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--- In CAD_CAM_EDM_DRO@y..., "Doug Harrison" <prototype@c...> wrote:

Depends on your controller. At present, the software-only

solutions (Mach1, cncpro, etc) do not have this capability. Somebody
jump in if this is incorrect. Art will probably have it available in
Mach1 eventually. Cncpro seems to be in its final form.

Mach1 has spindle control via step and direction since last week. For
a smaller spindle use a Gecko 340, larger spindle look at Rutex in
Australia. I haven't tried it (yet), I don't have an encoder on my
spindle.

Roger

I am in Atlanta. Not much to offer in these parts.
L297/8's are kinda special to be found in stores.
I order from Digikey or Mouser.
RichD

JJ wrote:

Try Ack off of Northside Drive.

They have a web site that you can check inventory, pricing, etc @



At 04:46 PM 10/25/02 -0400, you wrote:

Anyone know of a supplier in Atl

Be Kind, Be Careful, Be Yourself

Bubba

OLDER THAN DIRT
Country Bubba
(Actually the inventor of Country and Bubba)

axtein@...
LaGrange, GA

Yep,
Basically, what I did was to eliminate the servo motor and made new mounts
for the encoders and then modified Steve's program to work with my
computers. We now have a completely re-written version of the program along
with a new interface using 4 IC's and a handful of resistors.

All of the information including the updated software can be found in the
link in my tag line.
enjoy and write off line if I can help.

At 05:32 PM 10/25/02 +0000, you wrote:

With my servo controller turned off, is it feasible to use the
encoders off my servo motors for a DRO?

I have the kit from Camtronics and seperate linear scales (US
digital) but I'd rather not have to mount the scales if I don't have
to.


If the Camtronics kit wouldn't work, could I just use the software
from lindsayengraving.com?

anything wrong with this idea?

Bubba

OLDER THAN DIRT
Country Bubba
(Actually the inventor of Country and Bubba)

axtein@...
LaGrange, GA

Try

as this is where I got my package deal and don't regret it for a second:})

At 12:19 PM 10/25/02 -0400, you wrote:

Mark;

Questions such as yours are what this list exists for. We need to remind
ourselves of this from time to time.

You will only need three phase for the spindle. A VFD (variable frequency
drive) is probably your best choice. It will give you three phase from
single phase and also allow you to adjust spindle speed with a knob, or even
from the cnc. You can find them now for as little as $300 new. Art
Eckstein got a nice motor and matched VFD for about $350 as new surplus. I
think more are available (still looking for the bookmark).

Doug


----- Original Message -----
From: "natchamp_87" <mark@...>

Sorry if this is a stupid question. I am planning out my CNC mill
project and haven't bought a mill yet, but am leaning towards a BP or
similar 9/42. My question is: am I being realistic or not in
thinking single phase will be adequate for my mill? I know about the
single to three phase converters but want to avoid that if possible.
Am I also correct in that my CNC motors, whether servo or steppers,
will not require 3 phase because I will have a power supply
converting to DC for them? Sorry again if these are dumb questions.

Bubba

OLDER THAN DIRT
Country Bubba
(Actually the inventor of Country and Bubba)

axtein@...
LaGrange, GA

Sorry about that last email.

Anyone know of a supplier in Atlanta where I can buy a few L298s? I
managed to blow two of mine with a solder bridge and a cold solder
joint. Looks like I'm down for the weekend. Arg!

Thanks!

Regards,
JJ

Be Kind, Be Careful, Be Yourself

Hi Carlos,

Yeah, I know what you mean! I have a LARGE plotter in the garage, just
begging for some attention!

Perhaps if my son gets to building gliders, I'll want to build a foam
cutting machine!

Alan KM6VV

Carlos Guillermo wrote:

Anyone know of a supplier in Atl

Be Kind, Be Careful, Be Yourself

If you use a VFD most of them are able to accept some sort of signal for
speed control. The exact signal does vary with the VFD, but is commonly a
0 - 10 V. If you have a CNC control program that uses can output the proper
signal then you can have computer control of the spindle speed.

Tim
[Denver, CO]

I'm not quite ready to purchase yet but have been keeping an eye out
for a bargain. Does anyone have any experience with Induma mills?
This one seems like a pretty good deal. ???



Mark

Doug,
In your post, you indicated that the CNC could control spindle
speed. I'm just in the planning stage, but I didn't realize this was
possible.

