Laser cutter questions. How to set focus?

[Adrian Page]

Ever laser cut HDU Steve?

Adrian

[Scott Shepherd]

Ever laser cut HDU Steve?

Adrian

I haven't cut it, but I have engraved it. It does pretty well!

[Adrian Page]

I'm thinking I might be able to make signs out of it.

Adrian

[Sotos Patistas]

Adrian,

FWIW, I'm following your endeavor closely. Years ago I was looking for a nice Gee Bee kit and came upon your designs. In actually, your Newbee is more my speed as I had a fondness for smaller, tamer flying planes. About that time, I got my own laser and pretty much stopped buying kits, and just cut my own designs, though nothing as sophisticated as your designs. I stopped flying and kitting a few years ago, but not before designing a nice flying and reasonably well received 40 size 3D profile plane whose selling point was that the builder had absolutely no cutting to do. Every part was laser cut, and the parts interlocked and self aligned so well that no plans were needed for the build. I have more time these days and feel the itch to start building again. I have a bipe in mind that may be first on the list.
Once you get your laser, you'll see lots of opportunities to put it to use. I'll be continuing to follow your progress with interest.

Sotos

[Adrian Page]

Hi Sotos! So you cut airplane kits with a laser? What do you think of the RECI Z2 for cutting our balsa and plywood parts? Will I be happy or wish I had more power? Anything else you can tell me that would help me get the best combination of parts for my laser would be great.

Adrian

[Sotos Patistas]

Adrian,

I cut kits with a 35 watt RF fired laser, so I would think the 80 - 90 watts I see the Z2 listed at should give you plenty of power. With only 35 watts, cutting 1/4" balsa was at times a challenge. Going too slow left the edges unacceptably charred, going too fast and the cut didn't go all the way through. I don't think you'll have that problem with the Z2. The density of the balsa I was getting varied so much, that I ended up having to weigh each plank, and adjusting the speed accordingly. Cuts were always done at 100% power.
With my laser, a LaserPro Explorer, the stock 2 1/2" focal length lense was adequate. As you've likely learned at this point, the beam as it exits the focal lense is somewhat hourglass shaped, so with 1/4" balsa, in order to avoid cuts that were "angled", it was sometimes helpful to focus just a bit below the surface of the wood. The "throat" of the hourglass is deeper with a longer focal length lense, however, the focal "spot" is also bigger, and a little weaker. I tried a 4" lense once, but with only 35 watts at hand, I didn't have the power to get through 1/4" balsa. It's an option you might consider with your Z2 however. If you do, you may end up needing to adjust your drawings for the bigger spot, something I never did with the 2 1/2" lense. Also, my personal opinion is that you not overlook the usefulness of being able to engrave. I think there are lots of kits being cut with less than 80 watts.

I hope this info helps, and hopfully I didn't cloud the issue for you. Lastly, if you still have doubts about your choice of power, what you might consider is making a request of the members of the Sawmill community to cut some sample parts for you. Hopefully, someone with a similar laser to the one you are considering will volunteer. Send them the balsa stock and CAD files and ask that they cut the parts and either take photos for you, or send the parts back. I'm sure we have some Canadian folks here as that would ease the shipping hassle, though not certain any of them are Reci owners. I received similar assistance once when I was having issues by having another member with a like powered laser cut the parts I was having trouble with and it was a great help. As I gather you've noticed, there are some very helpful folks here.
If I can offer any additional info you might find helpful, please don't hesitate to ask. BTW, the Kickstarter venture is a great idea!
Lastly, here are a few of pics of the fast build I put out several years ago. What can I say, I like to build, but I'm always in a hurry. Start 1.jpgRudder.jpgStart 2.jpgHor & ele.jpgWing no plans.jpg

[Scott Shepherd]

Here are some parts I cut on our router.

struts.jpg

[Adrian Page]

Thank you Sotos for that lengthy thread! Very helpful. The 35 watt laser looks like it cut thin balsa very well.

Adrian

[Sotos Patistas]

Adrian,

Happy to share what I've learned. FWIW, the balsa shown in my pics of the rudder and hor stab/elevator is all 1/4". Also, with my 35 watt machine, 1/8" lite ply is no problem, however aircraft ply doesn't cut well at all due to the glue used. It can be lasered, but chars much more than lite or birch ply.

Steve,

I take it those are the full scale aircraft parts you mentioned earlier and that it is aircraft ply. May I ask, how thick it is and was it cut in one pass? Also, I don't see any tabs. Was a vacuum system of some sort used? thanks.

Sotos

[Scott Shepherd]

Steve,

I take it those are the full scale aircraft parts you mentioned earlier and that it is aircraft ply. May I ask, how thick it is and was it cut in one pass? Also, I don't see any tabs. Was a vacuum system of some sort used? thanks.

Sotos

Sotos, yes, they were full scale. No tabs, vacuum table used, it was 1/4" thick and done in 1 pass.

[Lucy Lee]

If without motorized up&down. the laser head, can be adjustable about 3cm or so ,so if you want thick materials, needs motorized up&down ,

[Adrian Page]

I think various arrangements could be devised to achieve the equivalent of an up down table function for occasional use.

Adrian

[Adrian Page]

Somebody once said,"How do you focus a laser without a motorized table?" Then somebody else offered a disparaging anecdote about horses and water...

Adrian

[Mike Null]

And a number of others offered that buying a machine without a motorized table would be a mistake. If I'm reading correctly you have over $11,000 to spend. Whatever you buy ought to have a motorized table for that price. And, yes, i understand that you can build a table--but why?

[Dave Sheldrake]

I'm of the school, better to have it and not need it than not have it and need it.

It does make on the fly adjustment easy (my up down is wired to buttons on the faceplate not via the PAD) other than the flatbeds that don't have the option I wouldn't buy a machine without motorised rise and fall.

cheers

Dave