Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- CAD-CAM-EDM-DRO
- Messages
Search
|
Re: 10 amps to drive steppers
Dan Mauch
The camtroinc controllers run just fine without a motor connected.
toggle quoted message
Show quoted text
No damage will occcurr with the drivers if a motor is left off. Never disconnect or connect a stepper motor while the power is on. You will create an inductive spike which can fry the output chips. If a stepper in connected to the power supply and the unit is shut off then the cap will be discharged by the motor. But if you are testing the ciircuits without a stepper connected then a resisdual charge will be held on the the electrolytic caps. Dan -----Original Message-----
From: Mo <mo@...> To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...> Date: Monday, June 14, 1999 8:02 PM Subject: Re: [CAD_CAM_EDM_DRO] 10 amps to drive steppers From: "Mo" <mo@...>somethingFrom: Jon Elson <jmelson@...>Jon, unfortunately both types of board I have here warn that this is a up and put it on Tim's site for members who would like to go that route.discussion of shop built systems in the above catagories. To Unsubscribe: |
|
Re: New member, something interesting
Dan Mauch
I have some low cost thompson 5/8" .200 pitch rolled ballscrews on my mill
toggle quoted message
Show quoted text
drill. They cost .98 and inch from McMaster -Carr and thre ballnuts are $18. I replaced the .1243 balls with .1248 ball and reduced the b/l to about .002. They work great on machines like the mill drill and the shoptask. Dan -----Original Message-----
From: Jon Anderson <janders@...> To: CAD_CAM_EDM_DRO@... <CAD_CAM_EDM_DRO@...> Date: Monday, June 14, 1999 3:20 PM Subject: [CAD_CAM_EDM_DRO] New member, something interesting From: Jon Anderson <janders@...>discussion of shop built systems in the above catagories. To Unsubscribe: |
|
Re: FAQ etc
In a message dated 6/15/99 3:45:25 AM Pacific Daylight Time,
rhj-rbj@... writes: So come on you lot express yourselves as I am sure I am not the only one.There are 201 members on the list this morning, and that means a lot of lurkers. I hereby give you guys (gals?) permission to join in on the discussions....... grin. bill List Manager |
|
FAQ etc
"Raynor Johnston" <[email protected]
Hi guys I think your response to the suggestion is great and certainly appreciated by yours truely but as it would take time for you busy guys to put together it might be a good idea to check out whether all those other lurkers do in fact exist out there and ask them if they would also appreciate the page.
So come on you lot express yourselves as I am sure I am not the only one. cheers Raynor J |
|
Re: ball screws Backlash
Dan,
I'm not sure how to reply without getting a bunch of the old mail included sorry. But about your lead screws, how do I contact Thompson? As far as the backlash error, if you preload two ballscrews against each other couldn't you effectively eliminate the backlash? I know the more expensive mills used backlash eliminators (see page 97 of "Machine Shop Practice" Vol. 2, if I ever get a scanner I'll send PICS instead of references) with two nuts and adj. preload on the nuts with acme lead screws. It not only nearly eliminated backlash but also prevented damage to the cutters servos, etc., when climb milling with heavy feeds. This was the approach I was going to take with my mill, however the ball screw setup seems to be a better way to go to cut down on the drag and size of the servos required. Tracey DeChambeau |
|
Re: Vac Forming
Hi Folks:
I am looking for someone to do some vaccum forming of RC micro heli canopies. Looking for 10 units at the moment. I provide the plug (s). Please call me or write to me direct. I do not want to go with a large company because of the high cost involved for such short order. I am looking for someone that knows how to vac form and has descent equipment. Someone that does this from home perhaps? I am pressed for time, otherwise I would vac form the canopies myself. Material has to be lightest available, styrene or similar clear. TIA Mario 773-777-1692 |
|
Re: MaxNC modifications
Andrew Werby
Jon Anderson <janders@...>
