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Re: Polar Coordinates CNC?
Ray Henry
Lee
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I think that the essence of your analysis of the mechanical stuff is true for a Puma robot type of thing but I can't see how that truth affects whether it is programmed in polar or Cartesian coordinates. The EMC could rather easily be configured to run such a device, it has Puma kinematics in the source files, but current programming is with respect to Cartesian space. When we command a coordinated move like g1 f10 x1 y2 z3 what the interpreter does is compute a vector and uses the f10 as the feedrate along that vector so in effect it is a polar move. I can't for the life of me see how specifying three angles and a distance would be more efficient or would somehow alter the fundamental thinking about milling or turning. Ray ? ?From: "wenger2k" <wenger2k@...> |
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Re: Stepper motor speeds
Carol & Jerry Jankura
Hi, Brian:
I'm running TurboCNC into Camtronics 2 amp drivers into Sherline's 100 oz-in motors. The power supply is a 24vdc regulated supply that's turned up to around 26->28 volts. I get 4500 sps on X and Z and 2600 on Y. -- Jerry | |I'd be very interested in hearing from others who use 23 frame motors |on small tools. What step rates are you achieving? |
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Re: EMC install question
--- In CAD_CAM_EDM_DRO@y..., Eric Keller <unterhausen@y...> wrote:
I am too stupid to use the BDI installation of emc, orPlease tell use why your computer refused to run BDI so we can help! Frank
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AutoCAD compatibility
dgmachinist
Hi all,
I just installed Windows XP on my computer so I could run Mach1. The problem with this is that now I can't install my copy of AutoCAD 2000 (educational version). It says that XP is an "invalid OS". Is there any way I can get around that? Any help would be appreciated seth |
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Re: Stepper motor speeds
Bryan Mumford
I did some research on the 23 frame motors we're using. They come from Shinano:
You can download a data sheet for the 23 frame motors and torque curves are provided. Typical step rates are nowhere near 1200 RPM. Typical values are 800 to 2000 pps. At 200 steps/rotation this is equivalent to 600 RPM tops, and most are closer to 300 RPM. This makes me think I'm not doing so badly with 3300 pps. I'd still like to hear from anyone getting faster rates from 23 frame motors. -- Bryan Mumford Santa Barbara, California |
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Re: Digest Number 2678
Ray Henry
Eric
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I hesitate to ask what breed of machine this is, cause I expect to see 4 of them during the install-a-thon. What is it? What did the BDI not do? What BDI was this? My guess is that you need to post this to emc@... Ray ? ?From: Eric Keller <unterhausen@...> |
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Re: Current factor of 0.707 in API CMD-260 Drive Current Setting
From data gathered at the API website it appears that the~~~ Thanks - Dan.The factor of 0.707 is 1/SQRT(2) and is the scaling factor applied to peak sinusoidal A.C. current to give the D.C. equivalent current to supply equal power. This gives the Root-Mean-Square value. Instanteaneous power being given by V^2/R necessitates finding the mean of V^2 rather than the mean of (absolute) V. I hope that makes sense in your quoted context. I haven't looked at (found) the source site yet. For some reason the figure is etched into my head next to the slightly more trivial fact that the first Boeing 707 took off at 7:07 a.m. I just found and joined this Group. I will have some dumb questions as soon as I figure out how to stop the emails coming. cheers, Don. |
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Re: Stepper motor speeds
Bryan Mumford
My motors are rated for 3.2 volts at 2 amps, driven with 24 volt choppers.
Higher voltages are a problem for small, low-cost tools. The Xylotex drivers (3977 chip) max out at 35 volts, and the SLA7044 chip I'm using is similar. I'd be very interested in hearing from others who use 23 frame motors on small tools. What step rates are you achieving? Is anyone getting substantially more than 3300 steps per second, and if so, what kind of driver are you using? -- Bryan Mumford Santa Barbara, California |
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Re: Stepper motor speeds
About 50 volts. That would likely triple your feed rates. The max RPM
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you can get is also dependent upon inductance of your motors. You do not mention how yours are wired or what voltage they are. This is not to say you need to have your Sherline go that fast, only how you would if you had to. Tim [Denver, CO] -----Original Message----- OFF Topic POSTS: General MachiningI 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 |
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Re: Flashcut
It does seem that users of Flashcut rave about it. I also have not quite
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understood what it has that makes it worth so much more than other controllers and drives that give the same or more features and more capacity for much less. Then again I always rave about things I send a lot of money on. Maybe that is the attraction? Tim [Denver CO] -----Original Message----- |
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Re: Flashcut
John Guenther
$900.00
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-----Original Message----- |
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Re: Polar Coordinates CNC?
