Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Smackre on November 22, 2006, 09:36:12 AM
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So i just finished up installing my VFD. My spindle is a 24000rpm spindle. The VFD speed control uses a 10v signal to tell it the speed. But some reason i cant get it to go the right speed that mach tells it.
If i set mach to max 24krpm and tell it to run 12krpms its is actualy running at 15krpm. But if i twist the nob on the speed controller going to the VFD so that its running at 12krpm instread of 15k then it runs slower than 24krpms when you tell it 24k.
Id like to get it running within 500rpm of the actualy speed typed in. Is this possable?
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Does your board have an adjustment pot for the 0-10 volt?
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Yes it does. even when i use that it only gets a sertain rpm right and then the other are way off still.
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Have you tried the spindle calibration?
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No i have not. Where can i find instruction on how to use it?
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Look here. I have never used this but I think it will have something here.
http://www.machsupport.com/documentation/M3M1_84-A2.pdf
What version of Mach are you running? In ver. 2.0.12 it is in the function configs. tab.
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im running whatever is the newest verison.
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I could not find anything about spindle calibration in that pdf.
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Someone will clear this up for you. I wish I could do more but I think I'm going to have to replace my hard drive now. Did you find it in function Config? I would play with it and try the auto cal.
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I ran the autocal and it didnt change anything. I dont think the spindle calibration has anything to do with how my spindle works. I may be wrong but i think its a diffrent setup you would use that for. My spindle works threw a chargepump that controls a speed control which hooks to my VFD.
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What are you using to sense spindle speed? Is the motor to spindle gearing one to one?
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I am not using anything the sense spindle speed. The computer is hooked to a spindle speed control via serial port and that is hooked to the VFD and the VFD tells the spindle how fast to turn.
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I wish I knew more about this for you. I had asked earlier if the gearing is one-one. I think it is direct drive isn't it? I think that with two adjustments that could be causing a problem, I'm not sure though. Some one will help clear this up for you. I'm going to send one of the smart guys a PM for you. ;D
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There is no motor. Its just a spindle controlled by a VFD.
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Yes, that is what I was talking about. All one piece. Maybe help will be here soon.
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Hey, what speed controller are you using? Could you tell us exactly what equip you are using and how it is all connected?
It should be possible to get it dialed in. On my big mill I just set the vfd at 18000 and switch it on and off. On my little mill i have a grex, so i use the analog out and it works pretty well. I know that doesn't help , sorry, i have not used the serial control yet but we should be able to figure it out.
Chad
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The controller is Sound Logic's new speed controll board. It runs off the parallel port. It uses a chargepump to control the speec controller. The VFD is a AC Tech. So it is connected like this:
Computer serial cable connects to the Sound Logic Speed controller which is connected to the VFD which hooks to the spindle.
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Ok so lets just assume for the moment that mach is sending what it should to the speed control.
The first thing i would do is make sure that the speed controller is scaling linearly with mach. Set mach to 0 to 10000 max spindle speed. turn off the vfd and get your scope or volt meter out and look at the analog out of the speed controller. If you set mach S1000 you should get 1v s5000 should get you 5v. Look at that then we will go from there.
Chad
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at 10000rpm it reads 10.000 at 75000rpm it reads 7.2 at 5000rpm it reads 4.64 and at 1000rpm u get 1.02
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Boy that is strange. As much as i hate to pass the buck i would recomend giving bob a call and see what he says. I sounds like an issue in his board or in the charge pump.
It should be linear..
Chad