[CAD_CAM_EDM_DRO] Linear Slide Components

I'm a relative newbie to this whole CNC thing but have come to some
conclusions and would like some thoughts from several of you that have built
machines. First of all my interest is predominantly for a CNC router as
opposed to a mill and or plasma cutter. Although I think my questions would
certainly apply to the creation of a plasma table.

One of the major elements is obviously the linear slide components and to be
perfectly honest I don't understand why the need (in other words, the
quantifiable difference) to use commercial quality components that increase
the cost so dramatically. People regularly bash any use of anything other
than commercial grade linear slide components? Why, why is it that a
V-wheel on angle iron or skateboard wheels against a hard flat edge is such
a horrible idea? From what I've seen, as soon as you use any commercially
available linear components the cost of those components alone is well in
excess of $1000 for a 4x8. Of course there is the eBay option but
personally, ideally, I'd like to do something that is reproducible as
opposed to a total science project.

I'm not being defensive but rather truly trying to determine the difference
between these approaches.

Another question I have is how does one go about squaring a large table. I
certainly know how to do traditional construction type of squaring and what
a 3-4-5 triangle is and all that but how on earth do you measure these
things to sufficient accuracy on such a large scale. I'm assuming my
framing square will be completely useless as it would only be suitable for
initial setting but I would need a far more accurate way to finalize my
squaring.

Last question, I don't own a mill and will need to make some parts for my
machine. Do you all have suggestions as to lower cost ways to produce some
of the machined parts I need made outside of the traditional commercial
machine shop?

Thanks in advance for all of your help.

Lee Wenger


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