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Jim:

Probably someone else has responded to this question already, but here's MY
2? worth:

A resistor is NOT like a semiconductor or battery, anymore than a piece of
wire with bits of paint on it! It will work the SAME, either way.

However, many of us "electronic types" will orient resistors with the
color-codes from left to right, just as the digits they represent, so they
are easier to read "at a glance". The GREY=8, the RED=2, and the ORANGE,
when it's the third band like this, means "three zeros" or "K". That is, you
have an 82K[ohm] resistor. The GOLD (last) band is the TOLERANCE. Gold
means "±5%" (Silver would have been ±10%, and NO band means ±20%).

Good you asked, as SOME would just "stick it in and TRY it", and possibly
wipe something out, had they NO clue what they were up to!

Lotsa luck! Jan Rowland


[Non-text portions of this message have been removed]

Hi,
On Steve's page, you will find a link (outdated) to my version of his
program and interface. I have made some changes to the interface and minor
modifications to the program. The program was then re-written by Robert
Duncan to include an (semi)automatic calibration routine and a new
interface. With version 5.1, there is also a great LARGE GRAPHIC readout on
the computer screen and the interface to drive it is only 4 ICs and some
resistors. You can see how I implemented this (with updates to allow a 2:1
mechanical advantage) starting at:



There are additional pages showing how it was also implemented on a 12
Atlas lathe.

As always, I will attempt to answer any questions.At 12:57 PM 10/23/02
-0700, you wrote:

A mouse is not really a good way to do DRO, as the computer can miss a count
and not bat an eye. Here's a better solution (but more expensive):


John

Bubba

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

axtein@...
LaGrange, GA

As with most things in the real world, it just isn't critical that the tool
be perfectly oriented for every cut. On a manual lathe you are always
confronted with a cutting operation that requires another tool, but are too
lazy to change and you just cut it with the other tool instead. Boring
tools used to take a facing cut after you finish the hole is an example.

Daniel J. Statman, Statman Designs
www.statmandesigns.com
dan.statman@...

For a CNC lathe, how do you go about cutting a spherical end without
changing tool bits?

A tool with a round insert on it works fine.

--- In CAD_CAM_EDM_DRO@y..., "John" <johnhe-uk@s...> wrote:

Rotating tool bits? That's a new one on me at the moment. I can see

the

sense behind it but I've not seen one that can actually do that

available to

the hobbyist. My CNC lathe cuts spheres and tapers with the tool

constantly

in the same position.

Sorry - I should have referred to why I thought this was the case. I
found this on another machining group:


ool.pdf

In his design, the tool is rotated on a yoke. Its a relatively
simple concept actually so I figured that all radius/sphere turning
tools were like this. You can see in his document that he is making
som sphere tipped shafts. So, suppose that you want to cut a shaft
that tapers down toward the end and then at the end you have a
spherical end and not just a half sphere but more like 75% of a
sphere (like what is shown in the above document). Now, your tool
bit has to be able to cut on both sides if you were to do this
without changing the setup. So what kind of tool would you use if
the tool isn't rotating - a cutoff blade? What I find interesting is
that the fundamental approach may have to be different if using CNC
versus manual. Of course, I may be off my proverbial rocker, too.

-Chris

Joe,

I put a Windows DRO program in the files section a while back that uses that
DRO board, You can try that if your computer will do windows. It is called
VB_DRO or something like that. I just wrote it as an exercise and it's not
perfect, but it does work.

I too was eyeing the MT3 version of the spindle. Problem is at $35
and 5 days left on the auction - you might as well buy it new. I
went to little machines:
and they have ALL the pieces, parts you could ever want, for the same
price. Plus if you know exactly what parts you need or want, they're
willing to do partial assemblies...

--- In CAD_CAM_EDM_DRO@y..., William J Blocher <wjb1060@j...> wrote:

Thanks for the heads up Jon. The guy that is selling this spindle

has

several things that the group might be interested in like stepper

motors,

ball screws, and a servo motor with an encoder.

ViewSellersOtherItems&userid=rllalo

nde&include=0&since=-1&sort=3&rows=25 will get you to the list.
Bill


On Sat, 19 Oct 2002 14:52:17 -0700 Jon Anderson <janders@n...>
writes:

Someone was asking a while back about a compact R8 spindle.

is a current auction on eBay for such a spindle with three

bearings.

There is no housing, nor do I see any provision for securing the
bearings. This has the look of someone that is making these for
sale, it
sure doesn't look to me like it came out of any existing machine.
Might
be worth looking and asking questions for anyone needing a short

R8

spindle...

