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Re: Past items????
"Mo" <[email protected]
It has Home and Limit switches, any chance that STEPSTER can support theBill, It wouldn't be welcomed by those already using Stepster only. There are people out there that already have Stepster working and wired up, this should not involve them in having to change their set-up when they get Charlie's update. I have not heard any mention of Microsystems LPT CNC stepper software which has solid G-code support and well thought out but may not be to everyone's taste. Anyone out there with experience they wish to share? A very promising development is the Indexer LPT 32 bit port for Win95/98. Bags of improvements over the 16bit version and serious jump in performance. The improved interpolation (helical) and buffer look ahead for smoothness is attractive - the lack of a g-code front end is already addressed with add on front ends available from other people. Anyone care to comment? Cheers Mo |
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Re: 10 amps to drive steppers
"Mo" <[email protected]
Tim I've got about 1Mb of stuff to send you is it OK to e-mail direct?
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Mo I would be interested in the circuit you are thinking of for an overheat |
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Re: Past items????
Charles Gallo
Bill,
I'm working on Stepster in my free time. (what little I have) - I know how to get the limit switch working, and I'm going to put it into test SOON (I wanted to do it 2 weeks ago). It's just that I've actually been cutting metal, and the like. I just got to run a live steam engine for the first time today!!! Charlie At 03:07 PM 6/13/99 EDT, you wrote: From: WAnliker@...discussion of shop built systems in the above catagories. To Unsubscribe:PGP Key Avalible upon request |
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Re: Past items????
In a message dated 6/13/99 3:57:54 PM Pacific Daylight Time,
mo@... writes: It wouldn't be welcomed by those already using STEPSTER only.I can agree with that, had not given it the thought that I should have. I believe that I asked before, does anyone have a copy of the schematic download that is mentioned in the description of STEPSTER? I would like very much to receive a copy by direct e-mail if possible. bill List Manager |
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Re: Past items????
In a message dated 6/13/99 2:36:16 PM Pacific Daylight Time,
Charlie@... writes: I'm working on STEPSTER in my free time. (what little I have) - Iknow how to get the limit switch working, and I'm going to put it into test SOON (II wasn't rushing things, but hadn't heard anything so got to wondering. I got the Sherline Mill today with vise and variable speed, works good, a few spots of rust, but they cleaned up nicely. Traded it for an old 55 gallon aquarium and parts and pieces. Grinning from ear to ear. Glad to hear it on cutting metal, also on the running the steam engine. I have not done that yet. A couple of models on air, but no steam, do have a boiler in the making. In this issue of Nuts and Volts, Dan has a schematic of the 2 amp controller. It has Home and Limit switches, any chance that STEPSTER can support the same switches and the same pin numbers? Would simplify things possibly. bill List Manager |
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Re: Newbee, Laser Machining Anyone?
I just subscribed to this list.
I built a 2ft x2ft 3 axix desktop router/CNC machine a few years back when not much info was published. I am using a 3 axix 2 amp controller from Camtronics Inc, along with some steppers I also purchased from the same company. I am quite please at the precicion I have been able to achieve. My various projects range from simple engravings to complex aluminum molds for making small plastic injection parts on a small tabletop injection molding machine, I also built recently. Although my applications are mostly related to developing micro radio and infra red helicopters (see my web page below for more details) which used simple machined parts, I have been contemplating upgrading my 3 axis machine with a laser head for more "clean-cut" parts and faster production. Has anyone on this list experimented or built a CNC desktop machine with a laser head? TIA Mario I. Arguello |
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Re: 10 amps to drive steppers
Tim Goldstein
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-----Original Message-----Dan, Pardon me for being a little thick, but what exactly do you mean by "I wired them into the Vin to the controller."? Tim [Denver, CO] |
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Re: EMC C Code
The Java program did not do real time machine control. There is a vast difference between being able to compile code on a platform and actually being able to execute it. With some work, you could probably compile the EMC code using the Borland compiler. However, you would not have all of the operating system real time calls that the code depends on. To be able to run the program, you would need to build all of the required functionality that is missing on Windows. Practically speaking, this is not realistic. Programs can be written to be platform independant, but this involves either writing for the lowest common denominator of OS services, or writing emulation libraries to supply missing functionality across systems. This does not work for something like EMC which relies on real time scheduling support from the OS. This is not something that can be grafted on later, but must be part of the running OS. -----Original Message----- -- Paul Amaranth | Rochester MI, USA Aurora Group, Inc. | Software Development paul@... | Unix / C / Tcl-Tk |
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Re: Machine geometry
On Sun, 13 Jun 1999 09:55:01 -0500, "Robert Campbell"
<rcamp@...> wrote: <debriefing snipped; thanks, most helpful to have these comparisons> After I build my new 2 by 2 fixed bridge system, I will retrofit my 4 by 4OK, so sounds like you're expecting that with stiffer/tighter rails, you'll be back to where you expected to be, in terms of "slop"? Sounds good to me. I'm always kinda wondering, altho I have attempted to be as massively stiff as possible (no, not me personally, the table :), what I'll end up with as far as repeatability. I don't really HAVE any reason to strain, given my interest in routing foam, thin alum sheet, and Rayite, but ya know how it goes; everyone wants to see and continually sanity check how closely their expectations are likely to match actual results. Thanks for the input. I tell people I'm building my own "four-by-four", but it's gonna run on rails, so they needn't worry; I won't get too far nor do too much damage. B) Gar |
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Past items????
