Darkly Labs Community

How to reduce damage of top surface of material from smoke/fumes/heat

Hi everyone, I’d like so advice about reduce the smoke/scorch marks left on the top surface of the wood.

I know air assist would help, presumably as it would help move the smokey hot air away from the surface.

I’ve just uploaded a video to youtube of a wooden bookmark sample I’ve made for someone, and you can see the smoke blowing towards the front of the Emblaser, and the marks on the finished item reflect this, as there is a discolouration to the surface on the bottom edge of the cuts/engraving.

Maybe increasing move speed and the number of passes would be the answer?

https://youtu.be/I31fktqdEpg 

1 Like

That’s a pretty simple, good looking item. How many passes and what speed did you use to perform the cut? I jumped over some parts of the video, so I didn’t count the passes.

Regarding the burning/smoking aspect. I’ve read of people using masking tape on acrylic to reduce the cosmetic damage of the laser. Perhaps that would work in this case, with appropriate adjustment to power, speed and number of passes?

Hi Fred, I know it was 4 passes, at 100% power, and I think it was 350mm/min.

Yeah I have heard that some people put masking tape on the surface.

I’ve been thinking of making a simple air assist, maybe running a small bore pipe attached to the laser housing that directs air onto the cutting area, and run some silicone tubing to a compressor?

Something must be amiss on my end. It’s taking me ten passes at 100% at 250 mm/min and I’m not getting cut-through. I though I had it well focused but it’s also possible that the minor bulges in my plywood are a factor.

Silicone tubing is quite light and flexible and probably well suited for the directed air you are suggesting. An overhead quadripod with the hose suspended below would take any real load off the gantry and laser assembly. I’ve been pondering such a mechanism for a while too. I’ll keep pondering until the dozens of other projects are no longer in the way of this one!

You should get enough volume and pressure from even a simple inflation device such as those used for bicycle tires (tyres?) and sports equipment. Another option is enthusiastic youngsters on a hand pump, but that’s mostly impractical.

John,

I just use 400grit sandpaper with a block on the finished product. A  couple of passes and residual smoke is gone and the quality off the engraving is not affected. 

 

 

 

 

Fred, yes, sounds like something isn’t right, although I did find that cutting on a honeycomb base seemed to reduce the number of passes need to cut through slightly.

I’ll confirm the settings I used later this morning as I have a last minute request to engrave a Chopping board!

Daryl, thanks for that, to be honest I hadn’t thought about sanding it, I may give that a try, although I feel that I’d prefer to prevent it in the first place I’d possible :slight_smile:

Fred,

I agree with John. My feeling is still some fine tuning on the focus is required. 

 

John,

Let me know how you go with preventing smoke from affecting the ply. I also use Shellite (Naptha) to clean smoke but I prefer the sandpaper.

The sandpaper also appears to sharpen the engraved edges of the job.

John,

Try increasing the air flow across the surface of the wood at a right angle to the laser beam with an auxiliary fan.  The Emblaser’s fan blows the smoke back down onto the wood, which, IMHO, increases the accumulation of smoke residue.

1 Like

Good call John C.  I forgot to mention that I always have an additional fan blowing across the work.

1 Like

Thanks for the advice John, I had been thinking about various methods and that was one of them, as it seems even a gentle airflow has a big effect on the smoke damage, or lack of.

As I’ve currently been using my emblaser close to an open window, the smoke is being drawn towards the window and explains why the area above the cuts is clean as the smoke doesn’t drift in that direction.

Fred, I’m sure it’s probably just a focus issue, although I did remove my lens and found it to be a little dirty, so cleaned it with a camera lens cloth.

Also, I made the mistake of having all the dip switches set in the wrong position when I first assembled my emblaser (doh!) and wondered why I had such low cutting power :slight_smile:

Can anyone from DarklyLabs advise me, I’d like to know if there’s enough capacity in terms of current draw, for me to add another fan to the laser head, by splitting off the fan power leads?

If so, I’m thinking if a solution that uses a second fan on the laser head, or possibly a single but more powerful fan.

Thanks, Johnnie

I changed ours out to this fan.

https://www.amazon.com/Delta-Electronics-FFB0412VHN-F00-40x40x28mm-connector/dp/B005IH0WUI?ie=UTF8&psc=1&redirect=true&ref_=od_aui_detailpages00 

The board rating to power the fan is 300ma. Here is the specs on the fan I used. 

CFM 15.79
RPM 9500
Current 240ma

I recommend adding one of these also to keep your fingers out of the blades. 

https://www.amazon.com/40mm-Black-Finger-Grill-Guard/dp/B00D7IH1OK/ref=pd_bxgy_147_img_2?ie=UTF8&refRID=4VF77N7E8MED51CNP0HB 

1 Like

Thanks for the info Jeff, I’m considering upgrading the fan to one from a computer server, however will need a suitable 40mm - 60mm fan adapter, and will also have to power it separately as the current draw will be much too high ( 1.5amps I believe! ) although it should give something like 50-60cfm of airflow, maybe this is too much?

You should not mount any to heavy on the laser. It may cause problems. Here is some more discussions on mounting different size fans. 

http://forum.darklylabs.com/index.php?p=/discussion/92/air-assist#latest

1 Like

Thanks Jeff, I’ve just read that thread, very interesting, yes, that was a concern of mine, so it seems that 50+ cfm would probably blow everything around too much.

Also, from that thread, the original fan used to be a model: SD4010S12M, rated at 0.09A, 7.7cfm.

My Emblaser has an SD4010D1S rated at 0.15A, so I’d imagine it would be something nearer 10cfm?

Looks like I’ll have to give this some more thought.

Jeff, did you notice an improvement in reduced scorch marks with your upgraded fan?

Actually, my intention of adding the other fan was to keep the laser diode cooler because I wanted to scorch the wood as much as possible by running it longer at a higher laser power. :slight_smile:

http://forum.darklylabs.com/index.php?p=/discussion/362/3d-engraving-using-picengrave-pro-5

It also has an air assist we developed for our EmBlaser. 

1 Like