EDM Capacitors

<Seems decent caps of high ratings are hard <to find. a Motor run
<capacitor is easy to find, are rated in high <voltages, should work
<but are limited to about 50uF in capacities.

I have had some success with the capacitors out of an old, professional,
flashgun - the type newspaper hacks and studios used to use. As in this
case, you can put a number of capacitors in parallel to increase the overall
capacitance. The one thing you do need to check though is that the
capacitors will withstand continually charging and shorting out - most of
the radio types won't whereas the flashgun types are made for just such an
application.

Best wishes,
Ian
--

Ian W. Wright
Sheffield, UK


The following added for automatic email harvesters!
abuse@... abuse@... abuse@... abuse@...
UCE@... abuse@... abuse@...

----- Original Message -----
From: <CAD_CAM_EDM_DRO@yahoogroups.com>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, January 07, 2003 4:45 AM
Subject: [CAD_CAM_EDM_DRO] Digest Number 2835


Addresses:
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OFF Topic POSTS: General Machining
If you wish to post on unlimited OT subjects goto:
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you have trouble.
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sister site to the CCED group, as many of the same members are there, for OT
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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


------------------------------------------------------------------------

There are 25 messages in this issue.

Topics in this digest:

1. Re: Bridgeport V2XT / DX-32 ???
From: Matt Shaver <mshaver@...>
2. Re: Cheap tach - was r.p.m. kit??? / 4 digit under $20
From: "turbulatordude <davemucha@...>" <davemucha@...>
3. Re: Cheap tach - was r.p.m. kit??? / 4 digit under $20
From: "deanc500 <deancouillard@...>" <deancouillard@...>
4. Re: Math for constant speed ellipse (Again)
From: "turbulatordude <davemucha@...>" <davemucha@...>
5. Re: laptop ( was Re: HELP: Bipolar stepper ciruit
From: Ron Yost <musik42@...>
6. Lathe/Mill Purchase
From: "jdbunn2002 <jd_bunn@...>" <jd_bunn@...>
7. Off topic
From: wanliker@...
8. Re: Lathe/Mill Purchase
From: "bdrmachine <bdrmachine@...>"
<bdrmachine@...>
9. Re: Re: Lathe/Mill Purchase
From: "Owen Lloyd" <sportbikewest@...>
10. Re: Re: Math for constant speed ellipse (Again)
From: "Brian" <ka1bbg@...>
11. Re: laptop ( was Re: HELP: Bipolar stepper ciruit
From: JanRwl@...
12. Re: laptop ( was Re: HELP: Bipolar stepper ciruit
From: "al" <101@...>
13. Re: Cheap tach - was r.p.m. kit??? / 4 digit under $20
From: Paul Amaranth <paul@...>
14. Re: laptop ( was Re: HELP: Bipolar stepper ciruit
From: JanRwl@...
15. Re: Motor cable
From: JanRwl@...
16. Re: laptop ( was Re: HELP: Bipolar stepper ciruit
From: "James Owens" <wotisname@...>
17. EDM capacitors and voltage
From: "turbulatordude <davemucha@...>" <davemucha@...>
18. LETS PULL THIS BACK TO THE LIST TOPICS..Re: Math for constant speed
ellipse
From: wanliker@...
19. RE: Math for constant speed ellipse
From: "Todd Fleming" <todd@...>
20. Re: Lathe/Mill Purchase
From: "Raymond Heckert" <jnr@...>
21. Re: Bridgeport V2XT / DX-32 ???
From: "Raymond Heckert" <jnr@...>
22. RE: Motor cable
From: "Carol & Jerry Jankura" <jerry.jankura@...>
23. Re: Re: Math for constant speed ellipse
From: "Todd Fleming" <todd@...>
24. Re: Math for constant speed ellipse
From: "Todd Fleming" <todd@...>
25. Re: Math for constant speed ellipse
From: "Todd Fleming" <todd@...>


________________________________________________________________________
________________________________________________________________________

Message: 1
Date: Mon, 6 Jan 2003 18:23:24 -0500
From: Matt Shaver <mshaver@...>
Subject: Re: Bridgeport V2XT / DX-32 ???

On Monday 06 January 2003 05:33 pm, you wrote:
> Would it be possible to add manual control to a V2XT BP mill (1998
> version)?
> With BP out of bussiness will repair parts be available?
> Any comments on the DX-32 controller?
> If I wanted to add a forth axis (rotation about the X axis) how
> difficult would it be to interface to the controller?

I've never worked with one myself, but here's an online review that might
interest you <g> :

http://www.chimicles.com/CourtComplaint_BP.html

Matt


________________________________________________________________________
________________________________________________________________________

Message: 2
Date: Mon, 06 Jan 2003 23:20:41 -0000
From: "turbulatordude <davemucha@...>" <davemucha@...>
Subject: Re: Cheap tach - was r.p.m. kit??? / 4 digit under $20

The non-contact photo sensor is easily the simplest form for home
brew, but man it would be cooool to have a tach from a old Vette or
or Jag.

now that would wow the spectators!

