Print Cycle in CW

[3d-stephen]

Hey all,
I am now in a status where I have Arduino, Ramps 1.4, two steppers and the projector working in an unassembled way together with Creation workshop.
The steppers move and the slices are projected - great so far.

I'll be using a Z-axis to lift the build platform, and the X-axis to slide the VAT,
however in the standard configuration this sort of print cycle will most likely not work with a sliding Vat.

At this point, the image get's projected, then the screen turns black and both stepper motors start to rotate at the same time first in one direction then immediately in the other to continue with the next slide.

With a tilting VAT, this may be ok, that VAT and the Z-axis move away from each other at the same time.

However for a sliding Vat, just like with the B9, to overcome the suction forces the Object slides over the waterfall when the VAT is moving.

So first the VAT needs to slide fully, only then the Z-axis can start to lift, then VAT needs to move fully back, before Z-axis can lower.

Additionally, I would like to have a Pause after each move allowing the PDMS to breathe, and allowing the resin to flow back and stop floating before the next layer is projected/cured.
This procedure ameliorates the print quality on the B9 very much.

To be precise, I would like to use the following print cycle, exactly like with the B9:

When the projector powers on, the VAT is in the "closed" position (bottom window moved away from the projected image) and the Z-axis is positioned slightly above it's zero position (zero position is flat on the PDMS). When the print process is then started the following should happen:

1) The VAT (x-axis) moves in the Open Position (X+)
2) Small Pause (approx 2-4 seconds) for the Resin to flow back over the PDMS
3) The Build Platform (Z-axis) moves to the 0-position flat on PDMS (Z-)
4) the first layer is projected/cured
5) The VAT (x-axis) moves in the Close position (X-)
6) The z-axis moves up 4mm (Z+)
7) Small Pause for the PDMS to "breathe"
- restart with (1)

I understand that I can define some custom GCode to be executed upon "Start", "Pre-Slice", "Lift" and "End",
but I am not sure what goes to what, and what these GCode commands would be for the pause.

Did I understand it correctly that the GCode only contains variables, and that the actual values are still pulled from the "Options" Panel ?

Where can I enter the Value for the Pause, I was only able to find ;<Delay> %d$BlankTime in the "Lift" section, but nowhere to define that delay value.

Can anyone help?

[@A2]

To be clear, you are not using the waterfall technique or the tilt vat, is that correct?

You want to:
1 slide the vat after photo-polymerization to break the mechanical bond of the object to the PDMS,
2 stop,
3 then lift the Z-axis up 4 mm,
4 pause to allow resin to flow over the PDMS,
5 then slide the vat back to it's home position, repeat.

Won't the build plate still have to over come the suction to lift the Z-axis up 4 mm?

[PacManFan]

Let's see:
1) The VAT (x-axis) moves in the Open Position (X+)
2) Small Pause (approx 2-4 seconds) for the Resin to flow back over the PDMS
3) The Build Platform (Z-axis) moves to the 0-position flat on PDMS (Z-)
4) the first layer is projected/cured
5) The VAT (x-axis) moves in the Close position (X-)
6) The z-axis moves up 4mm (Z+)
7) Small Pause for the PDMS to "breathe"
- restart with (1)

preslice code:
G1 X100 F200 ; slide the vat - assuming a x movement of 100 and a feedrate of 200
;<Delay> 2000

lift code:
G1 X-100 F200 ; slide the vat back
G1 Z($ZLiftDist * $ZDir) F$ZLiftRate ; move the z up
;<Delay> 3000
G1 Z(($LayerThickness-$ZLiftDist) * $ZDir) F$ZRetractRate ; move z back minus the slice height
;<Delay> 3000

You may need to play around with the delay values a bit, but that's about it... The slice exposure happens between the preslice and lift

[erenaud]

[3d-stephen]

thanks pacmanfan,

that worked - I'll be putting the machine together now, and probably come back later with some more questions

[@A2]

@erenaud:

Tks for the helpful explanation.

PDMS - Cliff vs Waterfall
http://b9creator.com/support/?minglefor ... pic&t=1703