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Re: Help with wire sizing
If you want to stick with cat 5 cable I would suggest you get some of the
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stranded type. It is normally used in the patch cables that connect from the computer to the wall jack. Tim [Denver, CO] timg@... <mailto:timg@...> -----Original Message----- |
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Re: DRO/cable source
I just looked in the issue #101 of McMaster Carr, they have coated aircraft
cable as follows: Galvanized. 7x7 strand 1/16 coated nylon or clear vinyl, breaking strength 270 pounds. 7x7 strand 3/32 coated nylon or clear vinyl, breaking strength 480 pounds. Stainless steel, same coatings, same strength, about 25% higher. Both are indicated as available in cut lengths, 50 foot rolls, or 250 foot spools. Call 1-310-692-5911 for prices, and to order. Also on the net, sales@... My question is which coating would be better?? bill |
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Re: DRO
Ted Robbins
At 08:06 PM 2/24/00 -0500, you wrote:
From: "A. G. Eckstein" <axtein@...>I believe that's called coated aircraft cable, availaable in most home supply, large hardware, and hydraulic supply stores. Ted |
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Re: DRO
In a message dated 02/24/2000 3:53:35 PM Hawaiian Standard Time,
rtr@... writes: << It is 0.35" dia, plastic coated, and has give or take 21 strands. Trying to >cut it is a bear so might be stainless steel! I believe that's called coated aircraft cable, availaable in most home supply, large hardware, and hydraulic supply stores. Ted >> Just checkin, Is that .035 or .35"? Peter THRD, Inc. |
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Re: DRO
A. G. Eckstein
I just went up to my shop, and found the roll of stuff I have been using.
It is 0.35" dia, plastic coated, and has give or take 21 strands. Trying to cut it is a bear so might be stainless steel! The roll it came on is so old, that no lables exist anymore so I can't help you there. This is some stuff that was in the junk box, available and so I tried it! It works. What with everybody doing CAD today, I'm not sure any of the office supply houses even carry it anymore. But then I am some what limited in where I can shop in the small town that I live in. When I went to Engineering school, they taught me two things (and thats about all I can remember): 1. KISS (Keep it simple stupid) 2. If it works, don't fix it till its broken! That is the basis of all my tinkering. If I can do it simply, it will usually work better. Had thought about speed increasers (backlash) and other ways of doing it, but this way works. Sorry, No pictures yet. Am still refining the pieces; and should be able to do something this weekend. Hopefully will be able to get the product down to the finish line by next weekend; then will have the blocks caded up and be able to post some pictures on my web site. Even then, probably won't be as pretty as some the items I have seen posted by this group, but we will give it a shot. Art At 07:22 PM 02/24/2000 EST, you wrote: From: wanliker@...discussion of shop built systems in the above catagories. To Unsubscribe, read archives, change to or from digest.A. G. Eckstein axtein@... |
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Re: wonderboard
D.F.S.
You need to keep in mind the fact that is is just an extension of how the standard printer "Port" is set up. The original "Driver" IC is the same one I would use for the the "Xcvr Chips" It required you to set the data lines then write data to the the data bit that runs the "strobe", then rewrite it then write the next byte of data... Yes, and no. When you switch the active port, it will take 3 extra port writes. Otherwise it will take no extra time or steps at all. Those port writes are simply an out() command. I was able to sustain 1/2 million of those a second on a old '386. The timing is a non-issue as far as I'm concerned. How many updates a second do we really need? If 200,000/second is not enough for anyone, maybe we need to look at it again. Remember, If there is no port change, there is no real overhead. Those 3 port writes open up the capability to over 1,000 bits of I/O, that was not even an option before. or make it more difficult to set up?Hardware wise, if you can handle a solodering iron and not hurt yourself, you could build it. Software wise, a simple API should do it, and a LOT simpler than the standard parallel port. Just go look at the requirements for directly interfacing to the parallel port. The inverted inputs and outputs can be a real pain in the butt IMHO. Here's a first pass at the pseudo-code: Wonderboard_Write(Port_val, Data_val) { If (Global_Current_Port != Port_val) { /* Set active Port */ Set address bit ON on parallel port; Set printer port date