Re: [CAD_CAM_EDM_DRO] Re: Ball screws for CNC plasma cutters

----- Original Message -----
From: "Jay Hayes" <xmas4lites@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, February 13, 2001 1:30 AM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Ball screws for CNC plasma cutters


>
> Joe,
>
> My CNC plasma has the servos, gear reducer are mounted on a spring loaded
plate. The spring removes the backlash between the rack
> and pinion. The encoder feedback is tied to the output shaft of the gear
reducer so the gear box backlash is not an issue. The
> machine will hold about .015, which is better than the plasma torch can
cut. The spring loaded pinion also allows it to be
> disengaged from the rack so the axis can be moved manually. This is a big
help when zeroing in a plate.
>
> Racks can be used on machines of unlimited length. They also help to keep
the weight of the drive system down. Low inertia means
> smaller drives.
>
> Jay
>
> Helen Fahy wrote:
>
> > Hi Jay,
> >
> > I am considering using a rack & pinion system for my machine due to the
> > 16'-20' x axis dimension. Did you use any of the zero backlash
hardware,
> > split pinions, harmonic gear drives,.. in your design? What kind of
> > tolerance and repeatability does your system maintain?
> >
> > Thanks for any guidance,
> >
> > Joe Fahy
> >
> > ----- Original Message -----
> > From: "Jay Hayes" <xmas4lites@...>
> > To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> > Sent: Monday, February 12, 2001 7:38 PM
> > Subject: Re: [CAD_CAM_EDM_DRO] Re: Ball screws for CNC plasma cutters
> >
> > >
> > > If you've seen a plasma cutter then you have also seen all the
particulate
> > slag and grit that is generated. This grit can play havoc
> > > with any type of screw. A better solution is a rack and pinion drive.
If
> > the teeth on the rack are positioned vertically or upside
> > > down the grit problem is minimized. Racks can also be of unlimited
length.
> > Screws on the other hand suffer from whip lash at longer
> > > lengths. My 72 x 126 inch CNC plasma, with rack and pinion drive,
holds
> > the same tolerances it did when it was new fifteen years
> > > ago.
> > >
> > > Jay Hayes
> > >
> > > Smoke wrote:
> > >
> > > > I'm just wondering...I've seen plasma cutters in use. It appears to
me
> > any
> > > > attempts to hold
> > > > REALLY CLOSE tolerances seems to be a lot of overkill. I've never
seen
> > a
> > > > plasma cutting torch
> > > > yet that will cut a really smooth edge, hence the lack of necessity
for
> > > > holding close tolerances.
> > > >
> > > > With this though in mind, i don't see why a person couldn't use
threaded
> > rod
> > > > for the lead screw?
> > > > Manufacturing an "antibacklash nut for this would be as simple as
> > placing a
> > > > heavy spring between
> > > > a couple of hex nuts which are trapped to prevent rotation.
> > > >
> > > > I've even seen commercial nuts (used on acme screws) made this way.
> > > >
> > > > Smoke
> > > >
> > > > -----Original Message-----
> > > > From: ozzietwo2001@... <ozzietwo2001@...>
> > > > To: CAD_CAM_EDM_DRO@yahoogroups.com
<CAD_CAM_EDM_DRO@yahoogroups.com>
> > > > Date: Sunday, February 11, 2001 10:22 PM
> > > > Subject: [CAD_CAM_EDM_DRO] Re: MillWizard + MaxNC-10, SuperCam &
> > > > Millwizard...
> > > >
> > > > >Tracy,
> > > > >I've found the website for Techno-isel and have found mountains of
> > > > >interesting stuff, but it's daunting to try wading through it all.
> > > > >Can you give us an idea of prices; for instance your 20" table, and
> > > > >if you know, ball screw and nut prices.
> > > > >
> > > > >Thanks,
> > > > >Jerry
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >One major "upgrade" I've
> > > > >> made is using 20" X & Y tables from techno-isel to give me more
> > > > >area
> > > > >> to work with. It works great but really needs stronger stepper
> > > > >motors
> > > > >
> > > > >
> > > > >
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>
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>
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