Resin printer slicer scaling problem.

[Chris GH]

Hi Guys,

     Am pretty new to resin printing and have a problem with a slicer possibly making a model smaller than intended.

    I use the RS Designspark Mechanical Cad program for design,  An Anycubic Photon Mono2 Resin Printer and the Photon workshop slicer program.

     After designing a project and importing the STL file into the slicer program, every thing seems to be ok dimensionally, i.e. the item looks correct on the build plate.

All the printer and resin parameters ( I have tried different resins) are entered as recommended and then sliced. 

This file is then added to the USB stick and printed on the Mono 2.

The resulting print comes off the build plate smaller than needed by as much as 25%

        As an example : a component drawn as 13mm x 7mm with a 5mm diameter boss with a 2mm hole, comes off as 7.5mm x 5mm with a 3.5mm boss and a 1mm hole.

I have read on the Anycubic wiki that over exposure can cause larger prints and that under exposure can cause smaller prints.

I have tried altering the normal exposure times in the slicer and on the printer to a higher than recommended number in order to get a more accurate print without any success.

Any suggestions will by much appreciated

regards Chris.

 

[EDDY100]

Run your model though Prusa slicer/Fix by window repair log.

Once fixed check dimensions and if all correct export the fixed model and import into your resin slicer.

I would go for Chitubox or similar, not home brand slicer as they are not the best.

 

[monkeysarefun]

A 25% discrepancy in size would not be caused by exposure settings, it'd almost definitely be a scaling issue caused by the slicer - perhaps it is incorrectly reading  the sizes inside the .stl file.

 

I'm not familiar with the Anycubic slicing software but I assume it would have a scaling tool/button  of some kind. Have you tried this to confirm the  dimensions are as you expected? If they are wrong then you can use the same scaling tool to set them to what you want them to be.

[njee20]

Anycubic slicer is (/was) a lightweight version of Chitubox. I'd be holding the software responsible at this point, and be trying a proper version of Chitubox. At one point it didn't support the Photon Mono range, but I'm sure that's long passed.

[Chris GH]

Hi Guys, Thanks for the replies. I have checked the dimensions as seen on the slicer virtual bed on the laptop and they seem ok using the grid as a guide.

There is a scaling button available and when I alter the scale, the dimensions change as well.

As suggested I will download a copy of Chitubox and try that . Will report back soon

regards Chris

 

[Blefuscu]

That's an odd one. I use Anycubic slicer a lot(*) and have never seen this problem before.

 

I would double check the printer bed settings, particularly the dimensions of the bed. It sounds to me like Anycubic workshop thinks your bed is 25% larger than reality. My thinking is sliced images will scale down on the printer to fit the screen, bringing the scale of the model down with them.

 

(*I use it for slicing my .pwmb, but make my supports in Prusa...  by exporting an stl with supports from Prusa into Anycubic workshop.

Maybe Prusa can do .pwmb's now, but I'm a creature of habit and haven't checked for a while)

 

[Chris GH]

Hi Thanks for the reply.

I was also setting the object at an angle with supports so that may have altered the scale.

But even setting the object flat on the bed didn’t make a difference.

Another issue I was also getting was that I am scaling STLs drawn full size (downloaded from Thingiverse) to 1:152(2mmFine Scale).

I have now switched to Chitubox which seems to set the bed dimensions correctly as a preset and every thing is scaling correctly.

I haven’t checked the bed dimension of my printer but will try to set them in Anycubic Photon Workshop as  it seems to be more user friendly but as they always say “If it ain’t broke, don’t fix it”. So I will probably carry on using Chitubox as my slicer.

regards Chris

Edited March 3 by Chris GH

[JimFin]

2 hours ago, Chris GH said:

but will try to set them in Anycubic Photon Workshop as

Should not need to do that, just select the correct printer from the menu and they will be set for you.

[bradfordbuffer]

On 03/03/2024 at 10:55, Chris GH said:

Hi Thanks for the reply.

I was also setting the object at an angle with supports so that may have altered the scale.

But even setting the object flat on the bed didn’t make a difference.

Another issue I was also getting was that I am scaling STLs drawn full size (downloaded from Thingiverse) to 1:152(2mmFine Scale).

I have now switched to Chitubox which seems to set the bed dimensions correctly as a preset and every thing is scaling correctly.

I haven’t checked the bed dimension of my printer but will try to set them in Anycubic Photon Workshop as  it seems to be more user friendly but as they always say “If it ain’t broke, don’t fix it”. So I will probably carry on using Chitubox as my slicer.

regards Chris

Need to check original stl file some on Thingivers the makers quote 00/Ho so when you scale to 2mm you might be scaling 00 to 2mm when in fact might be 1:87 scale so will end up smaller than expected also check printer /resin settings on lychee there is facility to alter scale on printer settings.

If this makes sense. 

G

[billbedford]

On 11/02/2024 at 10:21, Chris GH said:

 After designing a project and importing the STL file into the slicer program, every thing seems to be ok dimensionally, i.e. the item looks correct on the build plate.

All the printer and resin parameters ( I have tried different resins) are entered as recommended and then sliced. 

This file is then added to the USB stick and printed on the Mono 2.

The resulting print comes off the build plate smaller than needed by as much as 25%

        As an example : a component drawn as 13mm x 7mm with a 5mm diameter boss with a 2mm hole, comes off as 7.5mm x 5mm with a 3.5mm boss and a 1mm hole.

 

Stl files are undimensioned. So your problem may have to do with what your CAD software is outputting. 

[Graham R]

I have not had any problems using the Anycubic slicer. When you load an .stl file, if its orientation is outside the print envelope, the slicer asks if you want to scale the stl to fit. You should rather rotate/move the stl into the print envelope (the model colour changes on parts outside the envelope). A bit unlikely but is it possible you’re simply clicking “scale” when loading?

 

Graham

[billbedford]

Here's a clue:

 

The ratio of the actual to expected dimensions is 1:0.57, almost the same as 7:4. So the error appears to be in the CAD. 

[F2Andy]

4 hours ago, billbedford said:

 

Stl files are undimensioned. So your problem may have to do with what your CAD software is outputting. 

I do not think that is quite right. They have dimensions, but not units. That means the software will try to guess if you mean cm, mm or even inches. It does not mean it will be a random scale.

 

I use Blender and work in meters in there. The STL file has no units, but ChiTuBox usually just guesses mm because that is what fits the print area. For a small part it guesses cm and I have to scale it to 10%, but I once had it guess inches and had to scale it down to 3.94% (=1/25.4x100).

[Chris GH]

Hi Guys

Thanks for the replies.

The STLs I am downloading are drawn full-size.

As @Jimfin says I have set the printer correctly as per the  Photon workshop documentation, so the build plate is dimensioned correctly and also the resin and print properties are set correctly

The same can be said for the settings in Chitubox.

As already said, the STLs are obviously too big for the printer build plate.

I am scaling them using known measurements taken from line drawings and checking with the dimensions of existing models. This scaling works out at 0.66% of the original size.

Chitubox scales them correctly whereas Photon workshop doesn’t.

Regards Chris

 

[Graham R]

Have you tried asking Anycubic customer service? They might have come across the issue before.