Mahogany or charcoal?

[Carlos Chiossone]

Hi everyone, I am trying to cut some mahogany that is about 1/4 inch. It seems to be an extremely dry wood. While it looks great it seems to be flaming more than all other woods I have tried, even with air assist.

Question: would the vector cutting table make those flames go down instead of up? and if not, will those flames that every so often seem to touch the laser unit damage the unit?

I am cutting at 95% power, 2% speed at 200ppi.

Any used vector tables out there? :-) too expensive to buy new.

Oh I am using a ULS M-300 with 45W.

Thanks,
Carlos Chiossone

[Joe Pelonio]

A vector grid, if anything, causes more flaming since it allows more air from different angles into the area being cut. The newer Epilog machines with built-in vacum table may be an exception, I don't have one though.

There are varieties of mahogany, especially African, that I don't think can be laser cut no matter what you do. Someone brough some in (same thickness) and I tried everything including vector grid, up to 50 lbs air, and applying transfer tape and soaking that with water. All it did was burn, turned black and flames shot up. He ended up settling for some clear oak and stained it to look like mahogany.

[Carlos Chiossone]

Oh, mine is cutting fine, a little black but a dremel with a brush cleans it right off. I am just worried about the flames hitting the lens here and there.

Thanks.

c

[Mitchell Andrus]

The variety of Mahogany makes a difference. I cut Mahog all the time at up to 3/8" thick (95%, 175 ppi, 1.5 speed, 60 W Spirit). The denser the wood and the more oils, the worse it'll cut. I use the less dense stuff from the stack for cutting.

Mitch

[George M. Perzel]

Hi Carlos;
I've sent the fire trucks- should be knocking on your door about now.
First of all, are you using a cutting grid at all? Is the wood directly on the table? If you don't have a grid, elevate the material at least 1/2 inch using washers, quarters, beer tabs, whatever. This will provide clearance and most of the flame will be down.
Try raising your speed or lowering your power a little-settings are a little high for mahogany which is pretty homogeneous and cuts quite readily.
Send Mike Kull a PM-he's got a great deal on a cutting grid.
By the way, most laser head assemblies have a bit of plastic in them and will tend to try to melt if subjected to a lingering flame. Good Luck and invest in a fire estinguisher!
George

[Mike Mackenzie]

First off Carlos if you are using the air assist there is no possibility of the flames hitting the lens unless you don't have the cone on. Second try lowering the PPI bring it down to 100 and see if that helps. If you have a blast gate in your exhaust try to close it a little bit. Sometimes the exhaust is what causes the flames.

[Mike Null]

Carlos:

I have a little different take on your issue. I'd rather lower the power setting and make 2 passes. This will reduce the flaming.

Regarding the cutting table you can send me a PM.

George: Thanks for the kind words.

[Joe Pelonio]

Oh, mine is cutting fine, a little black but a dremel with a brush cleans it right off. I am just worried about the flames hitting the lens here and there.

Thanks.

c
I have cut some mahoganies OK too, unfortunately you can't tell which will cut well without trying it if someone brings it in. On the flames I'd be also concerned about them catching a belt or some electronics, probably less able to take it than the lense and could catch on fire.

[Rob Bosworth]

Carlos, you can also focus down into the material. I like to put my focus down a 1/3 of the way into the material. This should give you a squarer edge, and you are putting your smallest energy density into the material. Smaller kerf, less material being removed.

[Carlos Chiossone]

Thanks to everyone for the input. I have tried everything except the cutting table and double pass. It still flames, it cuts easily at 90%P 2%S at 175PPI I have played the numbers, still flames. I have been able to reduce it to about 20% of the cutting which is great so far. The Mahogany I have is extremely dry, I am not sure if its always that way. I am going to try the 2nd pass later on.

So far, while I am not burning the lenses, I am happy. I took it apart yesterday to check it and clean it and it seemed fine.

I have about 80 more boards to go... so have to go make some more charcoal :-)

Thanks,
Carlos