Cutting 3mm Birch okay with the k40

I tried to cut 3mm Birch ply today and to my surprise the K40 took 2 passes at full power 10mm/sec speed. I thought the k40 could do this in a single pass? I tried some test cuts at full power with a speed of 5. It still wouldn’t cut it fully in a single pass. I used a focus jig I made based on a slope test to determine the working height. Engraving was fine, vector trace was beautiful, but vector cut was disappointing.

Water pump was working fine, temps around 19c. Lens was clean. My first attempt I kept getting flare ups so on my second attempt I took the opportunity to install the air assist I had sitting around. No flare-ups after that.

Depends on the plkywood you are using, some plys have a very hard to cut through glue, especially if it is designed for exterior use.

You should be able to cut 3mm ply in one pass. I typically haven’t run into problems with 3mm except in isolated areas where a void caused a thick area of glue.
Problems with cutting usually are caused by several potential issues:

  • Mirror alignment

  • Mirror/lens dirty

  • Lens orientation - the lens should be oriented with the bump side up.

  • Bed height - for cutting the focus point of the lens should be 1/2 way into the wood.

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I checked the alignment of the machine when I got it last week. It was very close out of the box. I checked the mirrors yesterday when I cleaned the lens. They didn’t look dirty but I suppose they could have a film on them like the lens did.

The ply came from Michael’s crafts store in 12"x24" sheets. I looked for it at Lowe’s but they didn’t sell anything that thin.

The stuff you get from Michael’s should be okay. In the future it will be cheaper to order it on line.

I would double check your bed height / focus point. It’s something that’s easy to adjust the wrong way.

Yes I figure it’s cheaper online. But I wanted to play with it today. It was $4.29/ sheet and with a 30% coupon it came to $3.00/ sheet. Dumbest part is that a 12x12" sheet cost $4.59.

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