Alan Marconett KM6VV
Hi Al,
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This IS an interesting subject! Last week I was trying to develop a tool path to cut some detail on the periphery of block of aluminum. While I had digitized the surface I wanted (of a Stuart steam engine cylinder), and COULD cut that as a final, what I wanted to do was develop a tool path to "rough" it out first. Most of the surface is cylindrical, with flat surfaces on one side tangent, and ending in a flat on one end of the otherwise pear shape. Onto the surface would be cuts to make flanges at either end of the cylinder, and projections at several points for exhaust pipe, and drain cocks. Only way I know to create this contour is by projecting the required radius at various points along the periphery (like working sheet metal). I'm assuming a 4-axis CAD/CAM program will have a better way to do this, but I haven't been able to afford this for a "hobby" project. SO, I'm looking for better ways to design things like this! I wouldn't call this a Rho-Theta type application, just a simple cylindrical projection. Perhaps you'd like to describe a little more of your project and approach. Alan KM6VV alenz2002 wrote:
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Re: (unknown)
stevenson_engineers
--- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:
G43 is tool length offset. Not sure on G44Tool Length Compensation Syntax - G43 Hnn* ; tool length comp. away from the part G44 Hnn* ; tool length comp. toward the part G49* ; cancel tool length compensation The parameter nn for the H code is the identification number of the associated tool. This value is the tool number displayed on the left side of the screen in the Tool Size window. G43 - Tool Length Compensation Away From The Part G43 assumes zero length tools, meaning the G-code tool, or z-axis, coordinates will specify the length from the quill face to the desired destination position. The offset associated with the tool will then be added to the tool axis destination position. The tool offset data for this command will be the actual length of the tools. Example: If the distance from the quill to the destination position is 10 inches towards the part for the rapid move and 10.5 inches for the feedrate move, and you want to apply tool length compensation away from the part for tool number 0, the G-code commands will be: G43 H0* ; enable tool length compensation for tool number 0 G00 Z-10.0 G90* ; lower the tool at the rapid rate in G90 absolute mode G01 Z-10.5 F10.0* ; lower the tool to the cutting position at 10 ipm If the z axis starting position was at 0 and the offset length assigned in the Tool Size window for tool number 0 was 7.5 inches, the actual length of the G00 move in this case will be 10.0 - 7.5 = 2.5 inches. The offset length is always subtracted when G43 compensation is active. The next command will move the tool down an additional .5 inches, at a feedrate of 10 inches per minute. If a tool change was required at some later point it would only be necessary to cancel the current tool length compensation, retract the tool to the tool change position, and re-enable the compensation while specifying the tool to use for the operation, using the 'Hnn' parameter. However, the offset length must have been previously assigned for this tool before the file is executed. These additional commands might be: G49* ; cancel tool length compensation G00 Z0 G90* ; retract to tool change position M01* ; program pause for the tool change G43 H01* ; re-enable compensation for tool number 1 G00 X2.0 Y1.0* ; position the tool G00 Z-10.0 G90* ; lower the tool at the rapid rate G01 Z-10.5 F10.0* ; lower the tool to the cutting position at 10 ipm The last 2 commands simply continue the sequence of tool axis moves in a similar way as before. Even though the lengths of the two tools may be different, the G-code commands to move the tool to the same destination position remain the same as long as the offset length for each tool is specified properly. Remember that the offset length specified in the Tool Size window, must be the actual length of the tool when using the G43 command. It can be seen from these examples the danger in using the G43 compensation command. Because this command compensates the tool away from the part and assumes a zero length tool, the coordinates in the tool axis moves are all longer than actually desired. The compensation actually reduces the length of travel by the amount assigned in the Tool Size window for the offset length for the specified tool. If this value is assigned a zero the tool move will travel too far, possibly resulting in a collision with the part or table. Please make sure you dry run the program from the Main Screen before execution, if you use the G43 command, to check the proper display position of the z-axis coordinate. Never assume the Tool Size data still exists or have the same data the was previously assigned. This data is stored in DOS files which can easily be deleted, overwritten or otherwise corrupted. At the very least you should check to make sure the Tool Size data is still valid before you run G-code files containing tool length compensation commands. G44 - Tool Length Compensation Toward The Part G44 assumes that when creating G-code commands, the tool axis coordinates are assigned based on a standard length, for an imaginary tool, which is longer than any of the tools in the system. The tool offset length data in this case will be the difference in length between each tool and the standard tool length chosen by the programmer. The offset for this command will be subtracted from the tool axis destination position. An extra calculation is required when using the G44 command, since after the tool length is measured it must be subtracted from the chosen standard length, to obtain the desired offset. It is this difference that is stored as the offset length in the Tool Size window for each tool which will be used in a G44 tool length compensation operation. This method of tool length compensation is actually safer than using the G43 method, since the coordinates for tool move commands will be programmed with a shorter value than is desired. If an offset has not been assigned for the selected tool the resulting move will be shorter