MatterControl scaling down prints

[jeffnic]

MatterControl is shrinking the prints we send to our Max v3.

For example a bezel I made in Freecad measures 74mm wide, but printed just about 30.5 mm. The multiplier (~2.54) sounds suspiciously like a mm to inch conversion. Curious thing, the dimensions displayed in MatterControl are correct, so I can't scale up (MC thinks the result would be bigger than the bed). This has happened on 3 different prints (from different sources) including the calibration cube.

My son and I just finished the build, and this is our first printer, so we don't have a lot of experience. I'm wondering if there's a setting I'm missing -- or maybe there's a different profile for the v3? We're using the "RostockMax" profile as outlined in the video - step 6 of the Max v3 assembly guide.

Unfortunately we're struggling with a "heater decoupled" problem as well , so we won't be able to try any suggestions until we get that working.

Thanks in advance!

[morgandc]

The stl files don't appear to contain units. You must specify the units in the slicer to match your stl file. I finally just switch my cad file to mm to match all of the slicers. I grabbed the following off the matter control website:

Fritz, it sounds like your object was designed in inches, but MatterControl uses millimeters. To do the unit conversion, click on the icon next to your object to open it in a new window, then click the edit button. There will be a scale menu on the right side. If you click the down arrow next to ratio, one of the options will be inches to mm.
tanderson [MatterHackers] - April 27th, 2015 at 11:38a.m.

First mistake I made as well, I was just using much smaller prints so it was obvious before I printed for the first time.

[TwoTone]

My son had the same problem with Fusion 360 unti he changed the units to MM in it.

[Polygonhell]

Curious thing, the dimensions displayed in MatterControl are correct, so I can't scale up (MC thinks the result would be bigger than the bed)."

If what you are saying is that in the Matter control preview the dimensions are correct, but they are incorrect on the printer, I'd assume the issue is in the Steps/mm in the firmware, not in the model scale.
You can look at the GCode and verify the intended dimensions are what's being written to the file.

mm to inches issues are usually a very obvious 25.4 x scale