lines to Port_val; pulse parallel port Strobe LOW; Set address bit OFF on parallel port; } Set Read-Write bit to Write on parallel port; Set printer port date lines to Data_val; pulse parallel port Strobe LOW; } Int Wonderboard_Read(Port_val) { If (Global_Current_Port != Port_val) { /* Set active Port */ Set address bit ON on parallel port; Set printer port date lines to Port_val; pulse parallel port Strobe LOW; Set address bit OFF on parallel port; } Set Read-Write bit to Read on parallel port; Set Data_val to value of printer port date lines; return(Data_val) } Also, isn't what you describe just a digital I/O board of sorts?That is exactly what we are doing, although it is external, opto-isilated, open, free, and expandable be design. Ours won't cost $399.00 though, sorry :-). They are already available, though it's possible we wouldThis is just the starting point for an actual product. I got the Impression my talk of what COULD be added made you think this was something much more complicated than it is. Add a few DACs, some A/D converters, some opto-isolators and a few relays along with a timer and counter, and you have all the features of the Servo-To-Go Cards they want !! $900.00 for. We could do it for 1/10 the money, and THAT is 4 times the costs I add up at the moment. They are not that complicated, you do need a standard starting point though. Sure, I'll build one this week-end. Do was have any system to distribute binaries, like pictures, diagrams, PCB software board designs? Marc |
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Re: DRO
A. G. Eckstein
Joe,
Lets start from the botto, I also felt the same way when I started this project. However I am using a "cable" that appears to be plastic coated multi-strand wire. It is the stuff that is used on a parrallel bar for a drafting table. Its tough and so far, does not appear to be slipping. Check the diameter of the shafts on you encoders as mine were advertised at 3/16", but are actually 5mm. Makes a big difference when you order the drill rod for the shaft and try to stuff it in the hole??? So far, on the two axis that I set up using this with the 5mm shafts (no diameter reduction), I am getting a consistant 0.000177" resolution for my units to count by. On the z axis, I am attempting to grouve the shaft to reduce the diameter so I can get that magical 0.0001 resolution; but will settle for 0.000125. I am afraid of the slippage problem at such small diameters along with the possibility of bending the shaft due to tension of the cable. It appears we are talking physical diameter of the shaft in the bottom of the grouve on the order of 0.0988" ! But I had to buy a 3' length of drill rod so I guess I can afford to try as I don't see any additional projects in the near future that will use 5mm rod for anything and I use only about 2 1/4" of rod per set of axels.If I start having problems with this type of wire, may try some of the heavier guitar strings (don't ask what note, I ain't no musician;_) )as it appears these have a circular wrap around a central core thus giving the effect of a "tire track" which would be parallel to the axis of the shaft rather than the strands that are perpendicular to the the shaft. Hey, I'm just a country redneck that is doing this for fun and the fact that the numbers on the computer screen are eaiser to read than the ones on the dial and I have trouble trying to read a scale even with a loupe! So even if I am off a thou or so, that is still at least 20-30 times more accurate than I can do with a scale and a scribe!!!!! All fun aside, I want it to be as accurate a I can make it. Considering what I am starting with: 1 An oriental mill/drill which we all know has its problems in the accuracy department. 2 Acme thread screws that have a ton of backlash in them. Yes, I desire positional absolute accuracy, but more often than not a higher desire is to have relative accuracy. For instance, if I want to mount a motor with a bolt circle fastening pattern, I want the central mounting hole and the bolt holes to be really accurate. If it is off-center of the plate I am machining by .050, big deal. In the case of the blocks being machined for the DRO project, it is important to have consistant accuracy between the bearing hole and the mounting holes etc. Exactly how far from the edge of the block is of minor importance. Another point on the encoders; when I ordered the encoders, I also got some bearings they had advertised. Well, I ordered 10 and destroyed one of the motors in trying to see how everything was put together. Got down to the Z axis, and needed another bearing...Had run out of the loose bearings so I went to dig the one out of the encoder end of the motor I destroyed. It has a different OD than the one in the nose of the motor which was the same size as the loose ones that I ordered. So If you are planning on useing those bearings, please be aware of this small problem. Art At 09:08 PM 02/23/2000 -0800, you wrote: From: Joe Landau <jrlandau@...>OLDER THAN DIRT Country Bubba (Actually the inventor of Country and Bubba) |
