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

There are two ways to have handwheels on a CNC machine: mechanical, ie
connected directly to the ballscrew or electronic, ie encoder wheels
that connect to the software. Of the two, the latter is highly, highly
desirable.

The advantages of the encoder wheels over manual feedwheels are:

a) The CNC software becomes a DRO and all the benefits that go along
with that become available. No more watching the collars on the
feedwheels and counting ticks !

b) You've still got access to G code commands to move: G0 x2 y1, etc.
Precisely moving an axis to a specific point is VERY time consuming.
With electronic feedwheels, you get both manual and computer movement
options.

c) You've still got access to G code commands to machine things: g1 x2
f4, g78 z-1 i-0.1 f2, etc. g77 y2.0 z-1 i-0.025 f4, etc You can't
imagine how handy this is.

d) The servos hold the ballscrews steady while stationary.

e) Selectable resolution on the handwheel. We are running 100 count per
rev quadrature encoders from Digikey (Bourns, $50 ea), giving us 400
"jogs" per rev. With a jog resolution of 0.001", we are moving .4
inches per rev. At 0.0005", we are moving .2 inches per rev. At
0.0001", we are moving 40 thou per rev. This is great for setting up
tool offsets.

f) The feedwheels are away from the lathe and mill and moveable if
desired. When we are machining with heavy cuts, there is coolant and
metal chips flying everywhere. It is nice to be able to stand aside,
protected from the debris.

If you use feedwheels, I recommend one wheel per axis as switching back
and forth between axes is cumbersome. (Some software allows only 1
feedwheel for all the axes.) We've modified the TurboCNC source code to
allow 3 simultaneous axes and it works great.



Kim

On Tue, 2003-09-30 at 08:52, doug98105 wrote:
> Guys,
>
> Given a choice, I'd rather have handwheels than not. I don't think
> I'd pay a large premium to have them as an option on a machine
> though.
>
> I notice Haas and Fadal have handwheels as a standard feature on
> their new "toolroom" machines. LeBlond Machino had them on
> their "toolmaker's" mill. Virtually all the makers of CNC flat bed
> lathes have included handwheels. What do you suppose their
> thinking was?
>
> Incidently, all the above are electronic handwheels so the problems
> Richard mentioned of machining with ballscrews do not apply. The
> handweels as above require the control to be "on" to function.
>
> Doug
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers <rogersmach@y...>
> wrote:
> > 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@y...> 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:
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> > > > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
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> > > >
> > > > OFF Topic POSTS: General Machining
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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
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> > List Mom
> > List Owner
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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/
--
Kim Lux <lux@...>