Using a 4” Lens in the 1” Position is Amazing

I finally did this experiment today. This is something I have contemplated for a while.

The reasons driving me to want to try this were:

  • increase the safe Z distance from the cone to the material

  • reduce the potential for contamination entering the beam opening at the top

  • engrave acrylic without air assist (because it engraves so much better without it). Doing this without air assist will cake the acrylic on the nose cone and often lends itself to lens damage.

I bored out the tip of a nose cone for beam clearance and there is still ample air flow when cutting through material (having the shop air piped in and running 30 psi through the cone).

Wow. This is great.

Here is some UV printed (for coloring) extruded acrylic (unfortunately extruded) engraved And cut with ZERO post processing.

Here you can see the increased distance from material to cone:


So you’re still focused at 4", but using a smaller tube?

I’ll give it a go. I still have my original 2" tube and a bunch of 4" lenses.

My tubes are modular- screw as many 10mm extensions as you need to achieve the length you want.

It’s just one of my three dual position tubes (having an upper lens mount and a lower lens mount). This one lens holder tube in particular was designed for either a 1 - 2.5” in the lower lens holder or a 4” in the upper holder.

I just put the 4” lens in the lower holder. It’s not a shorter tube. But for the laser to clear the opening of the cone, I just drilled the hole out slightly larger (with a 7/32” bit).

I’ve run 8 hours worth of jobs on this now and it is perfect.

I think I can build that from the parts I have - just reverse the top tube and use a threaded insert to join it up. Cool. Thanks.

I am curious. I had my laser only 2 months and just been playing with lauan ply. Bought some cast acrylic and am ready to start playing.
What caught my eye was the reference that cutting with air assist creates something unwanted.
What effect does it have, the air assist I mean?
I certainly haven’t gotten around to playing with lenses.

Not cutting. I had mentioned engraving. When using air assist when engraving acrylic, the resulting finish is often a haze around the engraved areas. To mitigate this, you can use transfer tape, but that takes time to apply and take off, increases expenses, changes the actual engraved affect of the acrylic, and can limit you on other techniques where mask subtraction / painting is used in combination to engraving.

Understood, maybe.
Thanks for clarification.
Guess I’m just gonna have to experiment.
Thanks again.
Info found here is beneficial and much appreciated.