Speeds and power MDF vs Grainy hardwood

Hi there,
I’m new to laser engraving, just installed one on my 4’x4’ CNC router table.
Anyways… The laser module is a cheap Chinese 5.5 watt blue diode.

I’m having fun using it but notice a big difference between engraving MDF and Ash. MDF is consistent and the Ash because of the grain density and texture there is no consistency in the results. My question is for the Ash if I want the engraving darker, is it best to slow down the travel speed or up the laser power or both? For lines I’m running 1200mm/minute at 85% power. For fill I’m running 1400mm/minute at 75%

Thanks

Glen

MDF is darker due to the binder used to hold the wood flour together.

You can use a coating, such as baking soda. I’ve not done it myself, but have seen the results from others.

Google ‘baking soda laser’

the other option is to slightly defocus - it tends to burn rather than ablate, leaving a charred residue.

EDIT: exactly the process I was talking about: Baltic Birch Plywood Engraving Settings?

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Hi Bonjour,
Thanks for the great suggestion about the baking soda water.
It worked really well!!!
Boy it sure is nice to be able to have a forum to actually talk with like minded people who have the same interests! Sure I could have just googled my inquiry and gotten a answer, BUT then I don’t get the nice personal interaction with nice like minded people such as yourself :wink:
Google is cold and has no personality!!!

Glen

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Pics, or it didn’t happen :slight_smile:

Ok here you go!
Etches on Ash the wood was prepared with the baking soda/water wash.

Glen

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Wow! it really works. Great job!

I’ll give it a go.

Ok but you will have to show us your results!

Glen

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Tried the Soda wash on some old Oak board and it also worked!
Very pleased with the process. Also 3D printed this safety hood. It rides about 3mm above the surface.

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Seems like you don’t have a lot of headroom on power so going slower would get better results. However, as you have noted, Ash, in particular, is very heavily grained with open pores on the growth wood so getting a consistent finish, vs MDF for example, is going to be difficult. Finding a more closed grained wood, like Maple, Holly, or Basswood (if it’s hard enough for your needs), might be a better choice.

Pick a grainy wood like Ash or Hickory if you want to accentuate the ‘woodiness’ of it, otherwise look for something more uniform. One interesting choice might be a wood sold in box stores as ‘white wood’[sic] but is a domesticated pine grown in Central America call Radiata. It appears grainy, but there is not a lot of difference in hardness between the summer and winter growth so it’s very easy to get a nice smooth surface (less differential erosion as you burn into it).

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Radiata is our primary timber in NZ - it’s non -scientific name is Monterey Pine. Native to the Californian coast

Terrible product, in my experience. Easy to burn deeper than you want, and to keep burning as the air assist fans it to flame.

But, it’s plentiful and cheap, so I’ll give it a go with baking soda.

Interesting. Thanks for the info.
I haven’t tried to engrave it yet (I should have included that in my mention :flushed:), but I use it a lot in jigs and also in some interesting looking woodturnings. I glue up panels to create thicker pieces and the uniform grain creates very attractive swirling effects. Also very low cost and easy to turn.

FWIW, I haven’t engraved Basswood yet either.