Gantry sag as seen by a BLTouch

Topics around mechanical design, controller and electronics. Mods & hacks welcome.
Posts: 487
Joined: Sat Oct 21, 2017 2:02 pm

Gantry sag as seen by a BLTouch

Postby zemlin » Sat May 23, 2020 2:24 pm

I recently swapped out the control board in my N2 for a Duet 2 Wifi. In the process I added a BLTouch probe to the print head.

One of the weaknesses of the Raise design is the 8mm rods supporting the print head. They deflect slightly with the weight of the head. This isn't usually a significant issue because prints that cover a larger area are normally printed with a larger nozzle/thicker layer.

I'm a mechanical engineer in the industrial machinery business and when I bought my N2 and N2+ I did not expect machine tool precision, so all in all I've been satisfied with these machines. Any machine of this size at this price point is going to have compromises in design. My machines have been very reliable and have printed a lot of parts with very few issues.

That said, with the BLTouch in place, it's pretty slick to be able to cover the bed with parts in a build and not worry about the first layer anymore.

Just as a curiosity, I put a 12x12 piece of 3/4" MIC6 aluminum on the bed. I set the corners as close to level as I could (my 4-point measurements are about 50mm in from each corner), and then ran a 15mm grid over the whole plate (except for the front 50mm where the probe can't reach). Assuming the MIC6 is quite flat, any deflection in the bed mesh is coming from the sag in the gantry. Here's what I got.

4 corners
N2 Bed Mesh 1.JPG

Full bed mesh
N2 Gantry Sag.JPG

Return to “Hardware”

Who is online

Users browsing this forum: No registered users and 1 guest