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Re: "Light Bulb" EDM ???
Corey
I've built it, it works but VERY slowly. I would only
use it again after eliminating all possible mechanical solutions. The light bulbs are to limit peak current (they are in series). I posted the plans to one of the Yahoo groups last year, I don't remember which and I no longer have them on my drive. c --- mueller914 <mmueller@...> wrote: In the latest issue of one of the home shop Machine__________________________________________________ Do you Yahoo!? Y! Web Hosting - Let the expert host your web site |
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Re: "Light Bulb" EDM ???
Light bulbs are low cost high wattage and low resistance resistors. I looked
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at it quickly and it seems the light bulb was serving as a current limit resistor for when the electrode shorts out. Tim [Denver, CO] ----- Original Message -----
In the latest issue of one of the home shop Machine mags, they had a |
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Re: Capacitors for Geckos when using fuses
Jim,
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I agree with your take on this. Voltage is not mentioned because the norm with a capacitor is that the cap is rated as high or higher then the maximum voltage it will be exposed to. Tim [Denver CO] ----- Original Message -----
According the the gecko white papers(verbatum), "If a linear regulated ora switching power supply is used then a large capacitor should be placed across the output terminals. A 2000uF-10000uF capacitor should do." That is why I chose a 4700uF cap. for the power supply output terminals...It's about right in the middle of Mariss' suggestion of a capacitor for a switching power supply. He wasnt specific as to what voltage rating for this cap, he was onlyspecific as to what uF value (2,000-10,000uF) Your formula for computing the value of a capacitor, I think, is for whenbuilding your own power supply, in conjunction with a bridge rectifier and transformer. I dont think this applies to when you are using a regulated or switchingpower supply. The cap mentioned above, is placed on the output terminals to insure that the ripple current stays within the demand of the drivers current requirements. That is what I get from the papers. I may be wrong about this though.
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Re: Capacitors for Geckos when using fuses
Jim Brown
According the the gecko white papers(verbatum), "If a linear regulated or a switching power supply is used then a large capacitor should be placed across the output terminals. A 2000uF-10000uF capacitor should do."
That is why I chose a 4700uF cap. for the power supply output terminals... It's about right in the middle of Mariss' suggestion of a capacitor for a switching power supply. He wasnt specific as to what voltage rating for this cap, he was only specific as to what uF value (2,000-10,000uF) Your formula for computing the value of a capacitor, I think, is for when building your own power supply, in conjunction with a bridge rectifier and transformer. I dont think this applies to when you are using a regulated or switching power supply. The cap mentioned above, is placed on the output terminals to insure that the ripple current stays within the demand of the drivers current requirements. That is what I get from the papers. I may be wrong about this though. Thanks Regards, Jim turbulatordude <davemucha@...> wrote:Hi Jim, you ask two questions here. #1 470uF AT THE TERMIANL connector of the Gecko. required if you place ANYTHING between the main cap and the gecko OR if the lines are longer than the listed 18 inches. there are lots of posts that address this. the main thing is that the switching of the gecko will encounter voltage spikes from the stepper. the on-board cap on the gecko can handle some of this while the main cap handles the rest. and yes, as long as the voltage rating of the cap is well over the power supply the cap is fine. your 24 volts power supply will operate fine with a 35V cap. #2 main capacitor. check the gecko white paper on the cap sizing. again, as long as the voltage well above the power supply it is fine, but the cap size needs to be suffiecnt for the amp load of the system. You didn't list the total amps of all your steppers, but you need to total all motors for the main cap sizing. cap uF rating is = (80,000 x total motors amps) / ps voltage example is if you have 3 steppers at 3 amps. you have 9 amps total 80,000 x 9 = 720,000 720,000 / 24 = 30,000uF so you would need a total of 30,000uF with a rating of 35 volts. www.jameco.com has them for low cost, about $5.00 each for 10,000uF/ 35volt the 470uF/35volt are less than $1.00 each. Dave --- In CAD_CAM_EDM_DRO@y..., "jagco1998" wrote: I have a few more dumb questions.... Addresses: FAQ: FILES: Post Messages: CAD_CAM_EDM_DRO@... Subscribe: CAD_CAM_EDM_DRO-subscribe@... Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@... List owner: CAD_CAM_EDM_DRO-owner@..., wanliker@... Moderator: jmelson@... timg@... [Moderator] URL to this group: 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. 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 --------------------------------- Do you Yahoo!? Y! Web Hosting - Let the expert host your web site |
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"Light Bulb" EDM ???