Personally, I looked at the simplicity of just monitoring the pulses,
looked at mouse innards for sensors, and just stopped when you can
buy a kit for $20.00.

For just a few more parts, it would be easy to add a single point to
allow rotation count/posistion for threading.

Dave



--- In CAD_CAM_EDM_DRO@yahoogroups.com, Hans Wedemeyer <xyz@h...>
wrote:
> Yes it's a simple idea.... but nothing like looking at some digits
and not having
> to bother with coupling to a moving parts and the danger associated
with it.
> Fingers and eyes can be difficult to replace.... ! Now if you make
it a permanent fixture
> sure it's great...
> I'd say the idea has been around about 100+ years ! :-)
> The eddy current driven version has been around almost as long, in
most cars it known as the speedometer !
> If you goto a car junk yard you may even be able to find one of the
older eddy current version speedo's and
> adapt it directly to the mill.... just a thought... give me LED's
and LCD's any day... ! :-)
>
> Best Regards
> Hans W
>
>
>
> "deanc500 " wrote:
>
> > Hi, I just tried one of the suggestions on another group regarding
> > this subject. I was intrigued by the simplicity of the idea and
the
> > fellow mentioned that this is an old trick thats been around a
while.
> > You just need any small DC motor, a potentiometer, and a volt
meter.
> > The first potentiometer that I found in the junk drawer was a 50K
> > although other values will work. I hooked it up as in this
picture.
> >
> > http://www.members.shaw.ca/axxus4/cheaptach.jpg
> >
> > The motor is connected across the pot and the meter is connected
from
> > the center of the pot to one side. To calibrate, spin the motor
in the
> > chuck, and adjust the pot to read your known rpm (in mV or
whatever).
> > I was spinning it at 1460rpm in my mill drill. I adjusted the pot
to
> > read about 1.460V on the 20V scale. I walked over to the drill
press,
> > and spun the motor. I read 0.354V. I was amazed to see that the
drill
> > press was set to 360rpm. Very neat trick. I will use this method
to
> > measure servo and stepper rpm.
> >
> > Addresses:
> > FAQ: http://www.ktmarketing.com/faq.html
> > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> >
> > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@a...
> > Moderator: jmelson@a... timg@k... [Moderator]
> > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> >
> > 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.
> > http://www.metalworking.com/news_servers.html
> >
> > http://groups.yahoo.com/group/jobshophomeshop 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
http://docs.yahoo.com/info/terms/



________________________________________________________________________
________________________________________________________________________

Message: 3
Date: Mon, 06 Jan 2003 23:51:52 -0000
From: "deanc500 <deancouillard@...>" <deancouillard@...>
Subject: Re: Cheap tach - was r.p.m. kit??? / 4 digit under $20

Oh, I am not suggesting this as a replacement for a proper circuit and
readout, just thought I'd mention it for those odd times when you
could use some kind of a tach for whatever reason. I would use a
circut like yours if I needed a permanent display on a machine.
Dean


--- In CAD_CAM_EDM_DRO@yahoogroups.com, Hans Wedemeyer <xyz@h...> wrote:
> Yes it's a simple idea.... but nothing like looking at some digits
and not having
> to bother with coupling to a moving parts and the danger associated
with it.
> Fingers and eyes can be difficult to replace.... ! Now if you make
it a permanent fixture
> sure it's great...
> I'd say the idea has been around about 100+ years ! :-)
> The eddy current driven version has been around almost as long, in
most cars it known as the speedometer !
> If you goto a car junk yard you may even be able to find one of the
older eddy current version speedo's and
> adapt it directly to the mill.... just a thought... give me LED's
and LCD's any day... ! :-)
>
> Best Regards
> Hans W
>
>
>
> "deanc500 " wrote:
>
> > Hi, I just tried one of the suggestions on another group regarding
> > this subject. I was intrigued by the simplicity of the idea and the
> > fellow mentioned that this is an old trick thats been around a while.
> > You just need any small DC motor, a potentiometer, and a volt meter.
> > The first potentiometer that I found in the junk drawer was a 50K
> > although other values will work. I hooked it up as in this picture.
> >
> > http://www.members.shaw.ca/axxus4/cheaptach.jpg
> >
> > The motor is connected across the pot and the meter is connected from
> > the center of the pot to one side. To calibrate, spin the motor in the
> > chuck, and adjust the pot to read your known rpm (in mV or whatever).
> > I was spinning it at 1460rpm in my mill drill. I adjusted the pot to
> > read about 1.460V on the 20V scale. I walked over to the drill press,
> > and spun the motor. I read 0.354V. I was amazed to see that the drill
> > press was set to 360rpm. Very neat trick. I will use this method to
> > measure servo and stepper rpm.
> >
> > Addresses:
> > FAQ: http://www.ktmarketing.com/faq.html
> > FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> > Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> >
> > Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> > Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> > List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@a...
> > Moderator: jmelson@a... timg@k... [Moderator]
> > URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> >
> > 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.
> > http://www.metalworking.com/news_servers.html
> >
> > http://groups.yahoo.com/group/jobshophomeshop 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
http://docs.yahoo.com/info/terms/



