Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Flying Scot on February 01, 2008, 08:05:57 PM
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I have set up my spindle on my mill to run from 300rpm to 3500rpm with ratio set to 1 as my rpm sensor is reading from the spindle. I have set the Campbell board to give 0.to 5v (as required by my spindle control board) over this range and it seems quite linear as 1750 rpm gives a reading of 2.5 volts. the RPM as read by the index pulse is exactly the same as shown my tacho. I am using Mach 3 v2.64
The problem is that I can not get the measured speed to match the requested speed. I have use spindle feedback in sync mode checked in spindle setup. I have also tried spindle calibration.
Can anyone advise where I may have gone wrong.
regards
Arthur
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Arthur - I seem to have this problem. I take it you have done the spindle calibration on the automatic mode. This on my lathe then set the spindle moving at an increasing rate. It then came up satisfactory - save data (or something similar) which I did. But the spindle speed still seemed to be about 10% up in my case. This I reckoned to be because my feed to my Omron Inverter scaled 0 - 12v instead of the asked for 0 - 10.
That seemed to be the case all the last session with the lathe, and although I was using G96, Constant surface speed mode, the actual speed seemed to be up on the asked for speed. Today, when turning some little thing up, I set the speed using the speed DRO on the screen. I had reset the lathe with a G97 - The recorded speed was exact (within 2 rpm either way ) of the asked for speed of 800.
I don't know if the programming gang can comment on the apparent problem ???
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Have you gents made your own once per rev probe ? If so could you point me towards any posts that discribe what designs work ? I have searched for the data but not much luck so far. Thanks.
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Perfo
I use an Optec 917b slotted optical switch, can be had from RS in the UK.
You will also need a 220 Ohm resistor to limit the current to the LED in the switch.
You will then need to fit a disc to the spindle which has a slot in it, I use a 10mm wide slot on both the mill and lathe and they work well, disc Dia is 80-mm on the lathe and 100mm on the mill. Heres a pic of the one on the mill.
Hood
(http://mysite.wanadoo-members.co.uk/hoodsmachiningpages/BOSScomplete/SpeedSensor.jpg)
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Thanks for that Hood. It looks a simple enough addition and should give a pretty good clean output. Did you need any interfacing electronics? Are you coupling this directly to a breakout board or smoothstepper or what have you ? It looks like it's only £5 from RS so no point trying to build something myself
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I suppose I'm still on topic with the this question. Now I've got my OPR probe sorted what do folks find works for controlling the spindle speeds? At present my 626 mill has only got the swap the ratios of the pulleys type speed control. I could rig up a thyristor fired motor speed controller but this would only give me a wider range per ratio or is there enough torque if the ratios are left on the fastest setting and just control the motor speed. How do you fellows do it ?
Thanks
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Thanks for that Hood. It looks a simple enough addition and should give a pretty good clean output. Did you need any interfacing electronics? Are you coupling this directly to a breakout board or smoothstepper or what have you ? It looks like it's only £5 from RS so no point trying to build something myself
I just connect through the breakout, although on my first mill I connected directly into a second parallel port. Only thing you need is the optical switch and resistor and a 5v supply.
I suppose I'm still on topic with the this question. Now I've got my OPR probe sorted what do folks find works for controlling the spindle speeds? At present my 626 mill has only got the swap the ratios of the pulleys type speed control. I could rig up a thyristor fired motor speed controller but this would only give me a wider range per ratio or is there enough torque if the ratios are left on the fastest setting and just control the motor speed. How do you fellows do it ?
Thanks
What type of motor do you have? AC? Single or 3Phase? DC?.........
For AC 3 Phase you can use a VFD but you will not get good spread of torque so ranges still need to be used. Slow spindle speeds are used for large cutters/drills etc so you need torque, a VFD wont provide that unless you drop the gearing also. That is my experience and opinion at least, others have disageed and I suppose it all boils down to what you are doing and how capable your machine is.
Hood
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I just connect through the breakout, although on my first mill I connected directly into a second parallel port. Only thing you need is the optical switch and resistor and a 5v supply.
Hood, I can not seem to find the data sheet on that switch, any chance you have one? I'd like to give this a try in the future but can't find that particular switch in the USA so I thought I'd try to cross reference it with something else.
