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mayfieldtm wrote:

Does anyone happen to know the signal format for Mitutoyo Linear
Scales, series AT715?
I want to interface one to a microcontroller such as a PIC and need
the pinout and signal information.
These scales are intended to be exclusively connected to Mitutoyos KA
Counters.
These scales are Absolute reading units and I'm assuming they spit out
a continuous stream of serial data to indicate current position.
Or they send data upon a request, or???

Probably they are just quadrature incremental encoders with a special index
track. The way most of these work is that the number of quadrature counts between
index marks is different between every pair of index marks. So, you only need to
pass by any two adjacent index marks, and you know where you are. This is the
simplest form of absolute encoder, and it takes no more electronics than a standard
encoder with one index mark -- just 3 optical channels. A little bit of software
in the readout box computes the absolute position. This requires a small move
of the machine after turn-on before the absolute calibration is set.

Jon

Ron Yost wrote:

I wonder how much they sell for ?

Dave

I did a little searching by Google and the only pricing info I found was a
posting by someone on a (non-PlasmaCAM) forum somewhere. He said they're 'about $10,000'. May, or may not, be accurate. I found NO independent
reviews of the thing at all! Not one! Maybe someone else has?

One fellow on a forum said they're not nearly as robust as they appear
in the purty pictures on the PlasmaCAM site, for what that's worth.

This is not a great surprise. As best as I can tell, he has the rack mounted inside
a steel channel, and some kind of carriage rolls either slong the inside of outside
of the channel. Since plasma is a horribly dirty process, this seems like a pretty
good design from the standpoint of resisting contamination. But, you can't expect
great accuracy from structural steel components. And, since there is no scheme
to prevent racking of the bridge axis, that is going to put some stresses on the
thing that may accelerate wear.

$10K just seems a bit high for a basic X-Y table with a little Z travel.

The fact there's no pricing info on their site is a red flag, to me. I
like companies who are up-front with such things. If they're not, they're
usually hiding something, in my experience. In this case, I'll bet it's
the lack of value for $$ spent. Something you're not supposed to realize until after the dotted-line has been signed and the thing is in your
possession.

One's supposed to watch their video and send them 10-large (or whatever). Basically sight unseen. They discourage contact with present owners, provide no references at all, and you -can't- actually see and touch
the machine at the 'factory' before purchase. Gee, I wonder why?? :)

No posted price is not a great concern to me - yes they want you to call, not too
unusual. If all the rest of the previous paragraph is true, then that DOES raise a
red flag, for sure. Might be time to do some Google searches on the trade name to
see if anyone has posted from their experience.

Jon

Graham Stabler wrote:

--- In CAD_CAM_EDM_DRO@..., Mike Pogue <mpogue@...> wrote:

So, as long as I specify coordinates in 0.001" increments (which is
what I normally do), there's an exact representation in motor
coordinates (and no quantization error).

You are rounding which is fine if you are cutting out a square say but
what about a circle or a diagonal or a spline? You are effectively
adding the quantization error before you move the motors.
Unless you have a noiseless analogue computer or you stick with square
components there will always be some quantization error even before
the motors :)

Maybe I don't understand what you mean by "before the motors"?

With the algorithms I am using, there is no added software quantization error (other than the error that the steppers themselves introduce). I am guaranteed to always be as close to the circle in stepper motor coordinates as it is possible to be with steppers. It's not a PID algorithm, so I don't have overshoot to deal with.

Note that the quantization introduced by the steppers is way smaller than the backlash in the mechanical stuff. I'm running the steppers at 200 steps/rev, 10TPI leadscrew, with 16X microstepping. So, the resolution is about 1/(200*10*16)" = 0.00003125" per motor step.

Circles and diagonal lines would certainly have the largest quantization error. But, the furthest the steppers can get from a "true" diagonal line or circle is about 1/2 that number, or about 0.000016".

Mike

--- In CAD_CAM_EDM_DRO@..., "smeboss" <c65pratt@...> wrote:

Hi Guys

I'm wondering how fast a Fadal 4020 can drill a series of 15/16 holes
thru 3/8 mild steel, rectangular patttern, 2 rows of 4, 4" centers?

I don't have any experience with these machines, but it takes me

about

30-60 seconds per hole manually.

Thanks

Charles

Once you get into full sized CNC machines its not so much a question of
what the "machine" can do, more a question of what the tooling can do.

I had to drill a double grid pattern of 20mm holes on 26mm centers in
3/8" hot rolled. (heat exchanger end plates)

Using a Mori Seiki SV50B (CAT40) and a Kennametal solid carbide drill I
was punching thru in 1.3 seconds...

