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I thought I'd throw this out there and see what gets thrown back. Does anyone have any experience getting parts laser cut? I have a number of parts that are going to be cut out of 1/8" thin plywood, and I have a source that will cut them for me. The problem is the type of wood to use that cuts the best and is the most cost effective (although at this stage I can forego the costs for the end result!).

So far we've cut some from 1/8" plywood from Midwest products and some from a 3 ply 1/8" plywood from national Balsa. The Midwest products material came out great, but the 3 ply stuff charred real good on the edges. The problem is that the midwest stuff is $13 for a 12"x24" sheet, vs $3 for the same size. AND finding relatively flat stuff (so that it lays flat on the laser bed) has been a hassle.

From what I've read online, hardwoods are the best for laser cutting. Clean cuts, very minimal charing (if any, typically just a nice browning occurs). What kills the plywood is the glue and other "stuff" that goes into making it. But much more expensive per sq-ft than what I've used so far.

Any comments or suggestions would be welcome!

thanks, Ned
 

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Ned
If you go to this sight and do a search for laser cutting, you might find what you are looking for. If not, post your question and you should get lots of help. To post you'll have to sign up, but it costs nothing.

http://www.cnczone.com/

Big Mike :)
 

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Ned,


I do some laser cutting, so I can offer a few observations.

The problem with laser cutting plywood is not the type of wood making up the plys but the glue. Some glues take seemingly massive amounts of power to cut through a layer only 1 or 2 mil thick. Then there are some glues that cut easily but that burn and smoke like crazy making for a simply horrible cut. This can be mitigated somewhat by using air-assist, i.e., blowing air directly at the point of cut through. However some plys/woods may require use of a non-combustible gas (nitrogen) to minimize burning/charring.

There are laser-friendly plywoods available, but they cost significantly more than aircraft plywood from Midwest and may not be available in all thicknesses. Interestingly, I've cut some batches of Midwest plywood without problem and other batches have simply been impossible.

For cutting actual wood, basswood is probably the easiest/best for model work. In addition to cutting relatively cleanly, it is available in a large variety of thicknesses and sizes. Other woods, such as alder, walnut, poplar, etc., are available, but not in the range of sizes/thicknesses of basswood.

Acrylic sheet is easy to cut and solvent welds together and may be an overall better choice for model building with the laser. Should you need/want to have a wood exterior to your model. a thin layer of basswood can always be applied to an acrylic sub-structure.

Brian
 

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Part of the reason that the Midwest stuff lays so flat I believe is it is MANY layers of very thin plys. That is also why it is so Expensive. I can remember back 20 years ago when working at a laminate shop When it was time to do curved surfaces the shop foreman favored a very thin plywood with only three layers. The shop would then lay out a cookie cutter frame work to support the surface and nail on one layer then a layer of glue and then the next layer and the glue until they'd built up the thickness they wanted. This plywood was desirable for it's ability to curve but once glued up into 7 layers deep was a strong as the rest of the system.

I've probably not helped you much except for the explanation of why the Midwest worked much better than the other stuff. The higher the ply count the better the plywood. At least for this application.

Chas
 

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Allegheny,
You said you do laser cutting, could I contact you off line about a project I'd like to start.
Your post made me finally decide to join My Large Scale even though I've been lurking around for years.
 

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Discussion Starter #6
Thanks for the inputs! I think I will shop around and find some good sources of basswood and various other types. I've also been thinking about finding some plastic scale brick sheeting that is laser friendly. I can use what I got, but in order to do so we'll have to turn up the wattage to cut thru completely, which will then burn up some of the fine detail I'm looking for. It's already produced some amazing results which have garned some oohs and aahs from people that have seen it, LOL.
It's also one of those things where, if I don't point out the problems, they'd have never noticed...but I do!
BTW - my friend who is doing the laser cutting is thinking about offering his services for others as a way to more utilize his equipment. I'll post a note if he decides to do so, and I'll post some pics of the completed pieces as they get done.
 

