I’ve recently happened across AT from CNC at Home on YouTube, discussing kerf settings. This link takes you to his video, a well done explanation on a par with that from LightBurn on the support pages. His work is under-appreciated, in my opinion, as he creates clean, easily understood material and deserves more exposure.
His video discusses the fact that diode laser beams are not clean circles and instead are a wonky rhombus, which results in different kerf settings when the angle of the cut is changed. It’s especially a concern for the diagonal cuts, but there is also a difference along the ninety degree cuts as well.
When one is making a tabbed box, two of the sides are at one of the ninety degree alignments, while the other two are rotated by ninety degrees, of course. I had thought that one would break the box into the four sides and apply the kerf to each segment, until I saw the notice on the support page that the kerf applies only to closed shapes. That means this approach doesn’t “cut it.”
The support page also notes that the kerf is not applied in a visual manner, which means one cannot see the shift in the component in the workspace, but does apply in the preview.
With the change in kerf across the four directions, the result would be that one could have fairly tight joints in two of the panels and not quite the same for the other two. One pair could be perfect, while the other pair would be either less tight or more tight.
Is there an approach or workflow that would enable the optimum kerf settings to be applied to a tabbed box layout?
There are some big obstacles in the way of achieving what you want.
First, the oblong square is not the same for 2 lasers, in size and also in angle. If the shape of the laser beam was always, for example, in ratio 3 to 4 and exactly at 90 degrees, you would be able to make exact corrections for it, but unfortunately it is not.
You have also noticed that a shape must be closed in order to assign kerf. It is actually quite logical, because how would you assign a kerf to a separate line? , it is a bit the same problem as when using the offset function.
I have tried to find an average value for my diode laser and used a little extra kerf to compensate, but it is of course not optimal even though I have made quite a few boxes this way.
So, in my experience, a diode laser is not the optimal tool to make precise kerf connections with. The fact that more passes are required when using thicker materials does not make the task any easier.
If you have the room, turning your work 45 degrees will give you a consistant kerf size. You will need to test, as always, to determine what that size is. This only works with straight 90 degree lines. It will not work with circles or odd shapes as those cause the kerf to vary depending on where they are along the path. Hobo With Wood Youtube channel has a good video explaining this problem and the fix.
…unfortunately only for the diodes that are placed exactly 90/90 degrees in the laser head, mine has never been. But, my 5Watt laser is also a few years old, hopefully it is different today.
No Tim, unfortunately I think my laser beam comes out about 10 degrees distorted, in multiple mirror/laser systems they should be more precise and aligned with the laser housing, I think.
Do you think rotating the kerf test project (and the workpiece, if desired) in a series of various angles would determine a suitable operational angle if not forty-five degrees?
I have a currently static/idle Emblaser 1 machine and I recall noting a non-circular laser dot. I had purchased a filter that allowed me to view the beam with sufficient attenuation to be better able to focus and also see the shape.
Absolutely, I could “construct” myself out of that problem by rotating the subjects. But in the long run it’s too cumbersome and an extra step in the workflow.
It’s only a small 5Watt diode which is not suitable for cutting the material I use most, so it hasn’t been a real problem for me. I also don’t like using multiple passes to cut through material, in my experience it has a bad influence on the result. The right tool (machine) for the right job, that’s my way to go.
My wife and I are despicable hoarders and can rarely find items when needed. I was certain I was going to post that result, but in the last location I searched, I found it! Of course, that’s the logical development.
There’s no record in my financial system of the purchase and no record of having purchased it from Amazon, but I found a matching link on Amazon:
The one I found/own has a Fotga legend on the rim, as well as the adjustment markings shown in this image. Price on Amazon at this moment is twenty-five American dollars (Prime)
The indexing is not mechanical and the ring rotates three hundred sixty degrees, implying that the frequency blocking is accomplished via polarization.
I have sometimes given up searching for a Thing I know I have and buy another one. I’ll then put the new Thing away in its Right Place, where the old Thing looks up at me with a smug expression.
I had my laser pop an air fitting, with the resultant flinging-about sound inside the cabinet. I knew I had a bag of them, unable to find… purchased another bag (about two or three weeks ago) and yesterday found the previous and current sets. Same thing now with stick-on measuring tapes. I have one unfound, purchased a set of two more, can’t find them now!
Got my filter today. That thing can seriously block some light. Considering how well my machines cut, I do not expect to be able to improve the focus much.
Thanks for the lead. I had to buy myself something for Christmas!
