Build Platform and Projector Sync

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carlsgems
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Build Platform and Projector Sync

Postby carlsgems » Sun May 24, 2015 3:22 pm

I have my projector calibrated for light image on to the vat, test run had mixed results. exposed resin but not in the way that worked. The question I have after a dry run on slicing the stl file and movement of the platform. During the test run the light was projected toward the platform, the platform moved up and then light would project as the platformed moved down like it was going down to pick up exposed resin. That does not seem right to me. I have seen videos of other builds and the platform is down and not moving when light is projected, lift of platform, moves down, light hits vat again, exposed moves up as light is off. etc.
Should the build platform be moving at all when light is exposing the resin. does not seem right but I am new at this and trying to figure it out before I go at it again. Is the projector and build platform out of sync, thanks in advance

wesmain
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Re: Build Platform and Projector Sync

Postby wesmain » Sun May 24, 2015 5:15 pm

I had the same problem. You need to click the Auto Calc button in your slicing profile and then Apply Changes.

wcarver1
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Re: Build Platform and Projector Sync

Postby wcarver1 » Sun May 24, 2015 8:06 pm

I was going to post about this earlier, thanks for the reminder. Even using AutoCalc, you'll still likely experience this problem.

The issue is that AutoCalc doesn't properly calculate the change in 'lift and sequence time' caused by differences in the Bottom Layers. (e.g., exposure time, z lift speed, z retract speed)

AutoCalc only 'calcs' a standard layer and then applies that cycle time to ALL the layers, including bottom layers.

Thusly, I've found two options. Manually compute the exposure and machine cycle deltas, adding it to the 'lift and sequence time' compiled by the AutoCalc function. This means each layer takes the same amount of time and every layer past the 'Bottom Layers' has time wasted (since bottom layer exposure times tend to be longer).

The alternative is to run the slicer with the AutoCalc generated layer time then export to a .gcode file, manually edit the G04 block for each of the bottom layers, re-save, then re-import the file. This drastically shortens print times but is a bit of a PITA to compile. I was surprised that I couldn't edit the file from within CW, but I digress.

This is one of many irksome things I've noted about CW in my time working with it...

Interestingly, there is a $FirstLayerTime slice-time variable that goes unused. There may be a solution there that is a bit more automated.

(For the tl;dr crew, pick an arbitrarily long 'lift and sequence time' (20000 ms, say) hit 'Print' and go play quietly with your crayons for the next few hours)
^^^ Sarcasm

carlsgems
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Re: Build Platform and Projector Sync

Postby carlsgems » Thu May 28, 2015 6:39 pm

thanks I will try auto calc and if that doesn't work i will fish around and see if I can get a recommended file and try to slip it in the Gcode

jlmccuan
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Re: Build Platform and Projector Sync

Postby jlmccuan » Sat May 30, 2015 9:05 am

I've had no problems with the timing in CW. The first layers' times and subsequent layers each have their own timing and don't require any editing for everything to be right on with regards to the exposure, retract and return to the next layer. For one resin I use I have a 12 second exposure for the first layer and then 4.25 seconds after that. There is no dead time in the shorter exposure layers. As soon as the projector goes off the platform lifts and when it comes back down there is no delay in the projection of the next slice. Am I not understanding the OP's problem?


Here are the CW settings for that resin.
Screenshot (1).png

wcarver1
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Re: Build Platform and Projector Sync

Postby wcarver1 » Sat May 30, 2015 1:03 pm

What version are you on? 1.0.0.75 has a different slicing profile interface
^^^ Sarcasm

carlsgems
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Re: Build Platform and Projector Sync

Postby carlsgems » Mon Jun 01, 2015 11:52 am

I am using alphasense blue resin and have heard blue is a hard resin to cure. does anyone have any suggestions on blue resins? I am hoping to prctice on some simple stl files and soon get it to castable resins for jewelry. there are several out there and I even seen a commercial machine with a cartridge have issues in the prints and would not cast as advertised for $7000.00 investment, thats why i am going slow and sure and not throwing $$$$$ away to "avoid disappointment and future regret" quote the Franklin mint if you do not hurry up a pay 10 bucks for a gold plated nickel.


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