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Ned,

You can actually use the laser to "make" plastic brick sheets from acrylic. This could be very advantageous for large scale models as you could make sheets of brick as large as the cutting bed of the laser (Epilogs and Universals have 12-18 x 24" beds; my laser bed covers 20 x 36"). Also, since you only need to engrave a mortar line and not cut clean through, you could use whatever thickness of acrylic you had available (how about a bullet proof jail or bank made out of 1.25" thick material!

Bernie Kempinski - of N-scale fame - does just this process for his line of N-scale model buildings (Alkem Scale Models). The advantage here is that you can make bricks whatever size (and shape) and the mortar lines whatever thickness you want. The disadvantages are that it takes a huge amount of laser time (read: big $$$$) and you end up with perfectly uniform bricks and mortar spacing. Of course you can vary the mortar lines by programming the CAD file that way, but again this takes more time and money.

Brian
 

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Hi Ned,
I also do laser cutting and prefer to use wood over plastic.
I did all of the wood cutting for David Fletcher's Carter Bro's Master Class.

What Brian stated is 100% correct about plywood and its glue layers. But let me add a few more comments.
What makes Aircraft grade plywood so much of a pain to cut is not only the glue layers but the type of glue used. Aircraft grade plywood uses water resistant (waterproof in most cases) glue. This glue is much more dense then the glue used in other plywood. Density is a laser's worst enemy. The more dense a substance is, the more power it takes to cut. The more power you throw at wood, the more burning you get. Hence, ugly cuts.
Example, I have access to both 5ply and 3ply, 2mm aircraft plywood. I can cut the 3ply stuff without too much problems and even get a nice looking cut. The 5ply stuff can be cut with the laser but there is so much charing (burning) that the parts are almost unusable. The only difference between the two is the two extra layers of glue on the 5ply stuff.

On the flip side, I routinely cut 1/8" 3ply, commercial plywood, (which is almost twice as thick as the 2mm stuff) with half the power, twice the speed and with a very nice cut with no charing.

BTW I get my 1/8" Baltic Birch plywood in 60"x60" sheets for about $20 a sheet.

As far as solid wood, being that I have all the equipment needed to produce strip wood from a tree, odd size dim's are not a problem. Just tell me the species and the final dim's, and I can produce it.

I'm not trying to drum up business but just trying to inform you that you should look around for better prices. Any cutter that has been in business for a while should be able to easily beat Midwest's prices.

Doug Bronson
www.bronson-tate.com
 

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Hello everyone...

Are there different machines used for cutting wood and plastic??

It may be silly question but

I am new to this.
_____________________________
Marking Systems
 

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Has anyone tried laser cutting this stuff...?

http://www.micromark.com/GATORFOAM-BROWN,8427.html

Gatorfoam (tm), from Micromark. it is a thin core of foamed polystyrene with a wood fiber overlay on both sides.

I got several sheets of it to build something I wanted but never got around to even starting.

I did cut off a 1.5" x 12" section, left it unpainted and wedged it in a section of chainlink fence in my backyard just to see what would happen to it. It has been knocked off the fence many times (getting bent in the process), been stepped on at least once and has layed on the ground (on rocks) under leaves and several inches of snow and seems none the worse for wear after at least 5 years. I pick it back up and wedge it again in the fence when I find it on the ground, which might mean it has laid there for months. The only damage (other than the bends caused by being knocked off the fence and stepped on) is the core seems to have shrunk from the edges maybe 1/32 of an inch on all sides.

I have been wondering how it might take being cut by laser. Would the foam melt too much to hold dimensions properly?... could that be taken into account uniformly?
 

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One other possibility you might consider is water jet cutting. I needed to have some frame pieces cut from 1/16" brass and it worked perfectly.


The cutting is done with an ultra-high pressure water jet with some abrasive slurry mixed in. The cuts are accuarate to within a few thousandth's of an inch. The machine can cut anything: steel, glass, brass, aluminum, plastic, rubber and plywood are no problem.

The machine is big enough to cut parts from a 4 x 8 foot panel.


