Re: [CAD_CAM_EDM_DRO] Handwheels on a retrofit? Why!? was Re: software questions DRO

We have about 10 manual Bridgeports at work that have ball screws in the x
an y. These are older ('70's)machines that we sent out to be rebuilt 5 or 6
years ago. Many manual knee type mills can be purchased with ball screws as
an option! We have no problems with them.

Chris

----- Original Message -----
From: "R Rogers" <rogersmach@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, September 30, 2003 9:22 AM
Subject: Re: [CAD_CAM_EDM_DRO] Handwheels on a retrofit? Why!? was Re:
software questions DRO


> The most important reason to not use a CNC machine manually is a safety
issue. A mill with ballscrews is unlike a mill with acme threads in that:
when force is applied to the table it will "feed" the ballscrew. Acme
threads have an inherent binding effect. Think of a scissor jack. Try it,
unhook one of your drive motors and push on the table. Now turn the
handwheel in the direction you are pushing it will keep spinning. Push hard
enough and it will gain speed. So, if you are manual milling with ballscrews
and a large rougher and it grabs the work piece. The table will not hold
position on its own resulting in a very dangerous scenario. It's best to
operate as outlined below.
>
> Ron
>
>
>
> ballendo <ballendo@...> wrote:
> Kim,
>
> I completely agree...
>
> I just posted this on the turbocnc list; seems appropriate to this
> thread:
>
> Hello,
>
> How about these reasons:
>
> 1)"Jogging" is just power feed on all axes. Work all day without your
> hand/arm getting tired, and feed more evenly than most can turn a
> wheel... AND "GO" faster than you can turn the handle.
>
> 2)Using incremental jog values you can easily stop on a dime... or
> a "tenth" if you will EVERY TIME... Need to drill a series of
> holes? set the distance as a jog increment, and a single keypress
> replaces precision turning of the handwheel...(especially valuable
> when the distance is something like .3794;or do you wanna do that
> addition in yer head?) of course with the CNC powered up, you have
> DROS, so you can reset zero instead... When you get where you're
> going, another keypress (Z minus) drills the hole...
>
> 3)With some controls, you can save each jog move to a file, so
> whatever you've done can be repeated...
>
> Hope this helps,
>
> Ballendo
>
> P.S. These things are why I don't understand the desire to keep
> handwheels in place on a CNC retrofit... This type of 3 axis,
> distance precise, powerfeed is what most MANUAL machinists WISH FOR!!!
>
> I hear people saying, "I'll keep the handwheels for those jobs where
> it's just not "worth" turning the computer on." Just what type of
> part is that?!? In windows, maybe;with its long boot time. But in
> DOS, I'll betcha I have the part more accurately made faster than a
> person turning the wheels... The second argument is "feel", but one
> learns quickly to replace this feel with other senses; much like a
> blind person relies on senses other than sight. I can smell, hear,
> see, and yes, even FEEL(place my free hand on the ways, and feel
> vibration, etc.), what the machine is doing...
>
>
> --- In turbocnc@yahoogroups.com, " T . Ackland" wrote:
> > I was of the impression that the jog is just used to touch the work
> > piece with the cutter and then Zero'd or whatever figure you want
> > to entered through the jog screen.
> > I cannot see the advantage of machining with the jog over turning a
> > handle?
>
>
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Kim Lux wrote:
> >
> > We just put electronic handwheels on our CNC equipment. By
> electronic,
> > I mean that the feedwheel is attached to an encoder and the signal
> from
> > the encoder is fed to the CNC software, TurboCNC in this case.
> >
> > I think this is much more practical and powerful than retaining the
> > mechanical handwheels. For example, one can operate in MDI mode,
> using
> > the electronic feedwheels to position the tool and then issue a
> manual
> > feed like drilling (G78) or straight feed (G77). With mechanical
> > handwheels, one would be stuck drilling or feeding manually. With
> > TurboCNC, one has feedrate override as well. The time this saves
> when
> > drilling and milling is incredible, to say nothing of being able to
> > manually position and then do some arcs ie G02 and G03.
> >
> > Kim
> >
> >
> > On Mon, 2003-09-29 at 10:56, Jon Elson wrote:
> > > vlocci wrote:
> > >
> > > >I'm just getting started on a conversion and have a few
> software
> > > >questions that I haven't found answered in the archives. I'm
> inclined
> > > >to keep the handwheels on my mill, since I plan on the
> occasional job
> > > >done by hand.
> > > >
> > > >1) Assuming I use servo's with encoders, can I use the encoders
> as a
> > > >source for positiong info that can be displayed within a
> software
> > > >package as a DRO? Which software packages allow this? Is EMC
> my
> > > >only choice?
> > > >
> > > >
> > > I think Mach 1 and 2 may support this.
> > >
> > > >2) Is the above possible with steppers instead of servo's? Can
> it be
> > > >done without encoders? Which software allows this?
> > > >
> > > >
> > > How can you measure position without encoders?
> > >
> > > >I realize I'm limited by the accuracy of the axis ACME threads,
> I.e.
> > > >backlash induced errors (a ballscrew conversion is in the
> future, but
> > > >I want to get things running first)
> > > >
> > > >Realize that I dont necessarily need CNC capabilities and the
> option
> > > >of manual DRO read out at the same time. (real time jumping back
> and
> > > >forth) I'm only after the ability to either cnc a part
> automatically
> > > >(hands off), or elect to manually do things with a computer
> driven
> > > >DRO arrangement. Can this be done?
> > > >
> > > >
> > > Yes.
> > >
> > > >If it matters, I'm considering Gecko drives (either servo or
> stepper)
> > > >but am open to a change if it offers me DRO capability.
> > > >
> > > >
> > > You don't say what size machine you are planning on converting.
> But,
> > > for the
> > > larger machines, it may be cheaper to go with servos, if you plan
> on
> > > using encoders
> > > for DRO readout anyway. Also, sevo motors won't drag as much
> when you
> > > move the machine manually.
> > >
> > > Jon
> > >
> > >
> > > Addresses:
> > > FAQ: http://www.ktmarketing.com/faq.html
> > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> > >
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> > >
> > > OFF Topic POSTS: General Machining
> > > If you wish to post on unlimited OT subjects goto:
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> > >
> > > http://groups.yahoo.com/group/jobshophomeshop I consider this
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> > >
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> > --
> > Kim Lux
>
>
> Addresses:
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>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
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>
>
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>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
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>