Marv Frankel
Los Angeles

vrsculptor wrote:

The cost for commercial 10" inductosyn bars is about $250. Heads

another $250. The newall is definately cheaper unles you can make heads and boards yourself. As Jon points out the bar is just a square wave easily milled or etched. The commercial ones seems to have a zillion lines per inch but give you .00001 resolution which I don't need for a router.

I wonder how many lines per inch would you need for .0001 and if the evaluation board would drive/read it? I'd be willing to give it a shot if I could get by with a reasonable number of lines per inch and the board has a chance of working.

I don't think they are very fine grain. Something like 10 waves / inch. The rest is done
by interpolation. A printed circuit board maker that can handle a 30" x 1" circuit board
could probably make a batch of these for a couple of hundred bucks. I might run a quote
to find out what my favorite board house can do.

Jon

Dave Engvall wrote:

<snip> On 9/21/02 12:43 PM, "Ray Henry" <rehenry@...> wrote:

They

are the US National Insitiute of Standards and Technology.
<end snip>

Nice translation there Ray. For you younger people; NIST used to be called
the National Bureau of Standards but are usually now known at the National
Institute of Science and Technology.

Nope! It is still STANDARDS and Technology, check their main web page
to be sure.

natchamp_87 wrote:

Sorry if this is a stupid question. I am planning out my CNC mill project and haven't bought a mill yet, but am leaning towards a BP or similar 9/42. My question is: am I being realistic or not in thinking single phase will be adequate for my mill? I know about the single to three phase converters but want to avoid that if possible. Am I also correct in that my CNC motors, whether servo or steppers, will not require 3 phase because I will have a power supply converting to DC for them? Sorry again if these are dumb questions.

It depends on how much of the existing machine you plan on re-using. Bridgeport BOSS
machines generally have a 3-phase power supply that is hard to retrofit for single-phase
power. The spindle motor can be handled with a VFD, so that is a small problem.
Many smaller, non-Bridgeport brand CNC machines use single phase for the axis drives,
or can be fairly easily set up to run from single phase power. As long as you can provide
the proper DC power source for the axis drives, then even a machine that has a 3-phase
transformer can be converted, it is just more work.

The power requirements for axis motion on a machine with a 9x42" table are not great.
I'm running the CNC computer, axis drives, coolant system, work lights, etc. all off one
15 A 115 V outlet, and not even straining it. I even ran a shop vac from the same outlet
simultaneously to suck up plastic shavings on one job.

Jon

tedinoue wrote:

I recently purchased a 2HP PM DC motor, hoping to build/buy a controller so that I could use this on a small lathe. For those interested, it's a Leeson motor, designated 120v 14A, 4800 RPM. Model C42D340T7A. I plan to reduce the maximum speed then feed it into my existing lathe drive system.

Several questions:
0) the motor doesn't have any designations about reversability. I know electrically it works, but I'm not sure if the brushes are rated for reverse motion. As I manually rotate the shaft, the brushes sound smooth in one direction and click lightly in the other. Should I assume that the motor is designed for one direction rotation only?

Does the nameplate say CW or CCW? IF not, it probably can run both directions. After running
in the 'click' direction for a while, it will stop clicking, as the tiny sharp edge on the brushes
will be worn off.

1) I've seen a lot of postings discussing 90v DC from 110v AC and 180v DC from 220v AC, but little to nothing on driving a motor rated for 120v. I'd get plenty of power out if I ran it at 90v, so I'm ok with a controller that does the basic 110AC -> 90DC conversion. Any reason why this wouldn't be suggested?

If you full-wave rectify 120 VAC with a capacitor input filter, you get about 167 V DC.
Chopping that with an IGBT transistor will provide 0-120 V (with suitable pulse width
control).

2) If I do run it at 90VDC, that's 3/4 of 120VDC, so would I simply then treat the controller needs as 1.5HP / 90 VDC and 10.5Amps?

No, you can still use the full 14 A capacity of the motor. A 90 V controller will limit the
top speed, only, of the motor. Voltage is proportional to speed, current is proportional to
torque.

3) I've no problem making a tach circuit to provide closed loop speed feedback, and from what I can tell, a PWM circuit will provide the best performance. I've made my own PWM DC servo motors before on a small scale using encoders and DC gear motors. Is controlling a large, PM, brushed motor of this sort simply a matter of scaling up?

