"RogerN" fired this volley in
:

Sorry I didn't clarify. I was referring to an additional limit switch
provided by the user that would turn on contactors when deactivated
and turn the contactors back off when activated. Then you position
this limit switch, perhaps with magnets, so that it is activated when
the machine is at the park, tool change, or stop position. The
contacts from the contactor or relay could turn on the run fwd input
to the drive if you set it up so the contact had to be maintained to
run the drive. Additional contacts could be used to operate a coolant
motor or solenoid air valve for mist coolant.



You wouldn't need to add switches to the R2E4. It has them. They aren't
necessary for the control to stop past the limits, unless a motor drive
fault occurs. They could be used for double-duty.

I misspoke one thing. There are "M" codes to turn on coolant flow. Just
not to start/stop the spindle.

LLoyd

On 11/27/2010 09:15 AM, Pete Keillor wrote:
On Sat, 27 Nov 2010 08:29:07 -0600, Ignoramus18541
wrote:

snip
Controlling the spindle is slightly more important, as it lets me
change tools. But, I suppose, I could turn off the spindle manually.

Personally, I would be leery of changing a tool manually under a
program stop. I'd much prefer to turn it off manually. I wouldn't
want my hands on the spindle without being certain it wasn't going to
move. Or are you using a tool changer?

Mind you, that's in theory. I have no cnc equipment.
Well, I have no safety override, so the spindle is under computer
control all the time. However, the PPMC hardware does have a fairly
comprehensive E-stop circuit with a watchdog timer, so if it loses
communication with the computer, it goes to E-stop and shuts off spindle
and servo drives.

I have never had an unexpected spindle start or other wild event.
Just connecting a VFD to the parallel port, without some kind of estop
and watchdog circuit sounds risky, though.

I'm pretty sure I've seen Stuart Stevenson at MPM change tools without
e-stopping the machine, and those machines would throw you across the
room if the spindle started when you weren't expecting it.

Jon

On 11/27/2010 08:20 PM, DoN. Nichols wrote:


But add a switch in series with the run/stop command line to the
spindle's VFD, and set it up so removal of the wrench will disable the
spindle motor until the wrench is returned to its storage pocket.

Oohh, now THAT one I like!

Jon

This "excursion" into single-phase operation is the second for me on this
machine.

Back in late July, I hooked up, more or less by the "seat of the pants"
manner, and it worked -- more or less.

But it was throwing all sorts of BSP communications errors, and e-
stopping. I figured it must be the 1-Phase mods, and reversed them all.

I got an RPC, hooked it all up, and guess what? Same errors.

It took me a few months to find and replace some aged electrolytics that
were allowing ripple into the DC supplies, and I "crunched" all the chips
and board connectors a few times. Then it got pretty stable, with only
an occasional error on boot.

With the new, better-designed single-phase changes, it's about the same.
It'll probably take a while to make it bug-free; and that's part of the
incentive to upgrade the control.

LLoyd

On 11/27/2010 08:31 PM, Ignoramus18541 wrote:


See a specs page from my manual.

http://igor.chudov.com/projects/Brid...Mill/specs.jpg

``Positioning accuracy +/- 0.0005".''
This is the old thing about resolution does NOT equal accuracy.
Bridgeports are hand-scraped for accurate alignment of the ways, and ARE
pretty accurate. But, the kind of stuff you need to maintain .0005"
accuracy over a work envelope of 12 x 18 x 18" is pretty tough.
Just rest your hand on the table for a minute and the table will warp
enough that you will have several times that error at the extremes of
travel for 20 minutes or so. Run the X axis back and forth rapidly for
a couple minutes and the screws will expand and cause a dimensional
error for a few minutes. getting .0005" accuracy on a 2" cube isn't
that tough, if you can account for tool and workpiece deflection.
getting .0005" accuracy on an engine block-sized piece that you machine
over a 2-day period will drive the experts NUTS! High-end machines have
the spindle running in a coolant bath, and run coolant through hollow
ballscrews, too.

Jon

Jon Elson wrote:

On 11/27/2010 08:31 PM, Ignoramus18541 wrote:


See a specs page from my manual.

http://igor.chudov.com/projects/Brid...Mill/specs.jpg

``Positioning accuracy +/- 0.0005".''
This is the old thing about resolution does NOT equal accuracy.
Bridgeports are hand-scraped for accurate alignment of the ways, and ARE
pretty accurate. But, the kind of stuff you need to maintain .0005"
accuracy over a work envelope of 12 x 18 x 18" is pretty tough.
Just rest your hand on the table for a minute and the table will warp
enough that you will have several times that error at the extremes of
travel for 20 minutes or so. Run the X axis back and forth rapidly for
a couple minutes and the screws will expand and cause a dimensional
error for a few minutes. getting .0005" accuracy on a 2" cube isn't
that tough, if you can account for tool and workpiece deflection.
getting .0005" accuracy on an engine block-sized piece that you machine
over a 2-day period will drive the experts NUTS! High-end machines have
the spindle running in a coolant bath, and run coolant through hollow
ballscrews, too.

