Hi everyone! i’ve printed the .STL file and found the ring that seems to be the best fit. However, the STL file rings seem to be not that much connected to provided dimensions. I’ve even used 3d viewer to measure inner distance and it says ~21 mm, my caliper tells me the same, however what will be somewhere between sizes 11 and 12 according to dimensions PNG, as it says 11 = 20.73 (too small) and 12 = 21.55 (too wide). So should i trust the PNG or STL? If STL should be trusted, then what is the ring size of the ring in the middle?
What I recommend to do is to create the snapshot of the STL render with text labels for each ring, that should simplify life for people like me
As a note to Core Devices — the 3mf file format is pretty widely supported now and has the ability to store information like distance units which means that basically any slicer should be able to import at the correct scale. STL is just unitless points which can make things a little trickier, especially for things where accurate dimensions are needed
Yep, actually I now understood that if the final rings will have diameter according to https://repebble.com/index01-carousel/index01-dimensions.png then it means STL sizes are incorrect. @eric please can you confirm that actual rings will be 21 mm for “12” size, not 21.55 mm?
Hey all - got the answer. Long story short - the ‘individual ring’ STLs were dimensionally accurate in software to the exact dimensions of Index 01 but would shrink when printed on FDM.
Through trial and error on several printers (Bambu, Prusa and Creality), we developed an STL file specifically for FDM printers that would create prints with inner diameters as close as possible to the actual Index 01 inner diameters. We uploaded this STL to hardware/ring/pebble-index-01 at main · coredevices/hardware · GitHub about 3 weeks ago
If you printed one of the individual Index 01 STLs, please reprint the 20260222-index-01-ring-sizer-FDM-v1.STL file (for FDM printers), or the SLA file (in the unlikely event you use an SLA printer, we recommend FDM for this).
As always, I recommend that you measure the inner diameter of your prints with calipers and compare that against the image with inner diameters just to confirm that your print is accurate.
But according to individual STLs, their dimensions were 99% close to schematics (0.07mm difference), and the ring sizer have 0.2-0.3mm difference.
I am yet to confirm this, but still my index finger fit 9 US size from the ring sizer more freely than from individual STL.
And were wasn’t any shrinkage as I was using Bambu Lab A1 with 0.4 and 0.2 mm hotends and 0.20 or 0.08-0.06 layer heights - their caliper confirmed dimensions were almost the same.
(deleted my X posts to have this conversation here)
Unfortunately, different printers and print settings may result in different sized prints, and it’s possible that the same STL will print differently. We’ve tested the STL file on GitHub on many different printers with default settings in their slicer.
It’s always a good idea double check with calipers. If you’re finding that the print is incorrect, you can always use the scale feature built into your slicer.
Many factors can cause 3D prints to have different dimensions (printer type, filament type, print settings, etc).
It’s possible that our foray into recommending 3d print sizing is a mistake, given these inconsistencies with prints.
We’ll probably recommend that you a) print and measure with calipers, then scale the STL file to match your offset and reprint, or b) order the sizing kit
Let me rephrase again. The issue happens BEFORE anything is printed. Digital measurement of STL shows 21 mm for ring of size 12. So it makes me think it was just modelled wrong. Someone didn’t put 21.5 mm diameter for ring of size 12 in STL. I tried multiple viewers and they all show 21mm. No caliper or printing needed to check this.
The STL files will show a larger digital inner diameter than the actual physical rings. This to account for what we thought would be adequate offsetting for normal shrinkage during FDM printing
