Re: CAM in polar format

Jay

There are some polar coordinate computation routines in the about to be
released emc backplotter 2.0.0. They are incremental and are used to plot
the A,B,C axis and the 3D view. Paul Corner wrote them in Tcl.

EMC Backplot only runs on emc but you might be able to extract the routines
and use them. Let me know if you want to try it.

Ray

>Message: 1 [CAD_CAM_EDM_DRO] Digest Number 363
> Date: Mon, 14 Feb 2000 08:54:27 -0500
> From: "Fred Smith" <imserv@...>
>Subject: Re: CAM in Polar format
>
>
>> From: Jay Hayes <xmas4lites@...>
>>
>> I need to convert a simple 2D .dxf CAD drawing of a tool path to a
>> machine code in a Polar format, of the Vector distance and relative
>> angular Direction. I can manually write the code or manually extrapolate
>> the information from the verification functions in Bobcad, but i'm
>> looking to generate a post processed code automatically.
>>
>
>Tell us a little more Jay. It's not clear if you want to actually program
>in Polar coordinates, meaning R-Theta type annotation, or something else.
>What are you trying to program, what machine/control, are you sure you want
>Relative angular direction or Absolute? What is your orientation to the
>axes? Bobcad 17 has some very limited rotary translation capabilities and
>may be able to get the answers you need.
>
>
>Best Regards,
>
>Fred Smith
>IMService
>
>imserv@...
>Phone: 248-486-3600 or 800-386-1670
>Fax:248-486-3698
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 2
> Date: Mon, 14 Feb 2000 08:56:40 -0500
> From: Joe Vicars <jvicars@...>
>Subject: Display problems with old laptops
>
> I am in the process of trying to pick a software controller. I
>downloaded all the demos I could find, but was dissapointed when I
>couldn't get DeskNC up on my older 486/386 laptops.
> Does anyone know how to make DeskNC VGA compatible?
> I read alot about CNCpro on here as well, how do they compare? The
>problem is that I can't hardly get Mr. Yeager's demo configured before
>it times out on me. It's really hard to tell how it's going to work.
> Any help?
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 3
> Date: Mon, 14 Feb 2000 08:19:43 -0600
> From: hansw <hansw@...>
>Subject: Re: Display problems with old laptops
>
>Joe,
>
>Joe Vicars wrote:
>
>> problem is that I can't hardly get Mr. Yeager's demo configured before
>> it times out on me. It's really hard to tell how it's going to work.
>>
>
>I agree Doug could have made the demo a little more friendly, and perhaps

more people would buy it ( hint ! I hope Doug is is

>reading this)
>
>I seem to remembering trying DeskNC (I think) at the time I still had the

crappie MAXNC controller and the configuration menu

>was
>screwed up, it never worked for me.
>
>That's when I decided to go Step/Direction and ended up buying CNCPro

because the was the easiest interface ti handle.

>
>Hans Wedemeyer
>
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 4
> Date: Mon, 14 Feb 2000 08:32:26 -0700
> From: Roger Brower <rbrower@...>
>Subject: Re: CNCPro
>
>Jon Anderson Wrote:
>Snip...radius comp at that time wasn't
>as high on the list...
>
>Yeah, I'd love to have radius
>compensation in the controller, but
>that's apparently pretty hard to do,
>programming wise, with the lookahead
>function and all.
>I could be to blame! I probably told
>Doug I'd do that in the CAM step; Ahha
>has it? Does EMC do radius comp?
>reliably? Anybody know how to program
>it? If we can give Doug something
>useful, I suspect he'd try to use it.
>
>hansw wrote: Snip... home to opto
>switches or promity detectors, not
>Mechanical switches>
>I measured <.003 per axis, havent
>measured since. I'm changing the
>workpiece every time anyway.
>
>Adding a line editor to CNCPro should be
>simple; same to shell out to dos for
>file transfers;
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 5
> Date: Mon, 14 Feb 2000 10:58:26 -0500
> From: Joe Vicars <jvicars@...>
>Subject: encoders from servos?
>
>What is a quadrature encoder and how do I know if I have one?
>I have a bunch of old servos and want to take the encoders off to make
>Lindsay's DRO. Are these the encoders I need?
>
>
>
>___________________________________________________________________________