________________________________________________________________________
________________________________________________________________________

Message: 4
Date: Tue, 07 Jan 2003 00:09:44 -0000
From: "turbulatordude <davemucha@...>" <davemucha@...>
Subject: Re: Math for constant speed ellipse (Again)

I have a desire to do an elsipse once I get the plasma cutter up, but
also thought about telescopes.

the telescope would track the celestial bodies for both the arc and
some declanation ?

In thinking about that application, seems steppeers might have too
much vibration, but anything would need to be geared way down to be
accurate.

I'm surprised that no one else brought this application up. maybe it
is just too far off topic ?

Dave





--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Fred Smith <imserv@v...>"
<imserv@v...> wrote:
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "jcc3inc <jccinc@o...>"
> <jccinc@o...> wrote:
> > Todd F:
> > My approach to making an ellipse was:
> > 1. Generate a circle with diameter = ellipse major diameter
> > 2. Since data is in X and Y registers, Multiply the Y register by
> > a number < 1.
> >
>
> JCC wrote:
>
> > I talked to Fred Smith, I M Service, asking about his CAD/CAM
> > capabilities and he said:
> > 1. You can use straight line approximations to generate the
ellipse
> > 2. You can use arc approximations
> > 3. Either form may be cutter compensated . Thus you may
accommodate
> > the cutter diameter speed effect for sharp radii also. Either of
> > these seems like a workable solution.
>
> Vector Cad 9.4 can also represent the ellipse as a single drawing
> entity, Nurbs curve. The Nurbs curve may also be offset to
compensate
> for the cutter radius, or interpolated as a linear approximation at
> the resolution of the target machine, or interpolated and arc fit
> also at the resolution of the CNC machine (or less if desired for
> more compact programs).
>
> The arc fitting and linear interpolations of ellipsis in Vector are
> at the drawing general accuracy, which is usually smaller
> (.0005mm/.00002in by default) than the least increment in a CNC
> machine (seldom less than .0001 except for wire EDM, cnc grinding,
or
> optical applications).
>
> Fred Smith - IMService



________________________________________________________________________
________________________________________________________________________

Message: 5
Date: Mon, 06 Jan 2003 16:54:54 -0800
From: Ron Yost <musik42@...>
Subject: Re: laptop ( was Re: HELP: Bipolar stepper ciruit

These are handy little kits .. great for experimentation. However,
they work only with unipolar motors. I believe the original
poster was looking for cheap bipolar drivers. :)

Ron Yost

At 05:33 PM 1/6/2003 +0000, you wrote:
>Al,
> The cheapest way to run a small stepper is with a kit from
>HTTP://www.qkits.com Look for their item QK109. This is complete
>with all components for US $15. It's based on a UCN5804b driver chip
>that is good for 1.25 Amp at up to 36 volts. There is an onboard 555
>pulse generator with control pot to allow continious running at
>variable speeds. The unit includes a single step push button switch,
>along with a slide switch for direction. Also included are 2
>configuration slide switches to allow setting for full, half, or wave
>stepping. The board has an onboard 7805 regulator and filtering to
>provide +5 volts to its logic section. (You may need to replace this
>with a "Low DropOut regulator to run on 6v battery)
>
>With simple mods you can run this with step/direction signals from a
>parallel port, or from a pic processor. I am us 5 of these to run
>NEMA 23 and 32 motors on a 5 axis milling gantry. A friend of mine
>uses one to run focus on about a 10 inch reflector scope. He uses a
>Pic 16F84 to provide step/direction signals. The F84 is also used to
>remember the home focus position for various eyepieces.
>
>Hope this helps.
>
>Bob Hinze




________________________________________________________________________
________________________________________________________________________

Message: 6
Date: Tue, 07 Jan 2003 01:04:20 -0000
From: "jdbunn2002 <jd_bunn@...>" <jd_bunn@...>
Subject: Lathe/Mill Purchase

Since I am a newbie at this and am learning the basics I need some
advice . Please give some advice on the follwing machines:

Harbor Freight 12" X 36" Lathe (item #33274) On sale for $1699
Mill Drilling Machine (item #42827)On sale for $999

Are these machines good for learning and give pretty good accuracy?
Would they convert to CNC pretty easy on down the road?
Anything else in this price range any better?

I don't know if this is off subject, but I have to start somewhere so
I can finally get on subject.

Any and all replys will be greatly appreciated.

