holes are too small

Hello

I wanted to print a ramps to melzi Mount, but somehow all of the holes are too small to fit an m3 screw, but they have a radius of 2mm. I printed a 2cm test cube and everything was fine.

Printer : i3 variant with 0.4mm nozzle and 1.75mm Filament Diameter

Print Settings : 1.75mm Filament Diameter ; Extrusian Multiplier : 1 ; Hotend Temp : 200C ; Bed Temp : 60C ;

Layer Height : 0.2mm ; First Layer : 0.3mm ; 3 vertical and horizontal Shells ; Not printing external Perimeters first.

I tried printing a 10mm hole, it came out as ~9.5mm

Any suggestions? Thanks

Straw

This is a well-known problem and there are lots of existing threads about it. I find that checking "External perimeters first" makes the holes come out closer to the correct size, but still too small.

Either print some parts containing calibration holes so you can work out what hole size you need to ask for to get the size you want, or use a drill to ream out the holes to the correct size. You need a 3mm drill for an M3 screw clearance hole, a 2.5mm drill for a M2.5 screw, and so on. A 2.3mm drill is good for a hole that an M2.5 screw will tap into.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

@dc42 is this Problem stil appearing in other slicer Software, like skeinforge or cura? or is there any other slicer which doesnt has this Problem but still offers many Options like slic3r does?

Thanks

~Straw

I think you'll find it will happen with any slicer - its a mechanical issue. The problem is that when you are printing a small hole - as the nozzle is traveling around the circle - the filament is being pulled toward the center, making the hole smaller.
As dc42 suggested, you could print a Hole Calibration Test Block

In time You'll learn to compensate for slightly too small holes already when designing the parts.