Jon

Addresses:
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NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY

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Rotating tool bits? That's a new one on me at the moment. I can see the
sense behind it but I've not seen one that can actually do that available to
the hobbyist. My CNC lathe cuts spheres and tapers with the tool constantly
in the same position.

If you image the stock spinning around, you start the program so the tool
starts the same radius size away from the work as you want to create. It
runs through the program jogging the tool inwards bit by bit until
eventually it just starts to touch the end of radius (The furtherest part
in). From there it carries on jogging in fraction by fraction expanding the
cut it's taking until eventually it's making cuts right across the full
radius you want to turn. The cutting action all takes place on the point of
the tool, maybe a tiny bit to the side of the point sometimes but never
enough to cause a problem.

I don't know how well I've explained that but what I'm trying to say is that
the machine starts miles off from the work and moves in _slowly_ forming the
sphere from the most _extreme_ points first. In the end the tool can pass
the full length of it taking a normal depth of cut. So at the beginning you
have something that looks nothing like what you want. It'll look like a
piece of stock with a bump on the end. After a little while longer the bump
will have a noticable curve. That'll end up as a nice smooth radius. I have
to say here that the steppers on my lathe make a noise like Terminator
himself when they cut a radius, it sounds soooo funky as they cross over!

Tapers are easy and just done in a similar way. You only have a problem when
an angle is created that's steeper than the angle on the point of the tool,
but that's quite unlikely to happen. And even then you can always turn the
toolpost and run it as a seperate program away from the rest at the end.

Regards,
John H.

Another question for everybody. And for this question I need to
clarify that I'm NOT a machining wiz - in fact I don't even have my
own lathe yet.

If a lathe is converted to CNC, I thought that it would make
machining complex tapers and rounds or spheres much easier. But as I
looked at the current manual devices that cut these shapes - say the
spherical ends - the cutter rotates with the device. Which seems to
make sense because then your cutters' angles are always 'correct' in
respect to the tangency of your cut surface.

For a CNC lathe, how do you go about cutting a spherical end without
changing tool bits?

If this is a stupid question, I do apologize.

-Chris


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URL to this group:

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.

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

I ran my Shoptask with some 260 in/oz motors for a while and it worked, but
the feeds were what I would consider marginal. The Z actually requires a
pretty stout motor. You do not the reduction benefit of a screw on that
axis. It's effective reduction is slightly more than the X or Y but not as
much as you may think. So, I would say that 300 is about the minimum I would
suggest.

Tim
[Denver, CO]

Another question for everybody. And for this question I need to
clarify that I'm NOT a machining wiz - in fact I don't even have my
own lathe yet.

If a lathe is converted to CNC, I thought that it would make
machining complex tapers and rounds or spheres much easier. But as I
looked at the current manual devices that cut these shapes - say the
spherical ends - the cutter rotates with the device. Which seems to
make sense because then your cutters' angles are always 'correct' in
respect to the tangency of your cut surface.

For a CNC lathe, how do you go about cutting a spherical end without
changing tool bits?

If this is a stupid question, I do apologize.

-Chris

I'm planning to CNC my shopmaster when it arrives as well as a
mill/drill I picked up. In my parts bin I have a few double stack
Nema 23's which are supposedly 100 ozin, 1 triple stack 23 which is
150 ozin, and a couple of little 17's. I suspect that none of these
are adequate (well, for the Z direction of the mill/drill if I
attached to the current fine feed wheel, even the little 17's would
probably do OK actually). So I'm looking for some 34's (since that
what will bolt to the Shopmaster anyhow) and I've found some double
stack 34's Superior Electric 300 ozin. I'm planning on using a 63
volt supply. Would these be adequate for both applications?

I'm not bent on ultra fast rapids, but I don't want it to be turtle
slow either. I could get the motors for about $60 each which I'm
guessing is a half decent price.

Any comments?

Thanks,
-Chris

At 03:01 PM 10/23/02 -0000, you wrote:

How a drill actually cuts is another problem. If the two flutes were
perfectly ground, the drill would start, drill, then as the depth of
the hole allows the sides of the drill to engage, the drill would seize
in the hole ruining the drill. Drill bits must be ground off axis or
they will burn themselves up quickly. Most grinders do not have the
capability for perfect symmetry, and most people don't have the
patience to make that happen anyway.

You did real well down to here .. it is the aim of all grinders to make the
flutes equal, to prevent the drill cutting ovesize. That is also part and
parcel of all instructional materials on drill pointing. The reason they
don't burn up is the reduced land behind the edge.