____

>___________________________________________________________________________

____

>
>Message: 6
> Date: Mon, 14 Feb 2000 11:07:04 -500
> From: daveland@...
>Subject: sis 530 Chipset MB
>
>Darrel
>
>I have had several SIS 530 Motherboards. All have worked
>out great.
>
> But to get Xwindows working really well you need
>the latest version of Xfee86 3.3.3.5 (I think). I downladed
>it from redhat as RPM's ( 5-6MB). I can get the URL tonight when I get back
>home. It was not easy to find. I can also email the xf86config file for my

machine

>that is running this server. But It was a pretty simple setup using the

xconfigurator.

> I'll
>post and email late tonight.
>
>older versions can be fooled into working, but it isn't worth
>the time.
>
>
>dave
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 7
> Date: Mon, 14 Feb 2000 08:07:24 -0800
> From: Jon Anderson <janders@...>
>Subject: Re: Re: CNCPro
>
>Roger,
>
>Yes, Ah-ha does radius comp. I can believe it can be problematic to
>program.
>I got up to the MaxNC version that had radius comp, and it often made
>some really
>strange moves while calling an offset.
>My dad machines some highly abrasive stuff for a customer, on a Sherline
>I CNC'd
>for him. Radius comp is a must, to account for cutter wear and maintain
>tolerances.
>It's way too much of a pain generating 4-6 seperate G-code files with
>differing offset
>tool paths, then keeping track of them all.
>I'd have liked to try his program, but I do understand where he's coming
>from.
>Lots of folks window shop and never buy, he's concentrating on
>supporting those
>that support him. That means he'll inplement radius comp sooner if
>CNCPro users
>start asking for it, over non-users.
>
>Jon
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 8
> Date: Mon, 14 Feb 2000 11:47:07 EST
> From: WAnliker@...
>Subject: Re: Re: CNCPro
>
>In a message dated 2/14/00 9:15:14 AM Mountain Standard Time,
>janders@... writes:
>
><< That means he'll inplement radius comp sooner if
> CNCPro users
> start asking for it, over non-users.
> >>
>
>But a lot of no-users will stay that way, until the program has radius
>compensation.
>The way to sell more programs is to have the features that will fill
>non-users needs, then they will buy. Why would a non-user buy on the hopes
>that someday the author MIGHT add the desired features?
>bill
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 9
> Date: Mon, 14 Feb 2000 11:54:58 -0600
> From: Dan Falck <dfalck@...>
>Subject: Re: Re: CNCPro
>
>EMC has cutter comping.
>
>Dan
>
>
>
>At 09:32 AM 2/14/2000 , you wrote:
>>From: Roger Brower <rbrower@...>
>>
>>Jon Anderson Wrote:
>>Snip...radius comp at that time wasn't
>>as high on the list...
>>
>>Yeah, I'd love to have radius
>>compensation in the controller, but
>>that's apparently pretty hard to do,
>>programming wise, with the lookahead
>>function and all.
>>I could be to blame! I probably told
>>Doug I'd do that in the CAM step; Ahha
>>has it? Does EMC do radius comp?
>>reliably? Anybody know how to program
>>it? If we can give Doug something
>>useful, I suspect he'd try to use it.
>>
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 10
> Date: Mon, 14 Feb 2000 13:13:02 -0500
> From: Jay Hayes <xmas4lites@...>
>Subject: Re: CAM in Polar format
>
>Fred, what I'm trying to do is take a CAD drawing and create code that

