? and this is just to prevent the build platform trying to lower beyond the bottom of the vat ??
It can all get quite confusing with the actual direction of the stepper ( wiring), firmware stepper direction and firmware home at min or max as well as homing direction.

Option 1 From your recent post in the "After each layer section" first line i would try changing the "+" to "-"
so >>> G1 Z{[[LayerPosition]]-[[ZLiftDistance]]}
Worth a try !! ( on a dry run if possible)

Option 2
You might just reverse the stepper by changing the wiring . Its all down to perspective ! WHen you press down your platform should move "down the model" ie the print head (print effect / work point) gets closer to the base layer Try to think of it from the print head & model perspective rather than the physical direction of the platform
Example in a standard Prusa i3 Y axis The print head wants to go away from us to effect a + Y movement but the bed actually moves towards us!

PS What patched Marlin are you using ? Can you share it or post a link to it ...Thanks

Cheers
Phil
( im big my name is Phil and i currently live in SIngapore hence bigfilsing ( old gamer tag) :-) )

Last edited by bigfilsing (2017-03-11 06:22:09)

Kiroe · 2017-03-11 19:39:54

Hey Phil,

Thanks again for the help! So I tried G1 Z{[[LayerPosition]]-[[ZLiftDistance]]} but that didn't seem to work either, so I rewired the stepper and that did the trick! I've also set the Zero at Top, which is a better choice.

What's odd is now CW is backwards, haha. I've had to change the profile in there to be "bottom up" instead of "top down". So maybe something is still up NanoDLP, but whatever...its working!

Thanks again!

bigfilsing · 2017-03-12 03:41:26

Youre welcome. Glad it worked out

Kiroe · 2017-03-14 03:51:58

Well I spoke to soon. haha. I saw that it was doing the proper lift sequences and assumed it was working properly, so I did a quick calibration test. It seems that it is simply moving up/down the same amount and never advancing into the resin. Any clue what might be causing this? Sooo close!

bigfilsing · 2017-03-14 04:26:04

Good news and bad news :-) Bad news = im no expert but learning through research ! Good news is i have a few ideas. To start with take a look at this video which i believe shows a similar setup to what you are trying to achieve >> https://www.youtube.com/watch?v=osoOQjE … yF&index=8
The video at least confirms our previous logic that down = "down" the model and should actually move the platform up in the resin vat.
From what i can see you should try changing your syscall calc for movement from Layer position to Layer thickness so>> G1 Z{[[LayerThickness]]-[[ZLiftDistance]]}
You may need to change the "-" to "+"
You might also want to control the speed by adding the F variable at the end... see below

Example on my KLD LED 1260 " bottom up" printer i have in the "after each layer" section
M107 ; Turns off the LED light source
G1 Z[[ZLiftDistance]] F200 ; Lift printhead out of resin at F speed
G1 Z{[[LayerThickness]]-[[ZLiftDistance]]} F200 ; move printhead back into resin at Fspeed and by the layer thickness minus the lift distance ( creating a negative Z movement)
[[Delay3]] ; wait for resin to settle before printing next layer

Hope this helps

Last edited by bigfilsing (2017-03-14 04:36:26)

Kiroe · 2017-03-15 02:17:05

Hey Phil,

Thanks again for the help. I tried changing over to LayerThickness, but I was getting the same results. I even let it run for 280 layers just to see, didn't move at all. Just up and down, over and over, but never incremented. And what makes it even more odd, it stopped moving all together around layer 240, but the commands were still sending. So not really sure. Might take a break, do some prints with CW, then try this again with a clear head down the road. haha.

Thanks!

bigfilsing · 2017-03-15 06:06:36

Thats strange ...Couple of comments
1/ It stopping at layer 240 might be due to your setting for Z height. It is odd but the Z height is expressed in pulses ( rather than mm) Trying increasing that and see if it gets further.
2/ Both the operands "+" & "-" are supported according to the info page so i cant figure out why yours isnt moving ! Basically it should be at one postiion then lift then go back to a position that is the same + or - the layer thickness.
3/ During a print you should be able to go to terminal and issue an M114 gcode which should report back its current position so you can see at least where the machine "thinks" it is

Kiroe · 2017-03-15 12:38:10

Hey Phil,

Thanks again for the help! I'll check tonight that the Z height pulses are correct and also see what is being reported with M114 command.

I am using the Marlin (patched) firmware that is on the main download page for nanoDLP. Even some of the Z-Axis Calibration buttons work intermittently, like when I click -1mm then hit it again, sometimes it doesn't move at all. Something odd going on for sure.

Thanks!

bigfilsing · 2017-03-15 13:42:49

You are welcome . It just so happens that your issues coincide with my experiments . I had it all working with my top down a few months back but "lost" the SD card somehow. Now im back at reconfiguring from scratch

Z height >>For example i have my Z height at 192000 ( which in my case equates to 120mm of travel) Why this is expressed as pulses is a mystery to me but there's bound to be a good reason for it
If you set the pluses in the setup screen you can then see what actual distance is by going to the calibration screen and looking under "Platform information"

I too get the erratic movement of the Z axis when in the Z calibration screen. Not sure of the issue there ...probably the stock firmware jerk and acceleration settings . Regardless the motion during a print is fine

Last edited by bigfilsing (2017-03-15 13:48:05)

Kiroe · 2017-03-16 02:28:00

Hey Phil,

THAT DID IT! The Z height was set at 3000 and needed to be 226500! That must have been why it was appearing to be moving in place, but it actually was...super small movements. I will give it a proper calibration print tomorrow night to see what happens. Thanks again for all of your support, I would have never have messed with that setting.

Thanks!

bigfilsing · 2017-03-16 02:44:43

Dejavu You will have to excuse me for waiting on the celebrations till the test print is complete :-)

Last edited by bigfilsing (2017-03-16 02:45:20)

Kiroe · 2017-03-17 12:58:22

Hey Phil,

You can celebrate now! haha. I did a test print and other than some calibration on curing times, it worked! Thanks again for all the help!

nanoDLP

#1 2017-03-09 03:50:28

Top Down Printer - How do I match default CW behavior?

#2 2017-03-09 05:40:24

Re: Top Down Printer - How do I match default CW behavior?

#3 2017-03-11 05:04:04

Re: Top Down Printer - How do I match default CW behavior?

#4 2017-03-11 06:11:51

Re: Top Down Printer - How do I match default CW behavior?

#5 2017-03-11 19:39:54

Re: Top Down Printer - How do I match default CW behavior?

#6 2017-03-12 03:41:26

Re: Top Down Printer - How do I match default CW behavior?

#7 2017-03-14 03:51:58

Re: Top Down Printer - How do I match default CW behavior?

#8 2017-03-14 04:26:04

Re: Top Down Printer - How do I match default CW behavior?

#9 2017-03-15 02:17:05

Re: Top Down Printer - How do I match default CW behavior?

#10 2017-03-15 06:06:36

Re: Top Down Printer - How do I match default CW behavior?

#11 2017-03-15 12:38:10

Re: Top Down Printer - How do I match default CW behavior?

#12 2017-03-15 13:42:49

Re: Top Down Printer - How do I match default CW behavior?

#13 2017-03-16 02:28:00

Re: Top Down Printer - How do I match default CW behavior?

#14 2017-03-16 02:44:43

Re: Top Down Printer - How do I match default CW behavior?

#15 2017-03-17 12:58:22

Re: Top Down Printer - How do I match default CW behavior?

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