Printing thin resin sheets - NEW PROBLEM - finished

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philipy
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Re: Printing thin resin sheets

Post by philipy » Wed Jan 26, 2022 12:54 pm

ge_rik wrote: Wed Jan 26, 2022 12:02 pm With something as thin as this, I would be inclined to use plasticard.
I totally understand and if I'd known it would be this much of a pain I'd have gone that route myself.
The stupid thing is that the 0.5mm thick ( thin?) sheet is printing perfectly, but the bolt detail isn't. I've just printed a 0.5mm thick small plate 4mm x 10mm with 1mm diam x 0.75 mm high rivets and it is absolutely perfect. I then tried again with yet another redrawn roof sheet 74 x 40mm with the same sized rivets, the sheet is perfect but I only have half a dozen of the 30 odd rivets that should be there! :roll: :dontknow:

BTW, I've redone the levelling and zeroing again this morning and that seems to have fixed the 'stick to the bottom not the plate', problem.
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Re: Printing thin resin sheets

Post by philipy » Wed Jan 26, 2022 3:07 pm

This is driving me nuts and I think I'll have to give it up.

I have previously used the SketchUp array tool to run the bolts round the sheet and it crossed my mind that somehow that might be the problem. So I've redone it, inserting the bolts one by one by hand. It also crossed my mind that the number of bolts might be somehow part of the problem, so I cut the sheet in half. I then added the small rivetted plate which sits beside the coal hole. Both items are 0.5mm thick and the rivets on both are 1mm diameter and 0.75mm high. this is the result, still on the printer plate, with the drawing alongside. The sheet has printed perfectly, as usual, but half the rivets are missing in a pretty random way. The plate is perfect.

I am completely stumped. Cannot begin to imagine what else to try?
Screenshot 2022-01-26 14.52.30.png
Screenshot 2022-01-26 14.52.30.png (1.16 MiB) Viewed 3486 times
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Re: Printing thin resin sheets

Post by metalmuncher » Wed Jan 26, 2022 5:48 pm

Do you have some way to view the individual layers the slicer is creating? Maybe run the print without resin and see if the LCD mask shows the correct bolt pattern at the right time in the print? If the LCD is showing the the bolts, you know its some kind of printing problem, if the mask is also missing bolts you know its a model or slicing problem.

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Re: Printing thin resin sheets

Post by philipy » Wed Jan 26, 2022 6:28 pm

The LCD on the machine shows the layers as it prints them and although I haven't sat down and watched every single layer, I have seen it showing all of the individual dots as it goes through the final half a dozen or so layers. They just don't appear on the actual print.
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Re: Printing thin resin sheets

Post by metalmuncher » Wed Jan 26, 2022 7:00 pm

Well, that at least rules out problems with the slicer or model, it seems the machine can't reproduce what is being asked of it. I don't have any experience with resin printers, so I can't be of much use on that front. I know some printers peel each layer off the resin vat film, I wonder if some of the bolts are sticking to the film better than the already printed part. Don't know what knobs you can turn to try and help that if it is the problem - more curing time for the bolt layers? Slower Z axis movement to make the peel less violent?

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Re: Printing thin resin sheets

Post by philipy » Wed Jan 26, 2022 7:41 pm

metalmuncher wrote: Wed Jan 26, 2022 7:00 pm - more curing time for the bolt layers? Slower Z axis movement to make the peel less violent?
I've suspected something along those lines,myself, but I'm very reluctant to mess about with the settings which have always worked before. There is a danger of upsetting all sorts of other things. TBH I've wasted two days on this already and as Peter said, it would have been much quicker to use a sheet of styrene, especially since I wasn't actually planning on doing anything to the roof originally until I had a 'good' idea! :lol:
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Re: Printing thin resin sheets - PROBLEM SOLVED

Post by philipy » Thu Jan 27, 2022 9:28 am

Following MetalMunchers prodding, above, and despite what I said, I decided to have a look at what settings can be changed. :oops:

I discovered a number of things. Firstly, that as I suspected i had no idea what most of the variables were, or at least what effect they actually had. Secondly, I found that it is easy to set up a new print profile and retain the original one, which relieved my mind more than somewhat.

