Seed Scarifier

I need a tool to scarify some small seeds before planting. I found some online but they were expensive and made for high volumes of seeds. Scarifying by hand proved to be difficult and impracticable for more than a few seeds.

This design uses sandpaper glued to 2 cones one of which fits inside the other.  The glue does not have to be very strong. It just needs to keep the sand paper from moving during use. The angle of the vertex of the cones is slightly different in order to accommodate varying sizes of seeds.  A moderately coarse sandpaper will be needed. I used 80 grit. 100 or 120 grit should also work fine. There is a hole in the base cone to allow the seeds to drop through.  I used a paper plate underneath the scarifier to catch the seeds and debris.

Instructions: 

Print 1 of each part and 2 of the legs in your favorite filament. Printing parameters are not critical as long as it prints. The upright and legs slide in to the base. This is a snug fit. Use the sandpaper template to mark the outline of the pieces of sandpaper. Cut the two pieces of sandpaper. Notice that one is larger than the other. The larger piece is for the base and the smaller is for the cone. I used a water soluble glue to adhere the sand paper to their respective parts.

Use: 

Drop the cone into the base and place the handle/rod through as shown in the photos. Drop the seeds that you want to scarify in the groove between the cones and twist with a light to moderate pressure. It may take some experimentation to get this right. Reprocess any seeds that need more scarifying.