Laser Engraving / Cutting And Turnings

As a better way to keep the cats away from the lathe?

mac

Please remove splinters before emailing

I don't think a cat would like getting lasered this way. But one of those laser pointers sure are fun when there's a cat around - or some kinds of dogs : )

today, laser equipment with which I am familiar would have great difficulty with anything much beyond a basic cylindrical shape - certainly doing Andi Wolfe style motifs would require significant setup and some pretty advanced math to calculate the inverse projections from the object's surface to the laser control axis - my recommendation - don't give up your wood burning pen just yet

That seems to be the same opinion of my laser guy where I used get my wood pens engraved. He started doing humidor lids, plaques, mementos, etc., a few years ago. He had quite an investment into his system, something like 30K. But he still couldn't do anything that required more than simple 2D images.

Now he is looking at shutting down his business as the EPA licenses, classes and certifications will be taking a great deal of profits. And the city is going to require him to upgrade his exhaust system as well. All in all, I don't think he wants to put another 50K in his business and I think he will simply close.

Robert

I was thinking the same thing - but overlooked a couple of things the laser engraving machines makers didn't. The effective depth of focus on the laser I saw is about 1/8". Beyond that the laser begins to do what laser folks call "blooming", the beam beginning to spread out, losing it's effective "crispness". But when the beam is only 0.007" in diameter, and it blooms 10% - it's still only 0.008" in diameter.

Let me try and put that in perspective.

The finest wood burning tools, the ones with the razor blade thin tips can, in the hands of someone who knows how to use it, burn 100 lines per inch. I've got a book by a guy named Curtis J. Badger who is a master bird carver. He uses a pyrography for bird feather detailing. He does down (sp?) feathers that, from closeup photos, would require actually touching to realize that they are wood. And this guy can only do 100 lines per inch with the finest tips he can find.

So - the surface area on a curved piece you can laser with adequate crispness IS limited by the laser's effective depth of focus and a function of the amount of curvature in the area to be "engraved". I worked out the "effective width" for 2 to 8" diameter curves and did the illustration near the bottom of this page (I posted the url earlier and have since added to it)

So for an 8" diameter sphere, you'd have a circle about 1 7/8" in diameter to "engrave" in - IF - you set the focus at the high point. BUT - if you set the focus at the edge of the the "effective depth of focus" you could double the diameter. Of course that would mean that the "crispness" at the center and edges of the "engraving" wouldn't be as crisp as possible, but it probably wouldn't be noticeable to the naked eye, especially once you've added color.

Laser engraving wouldn't work with some of her curved bowls - on the inside. Could work on the OUTSIDE though But for her shallower ones, and her plates and platters, those are within the abilities of laser engraver

Re: advanced math and calculations

Actually, the "printer driver" that the laser engraver company provides with the laser does a lot of the complex math for you. Computer are really good at manipulating numbers and digital image files are just numeric data. So if that "printer driver" tells the laser to not fire when a pixel is "white", to fire at maximum power when it's "black" (pierce) and dynamically change the power and frequency of the laser pulse based on other pixels' "grayness" (carve, with depth defined by "gray" numeric value), the computer and software tells the laser what to do and where to do it - and it does it.

The laser's getting instructions on WHERE to fire (x,y location) HOW MUCH to use fire (power) HOW LONG to keep firing at that spot (frequency) HOW FAST to move to the next firing location

You get to set these "print" parameters, much like selecting "fast draft", "normal" or "best" with an inkjet or "laser" printer.

Now the cool thing about using a gray scale image to act as a plan view contour map for a 3-D shape is that there's software packages out there already that let you create virtual 3-D objects fairly easily - and then convert them into gray scale "flat" image files. There was such a software program called Bryce 3-D that was pretty powerful and fairly easy to use - but - because of the computational speed of computers at the time could take hours to render a 3-D object when you wanted photo realism.

This low relief 3-D "carving" using the laser has some really interesting possibilities. See the bottom illustration of a "basket weave" on the url I gave above.

I've since been playing with gray scale texturing using PhotoShop and some of the texturing filter plug ins for it look like they could make the texturing currently being done with flex shaft and burs and carving tools all look pretty primitive by comparison. Imagine doing scales or fur or clusters of tiny convex hemispheres in areas of a piece.

Right now all the stuff I've done about using the laser for engraving, carving and piercing are on our turning club site. I think I'll start doing some pages on it on my woodworking site. Will post the url here when I've got something to share.

SNIP

I think this will fall into the "depends on who is doing it" category. I will always have deeper appreciation for something hand carved or rendered over machine carved.

I was over at my friend Lewis' shop when he was finishing up a carved scene for the front of the podium of a small church. It was gorgeous, and he had been working on it for a while (3-4 months) to get it where he wanted it. It was lovely.

