How do you vector cut wood CLEAN?

[Don Gares]

Ok, one more question. When I vector cut any thickness of wood (from 3/32" to 3/8") I get a black charcoal residue on the cut edges. I have seen some real clean laser cut projects at craft shows so I have to assume that I am doing something wrong.......what is it?

Don

[Ross Lowry]

It sounds like you are running the speed to slow.
Try speeding it up a bit and see if that improves the look.

[Kim Vellore]

It depends on the type of wood. Wood with less oil and sap content lasers well, like balsa you cannot charr much, Bass wood is good too. Most hardwoods will charr and many will not even vector cut. Lower pulsing frequency also helps.
Kim

[martin g. boekers]

Sometimes you need to test and go quite a bit away of the manufactures suggested settings, frequency is a big key on cutting.

Marty

[Lee DeRaud]

I have seen some real clean laser cut projects at craft shows so I have to assume that I am doing something wrong.All of the above, plus, maybe you're not doing anything wrong:

1. Just because someone's finished product is clean doesn't mean it came out of the laser that way. For some woods, all it takes is a quick swipe with an alcohol-soaked rag to clean it up, or some light sanding.

2. For some projects, the contrast provided by the charred edge is a feature, not a bug. And usually just a quick hit of spray shellac will seal in the black so it doesn't come off on the customer's hands.

[Don Gares]

Kim and/or Marty,

You both mentioned lowering the frequency. I assume that is what is known as PPI on my Pinnacle machine. The following is a quote from the manual: "if you set the PPI value lower than the DPI value, the M-Series will adjust the PPI value at least equal to the DPI value".

Comments on the above quote would be appreciated.

Don (who likes Lee's idea of the charred edge being a feature)

[Richard Rumancik]

. . . I assume that is what is known as PPI on my Pinnacle machine. The following is a quote from the manual: "if you set the PPI value lower than the DPI value, the M-Series will adjust the PPI value at least equal to the DPI value".


Don:
Yes, frequency is called PPI (pulses per inch) on the LaserPro and Pinnacle machines.

For these machines, PPI is the parameter for vector cutting and DPI is for rastering. I believe that with the GCC line DPI (Dots per inch) is always equal in x and y axes. (Not true for all manufacturers.)

The way I read the quote is this: if you set the DPI to say 500 for rastering it will not accept a PPI less than 500 for vector cutting in the same file. Why they would have forced this relationship, I don't know. It could be some kind of hardware/firmware issue that caused them to do this because in my opinion they should be entirely separate parameters and it seems to be an arbitrary limitation. I was not able to get an explanation from GCC. On the other hand, I cannot say it has cause me a specific problem for a job so have not pursued it since.

This is from the Jorlink/LaserPro manual:

PPI – Pulses Per Inch. This setting should not be confused with DPI. PPI determines the gross amount of laser pulses there will be per linear inch. PPI is exclusively for the vector setting. A PPI setting of 500 results in the laser firing every .002” (500 times per inch). If the standard lens is producing a vector laser focal point of .007”, then higher PPI settings will result in deeper, overlapping laser pulses. PPI settings lower than 150 will result in the individual laser pulses being spread far apart, so they will not touch each other. Low PPI settings are a good example of how the LaserPro Mercury can perforate paper.

[Mike Null]

Depending on the brand of machine you have the PPI setting may also affect the raster mode.