I then went to the Anycubic support and looked at their recomended settings for their grey resin and compared them with the basic default settings that Chitubox has been using for the Photon-S. One thing jumped out at me and slightly put the wind up me, the Chitubox lift speed is 180mm/sec and the Anycubic figure is 3mm/sec! Not only is that a huge difference in itself, but it would increase print times by a factor of nearly 90!
So I went off looking at various forums and found a post by somebody who says he routinely uses the grey resin and has good success with various settings which he listed, the important ones being the exposure time of 16.5 sec compared to 8 seconds previously, and the lift speed of 30mm/sec. I found various other posts suggesting lift speeds in the 30-40mm/sec region, which gave a bit of confidence.

So I bit the bullet and copied his complete set of parameters as a new print profile, re-sliced it and pushed the button. It took 24minutes to print what was previously taking 11minutes, but it came out perfectly first go! :D :D

Of course these thin sheets are only 1.25mm high so quick to print by any standards. Anything very tall would start adding very significant time to the print, so I don't think I shall change to this as a default, but I might play around for a compromise. The thing is that it is only a couple of clicks to switch between saved profiles at the slicing stage, so no problems there.

Thanks for the prodding Richard. :D :thumbright:
Philip

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Re: Printing thin resin sheets - PROBLEM SOLVED

Post by ge_rik » Thu Jan 27, 2022 10:19 am

That is good news, great teamwork and shows how useful the forum can be.

Like you, I generally stick with the default settings for my printing and only tinker when it's absolutely essential. It's disturbing, though, the difference between the default and the recommended setting for AnyCubic's own brand resin.

I've not used my resin printer for a while ( we're having a new kitchen and I stupidly said I'd do all the prep work ..... Don't ask me about lifting ceramic floor tiles!!!! ..... :shock: ), but next time I fire it up I'll take a look at its settings.

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Re: Printing thin resin sheets - PROBLEM SOLVED

Post by philipy » Thu Jan 27, 2022 10:54 am

ge_rik wrote: Thu Jan 27, 2022 10:19 am It's disturbing, though, the difference between the default and the recommended setting for AnyCubic's own brand resin.

...next time I fire it up I'll take a look at its settings.
The settings are in Chitubox, not actually the printer - it's the "Settings" button just above the "Save" button after slicing. I suspect that Chitubox used some best guesses/middle of the road figures, plus the machine comes with the translucent resin and there are differences between translucent and coloured ( which I've ignored up to now!). The machine does a beautiful job of that lattice cube test print file using the translucent resin, we have both seen that at the beginning, so 180mm/sec lift is obviously spot on for that.
What is more concerning is the 3mm/sec lift that Anycubic state for the grey, which is plainly ridiculous. I suspect it could be a typo and should be 30 not 3, but Chinese proof readers can't tell the difference!
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Re: Printing thin resin sheets - PROBLEM SOLVED

Post by metalmuncher » Thu Jan 27, 2022 5:16 pm

Glad you managed to sort it. I want to get into resin printing this year - built a new shed last year so I can get one without stinking up the house with resin and alcohol. I enjoyed toying with my filament printer over the past few years, now its probably tuned within an inch of its life, pretty reliable and fast, but I think with the messiness I'd want a resin printer to just work without much tweaking.

Just a note on the lift speeds, I wonder if there is some confusing of mm/s and mm/minute somewhere. 3mm/s is the same as 180mm/min. Have to be careful of this in filament printing, the slicer normally has settings in mm/s, but the gcode/printer itself generally understands mm/min, so the slicer multiplies the set value by 60 when generating the gcode.

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Re: Printing thin resin sheets - PROBLEM SOLVED

Post by -steves- » Thu Jan 27, 2022 6:35 pm

I had a look at my settings which I print any colour in and never get bad results. One is the Photon S, the other is a Photon Mono. Speed difference is massive, but both work perfectly. I am surprised by how slow you had to lift away to get it to work.
Photon S DELETE.JPG
Photon S DELETE.JPG (51.08 KiB) Viewed 3620 times
MONO DELETE.JPG
MONO DELETE.JPG (45.91 KiB) Viewed 3620 times
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Re: Printing thin resin sheets - PROBLEM SOLVED