But I don't think a Compucarve would turn out the same thing. More detail, yes. Sharper cuts, yes. The nuances that show it was hand carved on wood, I guess you could program it. But it wouldn't be the same. Work hard on the design, finish it up and save it. Then putting in the board, turning on the machine and going to lunch doesn't really seem like carving to me.

Maybe "the craft" in the case of the Compucarve or a laser engraver is the design of the applied rendering rather than the finished product which allows others to enjoy the computer design work.

I know the laser and its related machinery and software can do much finer work than can ever be performed by hand, but I think that the decorations will become so ornate and complicated that they too will become just run of the mill.

But then again, you can only turn so much stuff round. We used to have a turner in our little club that decided that turning a vessel was no different than a painter making up a canvas and frame. that was his start point. He happily burned, pierced, cut, veined, stained and anything else his heart desired when he started operating on his forms.

As always, I'm looking forward to it!

Robert

In my youth I worked summers laying #3 sheeting. I had a Disston handsaw to cut and a Plumb hammer to nail the #3 SYP sheeting to 2X8 rafters. Down through the years handsaws were replaced by Skilsaws, hammers with pneumatic nailers, the twisted & knotty lumber with plywood CDX and the rafters with 2X4 trusses. As each of these 'advancements' happened many carpenters deplored the predicted loss of craftsmanship, losing jobs and wasting years of apprenticeship due to those damn machines. The increased efficiency and likely better product didn't bring on the present housing problems and caring craftsmen like Robert are still around and likely using handsaws and planes. So What? Seems to me that in any art or craft there is a sine wave of changes from simple (pure) to complex (mongrel) to simple again, etc. The oscillations in style, decoration, fabrication, medium and tools in furniture, architecture. painting and music are obvious.

I imagine that woodturning will follow similar curves and will probably come full circle some day, although maybe not all the way back to pole lathes, wooden trenchers and soup bowls, but who knows? Lots of previous owners of kevlar canoes are making strip canoes, so it might be birch bark and dugouts in the years to come.

OK, my tediously stretched out point is that to me laser engraving is just another point along the sine wave, a computer numerical controlled cutting system used for decoration instead of fabrication. Lasers for woodturners are not to be praised or deplored any more than electronic speed control or revolving tailstock spindles. If lasers advance the craft/art or are just a novel addition, I'm all for it, but save your buffers, chatter tools and wood burners boys, the well turned, nicely finished hand embellished wooden bowl is "gone rise again". :)

Turn to Safety, Arch Fortiter

Absolutely true. When I started swinging a hammer, we laughed at the weenies that needed nail guns to drive nails. There weren't many nailguns out there, and the old ones weighed a ton and cost as much. It was easy to make fun.

Plus, all of us had gone through the "learn how to drive a nail camp". Since I was not deemed better for anything other than hauling wood and sweeping, my next step up was a cloth bag with 8d nails in it to nail off decking. Vast, open plains of decking on apartments. I learned how to drive nails alright, but I couldn't open and close my hands without pain for months. I thought everyone should go through that if they were going to call themselves a carpenter.

NO ONE does that now. Hammers are not tools anymore, they are beating and adjusting devices. And so it goes. Looking back, I remember what disdain I had for those that couldn't drive a few hundred 16d nails in a day. Now I don't know anyone that can (including me!) and it really doesn't matter.

I think you are exactly right on that. What's the old saying? "What was once old is new once more" or something like that.

Some wild haired, bearded youth just out of college will feel "an organic urge" when turning wood and he will turn a simple bowl. He will feel connected to the elders of turning. He will be inspired by the ancients. He will meet one or more of the grand old guard of the craft that never owned a laser or a bag or prisma color dye markers, and he will feel a kinship to the purity of the craft lost generations ago.

Whatever.

It has to work this way; how else could it? If it didn't, the craft would be lost.

Look at furniture making. From the old days in Europe, simple, functional furniture was the design for homes. All the very best wound up in castles, estates, etc. Then furniture and craftsmen come to the USA, and there are craftsmen that can afford to make nice furniture for homes because they can keep all the money for themselves.

The incredibly ornate, highly stylized and tedious style of the Federalist, Sheraton, Windsor, etc. were all here. That lasted for some time.

Then Stickley.came along and brought his version of the British Arts and Crafts movement. Ouch. After looking at a fine Federalist buffet, looking at a Stickey piece was like looking at a middle school child's shop project. Simple woods, simple designs, simple finishes, straight cuts, exposed joints... it's all there. It went away, for a few decades, but it is back now. Simple, difficult, simple, difficult; it is no more than a swing of the pendulum.

I couldn't agree more. I think the computer driven stuff is neat, but it will lose its appeal. Someone will come along and "rediscover" the simple beauty of a turned bowl and a clear, uncolored finish. They will praise the shape, ask about inspiration, and it will all start again.

That's my take, anyway.

Good post, Arch.

