Buildlog.net 2.x 1250mm wide Laser Cutter

[TheZeroBeast]

Hello,

I am looking into building a 2.x Laser Cutter for my RC aircraft hobby and would like to get some input on my ideas to make it a bit more suited to my needs.
The main reason I am looking into a laser cutter is for cutting plywood and balsa for model aeroplanes and helicopters.
In saying this, the standard dimensions for balsa are up to 915mm x 102mm and for plywood, 2400mm x 1200mm.

So, I would like to be able to cut a strip of the ply at once and a whole board of balsa so I was thinking of extending the cutting width of the standard 2.x Laser to 1250 to comfortably accommodate a slice of plywood.

The question I have been thinking about while looking over all the drawings is whether these materials would still be ridged enough to span such a distance and hold together for CNC work?
The other area I have started working on is Australian suppliers for the parts required which is a lot of fun.

Look forward to your thoughts and the build, can’t wait for the fun

[bdring]

That is getting pretty big for any flying optic design. You might have trouble with the alignment. You might consider starting with the standard size and upgrading it later. It would probably be less than $150 of materials to upgrade it later. The skins would need to change, but you might be able to sell the old ones to a regular builder.

[mattrsch]

I have had trouble cutting high quality aircraft ply with my 40W laser. You may want to do some material tests before you commit. Balsa cuts like a dream though.

[TheZeroBeast]

Hey Guys thanks for the input.

I think your right Bart, starting standard would be the way to go, work out all the kinks before adding some new ones

Mattrsch, what thickness ply were you having trouble cutting, was it burning the ply because it was taking so long to cut?
If so would there be much work in upgrading the optics and tube to 60w to help out in these situations?
I would say at the start I only need to cut plywood at like a few mm thick.

[karmacappa]

Plywood is harder to cut than balsa because there is glue in the plywood. The glue takes more power to process than straight wood particles.
To disclose this: I do not have a 2.x laser, but I'm doing tons of research on it at the moment in prep for building one.
To upgrade your laser tube, aside from the obvious considerations of a higher wattage power supply and an adequate cooling solution for your water circulation, you need to consider the diameter of the tube and the length of the tube. To get increase wattage on the laser tube, they increase the volume of CO2 in the tube. This occurs by increasing the length or width of the tube. The tubes generally used in the base 2.x build are 40 watt (actually a 35 watt 700mm long, @50mm diameter tube). If you want a true 40W tube, it's usually 850mm long and 50mm diameter. If you want a 50 watt tube, it's usually about 1m long and 50mm diameter. If you want a 60 watt tube, it's usually about 1.2m long and 55mm diameter. Again, this varies by who produces the tube, so you need to talk to the person you are buying the tube from.
For the parts Bart supplies for the 2.x, you may run into a problem with the larger diamater tubes (I recall he said somewhere that his tube mounts will support up to about 53mm, but I can't give any more specifics offhand). You can buy larger mounts from other vendors like Lightobject, but you'll have to figure out how to attach them yourself to keep everything in alignment. Also, you need to account for the length, as I don't think any of the tubes larger than 700mm will fit in a base 2.x laser. You can easily extend the length of the cutter to accomodate longer tubes though, but you'll need to fabricate your own skins.

[mattrsch]

It depends more on the glue than the wood thickness. I usually work with 1/8" craft ply. I can cut that at a reasonable speed with no char in 1 pass. 1/4" ply can be cut with no char but it takes quite a few passes and has to be done in PPM mode (at least for the cheap home depot stuff I tend to use). I have tried some high quality 5/32" 5 ply from a hobby shop and all I could do is make ugly black marks. I'm pretty sure the deciding factor is the quality and quantity of glue. I don't know if a higher power laser would make a better cut or a bigger mess.

[macona]

The glue in plywood is not really the issue. The amount of glue in a piece of plywood is a small fraction of the material. The issue with cutting different woods is density. Balsa is mostly air, what fibers are there vaporize easily and the wood never gets very hot. With heavier materials there is more heat introduces into the cut and the wood burns more. We did cut and etch tests of almost all the major types of woods available and the result was clearly related to the density of the wood. The easiest woods to cut were Balsa and Pacific Albus, albus is almost as light as balsa, we even cut out little gliders from it. Then you got into the other softer woods like pine and fir. Many of those you could cut with little burning. Once you got to the high density woods like oak and walnut you start getting a lot of burning. Once you get to super high density MDF all bets are off. I had a heck of a time getting though a piece of 1/4" mdf on a 40 watt Epilog.

[karmacappa]

That makes sense Macona, the aircraft plywood is generally hardwood veneers. Did you test many different types of aircraft plywood?

[macona]

Tried a lot of the different hobby store aircraft plywoods. There was a patternmaker that worked there as well so we also tried various thicknesses of baltic birch ply. Nice stuff, burns pretty good like. But thats why we have sanders, unless you like the burnt look, personally I think it looks tacky, unfinished.

On other interesting effect was a friend was using the laser cutter to hollow out a section underneath a pinewood derby car for lightening. The effects of wood density were pretty obvious on the floor of the engraved area. Here is a pic I had taken (Almost 3 years ago now) while engraving. You can see the rough texture that follows the grain. The was with a 80w chinese laser.


IMGP4989 by macona, on Flickr

[TheZeroBeast]

Hi,

Thanks for the information guys.

I have looked through some posts on rcgroups and seen what the 2.x Laser can do when the ply selected doesn't have too much glue. Which I must say is extremely impressive.
http://www.rcgroups.com/forums/member.php?u=26240

I also like that he made it work with a little larger cutting area. Which may not be such a big step compared to the original 1250mm cutting area at least with a 24" x 20" cutting area I can cut the plywood in half and fit the 600mm wide sheet in.

Can anyone provide any guidance on ordering from MiSUMi Asia to Australia, I have been trying to create an account with them but I seams you need to be a business to get anywhere?