DIY Goniometer.. does it work?

[bucketstove]

I'll post here if I end up with one that works for more than a few days lol. The laser build quality must make a huge difference. I'm just buying mine from Amazon and the really cheap ones were junk. The Crimson Trace lasers on their pistol/revolver sights just work great and are reliable. They do use some type of button battery too.

Heh, yeah the pen/stylus laser pointer disassembles itself in short order

 

[bucketstove]

laser button/switch exposed
small "v" notches for every 2.5 degree angular change. Larger notches are 5 degree increments, with smaller notches at 2.5 degree increments in between.

Alternatively, I can make and print a scale on a piece of paper (I designed the goniometer to have a circumference that equates to 1mm for every 2 degrees of laser deflection so making a paper scale should be easy enough. I think I prefer the notches in the plastic to a paper scale, because they can never get dirty or get damaged.

Total size will be about 12.5cm x 12cm.
...
Any thoughts or inputs from you guys, feel free to comment!

Hi,
My first thought upon seeing the full sized pictures is, can you make it into a whistle?
Or better yet an ocarina flute?

A binder clip should grab onto blade about 5mm-10mm deep
If the goniometer can accept a binder clip,
for example 1-3 slits on the bottom
so the gonio sits on the binder clip,
leaves one hand free to take a pictures

Notches are good, but what about vertical grooves as well?
like grooves on a speed/rafter square, that user can fill in with crayon?

Classic hack for a laser pointer is a zip-tie as an always-on switch.
You could have always-on by pushing the laserpointer slightly forward,
or add a left/right slide button to depress the laserpointer button

Why circular instead of boxy? Makes each degree equidistant, but is that important?

1mm for every 2 degrees? Thats a small circle
Given circumference (C) = 180 says that makes diameter 57.295779513082,
shouldn't that be diameter be 120mm making 1mm for every 1 degree or?

If you dont taper the handle , if you use a lip as a handle, you can expand the radius,
but yeah moving parts are complexity

with 3 telescoping parts it can collapse by half

 

[777 Edge]

1mm for every 2 degrees? Thats a small circle
Given circumference (C) = 180 says that makes diameter 57.295779513082,
shouldn't that be diameter be 120mm making 1mm for every 1 degree or?

Close, but not quite. It's actually a radius of 57.3, not diameter.

You have to remember to take the reflection angle into account of the laser beam onto the side of the edge bevel.

A 90 degree reflection of the beam equates to a 45 degree edge angle on one side, not 90 degrees. So, this equates to 1mm deflection for every 2 degrees.

Think of a mirror and a laser shining into it at 45 degrees, the deflection angle of the light beam is 90 degrees with the mirror angled at 45 degrees.

 

[d.cutting.edge]

Right, I spent some time on this over the last couple days to finish up a design I started about a year ago. This thread made me revisit it!

Here is what I have come up with so far. I'm planning on using a mini laser pointer which I've designed a slot for (in the handle of the goniometer). I plan on sliding the mini laser pointer into the slot with a tight fit, and having the laser button/switch exposed in the recess seen in the picture. Your knife will then be held in the "V" slot with the edge facing the laser, and you should then see the edge angle reflected on the scale at the top. I've designed small "v" notches for every 2.5 degree angular change. Larger notches are 5 degree increments, with smaller notches at 2.5 degree increments in between.

Alternatively, I can make and print a scale on a piece of paper (I designed the goniometer to have a circumference that equates to 1mm for every 2 degrees of laser deflection so making a paper scale should be easy enough. I think I prefer the notches in the plastic to a paper scale, because they can never get dirty or get damaged.

Total size will be about 12.5cm x 12cm.

If this works well, maybe we can eventually sell a VERY affordable goniometer on Gritomatic... TBA.

Any thoughts or inputs from you guys, feel free to comment!

View attachment 1773433

View attachment 1773432

Would there be a way to adjust the laser position? Or is that not necessary?

 

[777 Edge]

Would there be a way to adjust the laser position? Or is that not necessary?

I'm planning for it to be a tight fit, and assuming the laser is in the center of the pointer then it should be nicely centered.

 

[d.cutting.edge]

Yup, it works.
A dollar store laser printer works well enough
However, it does require some uniformity to the finish
... I did a rough hand regrind on a chef knife,
and there is too much scatter to get a reading from the sides of the blade


Speaking of vertical edge reading, lots of links here
jasonstone20 makes basic verhoeven version Re: Making Your Own Goniometer: How To?

Turns out it has another name
The DILAGON: a DIY laser goniometer
square box version cyrano-dilagon-20-pdf.pdf

Speaking of 3d printing, binder clip on version, ~$3 dollars
https://dschep.github.io/imgur-album-downloader/#/xTma1cJ
imgur.com/a/xTma1cJ
... ... ...

B bucketstove I followed your links. Really good stuff out there. With what I have on hand, and no 3D printer, the Diligon square box version was very easy to set up and try. All I needed was my laser pointer and the pdf.. printed and folded. Thanks again.