3D (2D) scanning of propeller profile

[FinnFlyer]

Trying my luck on this forum.
Looking for help with DIY 3D scanning software.

I have an somewhat unfinished wood prop from 2007 that is rather grossly out of balance. Requires some 60 grams (more than 2 oz) on a prop bolt near blade to get somewhat in static balance. It's lso out of balance at right angle to prop blade axis. If I got it right maple weighs about 0.4oz/cu in. So I need to remove something on the order of 4 cu in on and near the heavy blade hub. I realize that the shape under the spinner is not aerodynamically important and I could just drill a 1/4" hole and fill it with carbide rods. However, seems like a band-aid solution, not handling the root cause of the static imbalance.

So my idea is to mount the prop on an old PSRU (reduction gear drive). Mount a DIY 3D scanner (see attached picture -- less turntable) on a bar above one blade. Take a profile snapshot, rotate the prop 180 degrees and take a new snapshot of the other blade. Comparing the two pictures should clearly show the profile differences on a 2D plot on a laptop at the chosen prop radial. This can be repeated along the prop blade, from hub center all the way out to the tip, by moving the 3D scanner a bit on the bar.

I should then be able to grind and sand down the heavy hub side and prop with confidence.

So, does anyone have experience with DIY 3D scanning software and can point me in the right direction?

I've searched for USB camera data output format but not found any useful hits. Basically I need to subtract or compare two pictures, isolate and measure distance between the two laser lines.

Finn

[Freemasm]

Can you rent a white light scanner where you are? This would probably remove a lot of uncertainty.

[FinnFlyer]

Originally Posted by Freemasm

Can you rent a white light scanner where you are? This would probably remove a lot of uncertainty.

Probably not. Looking at their prices I expect rental (if even available) will be well over my $100 budget. I ordered a package of 5 line lasers for $13 (just need two). Already have a 640x480 USB camera. I can get a higher resolution camera for $25 or less, if I don't want to use my 4608x3456 Panasonix Lumix camera. Looking for USB camera prices just now led me to the OV2640 Chip, a 1632x1232 B&W CMOS camera chip that looks promising.) Not looking for more than 0.1 to 0.2mm accuracy.

Finn

[Freemasm]

Then I would definitely do some validation scans on some objects with known, precise dimensions. Articles with compound curves would be even better. The set-up you're doing is beyond my experience, That said, a thorough validation plan would be essential to gaining enough confidence (for me at least) to apply any proposed remedy. Keep us informed. Best of luck.

[FinnFlyer]

Just came across and installed this:
https://imagej.nih.gov/ij/

Can subtract two images:
Open the two images (File |Open)
Process | Image calculator ... , select Subtract
or
Process | Image calculator ... , select Difference

The amount of functions in this program is stunning!

There a batch or macro functionality which I may be able to use to get prop profile differences automatically. We'll see.

Time to start building jig to hold line lasers and camera.

Finn