Vat hanging up during Projector calibration

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Vat hanging up during Projector calibration

Post#1 » Fri Jun 12, 2015 11:37 am

I upgraded to the V1.8 software and decided to see what all this MSM calibration stuff was all about. I guess I've been happy enough with leaving all the printer settings at their default values till now.

But now I'm having problems.

The vat is hanging during the printing of the calibration piece.

Here's a video of the start of the printing. All is fine.

http://leo.smugmug.com/photos/412725556 ... v-320D.mp4

And here's a video a few minutes into the printing. Note it's hanging up pretty badly. I had to abort this print.

http://leo.smugmug.com/photos/412727838 ... D-320D.mp4

Note that it looks like the build table has "forgotten" to lift prior to going back to the pdms section.



As I'm having trouble recoating the new resin vats (I have another thread running here on the forum), I decided to recoat a metal vat, and to calibrate the projector with it.

Can you please help? I have been stalled this entire week due to resin vat recoating problems, and now this....

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mikej
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Re: Vat hanging up during Projector calibration

Post#2 » Fri Jun 12, 2015 12:10 pm

After a certain amount of printing has occurred (the first .5mm by default) the overlift decreases from the default value of 3mm to just .5mm
Are you using the default settings?
Is there a lip or other raised area at the "cliff" of your pdms.
When you recoated the metal vat, did you use this method: viewtopic.php?f=23&t=1665&hilit=trim+pdms#p16495
Measure Twice, Cut Once.

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Re: Vat hanging up during Projector calibration

Post#3 » Fri Jun 12, 2015 12:22 pm

Hi Mike,

Nice seeing you in Vegas this past week.

Yes, the recoating thread you linked is the procedure I used. 34 gms of Sylgaard, 3.4 gms (give or take) of hardener, the black plastic dam about 1/4" away from the glass, cooked for 1 hr at 160 F (at least that's what my oven says), and then next morning, I cut the pdms off the dam with an exacto knife. This gives me a nice, sharp, smooth edge.

Yes, I'm using all the default settings. I'm software experimentation averse, so I hardly ever change anything. :lol:

I just dipped my finger in the vat (it's currently full of cherry) and felt around for the pdms lip. It's nice and sharp. No raised portion at all.


I've reloaded the v1.8 software, and am thinking of trying again. But should I change the "subsequent overlift?" Seems prudent...

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Re: Vat hanging up during Projector calibration

Post#4 » Fri Jun 12, 2015 12:27 pm

Here's a pic of how much of the calibration print has printed before it started hanging up.

Image

Apparently some of the resin was flaking off from the rubbing on the pdms

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Re: Vat hanging up during Projector calibration

Post#5 » Fri Jun 12, 2015 2:25 pm

Changing Subsequent Overlift from 0.5 mm to 3 mm did the trick.

Perhaps this 0.5 mm, while fine for the more precise resin vat, isn't a high enough value for the metal vats? Maybe if the dam is placed too close to the glass, some curvature in the pdms happens, making the 0.5 mm be too small a value?

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Robert Howle
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Re: Vat hanging up during Projector calibration

Post#6 » Fri Jun 12, 2015 7:08 pm

If u have a nice edge with no lip maybe the vat was not exactly level when cured. Just a thought.

When I recoat my metal vats i only use full recoat so I don't have to mess with the dam.

Using only new poly vats right now (have three) and recoating (no dam needed) and they, so far have been interchanging without recalibrating the build table. Reall like them. With the design u get consistent PDMS thickness as long as they are level when cured.

Robert
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Re: Vat hanging up during Projector calibration

Post#7 » Sat Jun 13, 2015 9:17 am

Thanks, Robert, Mike.

I'm rolling now. Well, at least with a seepy metal vat. :lol:

I'll try to finish the MSM calibration today. Changing one variable at a time is a bit of a PITA (pain in the *ss, for those unfamiliar with our slang).

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Metalcaster
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Re: Vat hanging up during Projector calibration

Post#8 » Sat Jun 13, 2015 9:30 am

should be able to paint some silicone rubber onto the leaking area of the VAT and cure it. Just have to make sure the area is very clean and dry before applying the silicone

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