Feed .027" / rev.

OK I know the Fadal won't quite do that (it was requiring about 24 of
my 30HP) but it would get close with optimal tooling.

--- In CAD_CAM_EDM_DRO@..., Jon Elson <elson@...> wrote:

Carl Mikkelsen wrote:

What are good ways to measure surface smoothness?

digitize on a cartesean machine perhaps, that's if you want to measure
it rather than just feel depressed :)

Graham

p.s. thanks for the info on the annealing stuff.
p.p.s sorry for all the bunched replies, no time for internet yesterday.

--- In CAD_CAM_EDM_DRO@..., Ron Ginger <ronginger@...> wrote:

For years Ive wanted a laser to cut parts for model engines, but to cut
metal I realize the laser power is too high and the prices way out

of my

range.

But maybe a plasma cutter could do it- are there plasma torches that
will cut real small parts? Could I cut something like a model

locomotive

frame, maybe 1" wide by 10" long, with a variety of cutouts?

Ive already built a CNC router for wood and plastic, and have a CNC

mill

for oterh parts, but cutting sheet metal with a plasma CNC would be

cool.

ron ginger

I'm going to get a bad reputation for silly ideas at this rate:



I created the holes in this rasor blade using a small 80v supply, a
plasma globe powersupply some brass tube and an airbrush compressor.

Taking this a step further into a machine that might cut something
seriously is probably a bit of a jump but not so daft. The smaller
plasma cutters have relatively low currents of around 12A and will cut
say 1mm thick steel at that I think.

I'm not sure how well plasma cutting scales, in industry they don't
consider it for thin sheet because laser fits the bill so well but
there are plenty of hobby applications where the ability to cut 1mm
thick steel to OK accuracy could be really handy. There are really
two main components to consider, the supply and the handpiece. The
latter is probably best bought as a spare part, the former could be
built fairly simply for low powers.

That all said perhaps minaturization of the nozzle diameter would be a
good thing if you are also going to thinner material.

You didn't actually mention the thickness.

I see a few of you are cutting some pretty thin stuff, can you give me
an idea of your settings, what is the voltage and current and what is
the starting mechanism of the torch? If I can select the right
handpiece I'll happily buy one to play with.

Graham

On Sat, 02 Sep 2006 21:20:13 -0000, you wrote:

I'm wondering how fast a Fadal 4020 can drill a series of 15/16 holes
thru 3/8 mild steel, rectangular patttern, 2 rows of 4, 4" centers?

I don't have any experience with these machines, but it takes me about
30-60 seconds per hole manually.

Ignoring that specific machine, my feed/speed tables reckon 2 inches per
minute at 400 rpm, using a HSS .9375 inch drill in mild steel. Power
requirement for that is .35 HP.

A CNC machine should be able to drill all 8 holes in approx 2 1/2
minutes from start to finish.

Steve Blackmore
--

--- In CAD_CAM_EDM_DRO@..., Mike Pogue <mpogue@...> wrote:

Since this might be of general interest to others as well, I'll post
here. Everybody -- feel free to send me comments!

I'm doing this in the context of a "special projects" class that I am
taking at the local community college (which has an excellent CNC
program). As part of that, I wrote up what I was going to build, and
then at the end, what I was able to accomplish in the time I had.

Here's the link to what I got done over the summer (I'm only about 2/3
of the way there, so I need to take the class again to finish!):



Mike

Very nice, its cool to see the real thing looking like the rendering.

I'm sure you will get it finished.

Graham

Hi Guys

I'm wondering how fast a Fadal 4020 can drill a series of 15/16 holes
thru 3/8 mild steel, rectangular patttern, 2 rows of 4, 4" centers?

I don't have any experience with these machines, but it takes me about
30-60 seconds per hole manually.

Thanks

Charles

--- In CAD_CAM_EDM_DRO@..., Mike Pogue <mpogue@...> wrote:

So, as long as I specify coordinates in 0.001" increments (which is
what I normally do), there's an exact representation in motor
coordinates (and no quantization error).

You are rounding which is fine if you are cutting out a square say but
what about a circle or a diagonal or a spline? You are effectively
adding the quantization error before you move the motors.

Unless you have a noiseless analogue computer or you stick with square
components there will always be some quantization error even before
the motors :)

Not that this matters.

Graham

--- In CAD_CAM_EDM_DRO@..., "Dennis Schmitz"
<denschmitz@...> wrote:

True enough, but I was thinking about straight-line movements and
non-linear resolution in cartesian coordinates. A straight line
movement through the range would have stepping.

