Subject:
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Re: the LEGO CNC-Machine
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Mon, 3 Sep 2007 20:52:06 GMT
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Viewed:
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20291 times
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"daniel" <daniel.formatc.at.gmail.com> wrote in message
news:Jnt54J.Jpy@lugnet.com...
>
> i'm not sure yet how exactly i will manage to make it stay there without
> excessive vibration or deformation of the frame. the ideal solution would
> be a
> tower built of classic lego bricks, that would be really stiff. bad thing
> i
> don't have too many of those. i hope i can come up with a nice technic
> structure.
I liked the technic beams because I could lock them together. I imagine
double wide bricks can make a good foundation. Put an ocassional beam in to
allow clamping the bricks together with vertical beams.
you can see a little test i made standing behind the table in the
> video, those skeleton-like technic beams. that's more or less the size it
> will
> need.
The center line of the spindle must align with the four corners on the
table. The size of the table depends on the size of the material you want to
mill. Remember you have to be able to clamp the material to the table. This
uses some extra room.
>
> something i noticed is that in my design the y axis gear rack (the one i
> mount
> on top in the video) presses really tightly against the gear that drives
> it, and
> i doubt that the normal technic motor will be able to handle it.
The geared Lego motor is really very powerful. I was not familiar with the
motor shown in your movie. If it is the same as the motors on my site, it
will drive the axes fine. I was surprised to see two rows of rack segments
on your axes. This would lend itself well to an anti backlash design. The
idea is to cause the drive gear to push forward on one side and the other
drive gear to push back on the other side. This takes up the slack in the
gear train. You have to do this gently or you will use too much motor power
just overcoming friction. Also, don't plan on cutting very deep into the
material. This would overload the motors and probably dismantle your
machine.
is there any
> site with tips on the geometry of the gear rack? like, how to build a
> structure
> that makes it mesh nicely with gears, without too much backlash but not
> too
> tightly? i haven't been able to figure it out... thanks!
There are several books that have some very good ideas. I have not seen
anything special on the rack drive. You have to design with the cutting
speeds in mind. You can slow down the motor, but is looses power then. Are
you going to use NQC to program your mill?
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Message has 1 Reply:
 | | Re: the LEGO CNC-Machine
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| "Bob Fay" <rgfay@earthlink.net> wrote in message news:Jnt8MF.n84@lugnet.com... (...) This is one of mine. Note the left worm is out if sequence by 1/4 turn with the other two. this is putting pressure on the dual racks to remove the backlash. (URL) (...) (17 years ago, 3-Sep-07, to lugnet.robotics.rcx)
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Message is in Reply To:
| | Re: the LEGO CNC-Machine
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| (...) thanks! it's nice to get that kind of feedback from someone who's not new to lego mills :) (...) yes. you can see it in my diagrams again, the cutter hangs over the table pretty far: (URL) i'm not sure yet how exactly i will manage to make it (...) (17 years ago, 3-Sep-07, to lugnet.robotics.rcx, FTX)
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