Thanks,
Dave
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http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=4550919
This is the switch in the UK you can view the datasheets on line.
http://www.alliedelec.com/Search/SearchResults.aspx?N=0&Ntt=slotted+optical+switch+917b&Ntk=Primary&sid=11B3A79D9029&i=0
This is the closest I could see on the US site.
The switch doesn't do anything particularly clever it's a light source (often infrared LED) and a photodetector often a photo transistor either mounted in an IR transparent package or has small lenses to stop cross talk etc. As long as it will run on the voltage you need and will provide a sink for the data pin (usual to put a pull up resistor on the output) you may also need to put a current limiter resistor on the feed to the LED depending on what one you get. Oh and ensure it will run at the max frequency you intend but this is unlikely to be a problem.
The thing I worried about is would the parallel port read it quick enough to get an accurate reading or would there need to be some electronic scaling but Hood has answered this one and fortunately it'll bolt straight on. I'll be trying to connect mine to the smoothstepper board (on order) which has a dedicated input for spindle speed (I think).
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It's a 1.5HP single phase. I suspected the low speed torque would be a problem if left on the high gearing. Still it's not a problem to change belt pulleys before a job and thus will give me a band of speeds available with some sort of variable frequency motor control. As I'm trying to do as least invention as possible to get it up and running have you any experience of a variable frequency controller that will work on Mach 3 for 1.5 hp single phase ? I've also got a lathe that I may be converting (if this one goes well) and hopefully building a large 8' X 4 ' router in the future and the good thing is all the drivers, speed controller and most of the CNC kit except for the steppers will be able to be used on all of them and thus will cut the cost of the conversion somewhat. Thanks again.
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I do not think that the speed of a single phase motor is variable. You will need to change your motor to a three phase one. Once you do this you can get several makes of single phase to three phase inverters to control it. Mine is an Omron (quite old) but very servicable. I changed my motor from a 1hp single to a 1 3/4 hp three phase motor - and controlled it with the Omron manually. The Omron gives full speed and direction control. The torque of the motor falls off if you try and use it below about 50% speed (30 hz), so I will be putting in some gearbox/pulley arrangements to turn some of my larger pieces.
Unlike Hood, who uses a slot detector, I use a reflective detector - same principle - ir.led shining and reflects onto a detector - mounted 5mm from my chuck mounting plate (painted matt black). A small reflector, made from my granddaughters "sticky" bits and pieces, stuck to the edge of the mounting plate, reflects the IR back once per rev.
As I put in the original post, it works well, but seems to over read. I put this down to a 12 volt supply to the Omron instead of 10. I will work on that.
By the way - one inverter (providing it is large enough for your largest machine, can supply all your machines, you do not need an inverter for them all. (You can only use one at once, though)
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VFD are normally for 3 phase motors but you do get ones for single phase motors. Never used one or even seen one for that matter but a quick google brought up this one.
http://www.minarik.com/cgi-bin/ECA_Software/ECA_Search/ECA_Search.pl?TID=minarikcorp%20-%20ProductDisplay%20-%20AC_DRIVES&TERMS_PARTS_CUSTOM.PART_ID=AC211S-1.1&TERMS_PRICING.DISCOUNT_CODE=USER&TERMS_PRICING.DBASE=DIST&TERMS_PARTS_CUSTOM.minarikcorp=1&TERMS_INVENTORY.dbase=DIST
Seems from a quick look it can be controlled by 0-10V so you would need a speed controller similar to the type Peter Homann (and others) sell. www.homanndesigns.com
Hood
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OOPS,
Forget that link for the VFD, further reading makes me think its only for a 3 phase motor.
Will do a bit more searching .
Hood
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http://www.anaconsystems.com/text/opti_e2.html This one looks more like it.
