New SF-A9 unable to focus

I finally got my new Sculpfun SF-A9 out of the box, into the its new enclosure and fired up.

Disappointing results for the first few tests. It’s not cutting nearly as well as expected. The finest line I can engrave is about 0.4mm wide. I’m thinking the laser module is out of focus. I tried an incline test. there is no noticeable difference in line width on plywood +/-3mm of focus. I don’t have any aluminium business cards to do a proper incline focus test. So far I’ve only tried the 20 Watt mode at low speeds.

Cuts are not much faster than I was doing with my old Sculpfun S10. Smoke stains are really bad, both when cutting and engraving. Also the engraved lines are brown rather than black and the edges are not as sharp as with my S10.

I’ve had a Sculpfun S10 for 18 months and have used it extensively. It’s not something obvious like a dirty lens, or a wrong height adjustment.

Are there any SF-A9 owners out there who can help me out.

I also have both. And yes, it’s true, the beam size of the A9 is really bad if you are used to the S10. But that’s the case with all high-power lasers. Up to 10W the diodes are phase coupled and create a narrow beam. More diodes create the beams next to each other and extend the beam size. Here are some examples.

Since the beam size is so much larger, there is more material that is burned and therefore more smoke stains. I use the A9 only for quick and dirty cutting projects and the S10 is still my main laser for everything that needs detail.

Many thanks Melvin. For this question in particular and for you wonderful wiki site. I’ve read just about all of it.

I ordered some black anodised aluminium cards to do the LaserGRBL test patterns. Then I found some 25 mm X 25mm black aluminium tube. It’s just big enough for the test pattern, but the surface is a bit uneven because of the extrusion process.

I ran some tests at 20 Watts 60% power 1000mm/m, and I set up my S10 and ran the same power and speed values. The S10 results were similar to yours, my SFA9 results were slightly better on the 20W mode, a bit worse on the 40W mode. I’ll repeat them with better materials next week.

The stated beam size of the S10 is 0.08mm and the SF-A9 is 0.1 mm (in the 20 Watt mode). Unfortunately the resulting line is not 25% wider, it’s more like 300% wider.

So far I’m not a happy customer. Most of my designs are not engraving correctly. Lines are too wide, contrast is too pale, too much smoke stain and cuts are not much faster.

I was planning on converting the S10 to a dedicated rotary engraver. I will need to rethink that plan.

It is possible that little gadget on the side of the laser head is not the true focus depth. Try making a series of 25mm circles with the lowest power possible and moving the head up or down in steps. I think that screw on the back is 1mm/rotation, but not positive. I do not have anything that can accurately measure it.

I have the S30 Pro and SF-A9 machines. I call one the scalpel and the other the chainsaw. A .15 or .1 mm dot can’t do the detail of a .06x.08mm dot.

That’s the usual problem with advertisements. Nearly all the advertisements I saw from any manufacturer state beam sizes of around 0.1mm for wattage far above 10W. In my opinion, that’s just more or less physically impossible in this price range of lasers. There is NO diode below 0.1 in the 10+W range. The A9 40W should have about 0.15 to 0.2mm in reality (as most others as well).

For the 40W especially, you can try to increase the focus height to about 43-45mm, many people reported this to get better results in engraving. Those lasers are more built for cutting purposes, and I think they intentionally lowered the focus a bit to better cut thick materials.

Thanks Mike and Melvin. I’ll test that when I get some anodised aluminium cards. I already suspected as much. The little “kick stand” height gauge has a inbuilt error. When using it, it supports the weight of the head. Once it’s flipped up the head sags down about 2mm. I’ve noticed slightly better results if I wind the fine adjustment up until the gauge just clears the work piece.

I had been planning on converting the S10 to a dedicated rotary engraver (credit to you Melvin) and freeing up some bench space. I need to rethink that plan!

1 Like