24/08/2026
Ok so 4" is good for 40mm/s across the entire table, but bu**er all else, I think we've found the sweat spot when it comes to carpets and underlay cutting, 2" 18mm GaAs Plano convex, set to 0.6mm below the optical point on my fully floating, self-levelling pneumatically controlled head.
With the 2” in testing, I’m hitting 80 for Tufted and 60 for Hessian and 200 for Auto velour, not that’s I’d cut at that speed coz of inertia issues, but 100 is fine for AV.
Last thing to try is Felt (underlay) normally 40 or 50 depending on the day, and Tufted with Felt glued to the back too, usually around 25/30. Both I’ll be playing with this week.
The issue I suffer with, that those with slimmer beds don’t, is beam divergence. My bed is split into 500mm quadrants A, B, C & D columns, and in D+ which is around, 1900 to 2000mm the Galician curve is so different, the intensity falls off and this is where getting the right lens comes into play. What I’m after is a consistent mm/s across the whole table coz at the mo, I reduce D by as much as 20%, which isn’t too bad for parts running up the bed, but often, I cut across the bed which means that speed reduction is carried through to A, B and C as well.
Had high hopes for the 4” due to what the paperwork and software showed, but sadly no.
Nothing beats a real-world full bed cut, as that shows all the good and bad points, testing is done at the control panel end, so even though I have all those numbers above, not likely to hit them when actually cutting.
But the best cuts are not the fastest, as what you save going fast, you then lose in the cleanup. An ideal cut is to be able to pull everything out, leaving the waste behind.
So that’s the sweet spot I’m after, and as carpet backing from the same supplier can be so varied, especially under a microscope and in particular Hessian backed, it degrades the beam, even before it pushed through, due to its complex build and glue amounts, but worst is the air pockets.
So far, after 4 years of head redesigns (lost count after 27), 3 different laser tubes (1 Vevor 130w B grade and 2 identical (but not) SPT 150w A grade), lens materials, lens types, orientation swaps, it’s come down to one, a GaAs Plano Convex lens, so let’s see if I can now run at 50mm/s across my 4 by 2m table consistently on all carpet and felt, without issue and zero clean up time. Only time will tell.
Josh
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