Re-opening Chitubox created .ctb files and (now) other solution opportunities.

[Ray H]

I created a file in Chitubox yesterday and saved it to a memory stick. The print failed so I want to review the file and possibly alter it.

 

I've tried re-opening the file in Chitubox and can only see a very small portion of what I believe is the top of a couple of the items in the file although Chitubox shows the print time so it is presumably reading the (whole?) file.

 

Is this a regular problem?

 

Edited September 3, 2023 by Ray H
Heading changed to reflect later woes.

[GWR57xx]

Hi Ray,

Is this the sort of thing you're seeing?:

 

If so, use the blue vertical scroll bar to the right of the black "build plate" image to set the limits of which slices you wish to see, such as:

 

 

Hope that helps.

Peter

 

[Ray H]

Thanks Peter.

 

Alas I tried that. The display looks normal on the right hand (black) window, The left hand window just shows a couple of small blobs for want of a better description.

 

The message "Slice image import is complete, 3D preview is being generated" appears across the bottom of the screen.

 

 

I've had a few successive print failures with either the same or different .ctb files. I'm currently trying several different things to see if I can pinpoint their cause. One idea I had was to re-open a .ctb file and play around with the supports as the failures that I'm having seem to relate to the model rather than the supports - the latter are generally printing out but the model itself isn't.

 

[GWR57xx]

Is it possible that when you originally saved the file that those few slices were all that was selected on the slide bar?

I don’t know if that is how Chitubox works as I haven’t had that problem, but perhaps if that was the case then those are the only slices Chitubox saves?

 

[GWR57xx]

PS: As soon as I’ve sliced the model in Chitubox I save it and quit, then import the file into UVTools to do the rest.

This has the advantage that you would have immediately seen that what UVTools is displaying is not what you intended to print. I also find it easier to view slices in UVT rather than CB.

 

[Ray H]

I hadn't thought of that so I've just taken a file I had open in Chitubox, closed it and opened it in UVtools with this result:

 

 

I got a similar result with another file that I couldn't re-open in Chitubox.

 

[GWR57xx]

How odd! I’ve pretty much run out of ideas.

Does UVTools suggest there are any errors in the file?

If you scan up the image do all the slices look ok (especially the first one)?

 

[Ray H]

I've renamed this file to have an accepted extension of .stl. Reset the extension to .cbt and it should open in UVTools.

 

_Buffer_Stop.stl

 

I'm not too sure of what I should be seeing but I don't think it looks right. Although iI thought it was O gauge, what was left in the resin bath makes me think it is OO.

[GWR57xx]

Yes, I'd agree - it appears to be OO from a quick screen measurement (build plate is 150mm across so each square in the CTB image represents 1cm.

 

Have you checked that there is no debris in your vat or anything stuck to the build plate FEP from previous prints?

 

Edited September 2, 2023 by GWR57xx
correction

[Ray H]

Did that file look OK in UVTools? Could you open the file in Chitubox?

 

I'm cleaning the bath after each print at the moment to make sure all the debris is removed.

 

The build plate has a spindle. That spindle is connected to its carrier by two bolts that you set with the piece of paper scenario. Is that spindle supposed to move up and down in the carrier during printing once the bolts are tight? I may have found my printing problem if it isn't.

 

I may not need to worry about reopening the .cbt files in the short term if I have found the cause of the print failures.

[GWR57xx]

No, the spindle should be firmly held in place by the two hex bolts (except when re-levelling the build plate).

 

[Ray H]

Thanks for that. I'll wait for this print to finish and check they're tight (although I'm not sure why they've worked loose).

[GWR57xx]

I’m using Chitubox v1.9.3.

I can open the file I downloaded from your earlier post (after changing the extension to .ctb) in Chitubox, but UVTools (v3.9.5) can’t open it. It says the checksum doesn’t match and it’s a malformed file.

Oddly though, if I open your file in CTB and re-save it I can then open it in UVTools and it appears ok, although there issues - the sleepers in particular don’t appear to have sufficient supports beneath them.

