I found these artists pallets on clearance for a buck each and they must be made of iron in the middle as they are tough to cut! I was eventually able to get through them, but gave up doing it without charring. I think it’s really dense mdf type stuff in the middle.
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I just tried cutting through .25" Bolivian Rosewood. It took 3 passes at 100%/4 (the slowest it will go) and there will still a couple of tabs of wood holding it together. It definitely depends on the material you’re cutting.
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Also try focusing 1/2-way through the material instead of the top surface. That puts the narrowest part (highest energy/heat) of the beam in the middle of the material.
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Oh, this makes me wonder if stepped focus would help with stubborn material?
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It might but you’ll need to resend the job between passes specifying the different focus height instead of using the GFUI’s # of passes setting.
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My experience with stepped focus (not very great thus far) is that it may help you get deeper, but not in a simple way. If you start out focused below the surface of the material, then your power/area isn’t as good at the surface, so you don’t cut as deep initially. So need more passes. If you do a first pass focused on the surface, then a second pass focused further down, a lot of the beam hits outside the kerf and doesn’t get down to the bottom to deposit energy. You have to open a good path for the beam first.
Here’s something I will probably try next time: initial pass with a double cut line about 0.5mm apart (that’s about the distance for me with cheap ply where the wood between the lines glows and consumes most of itself); then a second pass with focus at the bottom of the hole. If the whole thing doesn’t catch fire it might work pretty well.
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ya at some point we are supposed to have continues focus so that should resolve the issue you describe
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Oops! (was referring to adjusting the focal point.)
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There is no real disadvantage doing N passes N times faster because it takes the same time and uses about the same tube life as it is depositing the same energy in total. I think it chars less because there is less time for the heat / burn to spread sideways. My limited experience is that it actually cuts deeper. I think that is because there is less char and / or smoke to obstruct the beam.
With a 1W beam I can’t cut through 2mm of balsa in a single pass no matter how slowly I go. The char just gets wider and wider. I can cut through cleanly with four relatively fast passes though. This is with all passes focusing on the surface.
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I all depends on how big the auto focus area is. I’m not sure it will be able to focus on the bottom of the cut. My guess is that it would still focus on the surface. @dan do you know if this would be possible?
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Be careful with rosewood. It can be toxic. I always wear a respirator when sanding it, I can imagine that inhaling the smoke can’t be too good for you.
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I cut through 1/4" all day with my 30 wt too…lol
Havent tried thicker wood…I know I cant do thicker mdf.
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Thanks, I’ll keep that in mind. This is the first time I’ve used it.
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Awesome to see a production basic pull that off!
BTW this might go well in the “Beyond The Manual” section.
So I’m just going to bump it over there.
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the original surface, or do you measure each pass and refocus on the new “surface?”
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The original surface. I don’t have a way to measure the depth of the trench on the fly but I do have three point surface measurement that I fit a plane through and focus on that.
If I know it takes four passes to go all the way through I could assume each pass is 1/4 of the depth and move down by that much. However, I am not sure whether focusing lower would help. It depends on the width of the trench relative to the cone of the beam. When you focus on the surface all the beam passes through the slot you make at the surface and then spreads out below, reducing in power density. When you focus lower potentially some of the beam cone is clipped by the edges at the top of the trench, so you have less power available at the focal point below.
These are questions I aim to answer but unfortunately I destroyed my laser diode with a reflection, so I am waiting for a replacement to arrive from China.
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i knew this but didn’t think about it; it’s an interesting point and i wonder how much it affects the actual cutting.
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My perception is the convergence of the beam begins as it exits the lens, so it is a tall narrow cone to the beam waist or focal point. Seems the beam clipping would be minimal.
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