Not too long ago there was some comments about upgrading one of the smaller
CAM programs, I think it was Kevin Carols CNC981 if my memory is correct. I was wondering about the status of the work on it. If my memory is wrong please correct me. Also Dan mentioned a project he had for a CNC conversion in the works for Sherline equipment. Found a Sherline mill at the neighbors garage, and dealing for it now, if successful will need the kit. Dan could you give us an update on this project. As of this morning we have 199 on the list. Come on you lurkers, tells who you are, what you are working on. Or ask questions, what, why, how. LINUX is being well covered, now lets get some other subjects also well covered. bill List Manager |
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Re: Machine geometry
Robert Campbell
Gar,
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The 4 by 4 was built using Item aluminum extrusions. The X and Y rails were Ina bearings on 14mm shafting (top and bottom). The Z axis uses THK bearings with about 6 inches of travel. In order to reduce the racking of the gantry, I built a double cable system to counteract the racking. Now when I push on one side, the cables will pull on the other side. This has helped a great deal. After I build my new 2 by 2 fixed bridge system, I will retrofit my 4 by 4 with THK rails and bearings on the X and Y. Bob ----- Original Message -----
From: Gar Willis <garfield@...> To: <CAD_CAM_EDM_DRO@...> Sent: Saturday, June 12, 1999 9:58 PM Subject: Re: [CAD_CAM_EDM_DRO] Machine geometry From: garfield@... (Gar Willis)a of2' by 2' fixed bridge cnc router that should be very ridged. I cut a lot discussion of shop built systems in the above catagories.Corian and wood parts.I missed the description of your 4X4, if you posted it. Could you say To Unsubscribe: |
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Re: 10 amps to drive steppers
Dan Mauch
Let me chime in. On some units that I sold to people that live in very hot
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climates like india, I included some thermal cutoff switches. I simply mounted one rated at 135F on each heatsink. I wired them into the Vin to the controller. Thermal switches are available from www.meci.com for about $1.30 ea. Dan -----Original Message-----
From: Tim Goldstein <timg@...> To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...> Date: Saturday, June 12, 1999 8:27 PM Subject: Re: [CAD_CAM_EDM_DRO] 10 amps to drive steppers From: "Tim Goldstein" <timg@...>specs usefor the fans you intend to use and go for the highest you can find - I forthe Minebea Smartfan 4715ML-012P542-P1 12V 0.5A (commonly found in old discussion of shop built systems in the above catagories.manual setting or with a 1k resistor for an airflow that will have your To Unsubscribe: |
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Re: 10 amps to drive steppers
Dan Mauch
The kit contains some really nice but large heatsinks. I don't like to run
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mosfets much over 130F with heatsinks on them. One of my customers has one of the few units that I sold as complete units. It ran very well for about 11 months but a student diconnected the Z axis motor while running and blew a couple mosfets and a sense resistor.. It is back up running again. Yes you can increase the current by placing 2 .1 ohm sense resistors in parallel for 10 amps but I saw ecessive ground noise at about 9 amps so I deliberately detuned the specs to 5 amps where it runs very reliably. Yes the mosfets could be replaced with higher rated mosfets but you may run into new problems. One note. I NEVER run my stepper motors at the rated current. Why not ? Bacause a stepper motor on draws full current when it is stopped. Who cares that the motor is getting full current when it is stopped. NOT ME. The faster you run the motor the less current draw there is. The reason is that the coils can't charge fast enought at high speed. Additionally ,if you are using a 6 wire motor and wire the coils in series you now only electrically require about 80% of the rated current because the series resistance of the coils has reduced the current requirement. I have tested many motors with many drivers and measure the running torque with a special torque tester and have proven to myself that using 80% of the rated current is better for the motor and the electronics with no degradation in performance. Dan -----Original Message-----
From: Mo <mo@...> To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...> Date: Saturday, June 12, 1999 7:05 PM Subject: Re: [CAD_CAM_EDM_DRO] 10 amps to drive steppers From: "Mo" <mo@...>driveknow how it goes. The only modification to the board needed to allowhighercurrent is to parallel the existing .1ohm sense resistors with another.1ohmswhich will double the adjustment scale to 10 amps.Matt, the enable/disable pin.circuitry let me me know.further - need more current then add more cooling and continue your tests.discussion of shop built systems in the above catagories. To Unsubscribe: |
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Re: Servo motor question
Dan Mauch
That what I am using on my full size mill. Except that the PRM is up around
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1200 and the current is a bit higher. I am running two to 1 timing belts on the X and Y axis and 3.5 to one on the kneee. I simply chucked up the drive shaft and drilled the oposite end for a .250 hole, then press in a stub shaft and then mount my encoder. Works slick. Dan -----Original Message-----
