Gap around lettering - joining two acrylic pieces together

[Neckron666 (Shay Lattimer)]

Hi guys,

New to the forums and have been having trouble trying to cut some 3mm acrylic brooches.

I have a square with a cut out of a word in the middle and i make two copies, in two different colours to swap between them, I would think when I cut that the word would slot into the other piece with no gap but there is a distinct gap around the letters and I don’t know how to fix this. Is it related to the size of the path of the laser? I want the words to fit in snuggly with no line around thin gap around them.

I have a 40W laser cutting at 85% power (high/low).

Please see an example

Do I need to somehow take into account the width of the line the laser makes in the cutting?

[Stroonzo (Jeff)]

@Neckron666

Do I need to somehow take into account the width of the line the laser makes in the cutting?

Yes. Absolutely the laser has what is referred to as a kerf which is the width of the beam.

You could account for this through the Kerf offset on one of your jobs:

Observing this mocked finish creation:

Using the kerf offset feature, you would cut the blue material without kerf offset. Then you would apply the kerf offser to the green portion (outward) on the second job with the green material in the laser.

To find the optimal offset, make some tests with small circles on scrap material.

I prefer manually adjusting the closed shapes in the complimentary job / file to have complete control over each element.

[Hank (Hank Morgan)]

@Stroonzo

Using the kerf offset feature, you would cut the blue material without kerf offset. Then you would apply the kerf offser to the green portion (outward) on the second job with the green material in the laser.

FWIW,I usually do this by applying 1/2 of the desired kerf offset to both pieces.

[Stroonzo (Jeff)]

@Hank

I usually do this by applying 1/2 of the desired kerf offset to both pieces.

Also an approach for sure. As much as I prefer manual editing, if it is a one time job I am quick to just use the kerf offset.

[Neckron666 (Shay Lattimer)]

Thanks heaps guys, ill give it a try

[Neckron666 (Shay Lattimer)]

Hi guys, tried your suggestion and if i do as Jeff says it works great but i am trying to reduce wastage of materials and am doing it in two different colours so that I can use the letters cut from one in the gap cut from the other and vice versa is there a way to do this or will I just have to cut separate lettering and throw out the ones cut from the main piece?

[Stroonzo (Jeff)]

Alternate the colors making alternating sets otherwise, there is no other way. This is subtractive machining. But let me clarify that one of the jobs should only be the lettering (taking up much less material). Don’t run both color jobs containing all objects.

In fact, you can make the first outside job faster if you skip the lettering and only account for the outline of the lettering (removing the loops in O for example).