Jon

Yep, and that coolant is circulated through a special refrigeration unit
to maintain a very consistent temperature (not actually cold), it's not
to be confused with the coolant / cutting fluid which is an entirely
separate thing. Those high end machines have specific warm up procedures
you have to run them through at the start of the production day to get
them stabilized before you start your precision work. Even stuff like
night time setback thermostats on building HVAC can cause you problems
when you need real precision on big machines.

On 11/29/2010 05:37 PM, Lloyd E. Sponenburgh wrote:

It took me a few months to find and replace some aged electrolytics that
were allowing ripple into the DC supplies, and I "crunched" all the chips
and board connectors a few times. Then it got pretty stable, with only
an occasional error on boot.
Back in 1997 I got an Allen-Bradley 7320 CNC control from a guy on this
very list, and made it work on my machine, with my encoders, etc. with a
GREAT deal of tinkering, involving disassembling the executive and
modifying it. I had 3 major breakdowns in about 9 months, and any time
I opened it up, I had to play with wiggling connectors for several hours
to get all the panel controls and lights to work. There were constant
minor pains like losing the battery-backed DRAM every couple weeks, but
that was just a quick reload from a PC. I got EMC, the very original
one, from NIST in 1999, and never went back.

Jon

responding to
http://www.rittercnc.com/metalworkin...e4-429295-.htm
meatwad wrote:
Hi Lloyd,

I have no idea if you will get this email, but I though I would give
it a try. *I just purchased a bridgeport r2e4 boss 9 mill, and moved
it into my garage workshop. *I plan to convert it over to mach3, emc2
or centroid control, but in the meantime it would be nice to see if it
actually works. *Rather than buy/build a RPC, it would be nice to just
convert the control over to single phase 230. *can you elaborate on
how you changed your machine over to single phase?

Best Regards,

Thadeus Gregg



FINALLY, I got my r2e4 Bridgeport converted to single-phase.

No more of that damned RPC singing over in the corner, no.

As it turns out, the R2E4 machine is basically a single-phase machine,
anyway, except for the spindle motor (which is definitely 3-phase).

The electronics all run off two (single) phases of the incoming power,
and there are no references to the phases. All it took to get them
converted was to move a couple of leads.

To adapt the spindle, I installed a VFD and a relay isolator that would

track the F/R signals from the motor relays, and signal the VFD to
start/stop/forward/reverse.

It cost only $149 and some labor.

Now to make metal in the QUIET! G

LLoyd


--

On 2011-05-21, meatwad wrote:
responding to
http://www.rittercnc.com/metalworkin...e4-429295-.htm
meatwad wrote:
Hi Lloyd,

I have no idea if you will get this email, but I though I would give
it a try. *I just purchased a bridgeport r2e4 boss 9 mill, and moved
it into my garage workshop. *I plan to convert it over to mach3, emc2
or centroid control, but in the meantime it would be nice to see if it
actually works. *Rather than buy/build a RPC, it would be nice to just
convert the control over to single phase 230. *can you elaborate on
how you changed your machine over to single phase?

Hmm ... the BOSS-9 is one of the servo machines, is it not?

You've got a better chance than I did with the BOSS-3, which is
stepper motors, and has a big three-phase transformer from the secondary
of which each phase provides the power to a single stepper and its
drivers. Add to that a saturable reactor (also called a MagAmp) between
the secondary and the bridge rectifier for the stepper motor's power
supply to adjust the voltage -- something like 50 VDC or so when the motor
is stopped, or being stepped slowly, and 80 VDC when the step rate goes
up. This is because the maximum step rate is limited by the inductance
of the stepper windings, but at the 80 VDC, the current overheats the
steppers when they are *not* being stepped rapidly.

Anyway this does not gracefully accept the variable frequency
of a VFD. And it is also rather difficult to re-wire to single phase
power.

The actual computer part (a DEC LSI-11 CPU and a bunch of custom
electronics to go with it) is powered from a single phase, so it is no
real problem -- only the individual stepper motor power supplies.

So -- expect yours to be a lot easier to fix up. From what you
quoted and I trimmed, I gather that the two phases used to power it were
selected to minimize the total current drain from a single phase.

Of course, you will need a VFD or a RPC to handle the spindle
motor, which *must* have three phase to work properly.

Good Luck,
DoN.

--
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(meatwad) fired this volley in
oups.com:

ÿcan you elaborate on
how you changed your machine over to single phase?


Sent a PM. It's quite easy on the R2E4, which has two power transformers
operating in single phase, but from two separate phases. No phase
referencing is being done, so it's just a matter of re-wiring a bit, and
adding a VFD with some reversing contactor translation for the VFD
control inputs.

DO NOT attempt to use the existing reversing contactors on the output of
your VFD, or you will fry it.

LLoyd