than desired and a collision with the part or table should not occur. Example: If the distance from the tip of the standard length tool and the destination position is 2.0 inches towards the part for the rapid move, and 2.5 inches for the feedrate move, and you want to apply tool length compensation toward the part to tool number 0, the G-code commands will be: G44 H0* ; enable tool length compensation for tool number 0 G00 Z-2.0 G90* ; lower the tool at the rapid rate in G90 absolute mode G01 Z-2.5 F10.0* ; lower the tool to the cutting position at 10 ipm If the z axis starting position was at 0 and the offset length assigned in the Tool Size window for tool number 0 was .5 inches, the actual length of the G00 move in this case will be 2.0 + .5 = 2.5 inches. The offset length is always added when G44 compensation is active. The next command will move the tool down an additional .5 inches at a feedrate of 10 inches per minute. As with the G43 command, additional tools could be used at later points in the G-code program. As long as the tool length offsets were properly assigned, the tool axis coordinates would simply reflect the length of the standard tool, and the program would compute the actual destination positions for the specified tool. Since the tool length compensation commands allow the programmer to create G-code programs that are not dependent on the lengths of the various tools that will be used, the programs will be easier to write and maintain. With this greater flexibility and freedom comes additional danger and risk if the commands are not used properly. This is especially true with the G43, compensate tool away from the part, command. If you decide to use these commands please take extra precautions to verify the correctness of the program before actually driving an expensive power tool. G49 - Cancel Tool Length Compensation The G49 command is used to cancel any active tool length compensation operation. If you want to perform a tool change you will almost certainly want to include a G49 command before the retract move is made. If this is not done the retract operation may not be moved to a point that provides adequate clearance for the tool change operation. After the specified tool change or pause command, the previous tool compensation command should be included, to re-enable this operation for the new tool, if so desired. be a-----Original Message-----I consider this to sister site to the CCED group, as many of the same members arethere, for OT subjects, that are not allowed on the CCED list.THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ bill |
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Re: Stepper motor speeds
Bryan Mumford
At 4:26 PM +0000 11-03-02, turbulatordude wrote:
Size 42, 300 to 600 RPM, 800 in-oz or more low-speed torque.This seems too fast to me. Perhaps you would comment on this. Looking at a 23 frame motor, in half step mode (400 steps per rotation), 1200 RPM means 480,000 steps per minute or 8,000 steps per second. I am currently experimenting with 23 frame motors on Sherline tools using both the Xylotex bipolar driver and a unipolar driver of my own design. I'm stalling out at 3300 steps per second tops. It seems unlikely that this tool will ever run twice as fast as I'm seeing, and you list 1200 RPS as the low end. I'm feeding both drivers with 24 volts. What am I missing? -- Bryan Mumford Santa Barbara, California |
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Re: Flashcut
Hi JS,
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What so great about flashcut I hear good things about it but never really understands what sets it apart from other controller like mach1 or deskwinnc. Have fun Hugo --- In CAD_CAM_EDM_DRO@y..., "Jens Swales" <jipeess2000@y...> wrote:
hi all |
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Re: Stepper motor speeds
Marv Frankel
Tim,
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I guess it's my engineering background that makes me want to plug all the components into a formula, and come out with an exact answer. The mill I'm going to convert, is a full size Enco, about the size of a Bridgeport, 1 1/2 HP variable speed motor, 8" X 36" table, and driven by a VFD. I'd rather oversize the motors, and have some torque to spare, but I was just trying to save a little space on the quill feed, by using a slightly smaller motor. Thanks for the direction. Marv Frankel Los Angeles ----- Original Message -----
From: "Tim Goldstein" <timg@...> To: <CAD_CAM_EDM_DRO@...> Sent: Sunday, November 03, 2002 2:13 PM Subject: RE: [CAD_CAM_EDM_DRO] Re: Stepper motor speeds It is not as easy as just looking at a particular metal and getting aaol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble. 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. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ bill |
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EMC install question
Eric Keller
I am too stupid to use the BDI installation of emc, or
rather my computer refused to run it. Believe me, I tried. Anyway, I have RTLinux installed and successfully built rcslib. However, now that I am trying to build emc, the build gets to linking and there is an undefined referece to Tclx_Init. Since I have the tclx extensios installed, I am stumped trying to figure this one out. Any ideas? Eric __________________________________________________ Do you Yahoo!? HotJobs - Search new jobs daily now |
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Re: (unknown)
G43 is tool length offset. Not sure on G44
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Tim [Denver CO] -----Original Message-----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 |
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Re: toolpath creation problem or wrong interpretor setup?
Alan Marconett KM6VV
Hi Ian,
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Sorry! That statement wasn't an indictment of products from England! The truth be known, I probably ran them in too far into what turned out to be a flange, the tap was probably flexing against a surface DEEPER then that which I had drilled. CNC doesn't fix everything! The hole pattern looks nice, 'tho. Alan KM6VV "Ian W. Wright" wrote:
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