View Full Version : New lens issue

Walt Langhans
05-02-2015, 12:02 AM
Hey Guys!

I got a new lens with a smaller focal length to help get some better detail out of some acrylic jobs I've been working on. The problem is the distance from the nozzle tip to the material is 5mm. So what's happening is that the residue from the acrylic is building up on the nozzle and it's falling off on the acrylic and then can't raster though it, and / or it's closing off the nozzle tip and causing the same issue.

When I'm rastering I do have the air assist OFF. If I do turn it on, it tends to scatter the material which ends up back on the acrylic and leads to a fogging effect, if that makes sense. But I do have good airflow from the extractor/

Currently I'm just keeping my eye on the job, stopping the laser when it builds up and knocking it off... but I have to say this method sucks... I'm hoping someone has a trick or something


Chuck Stone
05-02-2015, 11:17 PM
what kind of airflow do you have for the air assist? It sounds like it may not
be a high enough volume of air. But coaxial assist does sound like the solution to
the buildup.

Dave Sheldrake
05-02-2015, 11:47 PM
You need a shorter cone Walt, a good 10mm of gap is useful when rastering and you can still keep the air on at low pressure to keep the lens clean (or it's going to junk up and crack eventually)

Walt Langhans
05-03-2015, 6:07 PM
You need a shorter cone Walt,

Where would I go about finding a shorter one?

Dave Sheldrake
05-03-2015, 7:06 PM
You can get different length lens units with cones from ColeCNC (Coletech) on ebay usually :)

Walt Langhans
05-03-2015, 9:53 PM
Thanks Dave!

Kev Williams
05-04-2015, 2:06 AM
Just me, but I never use those nose cones, more trouble than they're worth. My western machines didn't come with them...

Dan Hintz
05-04-2015, 9:12 AM
Just me, but I never use those nose cones, more trouble than they're worth. My western machines didn't come with them...

Both my ULS and Trotec came with them...

Mike Null
05-04-2015, 10:59 AM
On the Trotec operating without the nose cone is fine for rastering but negates air assist so if you need air assist you need the nose cone.

Dave Sheldrake
05-04-2015, 12:11 PM
On Chinese machines they have a multi purpose, they keep dust and backsplash off of the lens, provide an air blast to keep the kerf clean and, most importantly, keep the lens cool.

So long is there is some kind of air to keep the lens cool and dust away the cone isn't needed for engraving but is essential for decent cutting on a Chinese box :)