Thanks

J. Bunn




________________________________________________________________________
________________________________________________________________________

Message: 7
Date: Mon, 6 Jan 2003 20:14:32 EST
From: wanliker@...
Subject: Off topic

The reason for the group is the conversion part, so try to bend more towards
how hard these machines are to convert, rather which is best. As to what is
best well everyone has opinions.
try to get hold of the latest issue of Home Shop Machinist, it is just
starting a series on converting a mill, will give you a much better idea of
what is involved.
bill
List Mom


________________________________________________________________________
________________________________________________________________________

Message: 8
Date: Tue, 07 Jan 2003 01:19:44 -0000
From: "bdrmachine <bdrmachine@...>" <bdrmachine@...>
Subject: Re: Lathe/Mill Purchase

Check out your local paper and used equipment dealers first. If you
have the room get a beefier used machine. More metal less chatter.
With more and more small shops closing or converting to cnc there
are Tons of used metal setting around. As a closing note: Knee-
mills will give you less setup problems in the long run. When you
move the head up and down on a drill/mill kiss your reference
goodbye.

Good luck
Brian

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "jdbunn2002 <jd_bunn@m...>"
<jd_bunn@m...> wrote:
> Since I am a newbie at this and am learning the basics I need some
> advice . Please give some advice on the follwing machines:
>
> Harbor Freight 12" X 36" Lathe (item #33274) On sale for $1699
> Mill Drilling Machine (item #42827)On sale for $999
>
> Are these machines good for learning and give pretty good accuracy?
> Would they convert to CNC pretty easy on down the road?
> Anything else in this price range any better?
>
> I don't know if this is off subject, but I have to start somewhere
so
> I can finally get on subject.
>
> Any and all replys will be greatly appreciated.
>
> Thanks
>
> J. Bunn



________________________________________________________________________
________________________________________________________________________

Message: 9
Date: Mon, 6 Jan 2003 17:24:36 -0800
From: "Owen Lloyd" <sportbikewest@...>
Subject: Re: Re: Lathe/Mill Purchase

Yes Knee mills are superior however, there are several simple ways to
prevent the loss of reference after you raise the head on your M/D. For
example, you can fasten the rack to the column so it will not rotate. You
WILL lose the ability to rotate the head around the column but in all the
years of using my M/D I've never need to [rotate the mill head.]
They offer a less expensive alternative to a full size knee mill, also if
space is a problem, such as in my situation, the M/D is better suited.
Owen


:>Knee- mills will give you less setup problems in the long run. When you
> move the head up and down on a drill/mill kiss your reference goodbye.
>
> Good luck
> Brian
>



________________________________________________________________________
________________________________________________________________________

Message: 10
Date: Mon, 6 Jan 2003 20:29:51 -0500
From: "Brian" <ka1bbg@...>
Subject: Re: Re: Math for constant speed ellipse (Again)

Hi, if you go to some of the ametuer astronomy sites you will find them
using all kinds of steppers to track stars for long photo shoots, and for
finding stars. one uses 2 boards with a hindge driven by steppers to find
stars with a computer..Have a look at my friends site
http://www.astronomyboy.com/ to see some stepper stuff. cul brian f.
----- Original Message -----
From: <davemucha@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, January 06, 2003 7:09 PM
Subject: [CAD_CAM_EDM_DRO] Re: Math for constant speed ellipse (Again)


> I have a desire to do an elsipse once I get the plasma cutter up, but
> also thought about telescopes.
>
> the telescope would track the celestial bodies for both the arc and
> some declanation ?
>
> In thinking about that application, seems steppeers might have too
> much vibration, but anything would need to be geared way down to be
> accurate.
>
> I'm surprised that no one else brought this application up. maybe it
> is just too far off topic ?
>
> Dave
>
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Fred Smith <imserv@v...>"
> <imserv@v...> wrote:
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "jcc3inc <jccinc@o...>"
> > <jccinc@o...> wrote:
> > > Todd F:
> > > My approach to making an ellipse was:
> > > 1. Generate a circle with diameter = ellipse major diameter
> > > 2. Since data is in X and Y registers, Multiply the Y register by
> > > a number < 1.
> > >
> >
> > JCC wrote:
> >
> > > I talked to Fred Smith, I M Service, asking about his CAD/CAM
> > > capabilities and he said:
> > > 1. You can use straight line approximations to generate the
> ellipse
> > > 2. You can use arc approximations
> > > 3. Either form may be cutter compensated . Thus you may
> accommodate
> > > the cutter diameter speed effect for sharp radii also. Either of
> > > these seems like a workable solution.
> >
> > Vector Cad 9.4 can also represent the ellipse as a single drawing
> > entity, Nurbs curve. The Nurbs curve may also be offset to
> compensate
> > for the cutter radius, or interpolated as a linear approximation at
> > the resolution of the target machine, or interpolated and arc fit
> > also at the resolution of the CNC machine (or less if desired for
> > more compact programs).
> >
> > The arc fitting and linear interpolations of ellipsis in Vector are
> > at the drawing general accuracy, which is usually smaller
> > (.0005mm/.00002in by default) than the least increment in a CNC
> > machine (seldom less than .0001 except for wire EDM, cnc grinding,
> or
> > optical applications).
> >
> > Fred Smith - IMService
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
> Moderator: jmelson@... timg@... [Moderator]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> 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.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop 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 http://docs.yahoo.com/info/terms/
>
>
>




