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DIY spine tester using a digital scale

LeTuB

Member
Joined
Jul 10, 2020
Messages
86
Location
Toulouse, France
I bypass the background physics theory (refer to wikipedia :eek::eek: ) : Simply supported beam with central load

In the standard spine testers, a known load is applied to the shaft and the displacement directly gives the spine
AceSM203c.JPG



we can use the same principle the other way : a known displacement is applied to the shaft and the measured weight gives the spine :
schematic1.jpg
Result :
pic1.jpg
pic5.jpg
Plans :
I used scrap plywood, a 5/16 carbon shaft, 2 inserts, 2 field point cut to make screws, and a wood screw to tune the distance between the arrow to measure and the head of the screws to exactly 10mm

pic3.jpg

pic2.jpg

some pieces of aluminium to make the arrow support :
pic4.jpg
support on scale side shall be able to slide (use thread glue to block the screw with a little play)



Calibration table :
Cal_curve.jpg

Instruction :
turn on the scale
place the shaft to be measures between the 2 supports
zero the scale
push with the finger in the middle of the shaft until it contact the tuning screw
don't move(!!)
read the corresponding weight on the scale
convert it to spine with the table
 
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