Do it yourself paraglider line measuring device

Note: This measurement device is not a proper replacement for having your wings regularly checked by an experienced inspector. There is more than just line lengths that effects your safety in the air. But having your own measurement device is fun and helps understanding the dynamics of paraglider line lenghts. And it is a great excuse for having a 3D-printer ;-)

The basic idea was to create a device that assists in measuring paraglider lines. The materials are all simple aluminium strips and profiles, cheap bearings, 3D-printed parts and screws. The equipment used are a saw, a machine drill (on stand), thread cutting tools (M3, M5), some files and a 3D-printer using PLA filiament. The 3D-printed parts replace the smaller, more complicated parts which are harder to make in metal.

There are two main parts, the riser attachment ruler with 5kg weight and laser target and the measurement ruler with the laser distance meter. The latter part is optional, but it greatly simplifies measuring.

This is the second version of the measurement ruler part, which replaces the aluminium later meter cage with a 3D-printed part. The attachment to the ruler-trolley is simplified, making the laser-meter a separate part.

Riser attachment ruler

The riser attachment ruler consists of two aluminium U-profiles. The inner one is just wide enough for two risers to be attached side by side. The lines emerge from the other side. The inner profile glides inside the outer on eight bearings, four vertical and two at either side. A wide pulley on the outer profile provides frictionless movement of the line to the counter weight. Four 3D-printed parts connect the bearings to the inner profile.

Outer profile dimensions:
Width 80 mm
Height 50 mm
Wall thickness 5 mm
Length 800 mm
Inner profile dimensions:
Width 60 mm
Height 30 mm
Wall thickness 3 mm
Wength 600 mm

Bearing dimensions (8 in total):
Outer diameter 16 mm
Inner diameter 5 mm
Length 5 mm
Brand 625ZZ Bearing 5x16x5 Shielded Miniature Ball Bearings VXB Brand

3D-parts conencting bearings to inner prifile
counter weight pulley and riser connection

Measurement ruler

The measurement ruler is an U-profile with two L-shaped guards attached, so the laser meter trolley movement is restricted to one dimension; forwards and backwards. The 3D-printed carrage has bearings pointing in all dimensions perpendicular to this measurement axis.

The L-profiles are screwed with five Phillips flat head M3 screws, approx. 25 cm apart.

The center plate is connected by four M3 screws to the 3d-printed laser meter carriage and the basis for the Laser meter cage (this is an old version of the cage).

The line attachment point and handle are attached directly to the base plate. The prototype has a laser meter cage for the Leica GeoSystems D110 device. This device is Bluetooth enabled and can insert measurement data into a spreadsheet (on Windows 10, with a special driver installed. Alas not yet with Linux).

Measurement profile dimensions:
Width 50 mm
Height 30 mm
Wall thickness 3 mm
Length 1000 mm
Measurement ruler L-profile dimensions:
Width/height 10 mm
Wall thickness 2mm
Length 1000 mm
Measurement ruler center plate:
Width 30 mm
Length 120 mm
Thickness 4 mm
Bearing dimensions (12 in total):
Outer diameter 10 mm
Inner diameter 3 mm
Length 4 mm
Brand 623ZZ 10 Bearing Shielded 3x10x4 Miniature Ball Bearings VXB Brand

Laser meter in cage on ruler
Bearings inside laser trolley

3D-printed parts

The zip contains both the STL and the original SCAD files. The files are created with OpenSCAD and slized with the Prusa version of Slic3r. Printing is done with a Prusa i3 MK2 printer.
highTwoWheels5.scad - attached to the inner riser attachment ruler. Two bearings are attached; one horizontally to the side and one vertically to the bottom. The latter uses the separate axis1.scad part.
axis1.scad - a 5 mm cylinder to be pressed in the highTwoWheels5.scad part.
laserTrolley3.scad - The laser trolley connects to the bearings on one side, and the base plate on the other side. All bearings are attached with M3 cylinder screws. Threading is cut onto the holes. The red bits are some of the bearings, not to be printed.
laserCage.scad - The cage for the Leica D110. It is separately of the handle/line-hookup-point attached to the base plate, so can be replaced by another laser meter device (with custom cage).
backWheelPlate2.scad - attached to the end of the outer riser attachment ruler profile to provide overhang for the counter weight pulley.
measureRailStopPlate1.scad - cosmetic plate to close of both ends of the measurement ruler. Prevents the trolley from escaping.
pulleyFiller2.scad - fills the space between the 16 mm bearings and the 18 mm (inner diameter) tube and keep the bearings in place.
targetPlate1.scad - the laser target plate
targetHolderPinch2.scad - the part connecting the inner riser profile and the target plate. It is padded with thin black rubber (actual bicycle inner tire, glued with super glue).


Inspiring video's and information online, 2018-11-03