________________________________________________________________________
________________________________________________________________________

Message: 11
Date: Mon, 6 Jan 2003 20:47:07 EST
From: JanRwl@...
Subject: Re: laptop ( was Re: HELP: Bipolar stepper ciruit

In a message dated 1/6/2003 8:42:55 AM Central Standard Time,
davemucha@... writes:


> Another thing about laptops is that people trash them when the batteries
> die. But in most any CNC operation,
> line voltage is available so battery operation is not critical to the
> operation.
>
AND, a ten-year old laptop running ONLY MSDOS is just fine! Windoze,
mousery, and color is NOT needed to make a 3- or even 4-axis CNC machine
make
megawhompers! (See in PHOTOS, "Home Brew...") I have a ten-year old Tandy
1500HD running a CNC lathe just fine! I had originally expected to run it
with an old '386 monochrome desktop "minitower", but the little laptop in
the
photo was donated by someone who felt the price of a new battery was not
justified (he was right!). Ah, experience! It does have its uses, it does!
Jan Rowland



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



________________________________________________________________________
________________________________________________________________________

Message: 12
Date: Tue, 7 Jan 2003 01:48:17 +0000 (GMT Standard Time)
From: "al" <101@...>
Subject: Re: laptop ( was Re: HELP: Bipolar stepper ciruit

Thank you for your replies yes it is a bipolar and only a 4 wire :(
greatful for your comments. al

-------Original Message-------

From: CAD_CAM_EDM_DRO@yahoogroups.com
Date: 07 January 2003 00:55:15
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] laptop ( was Re: HELP: Bipolar stepper ciruit

These are handy little kits .. great for experimentation. However,
they work only with unipolar motors. I believe the original
poster was looking for cheap bipolar drivers. :)

Ron Yost

At 05:33 PM 1/6/2003 +0000, you wrote:
>Al,
> The cheapest way to run a small stepper is with a kit from
>HTTP://www.qkits.com Look for their item QK109. This is complete
>with all components for US $15. It's based on a UCN5804b driver chip
>that is good for 1.25 Amp at up to 36 volts. There is an onboard 555
>pulse generator with control pot to allow continious running at
>variable speeds. The unit includes a single step push button switch,
>along with a slide switch for direction. Also included are 2
>configuration slide switches to allow setting for full, half, or wave
>stepping. The board has an onboard 7805 regulator and filtering to
>provide +5 volts to its logic section. (You may need to replace this
>with a "Low DropOut regulator to run on 6v battery)
>
>With simple mods you can run this with step/direction signals from a
>parallel port, or from a pic processor. I am us 5 of these to run
>NEMA 23 and 32 motors on a 5 axis milling gantry. A friend of mine
>uses one to run focus on about a 10 inch reflector scope. He uses a
>Pic 16F84 to provide step/direction signals. The F84 is also used to
>remember the home focus position for various eyepieces.
>
>Hope this helps.
>
>Bob Hinze



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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.
http://www.metalworking.com/news_servers.html

http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister
site to the CCED group, as many of the same members are there, for OT
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NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON
T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
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Message: 13
Date: Mon, 6 Jan 2003 20:50:47 -0500
From: Paul Amaranth <paul@...>
Subject: Re: Cheap tach - was r.p.m. kit??? / 4 digit under $20

I've been thinking on and off about adding a digital readout to my bandsaw
to
read blade speed in fpm (it's a varispeed DoAll). This would be the
easiest:
just run a motor with a small rubber wheel against one of the band wheels,
use
a pot for calibration and run it to one of those cheap 2V LCD or LED
voltmeters.
Worst case would be to add an op-amp amplifier.

Very cool (and much easier than the PIC solution I was leaning toward).
Sometimes
low-tech is the answer.

Paul

> > Hi, I just tried one of the suggestions on another group regarding
> > this subject. I was intrigued by the simplicity of the idea and the
> > fellow mentioned that this is an old trick thats been around a while.
> > You just need any small DC motor, a potentiometer, and a volt meter.
> > The first potentiometer that I found in the junk drawer was a 50K
> > although other values will work. I hooked it up as in this picture.
> >
> > http://www.members.shaw.ca/axxus4/cheaptach.jpg
> >
> > The motor is connected across the pot and the meter is connected from
> > the center of the pot to one side. To calibrate, spin the motor in the
> > chuck, and adjust the pot to read your known rpm (in mV or whatever).
> > I was spinning it at 1460rpm in my mill drill. I adjusted the pot to
> > read about 1.460V on the 20V scale. I walked over to the drill press,
> > and spun the motor. I read 0.354V. I was amazed to see that the drill
> > press was set to 360rpm. Very neat trick. I will use this method to
> > measure servo and stepper rpm.
> >

--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows



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Message: 14
Date: Mon, 6 Jan 2003 20:50:49 EST
From: JanRwl@...
Subject: Re: laptop ( was Re: HELP: Bipolar stepper ciruit

In a message dated 1/6/2003 8:57:37 AM Central Standard Time, 101@...
writes:


> . . . and i could do with a laptop for another project also . . .
>

Simply do a SEARCH on E-bay for "Notebook" or "Laptop". THOUSANDS of those
in every age and condition for every price-range!