 

[billbedford]

The xxxx.cbt file is the sliced file used by the printer. There is a note about this on the Chitubox website:-

 

Quote

Please note that the .ctb file is the final sliced file, which is for printing only under most circumstances. You SHOULD NOT apply 3D model operations to it, only a few non-model-dependent operations like exposure time, lift and retract speed, layer pixel editing (CHITUBOX Pro only), etc. are available. Please ALWAYS modify your models on unsliced formats (.stl, .obj, etc.).

 

[njee20]

As above. In Chitubox you want to “save project”, which will save it with a .Chitubox extension, and allow you to reopen it and make changes. You can save as an STL, but then the supports will be a part of the model, and all you’ll be able to change is exposure settings. 
 

You can’t just alter a file extension and have it change. Nor can you edit a .ctb file in retrospect. 

Edited September 2, 2023 by njee20

[GWR57xx]

40 minutes ago, billbedford said:

The xxxx.cbt file is the sliced file used by the printer. There is a note about this on the Chitubox website:-

 

 

 

12 minutes ago, njee20 said:

As above. In Chitubox you want to “save project”, which will save it with a .Chitubox extension, and allow you to reopen it and make changes. You can save as an STL, but then the supports will be a part of the model, and all you’ll be able to change is exposure settings. 
 

You can’t just alter a file extension and have it change. Nor can you edit a .ctb file in retrospect. 

 

Yes, quite so. But that is not what is happening here.

 

Ray only changed the file extension to allow the file to be placed in his RMWeb post. He was not trying to convert a .ctb file to a .stl one.

 

BTW, you can edit pixels layer by layer in UVtools, I've done it. No need to pay for Chitubox Pro to get that functionality.

 

[njee20]

Opening a CTB will do weird things, so in terms of what will show in Chitubox or UVTools etc all bets are off I’d say.
 

In this instance I’m not sure what UVTools is bringing to the party? If you want to edit supports, orientation or anything about a model then you don’t want the actual CTB file.
 

If the supports are printing but the model isn’t then I’d look at either exposure or lift speeds.

 

 

[Ray H]

The build plate securing bolts weren't fully tight. That's been corrected and I'm running another different print.

 

I reverted to the black resin for the previous file I printed - the one that highlighted the loose bolts. There was a slight defect on one of the prints but the other two in the trio were fine.

 

I have also been having  trouble adding supports and despite watching a couple of YouTube videos to make sure that what I'm attempting to do should result in additional supports, I still can't do it.

 

Thanks for the tip about using save project, rather than a plain save. I'll try to remember that. For reasons unknown to me, I have just managed to save a couple of files with .cpddpl extensions. I haven't tried printing one of those yet.

 

I was only trying to open the .cbt to see if I could see anything obviously adrift that might have caused the print failures that I was having.

 

The settings I have used have, to the best of my knowledge remained unchanged since one of the first files I printed several days ago and I have subsequently (almost) successfully printed the most recent file again with the same settings. That said, the file currently printing does seem to be, with one possible exception out of four, printing just the supports and not the bodies again.

[Ray H]

The most recent print (after the aforementioned bolt tightening) was of four models (of people). One was successful, two had their supports on the build plate plus the lower parts of their bodies affixed to the FEP. The fourth only appears to have managed the supports - I have yet to drain the tank to check the FEP is clear.

 

I've checked the settings that I'm currently using with those on the Chitubox website.

 

The only significant difference that I've found is the exposure time 6s (Chitubox) above and 30s (mine) below.

I've no idea where the 30 seconds exposure time has come from and if that is the time between each layer's print I'm certain that it is nowhere near that value when printing. I'll reset the 50s to the 6s suggested and have another go either tomorrow or Monday.

 

Is my Lifting Distance setting of 6mm against the default setting of 5mm likely to make any difference?

