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--- In CAD_CAM_EDM_DRO@..., "Vlad Krupin" <vlad.cnc@...>
wrote:

This is a really old thread, but I am just catching up on my email and
wanted to add my 2c, for the record:

The one advantage of L297/L298 solution is that you can chain

several L298

chips in parallel. You can't do that with an LMD18245. Yes, the PCB

routing

gets hairy pretty quickly, but it can be done, and it works. I am

currently

using boards utilizing that very method - 3 L298 chips in parallel

per axis

driving stepper motors with 5A per axis (

).

Of course, one could argue that if higher currents are needed, one

should

just go with discreet FETs anyway, and I wholeheartedly agree, but

that's a

different topic. The point is that, in a pinch, you could get some extra
power out of a L297/L298-based solution, and it is a remarkably simple
circuit.

Vlad

Hi Vlad,

I thought that using big power FET's was a super simple solution to
the higher power problem ?

Dave

Carl Mikkelsen wrote:

What are good ways to measure surface smoothness? It would be interesting sometime to attempt to cut a plane, and see what the error actually is, and somehow estimate what portion is quantization related, vibration related, calibration related, and simple actuator error related.

One test I can think of is to try to cut a "bowl", the inside of a hemisphere. I
would think a lot of motion artifacts would show up in that, especially stickiness
or backlash in the struts.

Jon

"Best" is a subjective term, especially when it comes to CAD, so you
will probably get lots of opinions.

I've using Alibre Design for a couple of years for 3-D part and
assembly design and have been pretty happy with it. Prices from
around $1k to $2k depending on the version. There's a 30-day trial
version available at their web site and I think that they still
offer a free version (Alibre Design Express) that is somewhat
feature limited.

I'll be taking delivery on a Tormach CNC mill in around a month and
will be using SprutCAM Expert 4 for the CAM function. The mill
itself uses Mach2 for motion control. SprutCAM apparently lists for
around $3k but Tormach sells it for $1k. There's a newer version of
Mach (Mach3) that sells for around $150, I think. I haven't used
either of these yet, but they seem to be generally well thought of.

www.alibre.com
www.sprutcam.com

www.tormach.com

Mike

--- In CAD_CAM_EDM_DRO@..., "patcom1970"
<patcom1970@...> wrote:

Does anyone have any opinions on what is the best CAD software for

a

CNC milling machine? I am building a 3 axis gantry type machine

driven

by steppers. The motors will be controlled by Pic

List "Linistepper"

drive boards.

I intend to be milling PCBs as well as nonferrous metals &

plastics.

Both the metals & plastics I expect to be fairly complex 3

dimensional

shapes.

I will be using a pentium based PC running XP. Cost is an issue,

but

getting a good package is more important than outright cost.

Your advice would be most appreciated.

Tony.

Earlier this week I launched a new software product for CNC

enthusiasts on

the Mach3 group. For those that don't subscribe there or may have

missed it

here are the details.

Thanks,

Graham Hollis
www.d2nc.com

Hi Graham, I tried to install your program but got an error message
saying that the pleant.dll cound not load - so the install aborted.
Any thoughts? WJS

Does anyone have any opinions on what is the best CAD software for a
CNC milling machine? I am building a 3 axis gantry type machine driven
by steppers. The motors will be controlled by Pic List "Linistepper"
drive boards.

I intend to be milling PCBs as well as nonferrous metals & plastics.
Both the metals & plastics I expect to be fairly complex 3 dimensional
shapes.

I will be using a pentium based PC running XP. Cost is an issue, but
getting a good package is more important than outright cost.

Your advice would be most appreciated.

Tony.

A little late coming into this discussion, but just one more thing to
consider -- when the motors are holding their position, is one winding
energized, or both? If you have 1.4A flowing through one winding, it's quite
different from 1.4A flowing simultaneously through two. In fact, depending
on the ambient temperature, and how efficient the motor is at dissipating
heat, I think the temperature in one case can be close to twice that of the
other. At least theoretically that seems possible.

Vlad

--
Vlad's shop

I would guess an initial accuracy over the whole work envelope of

.1" at

best, as I'm
sure they do the minimal amount of calibration. They probably use a
square to
set the orthogonality of the axes, and that is ALL.

One would expect a final test to be a pen plotter.

a large square drawn, then rotated 90 deg, would show squareness
pretty well.

But, As you implied, alignment at the factory only needs to be
superficial. the breaking down, then boxing and reassembly would be
well past any factory calibration.

I wonder how much the sell for ?

Dave

does not yet work under crossover or wine. At least, not for me. Does work
under vmware.

Vlad

--
Vlad's shop

This is a really old thread, but I am just catching up on my email and
wanted to add my 2c, for the record:

The one advantage of L297/L298 solution is that you can chain several L298
chips in parallel. You can't do that with an LMD18245. Yes, the PCB routing
gets hairy pretty quickly, but it can be done, and it works. I am currently
using boards utilizing that very method - 3 L298 chips in parallel per axis
driving stepper motors with 5A per axis (

).