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Message: 15
Date: Mon, 6 Jan 2003 21:00:35 EST
From: JanRwl@...
Subject: Re: Motor cable

In a message dated 1/6/2003 1:16:42 PM Central Standard Time,
hickspj467@... writes:


> Any suggestions for a more flexible cable and where to get it? I would
like
> to get enough and of a suitable size that I can use it on my BP size
> mill/drill later on. I will probably use steppers on it also.
>

PJ: If you find a cable flexible enough for your Sherline, it will surely
be
too small a gauge for the Size-42 steppers you will have on the BP!

I don't have a Sherline, but I IMAGINE all you need the flexible cable for
is
the X motor (on the saddle). Ever consider MAKING a 1' length of
4-C/shielded yourself? Just find some highly-stranded #20, some
adequately-large "mic-cable shield", do some jiggery, and you have it!


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Message: 16
Date: Tue, 7 Jan 2003 02:02:32 -0000
From: "James Owens" <wotisname@...>
Subject: Re: laptop ( was Re: HELP: Bipolar stepper ciruit

Hi Jan,

What software are you using on your clockwork puter?

Regards,

Terry



> Another thing about laptops is that people trash them when the batteries
> die. But in most any CNC operation,
> line voltage is available so battery operation is not critical to the
> operation.
>
AND, a ten-year old laptop running ONLY MSDOS is just fine! Windoze,
mousery, and color is NOT needed to make a 3- or even 4-axis CNC machine
make
megawhompers! (See in PHOTOS, "Home Brew...") I have a ten-year old
Tandy
1500HD running a CNC lathe just fine! I had originally expected to run it
with an old '386 monochrome desktop "minitower", but the little laptop in
the
photo was donated by someone who felt the price of a new battery was not
justified (he was right!). Ah, experience! It does have its uses, it
does!
Jan Rowland



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Message: 17
Date: Tue, 07 Jan 2003 02:25:36 -0000
From: "turbulatordude <davemucha@...>" <davemucha@...>
Subject: EDM capacitors and voltage

Hi all,

I'm still working on the EDM project and have to make a decision on
which way to go.

From what I have read, the work performed is measure in joules. the
higher the joules, the faster the work.

If I go low voltage, I need a higher capacity cap(s) Using the
formula from the Build an EDM, it is
work(joules)=0.5 x capacitance X ((voltage)^2)

That said, a 700uF cap at 85 volts is roughly the same as a 100uF at
311 volts. (220 x 1.414 = 311)

Seems decent caps of high ratings are hard to find. a Motor run
capacitor is easy to find, are rated in high voltages, should work
but are limited to about 50uF in capacities.

If anyone knows of a good source for caps, please let me know.
McMaster Carr offers poly-metalized motor run caps for around $19.00
per 50uf@370V. stock # 7602K38

Have I got this right ? am I on the right track ? does higher
voltage create any problems ? I'm hoping to avoid some shocking
discoveries.

I know all the good talk radio is AM thses days, but, I'll not mind
if I just create some static.

And in response to the recent request from our fearless leader, I'll
offer some thanks in advance to save the bandwidth later on.

Thanks in advance !

Dave




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Message: 18
Date: Mon, 6 Jan 2003 22:13:54 EST
From: wanliker@...
Subject: LETS PULL THIS BACK TO THE LIST TOPICS..Re: Math for constant speed
ellipse

In a message dated 1/6/2003 6:30:15 PM Mountain Standard Time,
ka1bbg@... writes:


> http://www.astronomyboy.com/

I like astronomy also, but it is OFF Topic for this group. Lets all be
reminded that this group if for the making of, not the using of CNC goodies.

for the new comers, this list is restricted to 4 subjects only as outlined
at
the YAHOO site, if you have questions, PLEASE contac Tim or myslef off the
list.
Thanks,
bill
list Mom


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



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Message: 19
Date: Mon, 6 Jan 2003 22:53:11 -0500
From: "Todd Fleming" <todd@...>
Subject: RE: Math for constant speed ellipse

> I think I have some bad news if you expect to get f(t) in open
> algebraic form. The total circumference of an ellipse cannot be
> calculated in algebraic form because it involves the Elliptic
> integral of the second kind [E(k, phi) where k is related to the
> eccentricity and phi is the angle about the center of the ellipse],
> which can only be evaluated using an infinite series (or a suitable
> initial subset of terms giving sufficient accuracy) or by table lookup.

