# Why does small text burn through the wood

When I have small text and smaller vectors, and I have the speed and power settings the same as I do for the larger vectors that engrave just fine, the smaller text and vectors will actually burn clean through the 3mm basswood. I’ve even tried reducing my power to less than half the normal setting that I normally use, and it still goes all the way through. For example, I can engrave a large vector at 10000mm/m @ %90 power, but when I try to engrave text at, let’s say, 10mm height, it will burn through the wood; even when I set it at %35 power. What am I missing about the speed and power settings?

Try driving 100 miles an hour in a parking garage and you’ll have the basic idea - The laser simply doesn’t have room to accelerate up to the speed you’re asking for. If you’re using constant power mode, the laser will burn more when it’s moving slowly, and small details mean it can’t move full speed.

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I love the analogy because that makes perfect sense to me now.

I use a similar one when explaining to people why engraving faster sometimes takes longer, so I’ll include that here:

Drive 10 feet, at 5 miles an hour, but include the amount of space you need on either side to speed up and slow down. Most cars can accelerate to 5 mph in well under a second, and braking from that speed is nearly instant. The actual 10 feet also goes by pretty quick, since it’s only about 2 thousandths of a mile, so it takes about 1.35 seconds, plus the bit on either side.

Drive that same 10 feet, now at 100 miles per hour, and again, include the space you need on either side to get UP to 100, and back down again. The current fastest production car in the world, a Tesla Model S Plaid, will go 0 to 100 in 4.3 seconds, and braking time from 100 to 0 is about 4.5 seconds. The 10 feet goes by in an eyeblink, but the acceleration and deceleration time means that it takes almost 9 seconds in total from 0 to 100 to 0 again, and that’s excluding the driving time.

If we change the distance from 10 feet to a mile, things look a lot different - Now it absolutely makes sense to drive faster, because 1 mile at 5mph takes 1/5th of an hour, or 12 minutes, and you cover that same distance takes 36 seconds at 100 mph.

Most people assuming “faster engraving takes less time”, which can be true, but isn’t always. You have to be covering enough distance to make it worth getting up to speed.

I realize now that the marketing hype about being able to engrave at 54Kmm/m is all just selling points, because at that speed @ %90 power, it barely makes a mark. So, is say 20Kmm/m too fast? The only reason I ask is because I was engraving at 10K, but after doing a material test, I started using 20K.

60,000 mm/min would be 1000 mm/sec. Which is very fast, even for a CO2 laser. The head on a diode laser is heavy so getting it UP to that speed will take some time.

The only way to know when you’ve gone too fast is to try it. If it’s not given you the depth or darkness you want, and you don’t have any more power to give, your only option is to slow down, or use a wood treatment like borax or baking soda.

That makes perfect sense, and I do like the deeper engrave at 10,000mm/m @ %90 and I also like the lighter engrave at 20,000mm/m @ %80.

The other factor is doing a large area, the heat disipates at the start of the vector before you get to the end of the vector (say a circle). Where it meets, it again cool when the end meets the finish, get small and the entire area near start when it gets to finish will still be hot. Remember it’s all about how much heat is absorbs (and retained) that allows the laser to burn. It’s why not all lasers do all materials – its what the material absorbs on the diodes wavelength.

Small text, close together. You’re staying too long in one place.