Of course, one could argue that if higher currents are needed, one should
just go with discreet FETs anyway, and I wholeheartedly agree, but that's a
different topic. The point is that, in a pinch, you could get some extra
power out of a L297/L298-based solution, and it is a remarkably simple
circuit.

Vlad

--
Vlad's shop

Be careful about dismissing something as a toy, history is littered
with the remains of those who made that mistake, from steam shovel
makers about hydraulic diggers, to mainframe computer makers

about personal computers.

Tony

Too true! I apologize if I came off that way. It was not my
intention to be dismissive. I worded it very badly, it seems.
And I'm sorry.

Thank You all for your indulgence and thoughtful responses!
Education is always a good thing. Even one at a time. :)

Best of luck in your endeavors!!! And, thank you again!

Ron Yost

I didn't think you were being dismissive, it's usually hard to get your head
around something new.

A new idea either replaces something existing, or creates a new market (and
sometimes then wipes out an existing one).

Occasionally something is just 'right', like the compact disc. Since they
were seen as so much better than vinyl or cassettes, it wiped them off the
map in short order. An old marketing rules goes that something needs to be
10 times better than what's existing to do that.

Hexapods will probably create their own market, they are great at doing
'odd' stuff that are a pain on 3-axis mills. Whether they eventually
replace traditional machines remains to be seen. Same goes for the rapid
prototype machines.

Hydraulic diggers started like this. Derided and ignored by the steam &
cable makers, they started as small machines, like the Bobcats. They
created their own market for digging up peoples gardens. Eventually they
got bigger, and wiped out the competition.

60 years ago the idea of anybody needing a computer was seen as ridiculous.
Nobody could see why a business, let alone a person, would want one. Even
the computer manufacturers thought that!

I once worked for a company that provided telephone services. I said (about
8 years ago) that we should concentrate more on mobile services than
traditional landlines. My reasoning was that when the teenagers grew up,
they would have a mobile telephone, and never install a landline at home. I
was told that was silly. They missed the boat (& the $$$) on that one. I
now see newpaper articles astonished at the fact people are no longer
installing landlines. Ha!

Tony

Dennis Schmitz wrote:

All of this talk of water jet cutters and occasionally lasers led me
to this website.



Apparently you're supposed to buy your own plasma torch, but in any
case, it's a very spartan design of an xy table with a little bit of
z. They claim accuracy of 0.0005 in the xy, making me curious how they
built the actuators and bearings.

This is the classic confusion between resolution and accuracy. There's no WAY
they can provide ACCURACY of .0005" in a machine that size. It would be
VERY expensive to provide such accuracy in a coordinate measuring machine
that size, if built of granite and air bearings, and kept in a temperature-controlled
room. OH, but wait! They DO NOT claim such accuracy. The specs say "resolution",
and that is perfectly reasonable.

I would guess an initial accuracy over the whole work envelope of .1" at best, as I'm
sure they do the minimal amount of calibration. They probably use a square to
set the orthogonality of the axes, and that is ALL.

I'm pretty sure the linear actuation is rack and pinion, and the axis looks like
bearings roll along steel channels.

Jon

There are quantization problems with other than simple CAD models, however.

Curves and low-tangent cuts are particularly subject to quantization error
effects -- think of "jaggies" in graphics rendering.

I agree with you, though, that hexapods have unexpected quantization
errors. While a cartesian machine can cut an axis parallel surface with no
quantization induced variations (although the exact position of the cut
line or plane may be off due to quantization), a hexapod will intrinsically
have a surface roughness introduced by the quantization.

In my new hexapod, I have an actuator quantization error (theoretical) of
0.000025 inches. Each actuator is servo driven with 8192 encoder events
per revolution, and a 0.2" per revolution displacement. Depending on where
the platform is operating, one paper analyzing hexapod accuracy finds that
the expected platform error is about 1/2 of the actuator error. If so,
then the peak error should be on the order of 13 microinches. Of course,
that's with everything perfect, which strangely enough it never is.

What are good ways to measure surface smoothness? It would be interesting
sometime to attempt to cut a plane, and see what the error actually is, and
somehow estimate what portion is quantization related, vibration related,
calibration related, and simple actuator error related.

-- Carl

--- In CAD_CAM_EDM_DRO@..., Les Newell <lesnewell@...>
wrote:

SheetCam <www.sheetcam.com> can do this at a much lower price. I

can

write a post processor for you that will slow down to a preset
percentage of the normal feed rate on arcs. The post could even be
configured to slow down more for tighter arcs.

Les

afogassa wrote:

Hi Peter,
I do have deskcnc and it's good enough for this, but water

jets

needs a good cam that can look way ahead and predicts what is

going

to happen and than starts to adjust the feed rate before it

gets to

a corner or radius to compensate for Jet lag doing that manualy
would be a pain if not impossible.
Got a quote from PEPs and it runs at 10K US$ (ouch !!)
I've being thinking about getting a working G code, than work

this

out on excel to adjust the feed rate.

Hi Les,
For what I've read about softwares for water jets,is that the tool
path should change speed progressive from a straith line into a
corner or radius.not just change speed when it runs into a corner or
radius.
If you can do that Than we can work on feed rates percentage to
adjust for jet lag.