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Re: DRO
Terry May
First of all I tried to post essentially this same message two days
ago but it doesn't seem to have made it to the list. If anyone gets it twice, I do apologize./ Art, Like Joe Landau, I have ordered and received some of the servo motors you described from Goldmine electonics and intend to use them for a DRO much like you described. I would appreciate any further info you would care to post about your installation, especially the electrical hook ups. I would also love to see your CAD drawings. For thing you don't feel appropriate to post to the list I would be grateful for anything you could e-mail to me or post them to the drop box. My address is tmay@.... One other question I had was about the bearings you ordered from Goldmine, I only found one in their catalog which they list as having an ID of 7/32". It's part number is G1558, perhaps this is really a 5mm bearing? Thanks Terry May |
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Re: wonderboard
Harrison, Doug
Your argument has merit. Will this in any way slow down the board or make it
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more difficult to set up? Also, isn't what you describe just a digital I/O board of sorts? They are already available, though it's possible we would be adding features particular to our needs. The big problem: The level of design is beyond my abilities at this point. I hope to get there but need boards sooner. Do we have a volunteer? Doug -----Original Message----- |
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Help with wire sizing
I want to use CAT 5 network cable for wiring small stepper motors
(1.5 amp/phase or smaller) I am talking from the driver to the motor. The cable is sheathed with 4 twisted pairs (I believe). Is there a problem with doing this? The individual conductors are solid copper, appx .020" which I believe to be 24 AWG. I did the current density numbers and came up with about 4.8 amp/mm2 . The SAE handbook says anything below 30 amp/mm2 is good for intermittent automotive applications. Any input on this? Is this OK |
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Re: Help with wire sizing
<< From: Joe Vicars <jvicars@...>
I want to use CAT 5 network cable for wiring small stepper motors Any input on this? Is this OK >> Joe, My only problem would be wire flexing. I'm using some stranded 16 ga wire on my 7 amp drivers. The stationary Z axis motor is not a concern but my x and y motors move quite a bit. I'm bracing for trouble. Cat 5 cable in my opinion would not last very long assuming the current capacity is there. If you can support the wire a distance away from the RJ-45 connections or however you terminate, maybe it may last a while. I'd rather take 18 or 16 ga MTW and twist it like cat 5 for noise reduction. Put a cable tie every 6 inches or so. I've looked at buying flexible machine cable, they wanted $500 for 100 feet or some such outrageous thing. Peter THRD, Inc |
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Re: wonderboard
John Guenther
Doug,
I'm new to this list, and new to CNC, but for what ever my input is worth, I would think your original idea for the wonder board as an external cable connected board would have the greatest amount of flexibility for connection of the parallel port to various driver boards. It seems to me that for use by the greatest number of people the simple approach is better. John Guenther |
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(No subject)
Joel Jacobs
Hi Matt,
From: "Matt Shaver" <mshaver@...>Thanks!From: "Joel Jacobs" <jj@...>Wow, nice job! Schematic?Maybe - after it's done. Is that a 16CE62x?Yup, it's a 16C620 - good eye! Is this a unipolar driver (Six FETs and six resistors vs. four FETs andtwo resistors)?Yes, it's unipoler. I'm using a high side switch to the center tap of each phase pair for the chopping and the phases are selected by low side fets on each phase. When a phase fet turns off the other phase winding of the pair is used as a tertiary <sp> catch winding and the energy stored in the inductance is returned to the supply through some steering diodes. Very efficiant. The resistors you see are current sense. The current is limited to 1v across the sense resistors so I get 1 amp for each pair installed ( they are 1 ohm ea.) So as you see it there are three paralleled resistors for each side = 3amps/phase. The two low side fets on each winding pair can share the same sense resistors since they are never both on at the same time. Joel |
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Re: wonderboard
D.F.S.
