Gantry Holding the Tube?

General discussion of laser machines

Gantry Holding the Tube?

Postby mikegrundvig » Fri Oct 28, 2011 11:52 pm

Anyone built a cutter where the tube is mounted on the gantry? It seems like an extremely good design to me and I was wondering if someone has done this here. It seems very common on the larger lasers. Here is a link to see what I mean:
http://www.kernlasers.com/product_pages ... erview.htm

Thanks!

-Mike
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Re: Gantry Holding the Tube?

Postby twehr » Sat Oct 29, 2011 12:03 am

mikegrundvig wrote:Anyone built a cutter where the tube is mounted on the gantry? It seems like an extremely good design to me and I was wondering if someone has done this here. It seems very common on the larger lasers. Here is a link to see what I mean:
http://www.kernlasers.com/product_pages ... erview.htm

Thanks!

-Mike


Number one advantage is the ease of getting near perfect laser beam alignment.

Number one disadvantage is the added mass of the tube reduces the y speed. For engraving that's not a big deal. For cutting, you use a lot more y movement.
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Re: Gantry Holding the Tube?

Postby steppenshoe » Sat Oct 29, 2011 12:22 am

I have a thread discussing adding a laser to an existing CNC gantry router machine. The gantry is very similar in design to the one in the picture. The mass of a big tube is absolutely nothing for the stepper used to move that gantry. The weight and mass is insignificant. If the motors can move a gantry like that they are going to move an additional 50 lbs and that tube is nowhere close to that weight. Steppers are strong and I have moved well over 300+lbs with little 380's. Granted that's bigger by far than the steppers on this laser design, but on a gantry design it is a small motor. The Y speed will be faster than one would ever need or probably use with a gantry and the right motors.
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Re: Gantry Holding the Tube?

Postby mikegrundvig » Sat Oct 29, 2011 3:55 am

Ha, your thread is the one that got me interested in the idea. I've started designing my laser system and I'm going to go tube-on-the-gantry route. It really seems a good design overall. I'm looking to use 60 or 80 watt tubes and I want 4 x 2 as a minimum work area so the design seems doubly good for that. I've already got the basic design done in SolidWorks and am in the process of designing my mirror mounts and the like now. I figure in a few weeks I'll be machining the parts on my mill.
Thanks!

-Mike
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Re: Gantry Holding the Tube?

Postby steppenshoe » Sat Oct 29, 2011 4:24 am

Keep us posted.

Pm or email me what you have I would love to see it.
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Re: Gantry Holding the Tube?

Postby TLHarrell » Sat Oct 29, 2011 8:29 pm

Mike-

Exactly the size of laser I am thinking of designing and building. Definitely post your work as you go. I am interested in following it.

I had an idea as far as the Z-lift that you may want to look at for such a large table. Eliminates the issue of extremely long belts. The corners are set up with Sarrus linkages, and the lifting is provided by a set of cams in the middle of the table. See discussion here: http://www.buildlog.net/forum/viewtopic.php?f=13&t=42 I can send sketches if you're interested in using this design.
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Re: Gantry Holding the Tube?

Postby r691175002 » Sat Oct 29, 2011 10:16 pm

Depending on the kind of work that needs to be done you can cheat and leave the focus fixed. With a long lens you could don work from 0 to 1/4" very well.

Otherwise I'd try to focus more on moving the lens instead of the table.
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Re: Gantry Holding the Tube?

Postby mikegrundvig » Sun Oct 30, 2011 4:08 pm

I'll be posting my design as it stands later today. I'm pretty anal about designing projects like this so I'll actually get the entire thing into SolidWorks asap. It will be as accurate as I can make it (with exceptions, I don't add bolts and such unless there is a question on clearance) before I order anything. I've got a big-ish CNC milling machine (24" x 15" work envelop) in my garage so I plan on machining a lot of the parts rather than ordering off-the-shelf stuff. I'd like to keep the price down on little things as I'm increasing the cost with linear rails. Sorry, MakerSlide is a great idea and I think will be useful for many things, but I feel it's re-inventing the wheel a bit. Linear rails are the established (and ridiculously accurate) way to do linear motion in machines. If I'm going to spend several thousand dollars for electronics and parts, a few hundred more for totally worry-free linear motion seems a good investment. Anyways, I've got a few more parts to design and I'll post something in a few hours. Thanks!

-Mike
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Re: Gantry Holding the Tube?

Postby mikegrundvig » Mon Oct 31, 2011 3:54 am

I posted more details here:
viewtopic.php?f=2&t=877

Thanks!

-Mike
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