will output the length of the vector to one axis and the

>relitive change in angle between that vector and the next vector in the

chain to the second axis. Both axis will definately be

>incrimental moves.
>
>Jay Hayes
>Weston,WV
>
>Fred Smith wrote:
>
>> From: "Fred Smith" <imserv@...>
>>
>> > From: Jay Hayes <xmas4lites@...>
>> >
>> > I need to convert a simple 2D .dxf CAD drawing of a tool path to a
>> > machine code in a Polar format, of the Vector distance and relative
>> > angular Direction. I can manually write the code or manually extrapolate
>> > the information from the verification functions in Bobcad, but i'm
>> > looking to generate a post processed code automatically.
>> >
>>
>> Tell us a little more Jay. It's not clear if you want to actually program
>> in Polar coordinates, meaning R-Theta type annotation, or something else.
>> What are you trying to program, what machine/control, are you sure you want
>> Relative angular direction or Absolute? What is your orientation to the
>> axes? Bobcad 17 has some very limited rotary translation capabilities and
>> may be able to get the answers you need.
>>
>> Best Regards,
>>
>> Fred Smith
>> IMService
>>
>> imserv@...
>> Phone: 248-486-3600 or 800-386-1670
>> Fax:248-486-3698
>>
>> --------------------------- ONElist Sponsor ----------------------------
>>
>> GET A NEXTCARD VISA, in 30 seconds. Get rates as low as 2.9 percent
>> Intro or 9.9 percent Fixed APR and no hidden fees. Apply NOW.
>> <a href=" http://clickme.onelist.com/ad/NextcardCreative4SR ">Click

Here</a>

>>
>> ------------------------------------------------------------------------
>>
>> Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the

discussion of shop built systems in the above catagories.

>> To Unsubscribe, read archives, change to or from digest.
>> Go to: http://www.onelist.com/isregistered.cgi
>> Log on, and you will go to Member Center, and you can make changes there.
>> For the FAQ, go to http://www.ktmarketing.com/faq.html
>> bill,
>> List Manager
>
>
>
>
>
>___________________________________________________________________________

____

>___________________________________________________________________________

____

>
>Message: 11
> Date: Mon, 14 Feb 2000 10:16:09 -0800
> From: Jon Anderson <janders@...>
>Subject: Re: Re: CNCPro
>
>Bill,
>
>You might have missed an earlier comment of mine. I asked Doug about
>radius comp, saying neither my dad nor I would buy a program that
>didn't have it, and wanted to know when it might be implemented.
>His response was that he was concerned first with supporting existing
>customers and their wants before spending resources adding features
>for folks that hadn't bought the program. Radius comp at that time
>wasn't
>very close to the top. It was on the list at that time however.
>I agree with you entirely regarding the added desireability of a greater
>feature set. My point is that since he places more weight
>on input from paid users, that's where the most effect pressure would
>originate.
>
>Jon
>
>
>WAnliker@... wrote:
>
>> But a lot of no-users will stay that way, until the program has radius
>> compensation.
>> The way to sell more programs is to have the features that will fill
>> non-users needs, then they will buy. Why would a non-user buy on the hopes
>> that someday the author MIGHT add the desired features?
>
>
>___________________________________________________________________________