Robert

How about unadorned and adorned. 'Simple' is quite often more 'Difficult' to design and execute.

big snip

I think charlie (and others) that you missed my point - it has NOTHING to do with focus, it has to do with the projection of the desired shape onto an unknown geometric surface and the resultant distortions - I am unaware of laser drivers that can be programmed with a highly nonlinear surface, and I am unaware of laser etching equipment that includes a interferrometer or other equipment to measure the surface prior to etching so that the requisite image warping can be precalculated.

I saw a great show on 3D carving on of non linear surfaces where he laser rotated around the object and cut/burned exact depths to create round shapes for casting molds, part representation molds as well as making one off objects for various tests.

It was similar to this where he operator scanned a 3D image of a model and then let the laser carve the model as a duplicate in 3D, wrapping or warping around the CAD file to correct dimension and feeding it into the laser.

The intriguing part to me was that the laser in the documentary made the decision on how much power was fed to the laser while cutting. Don't know if the above laser was this sophisticated.

The science documentary I saw used the laser interferrometer (had to look that one up!) to measure a human skull with a clay face that was made for a "prehistoric man" exhibit. The didn't want the skull in the exhibit, so they fashioned a face onto the skull, put it in the laser chamber's hold, and measured the skull with the face on it. The idea was that the clay would come off after the face was recorded and the skull would be cleaned an safely stored.

The laser took something like two to three hours to scan the head in

3D. Then the image was rendered into a format the cutting laser understood. This took something like another 12 hours or so. After it was finished, they cut the head the next day out of foam in perfect 3D and the representation of the real skull with clay face was almost perfect.

That head would seem an easy task compared to the woman/model above.

Interesting topic.

Robert

Measuring the surface prior to etching is easy, depth is still difficult if not impossible to consistently control. There are a number of ways to handle the focal point, usually laser scanning based, or old school piezo based. Some of the laser cutters have a 3D scanning attachment. You mount the workpiece, scan in it's dimensions and map that to your model to verify positioning before you start cutting. Or just scan in and sculpt in your 3D app, then post your model to the cutter.

Many 3D shapes can be made with 4 or 5 axis linear tooling. "Non-linear" diamond tooling is made using lasers.

Lasers are used to cut gemstones and diamonds. You are correct that only a few home-user

Funny you should mention this- I've been considering getting a laser for just this purpose. So that those who haven't looked at this have a bit of an idea, an Epilog 45 watt laser with a rotary attachment (which would allow a guy to etch the outside of a turned piece) is about $17,000 new.

Granted, this is expensive, and I agree that etching family portraits and the like does not sound like much fun, but going off the car I bought new a few years ago (at a high interest rate, lucky me) a guy would have to earn about $400 a month for the tool to pay for itself. It'd be awesome to do that with laser engraved bowls or something, but I think the most realistic prospect is to etch family portraits on some relatively inexpensive wood like pine or balsa, and try to sell 5 or 6 of them a month to make the payment.

Looking at it this way, I figure that, if I actually get one (which is certainly not a decided thing yet) it'll be a matter of taking on a fairly easy part-time job in exchange for having a really cool toy to play with on my own projects. Hell, if I could impoverish myself for a reliable vehicle that is no kind of sensible investment at all, I figure something like this is a much wiser move.

As far as using the thing goes, it would seem to be simplicity itself- the unit hooks to a PC with a networking cable, and works like a regular printer. It needs Corel or CAD to cut parts from wood, but will evidently engrave from any program that can make use of a printer, so as far as I can see, the sky is pretty much the limit. With a handful of good filters, a guy can make just about any image in photoshop in an hour or two.

You raise a vaild concern here- but there's a lot to be said for designing the piece to fit the machine. While it might not work very well to etch a full-face scene on a spherical object, that doesn't stop a guy from applying some nice banding on some strategically turned planes.

Sure would be nice if the things used standard g-codes, though- while it might make for big programs, being able to control the z-hieght to etch contours would be excellent.

If you're looking to get into it yourself, I'd suggest waterjet- provided it won't mess up your wood. While I'm fairly comfortable with the idea of etching wood with the laser, cutting parts is another matter. The actual cutting is fine, especially if done with nitrogen as an assist gas- but the problem is in dust collection.

Without a dust collector, cutting wood with the laser smokes a lot. With a collector that is strong enough to be effective, there's a good chance that it will suck the smaller bits into it. I wouldn't have thought that that was much of an issue *until* I had the misfortune of having the dust collector at work catching fire on me. It wasn't mine, or anyone else's fault- but it was a horrendous mess and a lot of thick smoke to deal with. And, we cut metal- not wood. If a laser cutter can set aluminum and steel dust on fire to make a little impromptu thermite 20 yards from the actual cutting area, I would imagine that a collector full of charcoal and bits of wood would be even more likely to go up in smoke.