The design for the finished piece has to be defined by a CAD file (I assume that is true for laser cutting as well). At any rate, they load the design file into the machine control console.


Here, you can see the nozzle being positioned over the brass stock before starting cutting.


Those frame pieces would have been a nightmare to cut using drills, jeweler's saw and files. The cost was reasonable and each frame piece took less than a minute.

Llyn
 

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@import url(http://www.mylargescale.com/Providers/HtmlEditorProviders/CEHtmlEditorProvider/Load.ashx?type=style&file=SyntaxHighlighter.css);@import url(/providers/htmleditorproviders/cehtmleditorprovider/dnngeneral.css); @import url(http://www.mylargescale.com/Providers/HtmlEditorProviders/CEHtmlEditorProvider/Load.ashx?type=style&file=SyntaxHighlighter.css);@import url(/providers/htmleditorproviders/cehtmleditorprovider/dnngeneral.css); @import url(http://www.mylargescale.com/Providers/HtmlEditorProviders/CEHtmlEditorProvider/Load.ashx?type=style&file=SyntaxHighlighter.css);@import url(/providers/htmled); @import url(http://www.mylargescale.com/Providers/HtmlEditorProviders/CEHtmlEditorProvider/Load.ashx?type=style&file=SyntaxHighlighter.css);@import url(/providers/htmleditorproviders/cehtmleditorprovider/dnngeneral.css); Posted By BigMike4u on 10 Apr 2008 11:13 PM
Ned
If you go to this sight and do a search for laser cutting, you might find what you are looking for. If not, post your question and you should get lots of help. To post you'll have to sign up, but it costs nothing.

http://www.cnczone.com/

Big Mike :)
Also check out here:

http://www.kerfdevelopments.com/plasmacutting.html
 

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I think that gator board stuff would cut just fine with a laser, provided the operator knows his stuff! These modern laser machines are pretty cool and do a great job. I think different machines are needed for metal cutting (brass and copper are a problem aluminum, steel and Stainless are OK) RMS Laser near San Diego has cut Plywood for me many times (1/32, 1/16 and 1/8th) I think he is happy to do 1/4" or more and has done plastics and thin steel parts. he can etch too.
http://www.rmslaser.com/
 

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Alan at G.A.L. (www.thegalline.com) does laser cut styrene to make buildings and railroad cars. I'd send him an email and ask. Styrene is easy to work with, like acrylic plastic.
 

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I talked with the guy that runs Gatorfoam about the possibility of cutting it with a laser at the BigE show in Springfield back in late January.


Specifically, I asked if Gatorfoam contains PVC. The sublimation process (the laser sublimates, or vaporizes) whatever it's cutting. In the process, it can also change it chemically. In the case of PVC highly toxic (to you) and corrosive (to the laser) gases are generated, so it's generally considered a big no-no to cut up PVC on a laser system not specifically designed for it (stainless steel everything and very high air flow rates with provision to capture the fumes).

He gave me a few pieces to try out on my laser, but I have yet to give it a try as my air compressor pump died on me. Once I get the system back up and running, I'll cut some identical files on several types of wood, styrene, acrylic and Gatorfoam and report back. One thing I did notice is that Gatorfoam is not available in more than two or three thicknesses, unlike basswood or acrylic - this would need to be taken into consideration when designing a building or car body, etc. I'm finishing up the CAD drawings for a 1:20.3 Pennsy standard gauge flatcar (yes, it's quite big) and the availability of multiple thicknesses of acrylic is a great advantage.


Brian
Taxachusetts
 

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You can also look into water-jet cutting. This method does not generate the negatives side effects that a laser does with PVC. It is just as clean cut as a laser. I am not sure of the comparative costs, but for the Gator board it is a good option.

Bob C
 

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I use a 40w laser to cut gator board. 100% power and 60% speed and one pass. Fumes are ok as I added a external exast fan in the 4 inch duct. NO fumes ever as I use it on everything. I waite a few seconds before opening the lid so fumes clear.
 
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