My laser machine has a bed 420 x 300mm but I need to cut a wing spar 525 mm long.
Is there any way this can be achieved?
The only way I know to make something bigger than your laser bed is to make it in sections that you can join together.
Unfortunately I think that you are correct and I really do not want to place a join in the middle of an radio control aircraft wing spar
I guess it depends on how you do the joint. I’m not an RCA hobbyist, but my first thought would be to make a lap joint that you glue together. You could etch out most of the joint with the laser and then clean up the joint with sanding or a chisel.
That’s awful close to the 3/4/5 right triangle. But
sqrt((420^2) + (300^2))
516.1395
Almost long enough on the diagonal.
The tip of the spar doesn’t carry much load. So put the joint as far outboard as you can? I’m with @NedMan, make a lap joint. If it’s plywood there are lap joints here and there in the material anyway, and a lap joint near the tip will be no big deal.
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Thanks guys. It looks like its going to be done in two pieces.
BTW Michael, I cannot remember ever hearing the Pythagorean theorem described as a 3/4/5 right triangle but you are correct. It works.
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Anyone who has worked in the construction industry will know the 3/4/5 triplet.
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My dad taught me 3/4/5 triangles when he was doing some home carpentry … if you want a quick way to check if your work is square.
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My wife teaches some “fun math” classes. Among other things, she teaches about how ancient egyptians used the 3/4/5 right triangle to make massive construction squares.
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If you can extend the work stock material beyond the cutting area, how about adding some indexing pins on the outside of the part and use those to cut the first half and then a mirror cut of the second half flipped over?
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dougl, Virtually exactly what I did on the second spar.
Cut the 1st part in the left size of the material then repositioned material and using light laser and checksize of 2nd cut to make sure everything lined up correctly and proceeded to get a one piece spar bigger than my laser cutter. Always something new to learn.
Thank you.
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LightBurn even has a feature for adding alignment pins for doing this type of thing. I learned about that a month or two ago. Indeed it is always fun to learn new tricks.
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