Darkly Labs Community

3mm ply questions

Hi all, I love my new machine but a few things have me stumped!

I’ve got a few questions about cutting and filling 3mm ply. I’d love it if anyone could help.

  1. I’m using a protective masking tape but burn marks are still present. How do I overcome this?

  2. I’m not sure how to fill properly with the protective tape on the front… with it I don’t get a good enough crisp finish, but without it I have a few smoky/burn smudges. Could anyone share the best method for this?

  3. Is there a way of tracing around the fill that has been filled? To finish it off?

  4. I did a tonne of tests to work out the best cut was 14.5/180/2 passes with a piece of 3mm ply, but when I changed pieces (same type of ply) the grain was running at 90 degrees and the laser only cut one of 4 circles. Why would this be different to my test piece? And Is inconsistent cutting within one job of normal?

I’ll try to add some photos a bit later.

Thanks so much :slight_smile:

Hi Katherine,

I do a lot of work with ply so I will answer your questions using my methods.

1.  I don’t use masking tape and I don’t worry about burn marks on the surface. To get a nice clean finish and extra sharp edges I sand the finished job with 320grit sandpaper and a cork sanding block. Doesn’t take much to clean up and I have a lot better looking product.

  1. Not possible with protective tape. See step 1.

  2. Yes run a cut around the fill but with reduced power and  faster feed rate.  Say 25% power 1000mm/min single pass will give a nice shape edge to fill.   This is easily achievable in LaserWeb.

  3. Material has to be absolutely flat. Any buckling in the ply will give inconsistent results as the focal length changes. That is your optimum of 14.5mm will vary.  Ply also has variations in its structure and you will find this will create cutting inconsistences.  Increase passes if you have some difficult ply.

Hope this helps.  I can tell you that the E2 is great for cutting, engraving and filling 3mm ply and with a bit of trial and error you will get great results.

 

 

Hi Daryl,

Thank you so much! Your answers are very helpful.

  1. Ok good idea. The protective tape helps reduce the burns, but leaves a bit behind, I’ll try the sandpaper too. In the long run I’ll be using 3mm bamboo ply for my products, so this may be an issue, but hopefully I’ve worked out a good system on normal ply before then.

  2. Ok, good to know. With your filling on ply what settings do you use? Or what do you think is best to stop the smudge? (I haven’t done extensive testing yet) I used 60% 0.2 and 1200, does that sound about right? I’ll jump on my computer and add photos.

  3. Brilliant!! I didn’t think of that!! Thanks :slight_smile:

  4. And I didn’t think about a slight bow in the ply either. Might try a 3rd pass.

Tell me, my silicone mat looks pretty ripped up, is this normal?

Daryl, thanks again for your awesome help!

Ok, so here we have the smudged fill - might be too strong? The back burn marks and the under side of the inconsistent cutting. 

 

Katherine,

My thoughts.  The tape is not a great idea. Additional work that’s not required. Sanding will give you best results - promise. Trying to get rid of any smoke damage to timber during the imaging process is a flawed concept. If I cut timber with a sharp saw I still have to sand the edges. Laser cutting is no different. Some amount of post cleaning up is always required with timber.

Drop your power in the fill to 30%.  Running a low power cut around your text will sharpen that up nicely.

Your pics look pretty normal. I think you’re on the right track.  Be aware that the settings you are using for ply may need tweeking for bamboo.

I reckon the bamboo will give you more consistent and cleaner results.  In the ply, you are cutting through 3 layers of timber plus two layers of glue.

I have cut a lot of timber and ply is the most difficult to get consistent good results from.  I can cut up to 4.5mm hardwood on my old Emblaser1 and expect the E2 to give even better outcomes. 

Let me know how you go. I’m guessing by the time your posts are coming in at, you are also in Australia.

 

 

 

Forgot to comment on the silicon mat. What you are seeing is burnt residue from the timber you are burning.  I think the manual says something about washing the mats when they get crappy.  Silicon I don’t think is actually not being damaged.

Ah fantastic Daryl!

Thanks for the heads up re tape. And the laser intensity for filling. I thought I was doing something wrong to mess up the silicone, will give it a wash.

