The DILAGON: a DIY laser goniometer

[Petter]

I present the DILAGON 2.0, with a linear scale and no assembly required -- just print and fold:

Wonderful project.


(Not to disparage anybody if you were in doubt but) May I suggest a 3D printed version of this including knife guide like the CATRA device?

I will soon have a working 3D printer and might be able to help with development. I am not great at 3D drawing but it should be fairly easy to make something like the CATRA hobbyist device. It shold be possible to print the angles directly on the target surface, but I still prefer the paper/laser printer method.

Might also be a good idea to standardize on a laser. If visibility is a problem, it is always possible to try using a stronger laser (remember to use safety glasses of the correct type for the wavelength in question).

It might also be useful to find a way to make some simple calibration devices (I think of this more like a verification device since the unit should not require calibration for the accuracy needed). Perhaps a simple prism with some 3d printed adapters to set up a few points of verification - especially at the points of interest for that particular sharpener (for me probably 15degrees each side)?

[Mike Brubacher]

Sounds like a worthy project and welcome to the Exchange Petter! Please keep us informed and thanks for the post.

[grepper]

Yes.  Welcome to the Exchange and thanks for your post.

That seems like a cool project especially since you will soon have a new 3D printer.  Considering this post has over 10K views there is a lot of interest in it.

One thing about having your own printer is the ability to do rapid and inexpensive prototypes.  Having prototypes made is usually costly and time consuming even if you can find a company willing to do small runs.  Having your own printer significantly mitigates those concerns.

The least expensive portable CATRA goniometer model currently sells for $625.00 on the CATRA web site!  That’s a lot of room for duplicating its functionality far less expensively, especially since it’s just a plastic ring with a laser and lasers are pretty cheap if you shop around.

I’m sure there are a lot of considerations around calibration and design, but that’s what makes it a really interesting and fun project.

Please keep us informed as your project progresses.

[chino]

Interesting to say the least... Might have to try this.

[150cc]

Exactly what I was looking for, V2 is perfect !

[Petter]

Seems someone beat me to it. There is a kickstarter at $40 https://www.kickstarter.com/projects/las...sharpening , but at that price since I am outside the USA, I would rather consider Vetaco, particularly the Master at Euro 100, but they also have the Pro at Euro 60.

What I like about the Master is the dial can rotate, and the adjustable magnetic knife holder. Wow. https://sharpeningtool.eu/en/catalog/accessories

Then again, the Dilagon2, anyone can make so great work on that Hats off.

Oh just one thought - it seems focused laser beam might be a better illuminator. These do not cost much. Also lasers are usually slits (light up a small rectangle) so might be worth considering aligning it so that the slit is narrow on the blade. Then again what do I know!

Regardless, when I discovered Vetaco for this function, CATRA basically was blown out of the water for me.

[harilaos]

I present the DILAGON 2.0, with a linear scale and no assembly required -- just print and fold:

Hi Mr Cyrano, the dilagon printout is fine, but in the dilagon 2 printout when I measure the distance of one centimeter I measure 1.2cm, that's how it should be, or is it a mistake?

[WI_Hedgehog]

(not related to medical or precision cutting instruments)

I agree the bevel angles are likely not equal and think the best way to do this is to mount the knife/blade in a quality fixed-angle sharpener and set the laser in a holder at the same height as the center of the holder. A flat scale can be fixtured/mounted behind the blade holder and then things are consistent.

I put a TSPROF K4 on a granite work surface so for me the setup would be fast and simple. Doing this with a Lansky sharpener would not be so fast or simple, but then again Lansky or free-hand won't hold an exact angle, so there's not much point in using an accurate measuring device on an inaccurate edge--for hand-held (or Lansky) sharpening "close is close enough."

Much less messing around is mouting the blade and using a marker to blacken the cutting edge, then use a polishing stone to find the angle that removes the marker. This works with a non-exacting sharpening method such as free-hand or Lansky. I like the marker method better because it can be used to show the defects/variations along the whole blade edge instead of one point and that's valuable with convex and non-consistant edges.

Variations in sharpening angle can come from inconsistent hold angle (like when moving across an edge to sharpen the length of the edge free-hand), short arms sweeping across a comparatively long blade (Lansky), or using multiple arms that aren't all at the same angle (Lansky). Convex angles can come from free-hand sharpening and similarly from fixed-angle systems that have movement to them, both causing multiple angles to be ground while sharpening resulting in a convex edge.