Author Topic: Laser Shaper  (Read 9104 times)

PonoBill

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Laser Shaper
« on: October 25, 2014, 12:33:58 PM »
I looked at the cost of an AKU shaper recently and decided that was a bit rich for my hobby level interest. I've also looked at the massive custom built shaping system that Mark Nelson has, and wondered if there can't be a better way for a geek like me to build something like this. So project number 1543 enters the queue. After an evening of napkin sketches I've come up with a way to probably build a pretty cheap hobby level shaper--might even be pro-level.

The premise is simple--a shaping head runs in a lightweight two-motor X-Y frame. The frame will not be sufficiently strong to be precise at all positions--it will bend and flex all over the place. I'll probably make the frame out of cheap angle aluminum--maybe 1"--and the shaping head will just be in a cart that runs on rubber wheels in the long Y axis of the frame. The X axis is just a a second, smaller card moving the head within the Y axis cart. Positional accuracy of the cutting head does not rely on rigidity of the platform or precision in the cart position, instead it relies on controlling the Z axis with laser interferometer beam references aimed from the end and side of the platform. Positional accuracy should be within a thousandth in every axis.

You could store the frame on its side, hang it on a wall, or put it together from four pieces. Place the lasers and let them calibrate themselves, stick the cart on the frame and let it go.

I think I must be missing something, this seems like the obvious way to build one of these.
« Last Edit: October 25, 2014, 12:41:36 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

PonoBill

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Re: Laser Shaper
« Reply #1 on: October 25, 2014, 01:57:51 PM »
What makes this interesting I think is that the X and Y axis drives don't have to be precisely controlled. In fact they could just be driven randomly or in some predetermined efficient pattern. Randomly might be optimal. the only important parameters are the current location and Z height of the cutter.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

southwesterly

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Re: Laser Shaper
« Reply #2 on: October 25, 2014, 05:52:55 PM »
 Build it and Z will come.

Biggreen

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Re: Laser Shaper
« Reply #3 on: October 25, 2014, 08:05:51 PM »
I'm all in on your bandwagon, Pono. I say it's a go and I'll gladly be a part of the peanut gallery and only pepper your progress with positive comments. Hell I could even show up with a billet of foam and a bunch of plans/specs....you know, for experimentation  ;). But it would really be great if you could move it up in the queue from 1543 to say...3.  Hopefully the gallery is in agreement. We're behind you all the way!

pdxmike

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Re: Laser Shaper
« Reply #4 on: October 25, 2014, 08:57:53 PM »
Looks like Descartes got put before the bandwagon.
« Last Edit: October 25, 2014, 09:20:23 PM by pdxmike »

PonoBill

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Re: Laser Shaper
« Reply #5 on: October 25, 2014, 10:02:15 PM »
Yup, I think this has legs. I finished a few chapters in the new book, so I rewarded myself with a little research on laser distance measurement. As I thought, the interferometer approach would be the most precise, but might be unnecessarily expensive and the range might be a problem. Even hacking a cheap laser tape measure would give accuracy of 1/16 of an inch, which is probably adequate, but simple triangulation with two sensors for each axis would increase the precision to a few hundredths of an inch which is more than adequate. Range is a few hundred feet. Relatively simple electronics and only one axis to control. It's looking almost easy.

the Z axis controller can be pretty dumb. The top of the cutting head can have a target on it. the cutter control just keeps the lasers in the center of the target. the position measurement tells the lasers what height to be positioned above the bed, and the same laser beams tell the system exactly where the head. It would need to detect which direction the laser is moving and track it, but otherwise it can just follow the beams.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

surfcowboy

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Re: Laser Shaper
« Reply #6 on: October 25, 2014, 11:44:02 PM »
Pono, this is basically a Roomba for shaping. I love it and I think you're right.

Is the idea that you flip the blank and do it a side at a time?

supuk

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Re: Laser Shaper
« Reply #7 on: October 26, 2014, 01:27:23 AM »
are you talking about just having the position of the router controlled by a number of lasers?
« Last Edit: October 26, 2014, 01:34:17 AM by supuk »

Sup-position

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Re: Laser Shaper
« Reply #8 on: October 26, 2014, 06:05:20 AM »
Great, I'm looking for involvement in a project...

There are a few more pieces to the puzzle..

Do you know if dust will affect the laser?



