[rbocaz]

I have looked over the Internet about laser sawmill for cutting logs. I can not find any reason why this cutting hasn't been designed or commercialized.

Any info. appreciated.

Rick

[bpoulin]

A few reasons
1. Focal length of the laser is a fraction of a mm so getting one with a focal length to cut through a whole log would be near impossible.
2. Too much heat generation, It will catch the log on fire
3. Impractical cost. A machine large enough to accommodate logs and have enough power to cut through would cost hundreds of thousands of dollars. A band saw system would cost a fraction of that. Also the band saw is a proven technology that is cheap and easy to implement.
4. The CNC components would quickly get gummed up by the vaporized sap that would condense and settle on the components.

[rbocaz]

Thanks for your post. My doubts where about the heat. I'm not sure about the cost, a CNC laser cost are near the same that a bandsaw. I just heard years ago about laser cutting for wood and never heard of it again. Yesterday I found a site explaining the uses of laser in wood and it said about sawing with laser, but it didn't say more. The problem with bandsaw is the kerf (6 mm for cut) and waste...the ship

[bpoulin]

Newer systems use lasers to guide the blades. Pretty much a powerful laser line is shined on to the log that shows exactly where the blade will go. It allows the operator to know for sure where his cut is going to go through the whole log, no more multiple passes to cut the edge off the log, from there it precisely moves down with each consecutive cut to the programmed thickness. And as far as cost, laser cutters from china the large ones may cost the same as a bandsaw system, but won't have any where near enough power, once you get the size and power it'll be several hundred dollars. And even then, you'll have a giant lighter, because it'll just catch the logs on fire. Or worse it'll pierce the log and boil the center causing the log to explode.
Also the biggest lasers you can order from China have no way of moving the log, or moving along the log, having one custom built would be a huge expense there too. How much does an average log weigh? 1-2tons?

[rbocaz]

Newer systems use lasers to guide the blades. Pretty much a powerful laser line is shined on to the log that shows exactly where the blade will go. It allows the operator to know for sure where his cut is going to go through the whole log, no more multiple passes to cut the edge off the log, from there it precisely moves down with each consecutive cut to the programmed thickness. And as far as cost, laser cutters from china the large ones may cost the same as a bandsaw system, but won't have any where near enough power, once you get the size and power it'll be several hundred dollars. And even then, you'll have a giant lighter, because it'll just catch the logs on fire. Or worse it'll pierce the log and boil the center causing the log to explode.
Also the biggest lasers you can order from China have no way of moving the log, or moving along the log, having one custom built would be a huge expense there too. How much does an average log weigh? 1-2tons?

Thanks for your response. I'm aware of the laser lighting. I just wanted to go farther, you know...cutting. About moving, yes I was thinking building the carriage for the log. The laser would be fixed. The weight varies according to lengths from 100 to 250 kg. The moving part is a well known system, no problem with that.

Thanks

[MaryB]

Laser cutting doesn't leave a vertical kerf, it is v shaped.

[rbocaz]

Laser cutting doesn't leave a vertical kerf, it is v shaped.

Good point

[zax15uk]

Many of the problems would be solved with a water jet guided laser. I don't know if they are available in sufficient power levels for your purpose but it is something to look into.

Zax.

[rbocaz]

I have given it some thoughts but the problem I can see is the waste water. I would need a recycling pump and filters, etc. etc. but it's a good idea. Thanks.

[Andre' B]

Newer systems use lasers to guide the blades. Pretty much a powerful laser line is shined on to the log that shows exactly where the blade will go. It allows the operator to know for sure where his cut is going to go through the whole log, no more multiple passes to cut the edge off the log,

I find it more valuable when is shows me I a once again going to try to saw of one of the steel dogs.(wedge)

[laserbox_Bert]

Hi,
I'm sorry, but there are some points in this discussion which are just not right:
laser-cut edge is not v-shaped, except your focal position is wrong or you are talking about melt cutting - dont think you are able to melt wood... in case of sublimation and thick materials you will get a )( - shape, which is the form every em-wave propagates
wood will not burn or explode (why should it explode?) it will get carbonized and maybe it will glow. Water wont help against carbonisation, but shielding-gas will. Don't know which one will fit best, but it will help surly.
And of course there are laser which have enough power to cut the thickest wood you can imagine; I think you get CO2 Lasers up to 40kW - just a matter of money.
And that's the point: It would be very expensive and your cutting edge will be at least a bit brown due to carbonisation - so what would be the effort of it?

Regards

[bpoulin]

(why should it explode?)

Because logs are generally cut wet, not dried. So there is still moisture inside the log, the moisture will boil in the center because the heat can not dissipate, causing the moisture inside to expand making the log explode. It's a common occurrence in forest fires.

[bpoulin]

Also I'd be impressed if you can get a laser to make )( this cut, because you'd be bending light... It makes this cut ><

[laserbox_Bert]

Hi again, didnt know that wood is cut wet, is it cause of the chips?
But i still can hardly believe that the log would explode; at a fire you have a massive heat input which boils the water in the tree - you dont have this effect at lasercutting - total heat input is very low but it is at a very small area - so you are vapourizing a small volume and due to (the very small) heat conduction a small area next to the cutting edge will also be heated...
But if you are really interessted I can just try it - this effect should also occure at small rigs (some centimeters), or?

And the beam will never have a >< form it will always have a form like )(, but of course with lens you can strech and forge it. But you will always have a gaussian beam. If the cutting edge looks like that is a matter of heat conduction, heat capacity, and isotropic behavior.

shape