If there is a gap, sanding the surface to make it flat will help. Loosen the screws from the previous step that hold the printed part to the extrusion. Press down so the plates make full contact with the flat surface. Then carefully put the assembly on its side and tighten the screws again. Finally, put the M5 nuts back on.
I think a crucial step that should be added to the guide is to ensure that the extrusion and the plates are perfectly parallel. If your printed parts have a small ridge (elephants foot from printing), it can cause misalignment. The result will be that your linear rails will start binding when you tighten the screws that hold the plates to the rails. The rails can slide very smoothly until you fully tighten.
To check and properly align: remove the 4 M5 nuts at the bottom of the plate. With the screws inside but loose, put the assembly on a flat surface and press down lightly. Check that there are no gaps between the plates and the surface or the plates and the printed part. If there is a gap, sanding the surface to make it flat will help.
If there is a gap, sanding the surface to make it flat will help. Loosen the screws from the previous step that hold the printed part to the extrusion. Press down so the plates make full contact with the flat surface. Then carefully put the assembly on its side and tighten the screws again. Finally, put the M5 nuts back on.
I think a crucial step that should be added to the guide is to ensure that the extrusion and the plates are perfectly parallel. If your printed parts have a small ridge (elephants foot from printing), it can cause misalignment. The result will be that your linear rails will start binding when you tighten the screws that hold the plates to the rails. The rails can slide very smoothly until you fully tighten.
To check and properly align: remove the 4 M5 nuts at the bottom of the plate. With the screws inside but loose, put the assembly on a flat surface and press down lightly. Check that there are no gaps between the plates and the surface or the plates and the printed part. If there is a gap, sanding the surface to make it flat will help.
I think it is much easier to measure on the outside of the extrusions, especially when you have a panel.
You can just lock calipers at 107mm (47+30+30) and push the frame against the beak.
I agree, the heads seem small for the slots. I’ll have to first get some washers before I can continue the assembly.