A straight line diagonal or a circle or whatever in a serial machine
has stepping. True the quantization will not be constant in a
parallel machine but that is a different point.

Graham

--- In CAD_CAM_EDM_DRO@..., "Dennis Schmitz"
<denschmitz@...> wrote:

I'm not sure why the distinction. It's still the same number of
operations. Matrices are just an easy form to work with in code as
well as conceptually. Of course I spend a large part of most days in
Matlab, so I might be biased.

What operations? In the marix formulation I assume you are solving an
equation system. I've basically done then directly for a specific
case (the machine's configuration) and I end up with an equation that
amounts to A^2 = b^2 + c^2 I don't solve it I just evaluate it.

I'm also a matlab user but my machines won't run on it :(

I find the matrix to be a more general form, probably because I'm

used to it.

It is a more general form, you are representing a sytem of vectors
generally.

I saw the stuff about the clevis, but I think the ball with
self-lubed> plastic bushing is a simpler design.

Problem can be a lack of movement, the red delta at the bottom of my
page uses a pair of half sockets and a spring to keep them engaged,
that gives lots of movement. The igus ball joints don't have a lot of
motion as stock unfortunately, perhaps you know of better ones or
maybe I misunderstand the configuration. As it happens I don't intend
to use clevises in my triaglide model, I'll be using the bearing
cartridges from the arms of about 30 dead hard drives. Built like this:



I assumed you were talking about hexapods because you posted a link to
a hexapod.

Graham

Ah, so that's *you*! I have been to your site several times. Thanks for posting the pics and other info about your design!

Mike

Carl Mikkelsen wrote:

Since this might be of general interest to others as well, I'll post here. Everybody -- feel free to send me comments!

I'm doing this in the context of a "special projects" class that I am taking at the local community college (which has an excellent CNC program). As part of that, I wrote up what I was going to build, and then at the end, what I was able to accomplish in the time I had.

Here's the link to what I got done over the summer (I'm only about 2/3 of the way there, so I need to take the class again to finish!):



Mike

Graham Stabler wrote:

Does anyone happen to know the signal format for Mitutoyo Linear
Scales, series AT715?
I want to interface one to a microcontroller such as a PIC and need
the pinout and signal information.
These scales are intended to be exclusively connected to Mitutoyos KA
Counters.
These scales are Absolute reading units and I'm assuming they spit out
a continuous stream of serial data to indicate current position.
Or they send data upon a request, or???
Thanks!
Tom M.

I wonder how much they sell for ?

Dave

I did a little searching by Google and the only pricing info I found was a
posting by someone on a (non-PlasmaCAM) forum somewhere. He said they're
'about $10,000'. May, or may not, be accurate. I found NO independent
reviews of the thing at all! Not one! Maybe someone else has?

One fellow on a forum said they're not nearly as robust as they appear
in the purty pictures on the PlasmaCAM site, for what that's worth.

The fact there's no pricing info on their site is a red flag, to me. I
like companies who are up-front with such things. If they're not, they're
usually hiding something, in my experience. In this case, I'll bet it's
the lack of value for $$ spent. Something you're not supposed to realize
until after the dotted-line has been signed and the thing is in your
possession.

One's supposed to watch their video and send them 10-large (or whatever).
Basically sight unseen. They discourage contact with present owners,
provide no references at all, and you -can't- actually see and touch
the machine at the 'factory' before purchase. Gee, I wonder why?? :)

They're clever marketers tho, I'll give them that. The whole thing
is so slick, and sleazy-feeling, it really turns me off. I wouldn't
send them 10-cents.

Ron Yost

--- In CAD_CAM_EDM_DRO@..., Mike Pogue <mpogue@...> wrote:

Graham,

Let me second that -- your site is excellent. In fact, your site

was

one of the reasons why I started working on my design (which is a
"triaglide with vertical rails", as per your diagram).

Mike

Drop me an email, I'd love to hear some more.

Graham

--- In CAD_CAM_EDM_DRO@..., "Alan Marconett" <KM6VV@...>
wrote:

What is the stuff that looks like links (copper colored) down ON

the table?

There is a central hub with bearings and arms extend out to the
carriages. I guess it stiffens things.

The copper is some swish anodizing I think.

Graham

I do not use or call that dll at all. I've searched both google and my
development system for it and cannot find it or any reference to it. The
only thing I can suggest for now is to make sure no other application is
running when you run the installer. Try a reboot first before the install.
If there is a file called error.log in the C:&#92;d2nc directory please sent
that to me at support@...

Thanks
Graham
www.d2nc.com