Actually, that was a great explanation. Which only re-affirmed what I’d thought. So I’m still baffled by how halving my kerf parameter made things so much worse? Those tabs would have had no chance in hell of ever fitting ever ever ever. So now I’m wondering if I didn’t flub the decimal when I’d halved it. It just doesn’t make sense to me otherwise…
The other thing that thread made me think is… “What ever happened to jdodds?”
Yeah. I love this idea. And I have what’s left on this sheet should be just enough.
The kerf for the 1/8 maple ply is running roughly .007 to .01 inches. (Or about 0.25 mm)
Depending on where the beam is focused, either the surface of the material or the middle, it’s going to give a different kerf if you measure at the top of the material or the bottom.
(We’ve got tutorials on kerf in the Matrix. Check out the 2D Vector Programs Matrix or the Laser Matrix.)
Or you can just run a couple of test cases (small ones). If I kerf adjust, I generally just adjust by 0.1 mm ( .0035 inch) using an offset. No idea how the auto-program does it, but if you start with those values, you should reduce the gap by half. If that’s not enough, do it again. Two iterations and you’re probably tight fit.
In addition to the suggestions above, my cut calibration tool is handy for calculating kerf as well as power. The boxes are 1/2" x 1/2" so you can measure the cut out square, subtract from 1/2" and divide by 2. If you scale the calibration by a factor of 2, the squares should be 1".
The other tool I use is a box that is about 1"x1.5". I put another box that’s 1/4"x1/2" centered widthwise but aligned with the top inside the larger box. That cuts a U shaped box that I can use to slide onto a piece of stock. I make the internal box larger or smaller as needed to get the fit I want. I usually do a couple of different sized ones at once so I can zero in pretty quickly. This let’s me use up some of my extra bits & pieces that I wouldn’t otherwise use in scrap from other projects.
BTW, the reason you halve the kerf in the box programs is because you’re getting half the kerf on either side of the line (which is the beam center. The tab is going to be narrow by a full kerf vs the size in the drawing. Likewise the slots will be wider by a kerf than the drawing measurement.
Couple of things i’ve learned as i’ve jumped into this recently as well.
Make sure you’re using the right mode in illustrator, some modes will favor pixels over exact measurments. I found that making a 10mm square often rounded in weird ways until I played around with the art board settings.
Watch your conversions, everyone seems to use inches and the GF works in inches, but i’ve found millimeters to be simpler to deal with in designs. 0.01" is very different than 0.01mm. oopsy. hahah.
I did a small-scale test and, at least for this experiment, telling MakerCase my kerf .0025 gave it a very nice snug fit. So I’m gonna go ahead and give my full box a try again now.
Okay… So now I’m just annoyed… Somehow adjusting the kerf screwed my box dimensions?!
My first attempt, while the kerf didn’t work to allow the pieces to fit together, was the correct dimensions. This one, the kerf is pretty nice, but I lost like .2 in! So now my stuff doesn’t fit in it!
Anybody have any experience with that MakerCase site like this?
EDIT: It looks like the site needed to be refreshed. I’d been playing with it a while and I presumed that as I made changes, they were all applying. Turns out they weren’t. I just generated with the exact same settings and got a different result. So, in the words of President George W. Bush: Fool me once, shame on — shame on you. Fool me — you can’t get fooled again.
most if not all of this could be avoided if we had precision in a kerf and a spot in the UI to put the kerf and then designate waste side or center cut etc… instead of all our fudged designs to compensate
If you tell it to cut a 1" square the laser will remove half the kerf from all four edges. If you measure from one side to the other you’ll actually be measuring the distance remaining after two “half kerfs” are removed.
In other words, subtract the result from 1 inch to get the full kerf width, don’t divide the difference by two.
I love that about Vcarve for the ShopBot - I tell it if I want the tool to run on the inside or outside of the line. That way it will be just the size I want it to be.
Makercase wants the 1/2 measurement though. That’s the kerf they use vs the full kerf you get when subtracting from 1. Probably should have said “divide by two to get your Makercase kerf entry”.
exactly that’s how most if not all cnc’s work. you design your stuff in cad and then when you move it to the machine you tell it the tool’s and the sides . you never fudge your designs because if you did you would break every motion planning element because it would be all collisions
<palmsmack! /> I’ve got one of those next to my 3D printer. I’ve been focused on the caliper math approach – didn’t even think of direct measurement. D’oh!
The beam is 5mm out of the laser, but much smaller when focused. The observed kerf is material, focus, and setting dependent, though, as well as somewhat subjective.
sheet should be just enough.
