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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Fri, 31 Aug 2007 14:44:09 GMT
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Viewed:
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17060 times
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"daniel" <daniel.formatc.at.gmail.com> wrote in message
news:JnMwFu.CMs@lugnet.com...
> ok, now i understand what you mean. the problem is that this setup could
> be
> difficult for long axes, i guess the axle with the worm gears would flex
> too
> much...
I like the worm for a drive. It provides the best ratio and the least
backlash. It also acts as a brake while the slide is under the pressure
returned by the cutter. Backlash invites oscillation and vibration in a
loose drive. Real controls deal with this using tachometers to sum opposite
dc voltage into the drive amplifier. The control says go forward and the
tach says no. This allows high gain for that small move and control for the
high speed move.
This machine has worm in every axes,
http://www.ozbricks.com/bobfay/newmill.htm
You best
> > design your positioning device driven from the slide and not the drive
> > gear
> > train.
>
> why is that? i am planning to use a pole reverser short-circuited on one
> side as
> a rotation counter
Is this Lego?
Every imperfection from the position device to the tip of the cutter results
in an inaccurate cut. In the real world there are many expensive solutions
to this problem. Lego screams "TOY" and requires a tight system.
This is my worst position design
http://www.ozbricks.com/bobfay/OGSlider.jpg
This is my best. Look at the bottom of the page. The rotation sensor is
driven by the ring gear on the "C" rotary axis. You cannot see the gearing
but the wire from the blue brick is the rotation counter. This is "C"
because the rotary table is rotating around Z. This machine is a little
confusing. It is a vertical Z.
http://www.ozbricks.com/bobfay/om4.htm
Hope some of this gives you ideas.
Bob
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Message has 1 Reply:
 | | Re: the LEGO CNC-Machine
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| (...) 16t gear to the gear rack on the bottom of the table. also, the z axis seems to use an idler gear. that's exactly the setup i've built, you can see it here: (URL) top left, next to the tool changer idea (right next to the tiny word "tool"). i (...) (17 years ago, 1-Sep-07, to lugnet.robotics.rcx)
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Message is in Reply To:
| | Re: the LEGO CNC-Machine
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| ok, now i understand what you mean. the problem is that this setup could be difficult for long axes, i guess the axle with the worm gears would flex too much... (...) exactly what i was thinking. that's the way the machines i've seen change their (...) (17 years ago, 31-Aug-07, to lugnet.robotics.rcx)
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