Fogassa

--- In CAD_CAM_EDM_DRO@..., "Andy Wander" <awander@...> wrote:

Rick:

I have a 4699A hp plotter that doesn't work, that somebody trash-picked
and gave to me. I want to start fooling around with it and see if I can
make something useful out of it.

Did you have any problems deciphering the wiring to the encoders and the
motors?(I assume the motors are just 2 wires, and the encoders are....?)

________________________________________
Andy Wander

On my encoders on my HP plotter, the encoders sensing module is
branded with the manufactures name. I don't recall right now, but the
whole thing was on a small board with supporting chip to make
interfacing pretty easy.

Dave

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

All of this talk of water jet cutters and occasionally lasers led

me

to this website.



Apparently you're supposed to buy your own plasma torch, but in any
case, it's a very spartan design of an xy table with a little bit

of

z. They claim accuracy of 0.0005 in the xy, making me curious how

they

built the actuators and bearings. Getting both ends to move

together

on the first axis seems an issue -- maybe a rod with rack and

pinion

at both ends would work if you could get rid of the backlash.

Notice that almost all the structural elements are bent sheet metal
and the cable holder saves a bunch of expense from using a flexible
wiring channel.

A small handheld plasma torch is a bit expensive at $1500, but it's
way cheaper than a laser.

Yeah, you can build it to do 0.0005" but the problem is that the
torch won't hold that( repeat it) as the tip wears out prety fast.
It's dificult to get a large machine built out of square tubes
strait all the way withing that 0.0005".
The positioning carriages should not be part of the cutting table.
the one I've built has step motors and rack and pinion, and a long
shaft across the table driving both sides of the table.

Fogassa.,

--- 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

Hi Ginger,
I've built a plasma cutter last year 1,5 x 3m(meters), after
talking with a hiperterm sales person he told me that there is a tip
just for thin material good up to 1,5mm. I did not try it.
You can do details as small as 3mm,on the machine I've built.
You'll need a torch hight controller, got mine from rutex, or thin
staff will warp so much that the tip will hit the material and when
that happens the torch starts shooting to the sides.
You can also use water when cutting to minimize warp.
I don't think you can get better than 2mm details.
small holes are a pain to do below 6mm ID.
I would say it's good just for rough cuts than finish with the
mill.
It can save a lot time doing this way.
I've being thinking about a water jet, cuts about anything, cheaper
the laser but slower and with the advance in software and pumps I
think it's the way to go.( how about those beautiful granite
medalion up to 2" thick or more)

Fogassa

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

All of this talk of water jet cutters and occasionally lasers led me
to this website.



Apparently you're supposed to buy your own plasma torch, but in any
case, it's a very spartan design of an xy table with a little bit of
z. They claim accuracy of 0.0005 in the xy, making me curious how they
built the actuators and bearings. Getting both ends to move together
on the first axis seems an issue -- maybe a rod with rack and pinion
at both ends would work if you could get rid of the backlash.

Notice that almost all the structural elements are bent sheet metal
and the cable holder saves a bunch of expense from using a flexible
wiring channel.

A small handheld plasma torch is a bit expensive at $1500, but it's
way cheaper than a laser.

Dennis, come over to the CNCManualPlasmaCutting group and post that
same question. All plasma guys over there. We talk about the actual
accuracy of the plasma cutting process itself and about specific
brands of tables and plasma cutters.

I'm still getting my MP1000 Torch Height Control set
up from CandCNC.com but now that I've got a Hypertherm
1000, I'm getting great cuts cutting out 5/16" holes,
3/8" square holes, etc.. I have not tested the fine
cuts yet but I'm happy for what I'm doing w/ regular
tips so far, I'd like to try those fine cut tips on
some small detailed parts soon!

How about 4130, how do the fine cut tips cut on that?
Up to .100" or so??
Darren Lucke


--- caudlet <thom@...> wrote:

--- 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

Ron, you can do some nice detail with the smaller
plasma units like
the Hypertherm 600. If you can justify the cost you
can step up to
the Hypertherm 1000 and use Fine Cut tips and hold a
.035 kerf. I have
lots of experience cutting decorative and detailed
stuff with plasma.

Our new series of Digital THC's will hold the .050
to .63 gap you
need at 150 IPM over warped metal. We just had some
posts on cutting
14 ga steel on the CandCNCSupport yahoo group.
Newbees are welcome and
so are grizzled veterans like yourself (;-).

Tom Caudle
WWW.CandCNC.com

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--- 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

Ron, you can do some nice detail with the smaller plasma units like
the Hypertherm 600. If you can justify the cost you can step up to
the Hypertherm 1000 and use Fine Cut tips and hold a .035 kerf. I have
lots of experience cutting decorative and detailed stuff with plasma.

Our new series of Digital THC's will hold the .050 to .63 gap you
need at 150 IPM over warped metal. We just had some posts on cutting
14 ga steel on the CandCNCSupport yahoo group. Newbees are welcome and
so are grizzled veterans like yourself (;-).

Tom Caudle
WWW.CandCNC.com

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