Subject: New member, something interesting Hi, I'm new to the list, thought I'd introduce myself. [Welcome aboard, Jon!] I presently have a heavily modified MAXNC and am building a CNC retrofit for my Hardinge chucker, Omniturn style. Using Ah-ha software at the moment on the MAX, but I'm going to be building up a Linux box and giving that a shot. [What is the advantage to using Aha software on the MaxNC, over using their supplied software?] Modifications to my MAXNC include 198 oz/in PacSci motors, [Were these easy to mount, or did you need to machine new mounting plates? How much were these motors, and did you get them new or surplus?] Computmotor OEM 650 drivers, [Where did these come from? Are they what Aha recommends?] motor mount plates with preloaded ball bearings to handle thrust loads, [Were these something you purchased or built from scratch? ] BS&A ActiveCam nuts and 16 pitch screws, [Are these ball-screws, or is this an anti-backlash modification to standard screws?] a Sherline spindle assy and DC motor. Somewhere down the road when I get some free time I'm going to post drawings of all the mods, making them available at no cost. If anyone has seen the Flashcut CNC Sherline at the Santa Clara Machine Tool show a couple years ago, I built it. Something I just ran across that might be of interest to some folks is a new low cost ball screw from Thomson. They have a design contest going and are giving out free samples for as long as they last, you can apply at Just got mine today. These sure are no substitute for ground or even precision rolled screws, but they just might have some potential for the low end HSM CNC. Screw dia is fixed at .380 with a 16 pitch. Lengths available are 6", 12, 18, 24, 36, and 48". Nut has no provisions for mounting and is .75 in dia and .775 long. There is a single return tube held in place by an injection molded cap. Backlash specs are between .002 to .007, mine came in at .005. It should be possible to clamp two nuts in a split block with perhaps a spring washer to help set a light preload (obviously, before the nuts are clamped). [Do you think they would fit a stock zero-backlash nut?] Mine felt a bit rough, but was dry. A bit of grease helped a lot. Mounting these on a Sherline would require some significant modifications, less so for a MAXNC. They might well be a viable option for a scratch built machine. I saw this in last months Machine Design. The screw came out of new mfg methods developed for the automotive industry and mention was made that they could cost as little as $5 ea. Obviously a qty price, but it ought to give an idea where these might sit relative to existing ball screws. Jon [Do you think the 48" screws would be adequate to run a CNC router, or are they too skinny? Was there any indication of their price in small quantities (like six each?) I've been thinking about building a "big cube" router from scratch, and cheapness is definitely a consideration, but I thought I'd probably need beefier screws than this, or some other kind of drive mechanism. Any advice is welcome, including thoughts on the control system and the advisability of using linear motion bearings versus other systems, (like skateboard wheels rolling on angle-iron rails).] Andrew Werby Andrew Werby - United Artworks Sculpture, Jewelry, and Other Art Stuff |
|
Re: Installing rotary encoders
Jon Elson
From: "Ted" <rtr@...>Most encoder warranties are voided by NOT using an appropriate coupling. I use couplings made from a single piece of metal, slotted helically to provide radial and axial compliance, but no torsional compliance. Actually, many good encoders have a fair amount of drag in their bearings. They use a pair of angular contact bearings with preload, to stiffly constrain the shaft from any radial movement, which would show up incorrectly as rotation. They also have at least one, usually two shaft seals, to keep crud out of the bearings, and grease out of the optics. That all adds up to inch-ounces of static drag. I'm using 1000 line encoders, counting all transitions, so that is 4000 counts/rev, or more than a count for every tenth of a degree. It would be foolish to waste that accuracy with a homemade coupling that allowed twist to develop. Also, the metal coupling is good for many years, what if the surgical rubber turned to gum? Do you know what OIL does to LATEX? Yucck! I don't know how a precision machine could possibly keep any accuracy if there is .010" longitudinal movement of the screw! I have a total of .001" of slack in my mill, and I'd like to find the sources, and reduce it. But, that is the sum of ALL the sources of slack, like torsion of the leadscrew, shaft couplings, bowing of the screw, slack in the angular contact bearings, slop in the anti-backlash ballnut, etc. etc. Jon |
|
Re: EMC stepper & misc fixes
Tim Goldstein
OK, now I am guilty of replying to my own posts.
toggle quoted message
Show quoted text
I found a problem in the new jun-14 build. When in manual mode the first time you do a jog on an axis it moves at about .5 ipm. After the first move all subsequent moves are at the rate indicated in the feed rate box. If you go into another mode and then return to manual the S L O W move returns for the first move. I am not quite sure on this one, but I think it occurred. I will try it again next chance I have at the machine. I believe I ran the Verify on a file and it showed no errors, but when I ran the part it errored on a G2 command with the traditional "your end and start radius don't match within an angstrom". Tim [Denver, CO] -----Original Message----- |
|
Re: FAQ-Volunteer???