____

>___________________________________________________________________________

____

>
>Message: 12
> Date: Mon, 14 Feb 2000 12:40:53 -0600
> From: Jon Elson <jmelson@...>
>Subject: Re: Re: CNCPro
>
>
>
>Roger Brower wrote:
>
>> From: Roger Brower <rbrower@...>
>>
>> Jon Anderson Wrote:
>> Snip...radius comp at that time wasn't
>> as high on the list...
>>
>> Yeah, I'd love to have radius
>> compensation in the controller, but
>> that's apparently pretty hard to do,
>> programming wise, with the lookahead
>> function and all.
>> I could be to blame! I probably told
>> Doug I'd do that in the CAM step; Ahha
>> has it? Does EMC do radius comp?
>> reliably?
>
>Absolutely! It works in all movement modes except G00, which
>sort of makes sense. So, you can do linear, arc and helical
>moves with radius comp. I have never had any trouble with
>the radius comp, except getting the lead-in move to not
>get a squawk about concave corners. This is a problem with
>the way radius comp works, and I went through the same
>trouble with the Allen-Bradley control I started with. EMC
>is a bit more sensitive about these concave corners, but that
>is not really EMC's fault. The 'backplotter' (on screen preview
>of programmed moves) makes this a LOT easier and faster
>to debug. I pretty much have this down solid, now. I did
>some parts with radius comp this weekend, and it worked
>flawlessly. I often use it so that I can use the same program
>to make roughing cuts (with the tool diameter defined in the
>tool table to be larger than the actual tool) and then make
>a finishing cut with the tool table set to the actual tool size.
>
>> Anybody know how to program
>> it? If we can give Doug something
>> useful, I suspect he'd try to use it.
>
>Combining radius comp with alternating linear and arc cuts
>and lookahead sounds pretty tough to me. I think I'd want
>to spend a week at the blackboard with a colleague to bounce
>all the possible cases off of before saying anything with
>confidence.
>
>>
>> hansw wrote: Snip... home to opto
>> switches or promity detectors, not
>> Mechanical switches>
>> I measured <.003 per axis, havent
>> measured since.
>
>When using home switches with shaft encoders that have the
>index signal, the home switch just gets you to the right rotation
>of the encoder, the index pulse sets the actual home position,
>generally to one specific encoder count.
>
>Jon
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 13
> Date: Mon, 14 Feb 2000 12:44:48 -0600
> From: Jon Elson <jmelson@...>
>Subject: Re: encoders from servos?
>
>
>
>Joe Vicars wrote:
>
>> From: Joe Vicars <jvicars@...>
>>
>> What is a quadrature encoder and how do I know if I have one?
>> I have a bunch of old servos and want to take the encoders off to make
>>
>> Lindsay's DRO. Are these the encoders I need?
>
>If they are optical shaft encoders on servo motors, then they most
>likely are
>quadrature. Optical shaft encoders generally produce two signals with a
>
>90 degree phase relationship, so you can tell not only distance
>traveled, but
>direction as well. Many have a 3rd channel which produces one pulse per
>
>revolution, called the index pulse. For a servo motor application for
>rotation
>in only one direction, there might be only one pulse output signal.
>
>Other position readout types are rotary inductosyn and resolver. These
>generally require interpolation to produce sufficient resolution for
>machine
>controls.
>
>Jon
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 14
> Date: Mon, 14 Feb 2000 14:40:16 -0500
> From: Brian Bartholomew <bb@...>
>Subject: Re: BDI install disk for EMC -evidence that a braindead install

already exists

>
>Patrick, please re-read the actual terms I proposed in my previous
>postings. My offer was carefully designed NOT to have the obnoxious
>properties you describe below. Your critique is responding to an
>offer I didn't make.
>
>
>A member of the League for Programming Freedom (LPF) http://lpf.ai.mit.edu
>---------------------------------------------------------------------------

----

>Brian Bartholomew - bb@... - www.wv.com - Working Version, Cambridge, MA
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 15
> Date: Mon, 14 Feb 2000 12:16:45 -0800
> From: "Darrell" <dgehlsen@...>
>Subject: Re: Re: CNCPro
>
>> Roger,
>>
>> Yes, Ah-ha does radius comp. I can believe it can be problematic to
>> program.
>
>AHHA has been doing Both diameter and tool lenght allowing either G43 or G44
>for length. It works very well.
>Darrell
>
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 16
> Date: Mon, 14 Feb 2000 12:24:30 -0800
> From: "Darrell" <dgehlsen@...>
>Subject: Re: Re: CNCPro
>
>>> Does EMC do radius comp?
>> > reliably?
>>
>> Absolutely! It works in all movement modes except G00, which
>> sort of makes sense.
>
>Do you mean that if you turn on say G41 with a G00 move that you then have
>to do a feed move before the tool is properly offset?
>With AHHA, the tool is offset with a G00 G41 X Y move so you are ready to
>plunge.
>Darrell
>
>
>
>
>___________________________________________________________________________

