Description

The “Stubbie” design by LD.P worked really well, but in common with the commercial plastic anchors I was getting breakages and No. 8 screws tended to strip out the anchor.  So I set myself the following design goals:

• Should be able to use a 6mm pilot hole
• Should work with No. 8 Screws (2.5mm pilot, 3.57mm shank)
• Should be able to be driven in with an impact driver

Design

Whilst this started as a remix of the original STL I ended up redrawing the part and producing 4 different sizes.

• 1 dot - 6.5mm pilot hole
• 2 dots - 7.0mm pilot hole
• 3 dots - 7.5mm pilot hole
• 5 dots - 8mm pilot hole

Although 6.5mm part works there are a number of compromises in the design so it should probably be avoided unless you really need that size.  The 3 dot (7.5mm) part is probably the sweet spot in the series.

Performance

All sizes are capable of being driven in with an impact driver, care is especially needed with the 6.5mm part.  I have tested them when printed in ABS with a 0.2mm layer height, but as this is a test of your layer adhesion rather than material strength they should work in PLA or PETG.

The pull out performance should be similar to the original design.