mueller914
In the latest issue of one of the home shop Machine mags, they had a
feature with a home built EDM which for some reason used light bulbs (controlling the freq. I guess) anyone have more detailed plans for the electrical side of this project or point me in the right direction? I have a few broken exhaust studs that I'd like to remove myself Thanks, Mike |
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Update...dropped servo motor fixed
mueller914
a while back I dropped one of my servo motors which caused 3 of the 4
magnets to become unglued from the case of the motor. This morning I glued them back on with Loctite 9414 adhesive (had a sample of this stuff laying around for some reason) So far so good, I just ran the motor with 24v for a few minutes (both directions) I guess the real test will be tonight when I hook it up to my mill and put some current into it. Mike |
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Off topic Dumb question on the drilling of holes
This list is for discussion of CAD, CAM(CNC), EDM and DRO ONLY. The list is
aimed at the construction and use of this equipment in a Home Shop Machinist environment. It is not moderated normally, but can be, especially for content. I would hope that the discussion will consist of Links, sources, progress reports, challenges, innovative solutions, and things of this nature, on the above four subjects. It not aimed at the commercial professional systems, and their users in a commercial setting. NOTICE!!! LIST RULES, SUBJECT TO CHANGE. Arguments, OT postings, Flaming and Piracy not allowed. Banning will result. NOTE: This is not a general machining List. It is restricted to the four subjects of the list only. CAD, CAM(CNC), EDM and DRO. The list is strictly for the "Do It Yourself Bunch" Anything else is SPAM. bill List Mom |
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Re: Capacitors for Geckos when using fuses
turbulatordude
Hi Jim,
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you ask two questions here. #1 470uF AT THE TERMIANL connector of the Gecko. required if you place ANYTHING between the main cap and the gecko OR if the lines are longer than the listed 18 inches. there are lots of posts that address this. the main thing is that the switching of the gecko will encounter voltage spikes from the stepper. the on-board cap on the gecko can handle some of this while the main cap handles the rest. and yes, as long as the voltage rating of the cap is well over the power supply the cap is fine. your 24 volts power supply will operate fine with a 35V cap. #2 main capacitor. check the gecko white paper on the cap sizing. again, as long as the voltage well above the power supply it is fine, but the cap size needs to be suffiecnt for the amp load of the system. You didn't list the total amps of all your steppers, but you need to total all motors for the main cap sizing. cap uF rating is = (80,000 x total motors amps) / ps voltage example is if you have 3 steppers at 3 amps. you have 9 amps total 80,000 x 9 = 720,000 720,000 / 24 = 30,000uF so you would need a total of 30,000uF with a rating of 35 volts. www.jameco.com has them for low cost, about $5.00 each for 10,000uF/ 35volt the 470uF/35volt are less than $1.00 each. Dave --- In CAD_CAM_EDM_DRO@y..., "jagco1998" <jagco1998@y...> wrote:
I have a few more dumb questions.... |
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Re: Center tapped transformer
Dave Dillabough
this will work but will not increase the current capacity of the secondary as the max current must pass through each winding. It does save you 2 diodes though.
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At 01:17 AM 10/23/02 -0600, you wrote:
Matt, |
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Re: Center tapped transformer
Dave Dillabough
Look at the center tap wire. If it is a loop or 2 wire ends then you can split them apart to get 2 30 volt windings which can be paralleled to double the secondary current. To make sure that you get the phasing of the 2 windings right connect a light bulb in series with the primary to limit the current. Parallel the secondary windings and apply power with no load. If the bulb lights the seconday windings are out of phase, reverse them and try again. You should get the proper voltage on the secondary with the bulb unlit.
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At 12:55 AM 10/23/02 -0600, you wrote:
I have a transformer that is center tapped on the secondary. Voltage |
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Re: Dumb question on the drilling of holes
Dave Dillabough
If you end mill is not ground for center cutting you will need a pilot hole.
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At 11:15 PM 10/22/02 -0700, you wrote:
Jon, |
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Re: Dumb question on the drilling of holes
Dave Dillabough
You can get 3 flute drill bits that will do almost as good a job as drill/ream in one pass. There was a thread about this on alt.machines.cnc recently.