I’m in Adelaide :slight_smile: Will let you know how I go!

 Hi,

I’d also agree with checking your material height/flatness. I was having issues with half-done cuts and charring, but I raised the tool height in LaserWeb by half a mm and it made all the difference - consistent clean cuts and very reduced charring/overburn on Bunnings 3mm ply (2 passes).

 

 

 

 

Katherine,

I have found that most of the burning on the back of the ply is coming from a mixture of two things:

  1. the laser reflecting off the silicon mats and

  2. the smoke generated from cutting not having enough space to escape and charring the back of the plywood.

I made this pin board using 3mm bunnings ply and 25x1.4mm nails (also from bunnings). It effectively raises the material up 25mm and allows the smoke to escape without charring the back of the ply.

Since using the pin board I get no burn marks on the back. Previously I was getting the same results as you.

My cut settings for ply is 300mm/min two passes (no z change).

My engraving settings for ply are 2000mm/min at 40% for the fill with a 70% outline to finish.

However, every laser is slightly different, every piece of ply is different and results change with the relative humidity of the day.

If you don’t have the air assist I would recommend getting it as it helps with cutting and engraving.
If you do have the air assist then ensure it is adjusted correctly and pointing directly at the place the laser touches the material. I have found just tweaking the angle slightly makes a big difference with the cutting result.

Also if you do go ahead and make something similar to this pin board, just be super careful when entering your settings and jogging the laser around. If you put a nail through the lens of the laser I can imagine that would be an expensive mistake.

Let me know if you need more info on any of the above.

Jeremy

Hey Drew, it was most definitely the flatness - or lack of. I watched closely as my next job progressed and as it did the ply bowed significantly. I even had to try and weigh it down. Not sure how to over come this… maybe a different material would be better… hoping it won’t happen with my bamboo. 

Hey Jeremy, thanks so much for your response. Ah that explains the little squares I’m seeing in some spots on the back! Your board looks very interesting, i might have to give it a go if its going to help with the burn marks. So, a complete novice question… but what happens when the laser beam (not lens) hits one of the nails? Does it matter? And does your board underneath eventually get cut up? Sorry if they are really stupid questions! And I assume that when you enter the start height, you just add the extra height of the pin board onto that? 

I have an air assist, but i think it just died. Was making the normal noise then got really quiet then all of a sudden it went high pitched with massive vibrations. Hasn’t been the same since. When thats up and running properly again, I’ll make sure its pointed directly at the laser spot. Thanks for the tip. 

Thanks again, super helpful :) 

Katherine,

The laser beam hits the nails occasionally but just deflects down and off to the side. I haven’t had a problem with it yet.

Yes the board is a sacrificial piece. It doesn’t get cut at all since the laser isn’t focused on it but it will burn and char quickly. Also you need to be more careful as being timber it is flammable and poses a greater risk of being ignited when compared to the silicon mats.

Yes i recommend playing around with the start height to get the best settings using the pin board. The plywood board may be bowed slightly though. Mine is slightly bowed in the middle so I use magnets to hold it down flat to the bottom of the laser bed. Also be aware that the metal nails sit directly on the laser bed and may scratch the black paint. It is also prone to sliding around with the vibration of the air compressor so I use blue-tack to hold the corners in place.

Hope your compressor is back up and running soon. Darkly Labs support is fantastic so I doubt it will take long to be resolved.

Jeremy

Here is my result for 3mm ply, without air assist.

I am still playing around with my settings, and so far the best setting seems to be 2 passes at 270mm/min with 0.5mm pass height. I might change this to 1mm to see if it performs any better, because not all pieces were cut cleanly at this setting. 

image.jpg

Hey Jeremy, 

Bed of nails works a treat!! Thanks for the suggestion! I made it from MDF as that sat much flatter than the ply. When cutting my 3mm ply there were hardly any burn marks on the under side! WIN!

However, now I’ve got myself a bamboo issue (whether its a bamboo issue, or settings issue)… I’ve created a new post though - do you mind taking a look?  

Thanks again! 

Katherine