Marc; If I understand correctly, your vision of wonderboard included the abilityKeeping things simple open and based on a common starting point to allow expandability and common software libraries that are open to new features and uses is not a good goal? I am not an electronics expert. What I know is from playing around for the most part. This Perhaps my general description, and your admitted lack of understanding of digital electronics stand in the way, Maybe you envision something more when I say "Buffer" or "Latch" than a simple TTL Device. This IS "Bonehead Simple". Maybe the use of one of the extra outputs from the parallel port and a specific example will help: Use these pins from tha parallel port. Pin Name. 1 strobe (Output) 2 data 0 (Input/Output) 3 data 1 (Input/Output) 4 data 2 (Input/Output) 5 data 3 (Input/Output) 6 data 4 (Input/Output) 7 data 5 (Input/Output) 8 data 6 (Input/Output) 9 data 7 (Input/Output) 12 Busy (INPUT) 16 Read-Write 1 Read 0 Write (Output) 17 Data-Address 1 Addr 0 Data (Output) Now, DATA 0 - DATA 7 are the data bus. DATA-ADDRESS will activate either the "Address Latch Chip" or One of the Many "Xcvr Chips" connected to the devices, ie. Stepper or sense switches. "0" is the devices, "1" is the "Address Latch Chip". READ-WRITE is used only for the device access. "1" makes The "Xcvr Chips" send the outside data to the "DATA BUS". "0" Makes them latch the data on the "DATA BUS" into the outputs, stuff like the drivers for the Steppers. The address works like this... You set the "DATA-ADDRESS" bit to "1" Write the address, say 3. This will latch 3 into the "Address Latch Chip". That Chip is connected to a "3 to 8 decoder". Line 3 of that chip will come high and activate "Xcvr Chip #3" Now Reading from or writing to the printer port will either read from or write to the devices or switches connected to that chip. Not rocket science. At a minimum you would need 3 chips. Without adding an additional decoder you could run 8 "Xcvrs Chips" or 64 bits of I/O. All the "Xcvrs Chips" would be wired in parallel except for one pin which would be connected to one of the 8 pins on the "3 to 8 decoder". This make it dirt simple to design and build as well. A Full 64 Bit Interface would take all of 10 TTL ICs, (The 16 pin 5 for a buck type). Adding Opto-Isolators, Relays or LEDs would also be required for many uses, but that depends entirely on the intended use. I could have drawn it faster than it took to explain it, but not in ASCII. Marc |
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Re: DRO
In a message dated 2/24/00 3:14:49 PM Mountain Standard Time,
axtein@... writes: << However I am using a "cable" that appears to be plastic coated multi-strand wire. It is the stuff that is used on a parrallel bar for a drafting table >> any idea what the diameter is, and do you have any new pictures posted anyplace? Give us more, we are hungry about this. Thanks, bill |
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(No subject)
Joel Jacobs
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----- Original Message -----
From: <stratton@...> To: <CAD_CAM_EDM_DRO@...> Sent: Wednesday, February 23, 2000 11:51 PM Subject: Re: [CAD_CAM_EDM_DRO] From: stratton@...phases instabilityenergized it's drawing less than 500ma from my 40 volt supply. It's speeds -issues worked out. It seems to have some problems at certain motor Sure Chris, I'm using discrete mosfets for drive, and a microcontrollerI believe it's caused by the physical resonance of the motor armature.I'm sure I'm not the only one who'd be interested in hearing what you for brains. The micro is very flexible in that I can do half step, half power, power saver, and reverse direction signal by reading jumpers during initialization. The micro has two analog comparitors built-in that are used for current sensing. The micro can program the reference voltage for the current sense so it can do half power and power saver. Power saver is going to 1/2 current if the controller has not received a step pulse in a second or two - it will immediately go back to full power to make the step when it gets another pulse. I can also program the step pulse edge + or -. The prototype has it's own 5v logic supply derived from the 40v input. I don't know if this list accepts attachments so here is a link to a picture of it if you want to take a look. www.spyparts.com/users/jj/driver.jpg I also have some pictures of my mill there that I'm trying to CNC. they are. www.spyparts.com/users/jj/mill1.jpg www.spyparts.com/users/jj/mill2.jpg www.spyparts.com/users/jj/mill3.jpg Joel |
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Re: wonderboard
Harrison, Doug
Marc;
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If I understand correctly, your vision of wonderboard included the ability to use it for a variety of applications outside of the original scope. This was to provide a bonehead simple means of interfacing the parallel port to step drivers, limit switches and four general outputs. To elaborate, stepper systems are the logical choice for a beginning experimenter/hobbyist. They are simple, cheap, and plenty of ready to run software is available (in addition to CNCPro). Wonderboard helps to eliminate some of the problems beginners face, the biggest of which seems to be connecting the dots. Don't misunderstand me. Perhaps it's possible to incorporate the I/O capabilities you describe without comprimising the original vision. I lack sufficient knowledge of digital electronics to be the judge of this. Can we do it? Doug -----Original Message-----<snip> Here is MY take on the interface. |
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