r/FixMyPrint • u/Baller8 • 19h ago
Fix My Print Printer not printing the correct dimensions
Just got my Elegoo Centauri Carbon a couple of days ago and began printing this little adapter for the faucet in my bathroom. I ran all the calibrations on the printer when I first got it and again today to see if that would fix the size difference between what's in the model vs. what's really printing. As you can see in the pictures, the printer is off by somewhere between 0.15-0.30mm on all dimensions. I got around this by just adjusting the dimensions very slowly larger to fit the faucet, but I feel like in 2026 printers should be able to print exactly what's modeled. I couldn't find much info on this type of issue on Reddit or YouTube. So figured I'd make my own post. I'm printing in White PLA from Elegoo with the standard print profile for this material preloaded in the Elegoo slicer. I ran the One-click Self-check calibration on the printer which did Automatic Leveling, PID Tuning and Input Shaping. I am printing with a 0.4 nozzle at 220°C with the bed temp at 60°C. I am printing at 100% infill since the adapter needs some strength. I also printed a couple Benchys which came out really good. The layer lines in the photo of them look way worse than in person just because of the lighting. The black filament is Elegoo PLA+. The Benchys were printed at standard 15% infill. Thanks.
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u/normal2norman 19h ago
It could be shrinkage - most filaments shrink slightly as they cool, though usually PLA shrinks less than most other filaments.
I'd check if you have X/Y compensation turned on. A small negative value is often used to shrink the outer dimensions of an object, eg to compensate for layer line bulging and make mating parts fit better.
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u/Baller8 17h ago
Would this be X-Y hole compensation or X-Y contour compensation? Or both?
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u/AnIndecisiveOrange 11h ago
No actually, neither. And this is important. The issue you have is by definition a filament artifact. And slicers have a general XY shrinkage compensation settings right in the filament settings.
XY contour and hole compensation is for a printer artifact. Printing can either cause the deposited line to either spill over a bit more, or less, than the slicer predicted. This means holes can consistently come out too small (if it spills over more than predicted, very common) or big, idem for the contour. This is (mostly) independent of the filament, and therefore is a profile setting.
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u/UmDeTrois 15h ago
I feel like in 2026 printers should be able to print exactly what's modeled.
No process can do this. A large part of mechanical and manufacturing engineering is about making sure imperfect parts work as intended.
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u/Filtermann 13h ago edited 12h ago
This. Even metal manufacturing is subject to tolerances (ie an acceptable margin of imprecision). More in the order of 10 microns or so, but the 160 you get are pretty decent for 3d printing.
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u/Uramies 18h ago
It's shrinkage,
Shrinkage Compensation (%) = (Measured Size / Designed Size) × 100%
Is the formula you use.
Print a cube of even dimensions on all sides and measure it with your caliper and then do the math. Input that percentage in the shrinkage input in ur filament settings. It'll auto adjust to compensate.
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u/JolietJakester 17h ago
Obligatory: "I was in the pool!" Seriously: I had no idea that was a setting you could adjust. Thanks for the tip!
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u/normal2norman 17h ago
That won't be correct in this case, for two reasons, apart from the fact that PLA doesn't shrink much at all, compared to other filaments. Besides, shrinkage (and expansion) is different in Z than in X and Y.
Firstly, that will increase larger dimensions by more than smaller dimensions, which is the opposite of what's needed for the OP's print. The 6.35mm across flats is undersized by 0.38mm, while the larger diameter of 15.12 is undersized by only 0.16mm.
Secondly, because of bulging layer lines, measuring a cube gives an overall dimension over the bulges, not the correct average dimension. You need to print two cubes of very different sizes to calculate X/Y compensation first. See Ellis 3D Print Tuning guide, especially the sections about flow rate and Misconceptions & Bad Advice.
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u/Token2077 16h ago
The Calilantern is one of the best models I have purchased. Sure you have free models and can do the same other way, it's cheap. I've lost more than that in prints that didn't come out the size I needed. Can't recommend it enough for people who need accurate prints. Though to be honest most people including myself don't need prints spot on for most jobs.
