Trotec Speedy 400 Cut Issues

[John Breznicky]

Hey Guys! I've been getting quite efficient with my speedy 400 over the past couple months but I have had continued issues with cut settings. The material I am having trouble with is 6mm (1/4") blatic birch ply. As a point of reference, I also have a 50 watt epilog which cuts this material with ease. My speedy 400 has an 80 watt tube, so significantly higher wattage than the epilog and I am struggling to have consistent full "blow through" cuts. what's odd, is I have noticed that settings my z-offset to about a 1/16th or 1/8th" in the negative direction when cutting (closer to the lens) it will cut through the material much easier and have a much finer stroke and cleaner cut. This seem illogical to me because it is essentially taking the laser out of focus. It almost seems like when I'm focusing using the focus tool that the lens is too far or out of focus from the material.

These are the settings I'm using on baltic: 100 power/ .4 speed (which seems too slow for this material)/1500 hz. I clean the main lens and mirror daily. I'm using the stock 2" lens. Any ideas would help, I'm sure I'll get to the bottom of it, but I'm crowdsource brainstorming :)

Some possible scenarios I have thought:

1: they sent me a 1.5" lens instead of a 2" lens, but I have no idea how to test, lens carrier is black like it should be for the 2"
2: faulty lens, again I'm not sure how to test

[Kev Williams]

If you move the lens out of focus AWAY from the material you're moving the focal point above the surface of the material. In this case the focal point has "come and gone" before the beam reaches the material, and the beam just gets bigger the deeper you go. But moving the lens closer to the material, you're moving the actual focal point closer to the BOTTOM of the material. The beam is slightly wide at the material's surface, but is hitting sharp focus somewhere between the surface and the bottom.

I know nothing about Trotec's, but I have found in my years with lasers that focusing is not an exact science, and sometimes the best results come with changing the focus more than I think I should have to...

[Morris Mac]

Hello,
in an engraving process you need to focus on top of the piece that needs to be engraved so laser spot size is the minimum, if you move your z axis out of focus spot size of laser changes. In engraving process laser is pulsating you see small dots.
In a cut process laser is modulating frequency one continuos beam is where you select HZ and you need to focus inside material not on top like engraving. Now 2 inch lens is a good all around lens but for cutting you will need a higher focal lenght which gives you a longer depth of field. If your focus tool is not adjusted correct you can measure from bottom of you lens to the material that you need to cut make sure is 2 inch, lens should be inserted with flat part towards bottom and curved side on top.
Make sure you have a good vacuum at bottom material that've been cut need to exit some place. Also a good exhaust is needed usually wood generates a lot of smoke that can affect laser beam quality. Your settings sound about right you should experiment with higher frequency that usually give you a nice edge. make sure your wood sit flat on table if you have high and low spots your focus is changing.

[Allen Rawley]

The 50 watt Epilog is probably equipped with a different capability RF laser (there is more to consider than average power).

The Coherent G50 in the Epilog laser has a higher peak power than its average power. Again, the average maximum power of 50 watts is less than the peak power if you set it to pulse. See the example specification below for the G-100 from the Coherent G100 OEM manual. The peak power is 250 watts for the 100 watt average power laser. The benefit of using the G-series lasers on wood is that the peak power provides less charring and a better cut through wood. This also is true for the GEM series and DEOS lasers.

The 80 watt in your Trotec may be a Synrad brand lasers. In the case of these lasers, the maximum power is the average power. In other words, 80 watts is the maximum. See the Firestart T60 specification from the Synrad T60 manual (it lacks a peak power line item).

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Regarding the lenses, see the nice graphic below from the ULS folks to explain the lens cut capability:

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[Mike Null]

I would guess that the Trotec tube is ceramic and not Synrad.

[Morris Mac]

Well put and done !!!:)