Dark burnt cuts...

[David Sacks]

I assume there is nothing I can do with cutting 1/4" wood - 100% power and 5% - getting burnt edges, leave your fingers black..

I'm now using the Masking Material for the face - and it works great, now I want to know if there is way to solve the full cuts.

Thanks!
David

[Scott Challoner]

What kind of wood is it? A lot of it will depend on the type of wood you are cutting. I cut a lot of 1/4" poplar and it just darkens a bit. You can try lowering the ppi or increasing the speed.

[David Sacks]

Alder - prefinished from Laserbits - if I raise the speed, it doesn't cut all the way through.... I'm running at 600dpi. Are you saying run the raster first. Then run the Vector at a lower dpi?

[Chris J Drew]

For a less charred vector cut when you're lasering wood, just drop the frequency right down.
Frequency for the vector is independant of dpi... lowering it will mean less heat build-up in the cut & so less charring.
Still use full power for the vector so you can run the speed as fast as possible which also helps keep the cut as cool as possible.
You'll be surprised how low you can go with the frequency & still get a cut through wood.

[Frank Corker]

Chris is right - when you cut you will see that there is a frequency setting at the bottom of the vector area on Epilog driver interface. Wood is supposed to be at 500 - the default setting is 5000 which if you haven't altered it will char the life out of it.

[Chris J Drew]

500 is Epilog's suggestion - but all the values on their settings page should be viewed as a starting-point for your experimentation.
For example their suggestion for anodised ali can be way off depending on the thickness & quality of the anodising.
Wood in particular can be very variable.
I've cut wood with frequency below 100, this was 5mm cherry... certain plastics such as PETG which like to weld back together can also benefit from a really low frequency vector setting.

For your cut to be as clean as possible it's worth checking that your air-assist pipe is correctly aligned so it blows the vapourised material out of the bottom of the cut... over time it can "wander" a little by being occasionally knocked off-target when loading material etc.
Just aim it at your red-dot on some focussed material, there's a small grub-screw that holds it tight in the head (same size key as your lens-holder).

[Albert Nix]

Will PPI have the same effect as changing the frequency, I do not think I can change the frequency settings on my MII??

[Mike Null]

I make two passes and get a smooth medium brown cut. I cannot use charred wood as I must radius the edges and then lacquer them.

It is better to make two passes (it's really not much extra time) and get a good result than to have to do things over. We can all make the cut in one pass--who cares if it's not acceptable.

[Chris J Drew]

I'm not familiar with machines which lack frequency control for vectoring, and have not used lasers with a PPI setting, but I'd guess they do a similar thing.

I think it may go like this: ( my guess )
Pulse-per-inch is related to the frequency but depends on the speed.
For example frequency of 500Hz @ 1 inch-per-second = PPI of 500.
Slowing to 1/2 that speed effectively doubles the PPI.
If you know the frequency you could work out the PPI, if you know the PPI you could work out the frequency.

Perhaps this is just different manufacturers doing things differently but achieving a very similar outcome.
Hopefully someone with more knowledge of this will pipe in & let us know if this is true.

Try lowering your PPI & see what happens... as with most things laser, experimentation is your friend!

[Scott Challoner]

David

DPI only relates to rastering. It won't affect vector cuts. PPI is the same as frequency so the the others are right, lower the frequency. Alder should cut like butter.

[Mike Null]

Chris

I believe that PPI is constant regardless of speed. It is "pulses per inch" and not related to time.

[Albert Nix]

On mine PPI is varible when vectoring but not for raster. PPI range on mine is 30-1524 then it goes to X which is a steady burn.

[Rodne Gold]

PPI is also a time based function as it assumes frequency , IE 1000 pulses per second at a speed of 2" per second = 500 pulses per inch.
so with that in mind , something I have never investigated is that : if PPI is always constant the machine must be constantly varying Freq to get this constant PPI cos true linear speed of the head vectoring is never constant due to accelerations , turning , arcs etc.
Or is that assuming oversophistication for the sort of lasers we all have?

[Mike Null]

Rodney

I have not seen anyplace where PPI is identified as being in seconds. Granted my experiece is limited to just a few machines.

[David Sacks]

So I'm at 60 Freq - and run the raster (at 1200 dpi for nice dark images) first, then vector as a second pass...

But I have also solved the dirty faces too...

I first tried Pledge but found Murphy's Oil Soap better. A nice coat on both sides, and cover with light paper. Raser, Vector - and a quick wash in hot water - dry with a chammy.

This is working better than the lo-tack mask paper. which takes too much work to clean the small pieces inside of "O"s and the like.

Anyway - they look great..
Thanks everyone...
David