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At 03:24 PM 10/22/02 -0700, you wrote:
Tim, |
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Re: vexta stepper/driver
Alan Marconett KM6VV
Hi Zafar,
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You might want to check, The 5-phase Vexta I have is CW/CCW, and 100V. Yes, I ran it off a VARIAC, and made a special version of my controller program to do CW/CCW. Some glue logic could probably also convert step/dir to CW/CCW. The NEMA #34 was a little big for my uses. Alan KM6VV Zafar Salam wrote:
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Re: A few questions: 3:1 ratio okay for accuracy? is my setup correct?
mueller914
I happen to have one of the encoders right here....
part # E2-500-197-G, so it's a 500 CPR with a 5mm shaft I'll try your recommened setting tonight, thanks Mike is 500--- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote: I think that you do not have the proper numbers entered even if itmay be giving the correct steps per inch. I am assuming that you do nothave 25 line encoders which is what you would need to get 25 steps/rev.What we really need to know is the line count of the encoders and whatmultiplier ratio you have the G340 set for. Then with the other information wecan figure it all out.you have a 250 line encoder (far more likely than 25) you will get 1000encoder counts which = steps with this drive after you divide by the pulse10 than you would have 100 steps per rev (way to low, but it is an example).500 line encoder and that the drive is set to 10 x pulse multiplication.That means that the motor really has 2000 steps per rev and the drive is thenreducing it to 200 which equals the 100 step per rev then doubled by 2 xmicrostep. Works, but not my idea of optimum. I think I would set the drivesto 5 x pulse multiplication and then use the settings of 400 steps perrev, no microstep and keep the reduction and TPI you have. You may alsowant to play with the 2 x pulse multiplier setting and then use 1000 steps perrev.
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Re: CAM Software Options
Fred Smith
--- In CAD_CAM_EDM_DRO@y..., Chris L <datac@l...> wrote:
I could get to liking VectorCams toolpath creation more with MINORimprovements. 1. IF it would automatically place offset toolpaths for countouring operations instead of me having to draw them first, and more importantly,In a recent build, Vector has added a new function to the Pocket X-Z profile. If no curve profile is specified, it is assumed to be linear. The angle can be 0 and has the effect of automatically offsetting and making straight or angular passes to depth. Works great for auto offsetting, tool comped tapered cuts, or for creating V-tip offset cuts too. (This is being released with the new 9.4 CD) 2. IF it had a dialog that allowed you to install a specificfeedrate and plunge rate for the particular toolpath/cam action you are attempting to do. I can make it Ask me what feedrate for every line, (takes forever) and then I have to watchcarefully because it also throws in plunge rate when applicable. OR, the better option, it sticks in a default text ( i use FR for feerate, PR for plunge rate, then do I find replace in the editor.Use an NC script. It allows you to place a BMP image and up to 15 dialog items on an interactive dialog. Allows math functions and formatting into the CNC program. Set it up however you want. Works great for just about any kind of canned cycles too. Customize your setup so it only puts plunge rates and feed along rates where you want them. There should be no need to edit your programs with Vector. Put your needs on our user forum, in a posting with exactly how you would like the code to be and you will probably be surprised how easy it is to set up. Additionally it couldn't hurt to allow better toolbars sosimple "drawing tools" are easier to get at and not multimenus deep. It doesn't seem like rocket science.... and I can't imagine why thedevelopers feel these are not crucial additions. It is an incredibly capable program, no doubt about that, and I learn more everytime I use it.The new Vector programmable, Macro Toolbars should take care of any needs for this. Since we are doing a public beta test program on this, it is even available for free for the time being. You can easily automate your feedrate edits that you mentioned above. If they could finish those items, they could get the money I couldhave spent on TC ! Maybe they will come back to that when they are done fiddling with Nurbs, Something as best I can tell, I do not really need.Nurbs are the basis for most 3D organic surface modeling systems. IGES files rely heavily on the use of nurbs curves and surfaces. Rhino is entirely Nurbs based. Vector 3D surfaces now map directly to the same forms. We didn't go the Open Nurbs route (yet) because IGES covers more territory for less development. Solid models are converted to trimmed Nurb surfaces in IGES files. By adding Nurbs capability to VectorCam, we have made the entire modern design world available to our customers, at a very low cost. In the latest versions of Vector, the 3D surfacing option enables the creation of Tru-type text outlines as Nurb curves. Imagine a letter with one or 2 entities, instead of hundreds of tiny little splines. The independent axis scaling is also applied to nurb curves. (Who knows we might even see node editing some day.) Best Regards, Fred Smith- IMService Listserve Special discounts and offers are at: |
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Re: A few questions: 3:1 ratio okay for accuracy? is my setup correct?