[monkeysarefun]

You could try printing off the original demo file that may have come with the printer depending on the brand, the Elegoo rook or the anycubic cube? Their values will be optimised for your printer (resin aside) so might help pin it down. If that  prints ok it points to  your models settings as being an issue, if it sticks to the FEP or only partly prints it could be a levelling issue or something like resin temperature.

 

Maybe shrink the demo print  down and put multiple prints on one plate, this could pinpoint if your level is off if one side of the plate prints but not the other.

 

Also maybe  run some resin calibration tests to dial in your exposure time accurately, the manufacturers recommended ones can be off for your situation. For instance my Saturn 2 8k recommended print speed for abs resin is 2.8sec, but if I use anything less than 3.1sec  I get failed prints.

[Ray H]

Thanks for all the ongoing suggestions and comments.

 

I was wondering whether trying to test print something that is spread reasonably evenly across the build plate - something like numerous rings of "plastic" of say an 15mm diameter and perhaps 10mm high might be worth the effort. I haven't tried printing the Elegoo rook so multiples of that reduced in scale could be a better test.

 

The printer hasn't been moved since I first used it and several of my initial prints came out fine but I'll try a spirit level on the machine before the next print.

 

The printer is in a spare bedroom. The ambient indoor temperature currently is a little over 21ºC. Is that high enough & how do you keep the resin's temperature up once it is in the tank. Is simply having the machine on for a (continuous) period OK? Can you get/do I need a tank heater?

 

I've given the resin a good shake each time before putting it in the tank. This generates a number of small air bubbles in the top of the resin once it is in the tank. I've tried to push them aside before I start printing. Do they matter?

 

Your reference to resin calibration tests and print speed are new terms to me. 

 

I've just googled "resin calibration test" and will give that a go. Would it be necessary each time you change resin or should resins from the same supplier where only the colour varies be the same?

 

Another dumb question - how do you set the print speed? Is that the same as the lift speed?

 

[billbedford]

I've found this site useful for setting up:-

 

J3DTech

 

It also has some test pieces to help with the process. 

[GWR57xx]

1 hour ago, billbedford said:

I've found this site useful for setting up:-

 

J3DTech

 

It also has some test pieces to help with the process. 

 

Thanks for that - a very useful site that I hadn't come across during my searches for such things.

I'll be running their calibration test shortly - even though I'm fairly happy with my results at present this looks like it could improve things further.

 

[njee20]

Those exposure times are way off. It’s a Mars 3 Pro, right?

 

I’d delete the printer profile in Chitubox and re-add it, making sure you’re specifying that it’s a Mars 3 Pro (it’s odd your Chitubox shows “default”). Exposure time of 30 seconds will destroy your screen and give awful prints, so just in case you’ve got other weird settings you’ve accidentally changed I’d just start afresh. You’ll be aiming for something like 25s base exposure and 2.5-2.8s main exposure with 0.05mm layers. 
 

Ctbdlp is an old file format for the Mars series, I don’t think anything exported against the Mars 3 will print, it predates the printer by some years. 
 

Exposure tests can definitely be helpful, but I’ve found that sometimes actual prints don’t come out as well as they could despite ‘optimal’ settings. They’re a good way to get a great baseline though. The site linked above has a load of great advice. 
 

Be wary of the Rook test piece, even with the configured settings some people find it doesn’t print. 

Edited September 3, 2023 by njee20

[Ray H]

Other commitments have had priority this morning which was probably a good job because no matter what I tried to do earlier, the machine wouldn't recognise the files that I was trying to print. That said, I've just noticed from the icons on the machine's screen that either the computer itself, Chitubox or the memory sticks I'm using - not the one that came with the printer - are misbehaving.

 

Something must be amiss as the file I produced with multiple scaled down rooks is only showing with a file size of 1,211KB. The memory stick to which the file has been written still has over 13.5GB space so it isn't a disk space problem.

 

I'm half inclined to see either if my Chitubox program itself offers an update (for the free version) option or whether their website has an updated version available. This PC has only a few days left to live (hopefully) but it might be worth uninstalling the program and then trying again.

 

Heaven knows how the program arrived at the .cbddlp file extension.