Eeek, I had no idea.

> I therefore find it doubtful that the length of a segment of an
> ellipse could be represented in open form, and the same goes for
> anything involving the speed of motion along an ellipse.

Sounds reasonable given the above. :(

> Doesn't mean it is impossible though, just unlikely.
> -Kevin Martin

Out of curiousity, is this related to eliptic cryptography? If so, then a
solution to my problem might be bad news to security people.

Todd Fleming



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Message: 20
Date: Mon, 6 Jan 2003 20:44:43 -0600
From: "Raymond Heckert" <jnr@...>
Subject: Re: Lathe/Mill Purchase

My free advice (and since it costs nothing, is worth no
more than that): look for some good used equipment. Take
out an ad in a local 'shopper' magazine, or talk to the
instructor at the local Tech School. Maybe, sign up for
some classes at the Tech. Or, call some local business that
use that kind of equipment, and ask the shop foreman, (or
someone else in that capacity) for the name of a reputable,
local Used Equip't Dealer. Almost anybody willing to sell
you used equip't will turn a 'test bar' (in the case of a
lathe), or machine a test piece (in the case of a milling
machine). You may also get some helpful tips, etc. That
being said, I have not have had any 'really bad' problems
with HFS. I also have had some good experience with ENCO.
You'll get pretty much what you pay for. Best of Luck,
and keep us posted! As for CNC conversion (that puts you
'on-topic'), again, it's more of "you get what you pay
for". If you don't replace the leadscrews with ballscrews,
you usually have sloppy backlash to deal with. If the
machine, itself, is not rigid enough you'll get
inconsistent parts, even with CNC.

RayHex

----------
> From: jdbunn2002 <jd_bunn@...>
>
> Harbor Freight 12" X 36" Lathe (item #33274) On sale for
$1699
> Mill Drilling Machine (item #42827)On sale for $999
>
> Are these machines good for learning and give pretty good
accuracy?
> Would they convert to CNC pretty easy on down the road?
> Anything else in this price range any better?
>



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Message: 21
Date: Mon, 6 Jan 2003 21:47:20 -0600
From: "Raymond Heckert" <jnr@...>
Subject: Re: Bridgeport V2XT / DX-32 ???

In some recent post (I think it was on 'jobshophomeshop',
or Kepler's 'ml') someone alluded to the fact that some
'big-name' company (maybe it was Hardinge) had bought the
U.S. assets of Bridgeport, and would continue to support
the spare parts end of the business, as well. This would be
a very lucrative business to get into, since those machines
just don't seem to die! Sorry if this is OT, Mom, but the
initial question was rather 'on-topic'.

RayHex

----------
> From: Matt Shaver <mshaver@...>
>
***** someone else posted:
snip
> > With BP out of bussiness will repair parts be
available?
snip


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Message: 22
Date: Mon, 6 Jan 2003 23:15:04 -0800
From: "Carol & Jerry Jankura" <jerry.jankura@...>
Subject: RE: Motor cable

Has anyone used 'test probe wire' for their cabling? Years ago, Belden used
to produce a wire with a rubber type insulation that consisted of several
strands of high gage wire. The stuff was extremely flexible. A cable build
from four of these wires could be used for the X axis of a Sherline mill.

-- Jerry

> I don't have a Sherline, but I IMAGINE all you need the flexible
> cable for is
> the X motor (on the saddle). Ever consider MAKING a 1' length of
> 4-C/shielded yourself? Just find some highly-stranded #20, some
> adequately-large "mic-cable shield", do some jiggery, and you have it!




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Message: 23
Date: Mon, 6 Jan 2003 23:16:30 -0500
From: "Todd Fleming" <todd@...>
Subject: Re: Re: Math for constant speed ellipse

> Todd,
>
> I took a crack at your problem because it is interesting. I'm not
> much of a mathematician so I analyzed it graphically using my trusty
> TI calculator. I think I have a possible solution.
>
> (1) Draw an ellipse whose X-axis dimension is 5 times the Y-axis. No
> special reason for 5, I just needed to pick a number.
>
> x = sqrt ( 25 - 25*y^2) would define the ellipse. (EQ 1)
>
> (2) Inscribe a circle with a raduis of 1 inside the ellipse. Sweep a
> projected radius at a constant angular rate (I picked 9 degrees with
> an initial offset of 4.5 degrees).
>
> (3) Take the sine for each increment. That will give you the value
> for "y", which you plug into EQ 1 to get the corresponding "x" on
> the elipse.

x = sqrt ( 25 - 25 * sin^2(theta) )

> (4) Calculate the segment lengths between each pair of x,y co-
> ordinates. First conclusion: The segment length (thus velocity)
> around x=0 is 5 times the velocity around y=0 for a constant angular
> rate. From this one can conclude that the angular rate around y=0
> should be 1/5 the rate around x=0. What is the relationship f(x) for
> this 5:1 range in velocity?