____

>___________________________________________________________________________

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>
>Message: 17
> Date: Mon, 14 Feb 2000 16:26:24 EST
> From: WAnliker@...
>Subject: Re: Re: CNCPro
>
>In a message dated 2/14/00 11:23:30 AM Mountain Standard Time,
>janders@... writes:
>
><< I agree with you entirely regarding the added desirability of a greater
> feature set. My point is that since he places more weight
> on input from paid users, that's where the most effect pressure would
> originate. >>
>
>
>
>And this is why I made my comments, you would never go and buy a car with

the

>hopes that as an owner that you could lean on the manufacturer to include

air

>conditioning in the next model. The way to increase value is to add

features

>and get new buyers, they will furnish the new money needed to pay for the
>design times.
>I am still looking for a program to cut my teeth on, but with a retirement
>income, want as much as I can get for the dollars spent. Unfortunately
>Linux/EMC, has a bit more learning curve just trying to get it up and

running

>than I am able to handle with no programming experience. Linux, can

probably

>become a very great operating system, but not until it can be put into
>operation, with a lot more ease than it is now able to, at least for an
>individual that does not program.
>thanks for your comments,
>bill
>
>
>___________________________________________________________________________

____

>___________________________________________________________________________

____

>
>Message: 18
> Date: Mon, 14 Feb 2000 16:31:12 -0600
> From: Jon Elson <jmelson@...>
>Subject: Re: Re: CNCPro
>
>
>
>Darrell wrote:
>
>> From: "Darrell" <dgehlsen@...>
>>
>> >> Does EMC do radius comp?
>> > > reliably?
>> >
>> > Absolutely! It works in all movement modes except G00, which
>> > sort of makes sense.
>>
>> Do you mean that if you turn on say G41 with a G00 move that you then
>> have
>> to do a feed move before the tool is properly offset?
>> With AHHA, the tool is offset with a G00 G41 X Y move so you are ready
>> to
>> plunge.
>
>No, I ran into this just this weekend. You get an error message that
>says
>rapid moves are not permitted with cutter diameter compensation active,
>or
>something of that nature. Not a big deal, you generally wouldn't want
>to do
>rapid feeds with diameter comp on, anyway. I hit the error because I
>had a
>G00 by accident as the move where the diameter comp was to be
>interpolated
>in. The first move when diameter comp is activated interpolates the
>compensation
>in gradually over the length of the move. My Allen-Bradley CNC did the
>same,
>so I think that is the normal mode.
>
>I generally plunge to depth BEFORE I activate the diameter comp, so that
>the
>tool plunges when NOT in contact with the work.
>
>This is totally different behavior than how the tool length offset works
>(that's
>G43, I think). With the length offset, it just fully activates the
>offset immediately
>on the first Z move.
>
>Jon
>
>
>
>___________________________________________________________________________

____

>___________________________________________________________________________

____

>
>Message: 19
> Date: Mon, 14 Feb 2000 16:14:44 -0600
> From: hansw <hansw@...>
>Subject: Re: Re: CNCPro
>
>Bill,
>Well said.
>
>The main complaint I have heard about CNCPro is lack of "radius comp".
>I think you should ask yourself, how much will you use it.
>
>Myself, I think I can say never. If a tool needs sharpening, I don't have

the equipment to sharpen it, so I would

>never have the need to compensate.
>
>If I needed to use a tool that was different from the one planned. Well I

will simply redo the files to match the tool I do

>have.
>Which compensates very well for radius variations ! Becasue I car does not

have a GPS built in does not mean I can't use

>it, maps are wonderful things.
>
>As to Linux and EMC. Well I am a programmer, and must say this forum has

been an eye opener about the mess Linux is in.