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stoneaxe

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Re: Laser Shaper
« Reply #9 on: October 26, 2014, 07:41:54 AM »
Yeah....move this one up in the priorities will ya.
Bob

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PonoBill

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Re: Laser Shaper
« Reply #10 on: October 26, 2014, 07:56:53 AM »
are you talking about just having the position of the router controlled by a number of lasers?
In essence, yes. the Z position gets controlled by a stepper motor with it's height at any X-Y position determined by it's location. The height is precise and unaffected by precision of the bed because it's determined by the X-Y lasers, which also measure the X-Y location with adequate accuracy. Calling it a Roomba for shaping is a good analogy. It's actually possible to have no bed--to make the shaping roomba just crawl over the blank, but I think a bed is easier to build.

Dust will certainly affect the laser, but it's transient, and even cheap laser rulers dispose of readings outside the average value to deal with short transients. The laser is pulsed at high frequency and the time to return is calculated, they take millions of readings per second so it should be possible to find a steady reading bouncing off a target even in a flurry of dust. Triangulation will also help since a dust particle only affect one beam. Obvious errors can be tossed out in the software.
« Last Edit: October 26, 2014, 08:09:46 AM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

surfcowboy

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Re: Laser Shaper
« Reply #11 on: October 26, 2014, 09:30:02 AM »
Pono, I think you're on to something and while not critical that you have a great bed, the better it is, the better the output so this scales nicely from hobbyist to pro.

Build a loose one for your garage on the cheap, or build a really nice frame if you have the bread. That's a nice side-effect of the error correction built into the location-based cut.

PonoBill

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Re: Laser Shaper
« Reply #12 on: October 26, 2014, 09:39:43 AM »
I'm going to see if Maui has a Maker group. If they don't, I'll probably start one. I think I have sufficient chops to build the head unit, and the processing electronics and software, but it would be nice to have someone else hack the laser rulers or adapt something commercial. Best of all would be to have ten or twenty enthusiastic Makers working away at the idea. If we get it past the first prototype stage I'd do a kickstarter campaign to produce finished heads and lasers. The bed would probably be left up to the users. It could easily be a wooden track, so that shouldn't be a hindrance, and it can be any length and width up to the limit of the rangefinder tech.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

supuk

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Re: Laser Shaper
« Reply #13 on: October 26, 2014, 02:19:13 PM »
I spent two year researching before I started my build looking into all the options to build something cheap and reliable. I like the idea of lasers but tbh the electronics were the cheaper side to my build and the resolution and speed is fantastic. From my research any cnc type machine needs a solid base and the first thing I found I majorly overlooked was the stiffness even a basic machine would need. I thought I had really accounted for it using what you would think was overkill but in the end I still found myself trying to stiffen my machine up and ended bolting it to the floor and the wall. Any machine with moving parts and something like a router attached to it to get any form of accuracy especially while it is moving need to be a lot stiffer than you think especially if you want any form of cutting speed. you also have things like resonance to think about. 50% of the cost of my build was in building a stable platform to have the spindle mounted to. The weight and torque of a good water cooled spindle is enough on its own to twist a lightly built structure before you even bring cutting forces or resonance into the equation. There are some good forums out there with some very knowledgable people and I learned a huge amount as it turned out there is a hole lot more detail to a build than you first thin but I'm glad I did it myself as I know have a machine that is far better than most of the comparable machines on the surfboard market.

PonoBill

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Re: Laser Shaper
« Reply #14 on: October 26, 2014, 03:54:23 PM »
I"m certain that's all true, I'm riffing on a brainstorm. And I do understand the unexpected forces in almost any machine--I just recycled an arbor press I built that seemed absurdly overbuilt--it flexed uncontrollably when I tried to use it to press a dimple punch into 1/16th aluminum.

This approach might not work, but it's worth some fiddling. I'll spend some time in the forums and see what people are saying. That said, new technology brings new ways to do things that should NOT be built on the platform of what was necessary previously. I'm certain the CNC system you built requires that the X-Y plane be precisely managed. If the design and the electronics makes that unnecessary, then the overall design can radically change. If I can always position accurately in the Z axis then this idea will work, regardless of torque and twist. If I can't, it won't. It might take ten times longer to mill a board than a conventional CNC, but if a cheap robot is doing it, then who cares? I run my 3d printers for days on some projects, come back a week later, look at the log and see that it's been done for two days.

I started out saying I think I'm missing something, I would edit that to say I'm SURE I'm missing a lot. But if I ever get around to attempting this it will be an interesting voyage.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

 


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