Shading Clips

We have always had a “problem” with the greenhouse in that it catches the sun virtually all day. In summer it can get unbearably hot, even with the door and both windows open. Some form of shading was the answer but how to attach it to the aluminium frame?

I tried various ideas over the years, the best of which were suction cups on the glass. These worked really well until the weather got hot and they fell off – Doh!.

I ended up cutting some green net shade material into strips a little wider than the glass panes and threading them on net curtain wire attached to the apex of the roof, passing them behind the roof canes and another net curtain wire at the meeting of the side-wall and the roof. Finally inserting some 15 mm copper pipe, capped at both ends and filled with lead flashing off-cuts slipped into a specially sewn pockets on the bottom of each panel to provide a little tension.

This worked well but I still needed some way of preventing the shading material sagging and the edges curling, and it needed to attach to the slots in the aluminium extrusion and be easily removable for cleaning.

Enter the 3D printer…

Cross Section

This two-part design provides a semi-permanent solution. A stud that locks into the rail by twisting, the same way that other commercial items fit, providing a “spigot” that can be pushed through the shade material, and a cover that “snaps” onto the spigot to hold the shade in place.

As with the other items in my greenhouse, the prints were created using PLA and (so far) they appear to be standing up the rigours of temperature and sunshine really well. If (when?) they finally fail I will probably reprint them in PETG.

NOTE: This item was designed specifically for a Halls Greenhouse, the stud may not lock properly into extrusions produced for other makes.

Click to open the Fusion 360 Viewer
Click the image to open the Fusion 360 Viewer

Only the stud needs to be printed with support. Don’t use support when printing the snap cover, it will make it very difficult, if not impossible to attach.

Getting the support for the stud right was a learning curve. I sliced the STL in Cura and using the “out of the box” Support Settings for my first test prints resulted in the destruction of the entire base of the print whilst trying to remove the support.

Tweaking the support settings as illustrated below resulted in support that was easy to remove by inserting a craft knife in the “gap” between the support and the stud:-

Generate SupportTicked
Support PatternGyroid
Support Density10%
Minimum Support Area5 mm²

Don’t be tempted to repeatedly snap the parts together and take them apart unless you print a few spare snaps. Repeatedly snapping the parts together and popping them apart will quickly wear the fingers in the base of the snap reducing its efficiency gripping the spigot. Printing replacement snaps isn’t a big issue, even at 0.12 mm resolution they only take around 20 minutes each but there’s no point in wasting good plastic!

The design is quite dimension sensitive to get a good “snap”, and started with an existing item that “twist-locked” into the track on the aluminium extrusion. A pair of callipers made short work of duplicating this in Fusion 360.

The next step was to add the base of the stud and produce a test print to check the fit. The first prototype had a circular base and proved to be difficult to grip when inserting and removing it from the track, so the shape was changed to hexagonal.

The spigot was then added and the snap built as a new component around the stud to ensure a “snappy” fit…