deep cutting wood

[Phil Rasmussen]

I have not seen this question and am hoping that someone might be able to provide an answer.

A client wants me to laser a sign made of wood (California redwood). He has had signs in the past made using a router and has not been pleased. However he does like the "deep" grooves that the routers make.

In the past I have made deep laser cuts using a series of passes. Unfortunately in some cases the surrounding surface wood was scorched.

Am I better off reducing the number of passes by increasing the power and reducing the speed, or am I better off using the normal settings and making more passes? Also, will masking the top of the wood help or hinder the process?

[David Somers]

Phil,

How thick is the wood and what power is your laser?

[John Blazy]

With certain materials, the ash becomes an opaque blocker of the beam, so I would hook up your air compressor line to your air assist and regulate as much pressure as possible going through the cone. Then do several test passes - some at full power, very slow, and bracket through other passes at less power / faster, etc.

Also remember that deep cutting (3/4"? What thickness?) takes the focus out above and below the focus, so maybe 1st pass is focused 1/8" into the wood, and subsequent passes need the bed raised for final deep cut. Also consider a longer lens.

I would think that masking is a good idea, except for the adhesive melting near the cut edge - may need solvent removal.

[Phil Rasmussen]

The wood is about 1-3/4" thick but the cut needs to be at least 1/4" deep

The laser is a 40watt epilog.

Adjusting for focus is not a problem as it can be done with each pass. The question really lies with the combination of power, speed and number of passes.

Phil

[Ross Moshinsky]

Look into sandblasting. That's how wood signs have been made for years. Routers have taken a big chunk of that business away but it's still a very popular way to produce signs.

[Dave Sheldrake]

It's very difficult to control non penetrating laser beams to any degree of accuracy on wood

[Keith Downing]

John beat me to it, but I would agree increasing air to at least 30psi will all but remove the "burning" on most wood engravings; at least from a 40 or 60 watt machine. Then you can make additional passes (or potentially just increase power) to get the results you like.

Only potential issue I could see is the grain on some really hard woods can be fickle sometimes; and engrave un-evenly even on multiple passes. But on softer wood you should not have issues getting the effect you need with a little trial and error.

[Paul Phillips]

Hi Phil, welcome to the Creek, as someone who has decades of experience routing and sandblasting redwood signs, I'm curious what the client doesn't like about the routed method, can you be more specific, maybe I can help make some suggestions.
Paul