Regards, Hoyt McKagen

To prevent virus propogation, don't put this addy in your book
Belfab CNC -
US Best MC -
Camping/Caving -
I'm a married man and have no fear of Hell

A mouse is not really a good way to do DRO, as the computer can miss a count
and not bat an eye. Here's a better solution (but more expensive):


John

--- In CAD_CAM_EDM_DRO@y..., "Dan Statman" <dan.statman@r...> wrote:

I just received an e-mail with the following subject:

gcodeTESTFILE

This message came personally, and not through this list. But

obviously from

somebody's computer on this list. Check your sent mail folders for

e-mail

that you have not intended to send and get some virus protection

software.

The from field, which is unreliable as to the origin of virus

infected mail

was alenz at bellsouth dot net.

You have been warned, do not open the attached file.

Daniel J. Statman, Statman Designs
www.statmandesigns.com
dan.statman@r...

I've got a ton of this e-mail attachment all with diferent subjects
and senders, not only g codes, it's all infected.

Fogassa.

I have built this interface and tested it with both 500 line and 1000 line
encoders. It works great and really does not cost much to build, IIRC less
than $10 including a box to put it in, screw connectors for the encoder
cables and a db-25 connector to connect it to the PC. The software is
easily configured and seems to be accurate.

John Guenther
'Ye Olde Pen Maker'
Sterling, Virginia

I just received an e-mail with the following subject:

gcodeTESTFILE

This message came personally, and not through this list. But obviously from
somebody's computer on this list. Check your sent mail folders for e-mail
that you have not intended to send and get some virus protection software.

The from field, which is unreliable as to the origin of virus infected mail
was alenz at bellsouth dot net.

You have been warned, do not open the attached file.

Daniel J. Statman, Statman Designs
www.statmandesigns.com
dan.statman@...

Hi Tim,

Ground the center tap, and use a pair of diodes from the ends to the
cap. You could probably use 1/2 a bridge, also.

Alan KM6VV


Tim Goldstein wrote:

onecooltoolfool wrote:

I got the board address problem fixed by just installing in another computer. There is some kind of input comming in but it is erratic and not working properly. I have tried a couple of encoders and the result is the same. The numbers flicker and jump but don't correspond to any real values.

Does having the A and B channels reversed matter? I didn't think so.

Reversing A and B is a time-honored method of reversing the sign of the motion.
It most certainly will not cause problems in accurately counting the pulses.

Mixing up the pairing of the signals on a differential encoder WILL cause unreliable
reading, but most of these hobby boards don't accept differential signals. Differential
encoders have A and A-, B and B- signals. The A- and B- are often shown with a
"vinculum" or overbar, which I can't do here.

Jon

Tim Goldstein wrote:

Matt,

Been a while since I have noticed you posting. Hope all is well?

So if I connect as drawn what is the ratio of the ac voltage to the
resulting dc voltage? I would have to assume that it is different than
what I get with a bridge.

Really, it will always be about DC = 1.414 x AC (RMS). 1.414 is the square root of 2.
AC voltage is normally measured in RMS units, which works out to the same heating value
as a DC voltage of the same value. But, the PEAK reading of an RMS voltage is, magically,
1.414 times the RMS. A rectifer feeding a capacitor filter charges the cap to the peak
voltage every cycle (or half-cycle for a full wave rectifier, as we are discussing here).
SO, that's why it should always be about 1.414, whether half-wave, full wave, bridge
or center-tapped full wave.

Jon

Tim Goldstein wrote:

I have a transformer that is center tapped on the secondary. Voltage
from the center tap to either end is 30 v. from end to end it is 60
volts. I know that if I want 60 volts I just connect the ends to the
bridge and tape off the center tap. How do I connect it if I want 30
volts at the maximum amperage possible? I realize I can connect from one
end to the center and get the 30 volts, but it seems like I am missing
out on amperage by not somehow using the other half of the coil.

You don't get 30 or 60 volts from this, unless it is a resistive application, and you use no capacitors
in the power supply. You get either 60 x 1.414 from the full windong, or 30 x 1.414 for the
half-winding. That will be 84.8 for the full winding, 42.4 for half.

What you do for the lower voltage is to use only HALF of the bridge. Say, you connect the
center tap as the - terminal. Connect both winding ends to the AC (~) terminals of the
bridge. Connect the + terminal of the bridge to the capacitor's + terminal. Don't bother
with the bridge's - terminal, unless you have a need for a - 42 V supply, which you get
essentially free. You can also use two single rectifier diodes on heat sinks instead of
a packaged bridge.

Jon