Yes, but there are things to watch out for with bigger drives. IGBTs are the most desirable
device, but they must never be allowed to run in the linear mode. I suggest using the International
Rectifier 2110 - 2113 series of driver chips, made expressly for power FET and IGBT transistors.
A magnet and hall effect sensor can be your tach pickup, feed that to a 555 timer and integrate
the constant width pulses from that with a simple RC, and you have an analog tach voltage.
Feed that to one side of an op amp, and the other side with a voltage from the speed pot, and
you have a speed error signal. Feed that to a comparator with the other input being fed by a
triangle wave, and you have the PWM signal to drive the IGBT driver.

One thing missing from this is a scheme to extract energy from the motor to slow it down.
So, what is described above is a one-quadrant control. The advantage is it only has one
expensive power semi in it. You need a double pole double throw switch to reverse the
motor. A 4-quadrant control can also extract energy from the motor to slow down, and can
reverse without the switch, but you end up with FOUR power semis. Of course, a resistor
can be switched in with a relay to slow down, that's probably the cheapest way to go.

4) not having experience in higher voltage/power design, I'd appreciate a pointer to a web site with some designs. I'm not looking for someone to give me a tutorial on this forum, and I've done a lot of web searches but they've turned up fairly cold when it comes down to real designs for these types of controllers.

Actually, my PWM servo amp could do this, but it is a bit of overkill. See
<>for some more info. I don't have the schematics online,
maybe I should do that.

Jon

With my servo controller turned off, is it feasible to use the
encoders off my servo motors for a DRO?

I have the kit from Camtronics and seperate linear scales (US
digital) but I'd rather not have to mount the scales if I don't have
to.


If the Camtronics kit wouldn't work, could I just use the software
from lindsayengraving.com?

anything wrong with this idea?

Why don't you just buy one of the Enco Heavy Mill,drill tables for
$120.00 and swag it for the table. 6" x 18 table size. That would be
alot cheaper and give you a much greater capacity. T-slots on one
side and dovetails on the other with adjustable gibs. (check it out
but I think thats correct.

enco# AZ201-2536


Alan Trest
Pensacola Florida



--- In CAD_CAM_EDM_DRO@y..., "mueller914" <mmueller@n...> wrote:

thanks,

not big enough...I did find a company selling much bigger units,

but

the cost was 3x-5x higher....

i just ordered the quadralift and will find a way to be happy with

it.

Mike

--- In CAD_CAM_EDM_DRO@y..., "Doug Harrison" <prototype@c...> wrote:

Reid Tool has them but they aren't cheap. $299 for 4" wide and

5"

travel.

$355 for 9" travel. Smaller sizes are also available. These are

grade 40

cast iron with sliding (end adjusted - the best kind) gibs.

www.reidtool.com

Doug


----- Original Message -----
From: "mueller914" <mmueller@n...>

For my shoptask 3-n-1, I need to fix the very poor design of the
swinging millhead unit. I'm not too keen on thier newest design
option using the 4 posts (quadralift) to move the millhead up

and

down. I've tried to find off the shelf dovetails with no luck.

It

seems everyone sells linear rails but not a dovetail rail in

the

size

I'd feel comfortable with.

Marv Frankel wrote:

Guys,
I've gone into the archives, and read the formulas for motor sizing, and some of the replies, but I have a further question. My Enco mill has pretty easy movement on the x-y axes, but I intend to make the knee the z axis, and the cranking required to raise and lower the knee requires considerably more torque. Do I use a different size motor on z, do I do it by gearing, or both. I'm thinking ahead to a particular project that requires drilling 10 holes through a piece of steel tubing. Can I cycle the z axis quickly enough to do this in a timely manner? I don't want to use the quill fine feed as z, because of an excess of backlash. Any suggestions or experiences that might help my thinking?

You can figure the actual torque with a string and a fish scale. Measure the radius on the
leadscrew handle, and attach a string to the handle. Pull on the string with the fish scale
(make sure the string is at a right angle to the line formed by the handle and the leadscrew
center line.) The force reading on the scale divided by the radius of the handle will give
the torque (in In-Oz, in-Lb. or whatever your measuring instruments read). Now, this is only
for the torque required to raise and lower the knee. On a full-size knee mill, the table-saddle-knee
is so heavy, cutting forces are almost insignificant when raising the knee. But, maybe
doubling the static torque would make a good safety factor.

Bridgeport mills already have a gearing factor in there, the knee is 10 turns/inch, the X and Y
are 5 turns/inch. You need to figure out the desired speed at the torque already determined, and
select your motor based on that.

The overload clutch on the Bridgeport quill feed is set for 200 Lbs linear force on the quill,
by the way.

Jon