Re: Info on Taig Lathe carriage gears
- I agree with Hoyt. Once you've seen CNC, it's difficult to go back.
Depending on the controller you make/buy, you can have manual jog
settings and the MDI interface. Some manual jogs are just in certain
increments, which isn't really that helpful in this case, but some
you can just use a dial (or computer keys) to jog the cutter as far
as you want, as fast as you want, just like a manual mill/lathe with
a digital readout.
The MDI, or Manual Data Input (I think that's what it stands for)
lets you type in G-code one line at a time, and execute it instantly.
This can be very useful, BUT, it can be _VERY_ dangerous. If you miss
a decimal place, you can have your cutter ram into your headsctock,
tailstock, or work piece. Or, if you type G00 (rapid feed) instead of
G01 (linear interpolation, at reg cutting feed), your cutter could
smash into your piece. Limit switches are a _must_, and virtual ones
help lots if your software supports them.
As for the rack idea, I'm not sure that's such a great thing. In CNC,
you don't really want to have to mess about with backlash crap -
there are enough other variables to deal with. I've been using a HAAS
VF-2 at work and it's worth $120,000 CNC, IIRC. It's got ballscrews,
710 IPM rapid feed, etc. It still tends to cut screwy, or at least
not in a *linear* fashion. What I mean is that you're going to have
to deal with cutter deflection (that's a _big_ one, especially on a
CNC mill), machine flexing (very important with smaller machines),
etc. Having to deal with *dynamic* error like the backlash of a rack
would be really annoying. There are settings to compensate for it,
but this means the backlash has to remain the same, or you have to
reset everything. I would definitely consider using a leadscrew with
an anti-backlash nut.
This, of course, all depends on the tolerances of your work :)
--- In taigtools@y..., batwings@i... wrote:
> At 07:21 AM 2/1/01 -0000, you wrote:
> >The computer system is
> >magnificient, but I still cling to the idea that for a one-off
> >there's nothing quite like the feel of the crank handle in one's
> Actually you get used to it. I cut CNC teeth on a mill that didn't
> knob on it anywhere. I do still occasionally take a cut or two on
> my present machines but good software is usually pretty facile and
> used to pushing buttons easily and quickly. There is just one thing
> vital though: the BRB!! <=Big Red Button. If you don't have your
> up and functional, you will probably be a sad puppy at some time.
> Belfab CNC - http://www.freeyellow.com/members/belfab/belfab.html
> Best MC Repair -
> Camping/Caving -
> 'Has the Oval Office been steam cleaned yet?' <=George W. Bush
- At 07:21 AM 2/1/01 -0000, you wrote:
>The computer system isActually you get used to it. I cut CNC teeth on a mill that didn't have a
>magnificient, but I still cling to the idea that for a one-off job,
>there's nothing quite like the feel of the crank handle in one's hand.
knob on it anywhere. I do still occasionally take a cut or two on manual on
my present machines but good software is usually pretty facile and you get
used to pushing buttons easily and quickly. There is just one thing that's
vital though: the BRB!! <=Big Red Button. If you don't have your kill set
up and functional, you will probably be a sad puppy at some time.
Belfab CNC - http://www.freeyellow.com/members/belfab/belfab.html
Best MC Repair - http://www.freeyellow.com/members/batwings/best.html
Camping/Caving - http://www.freeyellow.com/members/batwings/caving.html
'Has the Oval Office been steam cleaned yet?' <=George W. Bush
- At 04:27 PM 2/1/01 -0000, you wrote:
>Depending on the controller you make/buy, you can have manual jogRight, jog is invaluable in set-up. It's basis for several functions too:
>settings and the MDI interface.
you can jog tools to a common reference position on part or datum and then
the CPU records their offsets in a table; next time the tool number is
called, it auto-homes, prompts user to change, delivers tool to the spec
position and displays corrected coordinates; hence every tool starts
working at its own zero values! So data to enter comes right off drawing.
Tool numbers can go into files or be called manually. Can even change
non-indexable tools in mid-program and as long as re-qual'd again by
touch-off at orginal ref, the software is set up to take the difference in
tip location, apply it, and then go back to the right position on part and
continue file. Can even re-cut lines previous if specified, to correct
effect of bad tool. I have my stuff set up so if you name a tool not
already in table, it calls jog routine and lets you qual it right then in
middle of program being written, and you la-de-da ahead with a smile. This
is only part of power of CNC.
Jogging is also used teaching arcs or feeds in multiple axes, then that
move is put into file being written just as were MDI lines. Very handy for
building something w/o actually having dimensions. The machine generates
the file for next part with whatever dimensions you taught it. Can mix
teaching of course with straight MDI. It all goes into file. I use teach to
make files for cutting copper gaskets. Just walk the machine around the
sample part giving it three points on each arc and two on each line,
touching off with the same tool to be used if desired. Then bingo, next
part is a dupe of that path.
>you can just use a dial (or computer keys) to jog the cutter as farMine uses exponent, give it a 2 and you get 100 steps, 5 and get 10,000.
>as you want, as fast as you want, just like a manual mill/lathe with
>a digital readout.
You can just enter the next exponent smaller amd smaller again to change
scale on your approach. One keypeck = one jogstep of whatever size. I use
metric screws, so jog is in metric too.
>lets you type in G-code one line at a time, and execute it instantly.That is the big advantage of conversational programming and canned
>This can be very useful, BUT, it can be _VERY_ dangerous. If you miss
routines. You can generate hundreds of lines with a few entries, such as
multipass turning, peck drilling, digitizing, etc. And the CPU doesn't make
math or format errors. In fact it hardly matters if you use G-code or not,
my setup doesn't. The actual code is something you seldom have to address,
just build it and run it. One of my basic principles was that every
movement, setting or parameter goes to file whether you named a file for
that or not. This way if you screw up and make something useful w/o
intention, you still have the file to run. The idea of course is skilled
machinist doesn't need to be a programmer. He merely needs to know how to
run machine. Machine and CPU take care of the rest.
>As for the rack idea, I'm not sure that's such a great thing. In CNC,Lash comp is almost never very effective. Ball screws are the answer. Not
>you don't really want to have to mess about with backlash crap -
only are they precise but they're very stiff mechanically. As I mentioned,
rolled screws are cheap, robust and pretty darned accurate. Certainly most
jobs can be done with precision of .005"/ft. HAGO