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Well heck I own a metal lathe, I can gather up some aluminum round stock and just make a extension tube for the existing one. One that slips into the mounted laser head and has the other end sized to go over the tube on the cone end. Easy peasy. The machined end of the tube is a sloppy fit anyway and I can correct that when I build my own extension.
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Dave,
If he wants a longer focal length lens, he'll want either a longer cone, or a similar-length cone with a wider hole.
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doesn't your laser have an up and down bed like the say in the specs. I use the bed to set the focal length and just fine tune it with the the lens tube.
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Your lens tubes are essentially just like mine, so there ya go...
Your 52mm lens is essentially a 2" lens (2.04"=52mm), this means the distance from the lens itself to the work surface should be 52mm to be in focus. However, ramp testing should be done to find "true" focus. A 75mm lens is roughly 3", a 100mm is roughly 4".
I took your pics and doctored 'em up a bit. The yellow lines are approximately where the lens is located inside the tube. With a 2" lens, the cone ends up pretty close to the material. Good for air flow when cutting. When moving to longer length lenses, the tip of the cone will obviously be much farther from the work. With a 100mm lens the distance becomes a country mile! If you're using air assist thru the cone, this is why you need a longer cone, so the air will actually reach the work. And a wider hole in the cone is good to compensate for the wider focused beam. Note that using a 4" lens with a short cone means the beam has only started focusing down, and the sides of the beam will likely hit the sides of the cone.
Me, I don't use the cone, I have my air (when I use it) routed around the lens with a tube, pointed at the work. For focusing I just have a bunch of 1/4" thick plastic posts cut to length and labeled, they fit between the bottom of the tube and the work...
http://www.engraver1.com/erase2/glens.jpg
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But if I just make an extension tube like my post above on the lathe. I can still use the same lens? Correct? It just extended the distance the beam has to travel by 1 inch or 25 mm from the mirror on top of the head. Or will that make a difference in the power?
I am just making a 1 inch (25mm) extension, not the entire tube and cone, lens holder and all.
The only issue for me anyway is finding some solid round aluminum bar or heavy tube stock. I have lots of 2x2 inch square on hand but gee that's a lot of machining to make it round. Trying to buy some here locally might be a waste of time.
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Dan,
Gotcha. Phew! I was just getting confused. It sounded like you were saying he needed a new cone with wider tip even if he used the same lens but with a longer tube or barrel, but you were really referring to the use of a longer lens requiring a different cone/wider tip.
Thanks!!!!!
Dave
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2 Attachment(s)
Ok got the proto type done and now in testing. It did not seem to lose any power and the Extension was done on the lathe on the fly via measurements from the cone slider and holder still mounted in the machine. Really don't know how close the Chinese CNC machines hold tolerances but I tried my best to make it fit snug. In fact the lower part where I added the 8-32 US Allen screws held in without the screws.
Used what I had on hand, sometime I will pick up official thumbscrews, and the longer air hose to the cone is a piece of snowmobile fuel line I had on hand also but works very well. I added a "O" ring to the top part of my Extension so it could be pushed up tight to the top and when the gold thumb screws tightened seem to hold tighter.
Minimum gain is 40 mm and it could be adjusted further out, but the OEM end has to much play to be really stable too far out.
The test cut was repeating a job I did yesterday with it at normal height.
Attachment 295714Attachment 295715