Post by philipy » Thu Jan 27, 2022 7:15 pm

Top are the default settings that Chitubox decided on when I first got my Photon-S and won't print my bolts on the sheet.
Bottom are the settings I got from somebody on a Photon forum, that has worked. That isn't to say that there isn't something somewhere in between
Screenshot 2022-01-27 19.07.07.jpg
Screenshot 2022-01-27 19.07.07.jpg (96.12 KiB) Viewed 3617 times
Richard could be right about me getting confused between mm/sec and mm/min though! :oops:
Philip

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Re: Printing thin resin sheets - NEW PROBLEM

Post by philipy » Sun Jan 30, 2022 11:21 am

Actually this isn't about thin sheets, but it does follow on.

Yesterday evening I tried printing a driver for the wee beastie. I used the same settings that worked for the flat sheet but did increase the lift times a little. What I got was a complete disaster! Basically the model pulled awy from the supports so I ended up with a flattened misshapen head and one leg degenerated into a flat sheet.

Sooo... this morning I copied Steve's settings from the screenshot above... and this time, this is what I've just taken off:
DSC_0003[1].jpg
DSC_0003[1].jpg (937.01 KiB) Viewed 3596 times
Which is, give or take, the same as I got yesterday. I don't understand it, because I've printed plenty of figures, flat sheets, and small parts in the past, using the default settings which are effectively the same as Steve's, and never had anything like these problems.

The only thing I can think of is that it is duff resin, but as I said above, it's a new bottle and the problems started with the old bottle. Anyway, I've just ordered a bottle of the Anycubic clear green, which is what came with the machine originally and I'll see if that is any better.
Philip

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Re: Printing thin resin sheets - NEW PROBLEM

Post by Trevor Thompson » Sun Jan 30, 2022 4:43 pm

I have had similar problems printing figures in the past - not necessarily with the same resin but similar problems.

Let me explain what I think might be happening:

When you look at the planes which would be printed at each layer there are large flat areas which are being printed at perhaps the point where the figure has parted from the supports. To begin with it is printing only the middle of the body. The middle of the body has stuck to the supports and then as you go up the layers the area being printed at one time gets bigger and bigger, until by the time we get to the head and leg it is the whole longitudinal cross section of the figure which is being printed at once. The force holding the layer just printed to the bottom of the tank is now overcoming the force holding it to the supports.

What I did when I had this issue was I tilted the figure at say 30 degrees so that the head was significantly higher then the feet. When it is printed like this the maximum area being printed at any one time is much less - as it is taking a slice across the figure at 30 degrees. That now means that the "stiction" force between the printed plane and the tank bottom is much less.

I sometimes use thicker supports for the parts further from the plate as well.

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Re: Printing thin resin sheets - NEW PROBLEM

Post by philipy » Sun Jan 30, 2022 4:56 pm

Thanks Trevor, that does make a lot of sense and I'll look into it. Instinct is to try to get it as flat as poss on the bed so that the print time is cut down, but it's a false economy if I have to print several copies to get one good one.

However, this afternoon I switched from the grey resin to some black but changed nothing else, and as far as I can see it has printed perfectly. I've had my suspicions about this bottle of grey for several days and I'm more than ever suspicious now. It's only a week old and has a Use By date in 2024.

It's the driver I've been struggling with and he is still on his supports, but I've got his mate on the printer now, should be done by bedtime and then we'll know...

Re supports, I normally use the "Heavy" ones, only occasionally going to Light for things like fingers, if necessary.
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Re: Printing thin resin sheets - NEW PROBLEM

Post by philipy » Mon Jan 31, 2022 4:32 pm

philipy wrote: Sun Jan 30, 2022 4:56 pm

It's the driver I've been struggling with and he is still on his supports, but I've got his mate on the printer now, should be done by bedtime and then we'll know...
Well, I've now printed 4 figures using the Anycubic Black and all have come out perfectly, so I have to put all of my problems down to the grey resin. A relief in one way that it isn't my drawing or the machine, but an absolute pain having to throw away nearly a litre of resin. It isn't worth messing about with it anymore after all the problems with the riveted sheets and the figures, plus the fact that it didn't cure properly either. I've had a sheet with missing rivets sitting on the window cill facing the afternoon sun ( what there is of it) for 5 days and the surface is still tacky.
Philip

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