This compass can be stuck on a whiteboard to draw arcs/circles. Radii of 40 - 175mm are supported, with 5mm detent intervals. Extra long, 330mm radius using two arms bolted together has not been tested. Whiteboard markers from 15mm - 18mm diameter have been tested.
Marker holder STL file with supports and bed adhesion is recommended (disable supports/adhesion in your slicer).
To mount the arm, drill/tap M5 or M6 into the base, or just install a M4 (x10) screw (M4 should self-tap).
Small slides for the marker holder may require some minor filing/post-processing.
Cheapo suction cups:
http://www.ebay.com/itm/50PCS-Clear-Transparent-Hanger-Kitchen-Bathroom-Suction-Cup-Sucker-20mm/311566424293?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
| compass_arm.stl | 14.4MB | |
| compass_marker_holder.stl | 12.4MB | |
| compass_marker_holder___slider.stl | 2.7MB | |
| compass_marker_holder___with_supports_and_bed_adhesion.stl | 12.2MB | |
| spinner_and_compass_base.stl | 1.1MB | |
| washer.stl | 78.0KB |