Jon Elson
WAnliker@... wrote:
From: WAnliker@...I don't know how much space I can get before people come after me with pitchforks, but a couple megabytes should be no problem. So, text would be OK, but if you are thinking pictures, then it could be too much. I already have a web site, which I intend to add a lot more CAD/CAM info to. Jon |
|
Re: EMC stepper & misc fixes
Tim Goldstein
I downloaded and installed the new build with no problems tonight and had a
toggle quoted message
Show quoted text
few minutes to play with it. The Verify button is a big improvement in my mind as we can now at least parse through some code real quickly without having to run the machine or start up a simulation. I played with using the Run From Set Point as Matt suggested, but found that it was a little flaky about starting at my chosen point. Seemed to work sometimes and not others. The Verify button seems easy to use and reliable. Thanks Fred for the rapid updates!! Tim [Denver, CO] -----Original Message----- |
|
Re: 10 amps to drive steppers
Tim Goldstein
Mo or Jon,
toggle quoted message
Show quoted text
Would love to have a schematic of this setup and would definitely be happy to get it posted. Regarding disconnecting a motor on a Camtronics board while it is powered and running, I inadvertently did this once and the board survived with no harmful side effects. I may have been lucky as I only had some small NEMA 23 motors set up at about 1 amp. Tim [Denver, CO] -----Original Message----- |
|
Re: electrical help needed: kinda ot
"Mo" <[email protected]
Ted,
Check out e-bay. When I searched on transformers I was flooded with a list of thousands of those darned toys that switch from a car to a robot...after wading through them there are a few links here - note shipping will be a @*!@'^1 though sea shipping should be reasonable. You can e-mail the advertisers to get more info obviously it's ultimately for you to check out the suitability of whatever you see. If you are real hungry check this out !!!!! there are smaller units which may be suitable: Mo I didnt make it clear, the problem is that most all the110(DC) hardinge is tring to find a wiring diagram, they said not to hold mybreath. thats why they said a step up transformer from 220 to 440 would be the way to go just hook it up |
|
Re: EMC C code - Real Time DOS and Win 3.1
James Eckman
From: Jon Elson <jmelson@...>
Well, it is not so simple, because EMC is not a single program, but aI never claimed it would be, but it could be done because it has been done in the past. The final nail in the coffin of these OSs is thatLinux can be unstable also, although the kernal has been greatly cleaned up over the years. A true benefit of open source. The problem with nailing this coffin is some customers insist on certain tools and OSes being used, even if there is a better alternative. P.S. I have started looking for a used laptop to run Linux/EMC on, anybody done this yet? I'll probably use steppers driven through the parallel port in some combination. The only problem could be is an X windows driver for a particular laptop combined with a non-standard parallel port. What is the minimum umph the CPU needs to run EMC with steppers? I would assume this would blow off the servo loops and unload quite a bit of CPU time. Jim Eckman |
|
Re: electrical help needed: kinda ot
Ted
rtr@...
You have three phase coming in so you need to find a three phase transformer to go from 220 to 440 or you need three single phase 220 to 440 transformers. If you can get two transformers that put out about double the required current (see below), and you have a ghost phase coming in, that is, there are really only two transformers on the pole stepping down from the higher voltage lines to the 220 three phase coming into your shop, you can use just these two heavier duty transformers on the real phases coming in. You need about twice the capacity on these two transformers because the current for the ghost phase is still going through these two transformers. You can usually discover with a voltmeter and a clamp on ammeter which is the ghost phase. When you load it with this machine or any other, if you are loading the ghost phase, the three voltages on the primary will be further out of balance than if you are not loading the ghost phase. The shop may be wired with a delta off which the main phase is split so you get 120 volts on each end of that phase to the center of that phase, which is grounded. When you look at the power pole, the large transformer is providing that phase. You hook up one transformer across that to get two legs of 440v. Then you hook up the stinger, the 208 volt to ground to either leg of the main phase you already identified. Record your readings, then disconnect from the main phase transformer and reconnect to the other end of the main phase transformer. Record your readings again and, if it is now more balanced than when hooked to the other leg, leave it. Otherwise, disconnect it anc reconnect to the other leg. Not as easy as the first two solutions. The other way, and you are going to have to do this anyway if the manufacturer can't find the prints, is to trace out the circuits. Time consuming, but you can't really troubleshoot properly without a print, so if you can't get one you must make one. Experienced people who do any more than very simple troubleshooting without prints often burn up machines. This sounds complicated, but it isn't electronics, it doesn't require a scope, and it submits to any reasonably intelligent person for the price of only a few pints of blood. Good Luck, Ted ---------- From: mike grady <mgrady@...