>
>Sure people manage to get it working, but the messages clearly show Linux

is not for the faint of heart.

>
>I have a kind offer from someone to set up a drive with Linux, but I'm

more and more inclined to forget it. I simply don't have

>
>the time, or want the hassles of it.
>
>CNCPro has other features I think EMC does not have at the moment, and may

or may not have. At least CNCPro is supported by

>a person that "gets hungry" and hunger is a darn good driving force....
>
>Hans Wedemeyer
>
>
>WAnliker@... wrote:
>
>> From: WAnliker@...
>>
>> In a message dated 2/14/00 11:23:30 AM Mountain Standard Time,
>> janders@... writes:
>>
>> << I agree with you entirely regarding the added desirability of a greater
>> feature set. My point is that since he places more weight
>> on input from paid users, that's where the most effect pressure would
>> originate. >>
>>
>> And this is why I made my comments, you would never go and buy a car

with the

>> hopes that as an owner that you could lean on the manufacturer to

include air

>> conditioning in the next model. The way to increase value is to add

features

>> and get new buyers, they will furnish the new money needed to pay for the
>> design times.
>> I am still looking for a program to cut my teeth on, but with a retirement
>> income, want as much as I can get for the dollars spent. Unfortunately
>> Linux/EMC, has a bit more learning curve just trying to get it up and

running

>> than I am able to handle with no programming experience. Linux, can

probably

>> become a very great operating system, but not until it can be put into
>> operation, with a lot more ease than it is now able to, at least for an
>> individual that does not program.
>> thanks for your comments,
>> bill
>>
>> --------------------------- ONElist Sponsor ----------------------------
>>
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>> are willing to answer your questions for FREE. Go to Xpertsite today
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>> ------------------------------------------------------------------------
>>
>> Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the

discussion of shop built systems in the above catagories.

>> To Unsubscribe, read archives, change to or from digest.
>> Go to: http://www.onelist.com/isregistered.cgi
>> Log on, and you will go to Member Center, and you can make changes there.
>> For the FAQ, go to http://www.ktmarketing.com/faq.html
>> bill,
>> List Manager
>
>
>
>___________________________________________________________________________

____

>___________________________________________________________________________

____

>
>Message: 20
> Date: Mon, 14 Feb 2000 16:53:11 -0700
> From: Greg Nuspel <gregnuspel@...>
>Subject: Tool radius compensation
>
>On thing about tool radius compensation is that it allows you to program
>in the part profile with no further calculation.
>
>--
>Greg Nuspel
>
>"Make everything as simple as possible, but not simpler. "
> - Albert Einstein (1879-1955)
>
>http://members.home.net/gregsdiversions
>ICQ 13585790
>
>
>
>
>___________________________________________________________________________

____

>___________________________________________________________________________

____

>
>Message: 21
> Date: Mon, 14 Feb 2000 18:57:00 -0500 (EST)
> From: stratton@...
>Subject: Re: encoders from servos?
>
>> From: Joe Vicars <jvicars@...>
>>
>> What is a quadrature encoder and how do I know if I have one?
>> I have a bunch of old servos and want to take the encoders off to make
>> Lindsay's DRO. Are these the encoders I need?
>>
>
>If you are by chance talking about radio control model servos, then
>the answer is no (those are simple variable resistors).
>
>If you mean large servomotors designed for machine tools or similar
>applications then yes, there is a good chance they might work. On the
>other hand, perhaps you could use the servos AND the encoders to CNC
>your machine tool.
>
>Chris
>
>--
>Christopher C. Stratton, stratton@...
>Instrument Maker, Horn Player & Engineer
>30 Griswold Street, Cambridge, MA 02138
>http://www.mdc.net/~stratton
>(617) 492-3358 home/shop
>
>
>
>
>___________________________________________________________________________

