Let’s say I have two rectangles to cut and I “snap” them right next to each other (left and right), for the purposes of turning on “Cut Optimization Settings” → “Remove Overlapping Lines”. At the same time, I also want to set the Kerf size, so that the cut out pieces are 100% precisely the size that I’ve set.
My understanding is that the top and bottom sides of the rectangles, as well the left rectangle’s left side and the right rectangle’s right side, would be offset with half the kerf (actually I am not sure what the math is). What would happen to the middle side, that is “shared” between the two rectangles? How would the kerf be interpreted, since we’d have a single cut over there?
TL;DR; If I set Kerf and align two rectangles and remove overlapping lines, would they turn out to be 100% the exact size with Kerf accounted on all sides.
“remove overlapping lines” does not work when kerf is assigned, it is practically not possible.
The edges that lie against each other will overlap by the amounts that your kerf is set to.
It actually works. But you need to do the math yourself. And it would only works for rectangular objects.
You can have two objects with kerf setting enabled. If you now overlap them as much as the kerf reduces the size again, LB will remove the overlapping lines. So if you know the beam size very well and can compute all values, it’s no problem to do so.
Take this example: both boxes have an inward kerf of 1mm. I then overlapped them by 2mm. The resulting cut removes the overlapping lines. So, LB first reduces all shapes to the desired sizes and then checks for overlapping lines.
Minor addition: no, the kerf value is used as the total value. If your kerf offset is 1 mm, it will offset all lines by 1 mm, not 0.5. So, you calculate your beam width and use half of the beam size as kerf value.
Just because it is possible doesn’t mean it has to be correct/practical.
Kerf is primarily (only?) used to make the appropriate connections between 2 interfering objects/shapes, where both parties must fit more or less tightly.
If there is someone who uses Kerf for something else, it would be interesting to hear.
If you have 2 “plates” it is pointless to add an extra function that is not even suitable for that.
If you have 2 shapes (as you draw them) they should just have the plus or minus value assigned to their nominal size.
Ie. 100x100 which is desired 100.2 should just be processed with these values - 100.2.
The advantage is that you can in this way put all shapes with a straight side together that you want to use “remove lines” without detours.
Kerf is meant to compensate for the laser beam size. It absolutely doesn’t matter where it is applied; connections between two objects is one (small) use case. You gave the example: if you want to cut an object exactly at 100x100, you have to draw it exactly this size in LB. Then you will add a specific kerf offset for each laser you use. You should never draw it at 100.2x100.2 because you know that the outcome (at one particular laser) is 100x100 then. Because as soon as you switch the laser, all drawings will not work anymore. That’s why you design each drawing at exact sizes and use kerf offset to adjust it to the laser that is cutting it. Slots and tabs are one use case, but boxes, lids, adapter plates.. are all examples where you might need exact dimensions.
Of course, my use case doesn’t really make sense; absolutely true I never came across such a requirement, but it’s possible; that’s what I wanted to show
Not here, I want a square 100x100mm or a circle ø100mm, then I draw and cut them at their nominal value, I never use kerf settings for anything other than press fits for finger joints and the like, when needed. My kerf is usually set to 0 to avoid errors on “normal” items.
I have been making boxes all day today again, the ones with the little wedges instead of finger joints, the inside dimensions of all boxes must and are measured and checked to 100mmx100mm.
Whether I’m just not meticulous enough I don’t know, my kerf is relatively small, 0.1 mm or less, which is 0.1% of 100…
Hi Melvin, I would like to have the option to exclude individual parts/sides of a shape, to be able to use “remove overlapping lines” anyway, it would save me some material. But I quickly realized that it is technically too complicated for LB to integrate this option. For example, as we know, shapes must be closed to be able to use the function, that alone makes the “desired” difficult/almost impossible or complicates the function too much for normal use.
Thanks for a good discussion/exchange of thoughts, that is what I miss a bit here on the forum in recent years. It is not about “who is right” for me, I just enjoy the exchange and the opportunity to learn something new or revise my ways of doing things in/with LB.
Same here I’d say I use kerf only once in half a year Usually, I don’t care about slightly loose slots and tabs either. Some glue will fix it I mostly only use it if it’s a big project where manually adjusting all connections is too much effort.
As you said, in most cases, you won’t ever notice whether the cut is 100, 100.1, or 100.2 mm.