>110(DC) hardinge is tring to find a wiring diagram, they said not to hold mybreath. thats why they said a step up transformer from 220 to 440 would be the way to go just hook it upThey coursewill be marked with the control voltage used on that machine. Of willit's easier if you have a copy of the wiring diagrams. Manufacturere 220/240usually sell you a copy from their archives, though they sometimes will onor 208 volt (depending on your own mains) transformer that takes 8 amps itthe primary. If it is the secondary winding that provides 4 amps, then ------------------------------------------------------------------------still only needs to provide 4 amps at the secondary voltage. ------------------------------------------------------------------------Having difficulty getting "in synch" with list members? ------------------------------------------------------------------------welcome to CAD_CAM_EDM_DRO@..., an unmodulated list for thediscussion of shop built systems in the above catagories.To Unsubscribe: day!Who is the most visited e-mail list community Web Service? ------------------------------------------------------------------------ discussion of shop built systems in the above catagories.welcome to CAD_CAM_EDM_DRO@..., an unmodulated list for the discussion of shop built systems in the above catagories.To Unsubscribe: To Unsubscribe: |
|
Re: 10 amps to drive steppers
"Mo" <[email protected]
I was asked recently by another member about how to size up a suitable size
of smoothing capacitor for the linear power supply that most steppers use, the linear type with a transformer, bridge rectifier etc.and if there is a formula. The answer is heavily dependent on the current load demanded by the stepper driver(s) that the supply must service. Recently there was a thread here where Dan Mauch gave some guidance in quantifying the current load on the supply. When you have the current load look at the specs for the capacitors and you will gerally see a spec that indicates the max current at a frequency of 120Hz or 100Hz and then another at 20KHz. The one that most interests us is the one at 120Hz or 100Hz. When you rectify the AC voltage from the transformer through a full wave bridge diode, you will get the negative going half cycle flipped positive so we get two positive peak - so our 60Hz AC frequency has become a 120Hz varying DC frequency countries which use 50Hz AC will result in a 100Hz rectified frequency. So the spec will indicate the max current suppliable at frequency. For thsoe interested in a formula to derive the capacitance themselves, it is : Vripple = I load / ( f x C) or C= I load / (f x Vripple) you need to decide what level of ripple voltage you will accept. As the voltage waveform reaches a peak then falls off, the capacitor will start to discharge into the load acting as a reservoir during the dip in rectifier output. Whilst discharging, the capacitor's voltage will drop until the rectifier volatge rises again and starts to recharge the capacitor this causes a not so constant final voltage but one with a ripple. The ripple voltage is the difference between the highest and lowest ebb of the smoothed voltage. if you require a capacitor value C to allow a max ripple of say 2 volts, and need to supply 8A at a rectified frequency f of 120Hz the calculation would be: C=8A / (120Hz x 2V) C= 33,000 uF The current in the above formula is assumed to be constant which of course a stepper chopper load is not and as the voltage drops the driver will hold the phases on just a tad longer until it gets to the trip current for the chopper but armed with an averaged value for load current with greatest nummber of phases driven as in Dans message should be a good start - if the cost difference is not too great then go one size up e.g 47,000 but at least you have a calculated value range to work with now. Mo |
|
Re: electrical help needed: kinda ot
mike grady
I didnt make it clear, the problem is that most all the
toggle quoted message
Show quoted text
control, heaters, transformers, would have to be changed some 440 some 110(DC) hardinge is tring to find a wiring diagram, they said not to hold my breath. thats why they said a step up transformer from 220 to 440 would be the way to go just hook it up Ted wrote: From: "Ted" <rtr@...> |
|
Re: electrical help needed: kinda ot
Ted
rtr@...
That's a control transformer, It takes line voltage and reduces it to control voltage. Depending on the year, the secondary winding on the transformer is typically 110, 12, 24, or 48 vac. Other voltages are sometimes found. Just look at the devices fed by that transformer. They will be marked with the control voltage used on that machine. Of course it's easier if you have a copy of the wiring diagrams. Manufacturere will usually sell you a copy from their archives, though they sometimes will give you a copy. If the primary uses four amps you will need a 220/240 or 208 volt (depending on your own mains) transformer that takes 8 amps on the primary. If it is the secondary winding that provides 4 amps, then it still only needs to provide 4 amps at the secondary voltage. Don't forget that overload protection and full voltage coils must be changed to handle the halved voltage and the doubled current. Control circuits do not require any changing. Any normal industrial electrical supplier should be able to provide a transformer. Ted Robbins. ---------- From: mike grady <mgrady@...>discussion of shop built systems in the above catagories. To Unsubscribe: |
to navigate to use esc to dismiss