Hood
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As far as I know the common single phase motor runs at a speed slightly behind the circulating stator field, as you apply load the 'slip' or difference between the applied field and rotor field increases and draws more current trying to catch up. so in essence all you have to do is provide it with a sort of sin wave at whatever frequency you want (within reason) and the motor will try and match it ( I may be completely wrong of course). Problem being it is a lot harder to produce a good variable frequency controller than some sort of chopper controller that basically turns the power off for part of the cycle and thus gives you poor low speed torque . Handy you only need one converter and just switch it to one machine or the other but it would mean swapping the motors on the lathe and miller which I suppose isn't a huge problem as they have the same foot print and shaft size but is extra hassle and extra cost as well as the cost of the converter. So I may have to leave it as it is for now unless I come up with a cheap set up for either. Hood if the VFD thing requires 0 to 10v to set the speed, what does Mach3 give out to try and control it? Is a frequency control or a pulse width controller? either one is fairly easy to get 0 to 10v out of especially if it can be set up as part of a feed back loop and thus any inaccuracies in the drive circuit get noticed by the once per rev and will auto compensate. The sticky reflective pad is also a good idea as I could mount this in the pulley housing on the spindle pulley and thus keep it out of the way of danger though I suppose I could also mount a slot plate up there so both are possible.
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I looked at that one Hood yep it looks like it would do the job but $525 plus tax plus shipping...hmmm it may just end up a would like for the future.
Jim I've had a thought about your over speed problem and I'm thinking it would be unlikely to be the supply voltage to the box as it's a digital signal it's not easy to see how supply fluctuations can give you a multiplier effect. I would tend to think you are getting multi pulses from somewhere these things are quite fast enough to trigger a couple or more times on the same target. Is the target as small as possible and completely flat i.e. no bent corners ?If you use reflective material such as the reflective strips on clothing they contain a number of miniscule reflective surfaces to maximise the chance of getting a reflection no matter where the light source is and thus something like this could give you multiple triggers. The other thing that can effect IR receivers is back ground light. I know it's not meant to but there is a fair bit of IR in normal light so maybe something is being reflected off something else? I would think a small blob of Tipex would give you a good enough target to try in case the multi trigger is your problem. I'm thinking aloud here so please feel free to ignore me if (no doubted) you've already thought of all this. The only other thing I suppose is noise pick up on the cable it it’s long enough or goes near enough to an electrically noisy thing.
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I think Mach can either use PWM or Step/Direction for the spindle.
One thing might be worth looking at is getting 3 phase motors for your machines, single to 3 phase VFDs can be got often quite cheaply on eBay, think the most I paid for any of the ones I got was £45 and £60 for my 5HP ones for the Bridgeport. I have 3 phase so the ones I have are 3 in 3 out but some can be used single in 3 out with a bit of derating, a quick check of the manual of any you see will let you know if thats the case. Also eBay is a good place to pick up 3 phase motors as they go fairly cheap and once you have them you will get more for your single phase motors ;)
Hood
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http://www.alliedelec.com/Search/SearchResults.aspx?N=0&Ntt=slotted+optical+switch+917b&Ntk=Primary&sid=11B3A79D9029&i=0
This is the closest I could see on the US site.
The switch doesn't do anything particularly clever it's a light source (often infrared LED) and a photodetector often a photo transistor either mounted in an IR transparent package or has small lenses to stop cross talk etc. As long as it will run on the voltage you need and will provide a sink for the data pin (usual to put a pull up resistor on the output) you may also need to put a current limiter resistor on the feed to the LED depending on what one you get. Oh and ensure it will run at the max frequency you intend but this is unlikely to be a problem.
The thing I worried about is would the parallel port read it quick enough to get an accurate reading or would there need to be some electronic scaling but Hood has answered this one and fortunately it'll bolt straight on. I'll be trying to connect mine to the smoothstepper board (on order) which has a dedicated input for spindle speed (I think).
Thanks for that, no wonder I couldn't find anything on it, Hood speelled it ending with a "C", not a "K", lol!
Thanks again- :)
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spelling is not my strong point ;) Come to think of it I dont think I have any strong points :D
Hood
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No sweat, my friend, thank you for the future help on this when I need it ;)
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ha ha no probs
Hood
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Hood you put your weak points in the CNC and now you've got a box full of strong ones. :-)
Very good point about selling the single phase motors they do go for more than three phase and would off set the costs of getting the converter I think I would still have to use the gears though unless upgrading to a 3hp motor would give me enough torque at the bottom end.
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That is the way the industrial machines used to do it before they started going with Servos for spindle motors, Brett has a Hurco which he is doing at the moment, think its got and 8 or 10Hp motor on it, there is no need for that HP from a machine that size other than it was controlled by VFD so to get the low speed torque the HP had to be a lot greater.