____

>___________________________________________________________________________

____

>
>Message: 22
> Date: Mon, 14 Feb 2000 19:17:34 -0500
> From: "Fred Smith" <imserv@...>
>Subject: Re: Re: CNCPro
>
>>
>> Myself, I think I can say never. If a tool needs sharpening, I don't have
>the equipment to sharpen it, so I would
>> never have the need to compensate.
>>
>never say never ;-)
>
>The main reason for cutter comp is not tool wear & the use of tooling that
>is different from that which was used in the program. The primary reason is
>to hold tight tolerances. If for instance you had to mill a slot that had a
>+/-.002 inch tolerance. You would be able to cut this by programming with
>offset curves in a Bobcad or Vector type of application. The usual way
>would be to program the offset curve just larger than the tool radius,
>measure the resulting size, then *reprogram* the part with the difference
>between the desired size & that actually cut. The reprogramming would
>involve drawing another offset curve & regenerating the portion of the
>program involved with the slot.
>
>With cutter comp capability, (G41/G42) The tool radius offset would be
>changed from +.002 to whatever adjustment was needed to bring the slot to
>size, then the same tested program would be rerun. While it is quite easy
>to regenerate the entire program, and it will make as accurate of a part,
>the chances for error are much greater when using an untested program or
>even a regenerated one, vs just re-running one that you have already tested
>out.
>
>It is very easy to control turning on and off of cutter comp, by using the
>approach and depart function. This generates a teardrop shaped construction
>that allows a beginning straight move during which you turn cutter comp on,
>and a corresponding straight ending move, during which you turn cutter comp
>off. Bobcad allows you to do this manually, and Vector automates the
>process.
>
>
>Best Regards,
>
>Fred Smith
>IMService
>
>imserv@...
>Phone: 248-486-3600 or 800-386-1670
>Fax:248-486-3698
>
>
>
>___________________________________________________________________________

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>___________________________________________________________________________

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>
>Message: 23
> Date: Tue, 15 Feb 2000 00:39:20 -0600
> From: Jon Elson <jmelson@...>
>Subject: Re: Re: CNCPro
>
>
>
>Fred Smith wrote:
>
>> From: "Fred Smith" <imserv@...>
>>
>> >
>> > Myself, I think I can say never. If a tool needs sharpening, I don't
>> have
>> the equipment to sharpen it, so I would
>> > never have the need to compensate.
>> >
>> never say never ;-)
>>
>> The main reason for cutter comp is not tool wear & the use of tooling
>> that
>> is different from that which was used in the program. The primary
>> reason is
>> to hold tight tolerances. If for instance you had to mill a slot that
>> had a
>> +/-.002 inch tolerance. You would be able to cut this by programming
>> with
>> offset curves in a Bobcad or Vector type of application. The usual
>> way
>> would be to program the offset curve just larger than the tool radius,
>>
>> measure the resulting size, then *reprogram* the part with the
>> difference
>> between the desired size & that actually cut. The reprogramming would
>>
>> involve drawing another offset curve & regenerating the portion of the
>>
>> program involved with the slot.
>
>Right, you can compensate for tool deflection. I also find that cut
>rate
>end mills are not exactly on size. Many of them vary up to -.003" or
>so. Another reason I use it is to make one program, either manually or
>with a CAD/CAM package, and use it both for roughing and finishing
>the part. I enter a cutter diameter larger than the actual tool size,
>which
>causes the CNC control to offset the tool farther from the part than the
>
>radius of the actual tool. This makes the roughing cut, leaving maybe
>.010" on the side of the part. Then, I make several passes, stepping
>the
>depth down each time. Finally, I set the tool table to the actual size
>of the tool, and run the program again, milling the sides to the exact
>dimensions.
>
>Jon
>
>
>
>___________________________________________________________________________

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>
>
>
>