I think that you do not have the proper numbers entered even if it may be
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giving the correct steps per inch. I am assuming that you do not have 25 line encoders which is what you would need to get 25 steps/rev. What we really need to know is the line count of the encoders and what multiplier ratio you have the G340 set for. Then with the other information we can figure it all out. Steps per revolution will equal 4 x the lines on the encoder. So if you have a 250 line encoder (far more likely than 25) you will get 1000 encoder counts which = steps with this drive after you divide by the pulse multiplier setting. So if the pulse multiplier is set to 1 X (no multiplication) than you have 1000 steps per rev. If it is set to 10 than you would have 100 steps per rev (way to low, but it is an example). You should have 0 in microstepping as the drive does not microstep. The way you have it configured I would guess that you really have a 500 line encoder and that the drive is set to 10 x pulse multiplication. That means that the motor really has 2000 steps per rev and the drive is then reducing it to 200 which equals the 100 step per rev then doubled by 2 x microstep. Works, but not my idea of optimum. I think I would set the drives to 5 x pulse multiplication and then use the settings of 400 steps per rev, no microstep and keep the reduction and TPI you have. You may also want to play with the 2 x pulse multiplier setting and then use 1000 steps per rev. Tim [Denver, CO] ----- Original Message -----
A few questions: 3:1 ratio okay for accuracy? is my setup correct?aol://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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Balls in tube DRO Resolver to Digital
vrsculptor
A while back there was discussions about using ball bearings in a
tube for a DRO scale. The reader used several excited loops to read its position? I'm not an analog type but would the resolver to digital converter metioned previously: allow you to build a ball encoder? Is it easy or a stretch? Any volunteers to design one? Cost seems reasonable, I'd be happy to spend $89 for the possibility of an arbitrary length DRO. AD2S90-EB PRODUCTION Evaluation Boards - COMMERCIAL $89.06 AD2S90AP PRODUCTION PLASTIC LEAD CHIP CARRIER 20 COMMERCIAL $29.16 Roger |
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Balls in tube DRO Resolver to Digital
vrsculptor
A while back there was discussions about using ball bearings in a
tube for a DRO scale. The reader used several excited loops to read its position? I'm not an analog type but would the resolver to digital converter metioned previously: allow you to build a ball encoder? Is it easy or a stretch? Any volunteers to design one? Cost seems reasonable, I'd be happy to spend $89 for the possibility of an arbitrary length DRO. AD2S90-EB PRODUCTION Evaluation Boards - COMMERCIAL $89.06 AD2S90AP PRODUCTION PLASTIC LEAD CHIP CARRIER 20 COMMERCIAL $29.16 Roger |
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Capacitors for Geckos when using fuses
jagco1998
I have a few more dumb questions....
I dont want to burn anything up, in using components that are incapable of handling voltage/currents correctly. The gecko white papers say that when using a 5A fast-blow fuse to protect the drivers, that a 470uF 100V cap needs to be placed on across power leads. My 1st question is this..Can a 470uF 35V cap be used, instead of 100V as the white papers suggest? I can find them at every elec. supplier in my small town of residence. I am only using a 24Vdc/10A switching power supply to power 3 gecko G201's, and have already placed a 4700uF 35V cap across the PS outputs(I couldnt find anything larger than 35V. I live in the sticks!) Also, is the 4700uF 35V cap going to be sufficient for my PS? Without the cap, a dig. voltagemeter across the output leads tell me that the power only fluctuates from 24V to 24.2V no load. I realize that this probably will become a substantially larger fluctutation once a load is applied. Will a spike or short in the power going to the motors damage them if not protected with a fuse? Would it be wise to also fuse the lines going to the motors also, or is this necessary? Any suggestions or comments will be appreciated. Thanks. Regards, Jim |
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A few questions: 3:1 ratio okay for accuracy? is my setup correct?
mueller914
A few questions: 3:1 ratio okay for accuracy? is my setup correct?
1)I am running a 3:1 ratio for my servos, will this have an effect on accuracy since my step increment will be .00033333333 inches and is not a nice even number such as .0001 or even .0005. 2)I have no idea of the "Steps per Rev" of my motor. I just played with different numbers until "100" gave me the motion I wanted. I also played with the "Microstepping" input as well, so I am not sure which number is correct or if I was just lucky. This is my setup: Steps per rev: 100 TPI of screw: 5 Microstepping: 2 Reduction: 3 Motors are Litton 420oz brush DC servos (bought from Camtronics many moons ago) I did spin the motor manually and counted 22 "detents"...does this mean anything? I'd like to be as accuate as possible with my setup and I am not sure if 100 SPR is okay or not, just 'cause it works, does not mean it's correct.... I'm running Gecko 340's as well. Thanks |
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