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u/brutal4455 Bambu H2C/H2D/P2S/Multiple AMS2/AMS-HT's (Ender5+ even) 13h ago
PLA shouldn't be shrinking that much. If necessary, I've found this to be most accurate and useful for high shrink materials like ASA, etc. Print, then input data into a spreadsheet to get an accurate shrink percentage. I regularly print ASA using this and it's spot on the CAD dims.
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u/epicfail48 4h ago
Large volumes are going to contract more when cooled, so printing at 100% infill is going to cause more issues with regards to dimension
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u/conflan06 5h ago
I feel like in 2026 printers should be able to print exactly what's modeled
yeah thats where you went wrong
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u/Baller8 4h ago
haha yeah I think you're right
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u/DPJazzy91 56m ago
Lol I always have that issue when trying to make screw holes. End up having to oversize by .5 mm to make it work. You can always sand things down a hair I guess hahahaha
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u/Gimly161 17h ago
What is your flow multiplier? That also influences line thickness and therefore outer dimensions. Are the tolerances in all directions the same? There will be some standard deviation buy you can fine-tune to be ± around the nominal dimension instead of always being under sized.
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u/Confusedlemure 16h ago
Oh and since no one mentioned it, if you want it strong, increase your number of perimeters not infill. Lots of videos about this out there.
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u/Angelworks42 11h ago
I've found btw in cases like this - if you don't want to fine tune every setting - the slicer the vendor supports along with the correct profiles actually compensate for material shrinkage (at least this is true for Prusa).
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u/Gigstorm 8h ago
I used a Califlower and it’s documented process to dial in my printer. It now prints to enough accuracy that i can make parts with enough accuracy to do what you need.
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u/SavingsOld7350 6h ago
Not for nothing but digital caliper sometimes loose zero. It appears as if you know what you are doing but did you close the calipers and zero it out.
I like dial calipers...you feel the skip of a gear..digital seems to always loose zero or if dust/dirt are on the ways...it messes with the reading
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u/Rare_Bass_8207 3h ago
Calibrate each brand (and type, like silk, etc.) of filament (with each size nozzle):
- Temperature
- Flow rate
- Pressure Advance (“K”)
- Retraction
in that order.
https://github.com/SoftFever/OrcaSlicer/wiki/Calibration
Our printer prints to better than 0.25% accuracy in all three dimensions.
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u/EvilNickel 11h ago
It's shrinkage, you can use formula for finding out your shrinkage percentage and then put it into a custom profile for that specific spool of filament. Not color, or brand, but spool, every spool shrinks slightly different, so if you want accurate results you gotta do it each time. The test is as simple as printing a tiny cube, measuring it with your calipers, and then using the formula "((File dimension - printed dimension) / File dimension) * 100"
That formula gives you a percentage that you put in your slicer and it will automatically compensate for shrinkage.
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u/Cultural_Gap_4924 17h ago
Somewhere in the slicer there is a shrinkage modifier. On Bambu it’s under the filament settings. Do the math and make that adjustment.
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u/StumpedTrump 18h ago
Huh, usually I have to opposite issue where I need to underside by about 0.10 to get the right size.
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u/GreenMirage 12h ago edited 12h ago
Tbh if its more than 0.2 difference like you have, i would consider taking a look at calibrating the stepper motors.
0.38 difference is pretty dramatic ime for shrinkage on an item that small in PLA. Motors are traveling less than they should. I’d test calibration using lengths of 100mm using 5x5mm profiles first.
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u/EmotionalChildhood46 16h ago
Divide the measured dimension by the designed CAD dimension to find your scale percentage -
Example: If a designed 50 mm cube measures 49.85 mm, divide 49.85 by 50 to get 99.7% (or a 0.3% shrinkage rate)
Then in your slicer go to your Filament Settings, find the Shrinkage Compensation field, and enter the measured percentage (e.g., 99.7%) or the calculated scaling factor so the slicer automatically enlarges the model
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