Ok. I plotted the segment lengths in Excel. The result is a non-linear
sawtooth.

> (5) Sum the segment lengths. Normalize the results by dividing the
> lengths by 5. Subtract each from "1". The resulting table now looks
> suspiciously like a sine table for every 9 degrees. It is in fact.

Maybe I'm not following correctly. The graph of this also looks like a non-
linear sawtooth.

> (6) Fooling with the calculator suggests the angular velocity for a
> constant path velocity should be:
>
> The relationship seems to be x/y -(x/y -1)*cos theta over the span
> of +/- pi/2. The result must range between 1 to 5 from +/- pi/4 and
> is the multiplier for "delta" summed to "theta" angle that sets the
> path velocity.

By x/y, do you mean the width of the ellipse divided by its height?

> Mariss
>
> None of (6) has been carefully checked.

Todd Fleming
flemingcnc.com



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Message: 24
Date: Mon, 6 Jan 2003 23:34:10 -0500
From: "Todd Fleming" <todd@...>
Subject: Re: Math for constant speed ellipse

> I suppose you want constant speed so that you chew up your workpiece
> at a constant volume per unit time. However there are at least four
> other factors that you might want to think about as you choose a
> speed. These should only be a concern when the ellipse is very long
> and skinny.
>
> - If you are milling around the outside of the ellipse, then you
> will be chewing up a higher volume per time of material as you go
> around the end than when going along the sides, if you go at a
> constant speed along the ellipse that you are milling.

Interesting; can you explain why this is so? Better yet, do you know of an
approach that will chew the same volume of material per unit time? This
would be much better.

> - If the center of your tool is tracing the ellipse, or if you are milling
> the inside of the ellipse, and the tool width is a substantial
> fraction of the minor axis of the ellipse, then as you come away
> from the corner of the ellipse, you'll be cutting less volume per
> time because some material has already been removed. (For a proper
> inside cut, check that your tool radius is smaller than the radius
> of curvature of the ellipse at the ends!)

I have the same questions as above. I do see the problem that occurs that
you noted in parentheses.

> - Even if you move at constant speed, the acceleration is not
> constant - it peaks at the ends of the ellipse.

Yep. This I understand.

> - If your step size of theta is too large, you will have flat, polygonal
> sides on the ellipse at the ends.

I'm trying for direct elliptical interpolation; the sides of polygon will be
at most sqrt(2 * d), where d is the step size (or micro-step size) of the
machine. I'm starting to realize this may be impossible for a constant
speed. It worked out quite nicely for quadratics though; see my paper at
http://www.flemingcnc.com/ .

> At any rate, since whatever calculus and DE brain cells I may have
> had have mostly died, I would look for a less math-intensive
> approach to the problem: pick an approximate step size for theta,
> calculate the new x,y position that you are headed for, calculate
> the distance from where you are now to over there, and if the
> distance is too far (i.e you are trying to go too fast), just move
> an appropriate fraction of that distance, or if you have time (the
> processor is fast enough), interpolate another value of theta and
> head for that point. Or slow down the clock so the machine takes
> the appropriate amount of time to get there.
>
> BETTER YET!! Look up Breshenham's Algorithm on the net or in a computer
> graphics book. It's how graphics hardware draws straight lines into

I'm using Breshenham's Algorithm for quadratic interpolation. This provides
super-smooth accelleration.

> graphics memory, or controls an XY display. It's probably used in
robotics
> as well. The idea is that if you are drawing a straight line whose
> slope is between -1 and 1, you go to the starting point, then take
> one-pixel steps in the x axis. At each step you decide whether to
> keep the same y value, or step up or down one pixel. This can be
> done with just an addition and a comparison at each step - no
> multiplication or division needed! On the other hand, if the line
> has a steeper slope than +-1, you step one pixel at a time in the y
> direction and decide at each step whether to move the x position.
>
> Breshenham's algorithm can be adapted to draw circles - very nice,
> round, smooth-looking ones, better than you can get by calculating
> points along the circle with sines and cosines. As I recall (from
> implementing it once, long ago) it takes some preliminary
> calculations to find where the circle has slopes of +-1. While
> plotting the points, you only need about one multiplication, one or
> two additions, and a comparison at each step. No trig or square
> roots needed during plotting. It's very fast!

Do you know off-hand how much variation in speed Breshenham's approach will
produce when applied to circles?

> Apparently the algorithm can be adapted to work with any conic section
> (ellipses, parabolas, hyperbolas), but I haven't gotten involved in the
> details.

cool!

> Enjoy!
> - Jan

Todd Fleming
flemingcnc.com



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Message: 25
Date: Mon, 6 Jan 2003 23:45:38 -0500
From: "Todd Fleming" <todd@...>
Subject: Re: Math for constant speed ellipse

> will be at most sqrt(2 * d), where d is the step size (or micro-step

Oops, that should be sqrt(2) * d.

Todd Fleming
flemingcnc.com



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