From: Tim Goldstein <timg@...> To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...> Date: Saturday, June 12, 1999 11:13 AM Subject: [CAD_CAM_EDM_DRO] Servo motor question From: "Tim Goldstein" <timg@...>discussion of shop built systems in the above catagories. To Unsubscribe: |
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Re: EMC C Code
Robert N. Ash
Thanks
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My misunderstanding as to the real meaning of "code portability of C and C++". JAVA version would be a platform independent software maybe but still need a RT OS??? -----Original Message-----
From: Jon Elson <jmelson@...> To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...> Date: Sunday, June 13, 1999 1:22 AM Subject: Re: [CAD_CAM_EDM_DRO] EMC C Code 4.From: "Robert N. Ash" <esccmail@...> Generally, NO WAY! Consider that this is about 50,000 lines of mostly C++,SNIPPED>>
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Re: Stepper controllers
Andrew Werby
From: "Ian W. Wright" <Ian@...>
Subject: Re: Stepper controllers Thanks very much Paul, this is helpful. I did try using opto isolators on one of my early experimental circuits but they just seemed to gum things up, however, I think now that the problem might have been a current limitation on the parallel port - I hadn't thought of that. I have been surprised that I can't drive the steppers reliably with the 486 computer and that stepster and MaxNC both seem to need a pentium as I too can remember 8080s doing the job admirably in industrial environments. In fac, only last year I was playing with a giant Asquith miller (12ft x 8ft bed!) at a military aircraft factory which still uses an early computer fed by 8" floppy disks. Ian [How fast are you trying to run your steppers? I've run MaxNC's software successfully on one of their machines, using an antique 386, and it worked fine- no lost steps. Perhaps if you get into higher speed ranges you need a faster CPU. But there might be a problem coordinating the speed of the motors with the speed of the computer. MaxNC has a program called "Timeset" that you need to run when initializing a machine- did you do this?] Andrew Werby Andrew Werby - United Artworks Sculpture, Jewelry, and Other Art Stuff |
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Re: 10 amps to drive steppers
Jon Elson
From: Dan Falck <dfalck@...>No, the FETs themselves are too small to radiate much RF. The traces connected to them, however, are large enough to radiate. You have to minimize the area inside the loop of the current paths. I did a lot of work minimizing the current loops on my 100 KHz PWM servo amps, and apparently I must have done it right, as I have no RFI, and can even run a radio within a couple feet of the CNC system. (Umm, that is FM, of course. AM radios don't work so well anywhere in my house, due to all the electronic gear. But, it doesn't bother the TV, either.) Things that I could have done better:Twisted pair cables are very good at shielding. Maybe this is why a lot of people use opto-couplers on their stepper drivers. Not only does it provide isolation, but can be quite effective in reducing EMI glitches. I will use an etched circuit board next time. I suspect the milled boardRaggd edges have no effect (below the GHz range, anyway). But layout is REALLY important in any power switching circuitry. Yeah, well I just don't understand why these fets are running so hot. They may not be driven into the proper gate charge to cut conduction losses. My servo amps are switching continuously at 100 KHz, and often idle at about 1 Amp output (plus the 1.5 Amp or so triangle wave going into the filter). The transistors run cool, even with NO fan at all. Just to be sure, I have a whisper fan on them. Jon |
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Re: Servo motor question
Jon Elson
Tim Goldstein wrote:
From: "Tim Goldstein" <timg@...>What model tape drive? My question to you servo guru's (Matt, Jon, & ??) are these motors of anyHmmm, the .5 Amp rating sounds REAL fishy. If that really is the limit, at 24V, that is a 12 Watt motor! It shouldn't be able to even move a Bridgeport table. If 0.5A is the continuous duty rating, there is some hope. First thing I'd do is use an ohmmeter on the armature terminals. If you get readings below 1 Ohm (you'll have to wiggle the motor to get a good commutator contact, then let the meter reading settle) then you are in good shape. We have found some motors that have about 5 Ohm armature resistance, and similar voltage/RPM ratio. The resistance is the killer (I think). If you have a couple of amps running through a 5 Ohm motor much of the time, it will run VERY hot. If the average current is 1 amp or less, and the peak is just a couple of amps, then it might do fine. Still, it's hart to answer the question without enough data to calculate Kt and Ke. These are the Torque and voltage/RPM constants for the motor. Using my own servo amps as a guide, a Kt of no less than 25 in/Lb per Amp (assuming a modest belt reduction ratio), or maybe 50 in/Lb per amp if you want direct drive. Doubling or even quadrupling these numbers gives a good safety factor. As for Ke, you must have an armature voltage no higher than the servo DC power supply when the motor is driving the machine at the desired rapid feed rate. But, you want the Ke not much less than half that figure, so you can deliver decent power without excessive currents. If you can find direct drive motors from a 75 IPS, start-stop tape drive, you are onto something. A 125 IPS start-stop drive would be even better, although some of these motors start to get big and heavy. Jon |
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