Hood
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Anything above about 3 hp would start to give me problems with my supply. Still I may give it a go once everything else is up and running. I've got my eye on a small three phase motor already that I may be able to get for a very reasonable price as it's in a mates garage and he isn't doing anything with it. I work in a power station so you'd have thought there would be plenty getting scrapped here and there but unfortunately most of them you'd also need a power station to run.
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Hello,
Could any body help me how to configure spindle in PC base MACH3 softwatre vresion 3.041 ? I have milling machine ibn which i am facing this problem .Please help me tos et the spindle of the machine. It does not move at all i am starter for Mach 3 .
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Please detail what hardware you have the motor connected to, that way someone will be able to tell you how to set it up.
Links to the hardwares web pages would be good if you have them.
Hood
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Mr Hood
Thank you very much for you reply regarding setting up spindle run.
When i opt step/dir motor option spindle does not run at all. BUt when i Opt PWM and spindle output motor option. and put test command M03 s1000 or s200 or anything. Spindle just move farction of seconds than it gets stopped.
on the lowest window one comments shows up PMW limiting value low or something.
I would be thankful to you if you could help me to set the spindl e up.
My mill is mini mill by sumore It is MACH3 PC base . Connected through one end of chord to a machine and another chord to 25 pin connector which is in built in the PC board.
Please help
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I did a quick search for your mill and didnt come up with much, do you have a link to any documentation. Without knowing what hardware the spindle uses for speed control no one can tell you how to set it up.
Hood
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Mr Hood
Hello, are you oline? Some how i am able to start Spindle of my mill. But now i cannot control it at all. It always moveio on anticlockwise wth high speed.
I did a little setting I went to
Pin and ports. then i enable spindle. after enable it i went to spindle option. there i selected PMW option. and us spindle motor out put.
After this when i gave command M3 or M4 in Input then spindle moves at good speed but anticlockwise. Please tell me how i control it .
I am using mini mill SP2215 www.sumore.com
Please advice
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Breezetools, It looks from the picture of your mill that it has already been set up as a CNC and thus the spindle problem should have already been checked as working. Did it originally come with Mach 3 and a PC or are you trying to convert it ? Is the motor 3 phase ? or single phase ? If the only problem you have now is it turning the wrong way and it is a three phase motor then all you need to do is to swap two of the phases over.
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Mr Hood
hello, Thank you for your reply. It comes with MACH3 ready and it is a pc based, We have our own pc as per Mach3 requirments.I purchased a license also.
Now as per guidelines i am trying to conect my pc to to machine with 25 pin chord.
i am able to set the axis somehow i am able to start the spindle but i am not able to control the spindle. When i give command m3 or m4 it moves only anticlockwise,
My motot is SINGLE PHASE
Please help me to set my PC As per required settings.I would be thankful to you.
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If you bought this machine new then ask the supplier for the xml file. You may already have it if you got a CD with Mach on it.
Without knowing how the spindle works I cant really say how to set it up, if you had documentation of what hardware is used then it could be worked out.
If your motor uses relays to switch on then possibly both relays are set for the same pin and should be set for two different (1 for M3, 1 for M4) but again without knowing the hardware on the machine its impossible to say how it should be set up.
Hood
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Tis indeed a tricky one without any details.
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Hi, I'm struggling to make sense of what's happening with my spindle control. MACH4, Microsoft XP, Parallel port and Darwin. I see the pulse rate affects the outcome on my speed? Is that right? My set up is on a 3040 chines mill with the router that comes with the original unit. 300 – 8000 rpm. Putting a taco on it I seem to be getting a range from 5700 to 10830 rpm, and that's trying to control it via Darwin. 0 gives me full speed and 20000 gives me 5700rpm. So from Darwin I get a reasonable range. MACH4 I'm lost. The on/off works, PWM seems to work but not full range and same effect with the min/max freq setting. In the freq range I used 0 to 20000. When controlling from the GUI, there is a limited response from the slider 50 % to 150%, which also has the opposite affect i.e. 50% runs faster that 150%? It put values in at the top when running, 150=50%, 300=100% and 450=150%, but I can't work out where its getting the 300 from? The PWM set up does pretty much the same. ???
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You would be better posting this on the Mach4 section as this section deals with Mach3 for the most part.
Hood