How to 'cut out' a shape from 3mm mdf or 5mm ply

How do I ‘cut-out’ an accurate shape out of either 3mm mdf or 5mm plywood.
I’ve been trying to do it with a small mdf blank.
I set the power to 95%, the highest I’ve ever used. Tests have been done using 3mm mdf, 95% power on a 15W blue diode. Focus as good as I can get it.
Setting started on a 4 times run, gave me a nice black circle. Found Z step per pass and set it to -1m which if I read it right should have burnt the sacrificial tabletop. Nope. set it to -0.5mm, no change.
Finally set it to 10 Passes with a -.3mm.
Got no further than some very burnt surfaces with maybe a 1mm deep circular cuts in them.
Have I lost the plot again?

Kevin, do you have air assist setup with the cut? If not, this may be challenging as the leftover debris will literally impede and disperse the laser energy before it gets to depth.

What you’re describing in your setup seems fundamentally correct. You may want to try measuring your actual cut depth for a single pass to determine Z-height adjustment. Maybe try cutting through a profile of the burn to measure.

With a good setup I’d expect you to be able to get through 3mm plywood in under 5 passes. MDF is fundamentally harder in my experience. The resins, binders, and other chemicals in there along with the wood density make it messy and slow going. 3mm MDF should still be manageable with air assist.

This all assumes that you’ve got proper focus and your setup is working well. Make sure you haven’t gummed up the lens with debris and residue from your previous burns. MDF especially makes a mess. If you have any residue on the lens that will greatly diminish cutting power and likely shorten the life of the laser. Clean with IPA or other alcohol solution that doesn’t leave a residue.

One last variable is the lens type. Typically you’d want a longer focus lens for cutting operations. The lenses that come with these systems are typically made for engraving. However, with your Z-adjustment you should be able to mitigate that.

What speed were you cutting at?


Hi, berainlb,
I am not sure what’s happening.
I have tried it on 95% on 3mm ply. A number of passes x 10 at 100mm speed. Didn’t even make a shadow on the other side. You have probably seen that I have a problem with my laser focus. I’ve spent hours today just on the focus, As far as my eyes were concerned it was the smallest dot possible on the base (table) Then I add offsets to the Z-axis to take the thickness of the material.
Now as for air assist. My laser has a fan on the top and it blows air through and over the laser, but not at high pressure. I have seen specks getting blown off before now. But no added device for air assist.
With regard to the boards, I am aware of the fumes problems, especially when there are resins involved in their manufacture.
I have used IPA (Isopropyl… etc) to clean my lens a few times.
There’s always a window open now, especially with COVID.
Going back to focus, I have ordered a new microscope which allegedly should allow me to focus better than by eye. Old eyes are not as good as they used to be.
The lens is a variable one. I have the laser body about 55mm above the work surface. as per the manual.
OK, thanks for your response always nice to know there are people out there willing to help.
I can’t remember all the Christmas arrangements, we have children, grandchildren and also great-grandchildren over the holiday times. So may have my time to play cut back a bit.
I’ll wish you all the best for the season.

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Thanks for that JMichael, Noted and will start using a resp mask soon.

A very quick note to all that are in the group especially all those that have been helping me sort out a few problems I have.
Happy Seasonal Greetings. Many Thanks for all the support you have given me.


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Yep, sure was a lot of charring, but I’ve just been trying different settings to see if anything would get through.
How many hours? I’m thinking about 55-60 hours max. What is normal time for a diode laser to last for? I have noticed that 15W lasers (blue) seeem to have gone up in price in the last month. It’s going to be an expensive hobby if the cost is going to be around £100 for under 200 hours. Unless of course you know a good UK source for them nudge nudge.
Thanks again

Hi JMichael,
Thanks for the information. Makes me a lot happier 8-10 k hours is a far happier place to be haha

I use 3 passes at 250 mm per minute but my z offset per pass is a positive 0.5 mm. When I first tried it I assumed that negative z was required but when I reread the definition, positive z moves the focus down, which is what you want. I have also tried positive 1 mm offset per pass and it works as well. Sometimes it doesn’t quite break through 3 mm so I have to slow the speed to 220. Mdf is a little darker and may absorb more laser energy.

Try changing the z offset per pass to positive and see if that helps, and try plywood first if you can.

All the recommendations sound solid, one variable that I don’t see discussed is actual optical power. Your experience mirrors mine with my first laser. It drew 15w but measured optical power was 5.4w and I could never burn through much. My 15w optical output laser makes quick work of ply and mdf up to 5 or 6 mm. Air assist is critical. Best of luck!

Hi all,
Thanks for the replies. Plenty to get my teeth into. I’m slowly getting the hang of it.
But one common item that comes out from this and other tickets is ‘air assist’.
Can’t remember where I mentioned it, but my laser is a blue diode 15w and has a fan on top which send air down to the workpiece.
In the various photos, I have seen there are tubes pointing to the actual laser target area. Now I am assuming that this is an add-on that different users are adding.
Can anyone throw any light on that, is there an actual addon available?
I’ve stopped trying to do cuts at the moment, after all, you can only char a load of wood so much haha.

I have read through several of the responses. I have a 10W blue diode and cut through 1/4" (roughly 5mm) plywood in one pass using 85% power but only 2mm/s speed. at 100mm/s you will not likely get through the wood. I have also cut through 1/4" roughly 6mm solid poplar wood running about 90% at 2mm/sec.

Slow down your speed on your cut layer and you will likely get MUCH better results with your cut.

Can you confirm if you were using air assist with this? I suspect that if @Princy_Lightburn attempts this without air assist he’s going to end up having a bad time and a nice fire.

Have you compared the cut quality of cuts made at these settings vs faster cuts with multiple passes? Curious what kind of kerf you’re getting and scorching levels.

Is that 100mm/minute or 100mm/sec? 100mm/sec is really quick, where as 100mm/minute is extremely slow. Look at which your system is using mm/min or mm/sec.

I have attached a couple of items that I did with my Xtools D1 10W laser. The Keep Logo I have uploaded is 1/4" poplar cut with 90% at 2mm/sec (120mm/min). The Zamuza one is 1/4" birch plywood that was cut with 85% at 2mm/sec (120mm/min).

I hope this helps.

I am not using air assist

It is not directly available for the D1 and I have not modified for that yet.

I’m impressed that you can get through the 1/4" plywood with one pass without air assist.
Do you think you can take a closeup photo of the side of the wood to show cut quality? Was the material post-processed in any way or this was directly after a cut?

There was no post processing. This is straight from the laser. I have not even applied any finish to this at this time.

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Some times there might be a small section that does not cut all of the way through (possibly a couple of fibers that do not go all the way through). Those areas I use an Xacto knife to cut from the back side. The next time I cut it I raise the power by 5% and it works fine.

I have also only had this laser for 1 month yesterday. I have not built an enclosure or messed around with creating the air assist. I typically set up a fan4-6 feet away blowing across the project as it burns so I do have air flow. However, when people speak about air assist they typically mean a focused air stream pointed where the laser is focused.

Slow down the speed with a 5w atomstack, I used 3.5mm/s with about 8 passes. I do notice a difference in material consistancey between both ply and mdf and within the material range itself. That said, I upgraded to the duel mirror laser that pumps out 10w at the beam. It now blazes

HI JMichael,
OK on the pump, I had been wondering where to get the air from, sounds like a practical idea to use an aquarium pump. Hope I can find a reasonably priced one. I believe they are normally quite quiet too.
I think that’s tomorrow’s job.
Thanks for the advice and comments.