Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: guynamedbathgate on December 12, 2006, 06:28:34 PM
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well Ive just put my kit together for my cnc mill and ive got my first software question.
ive set the steps per inch to 20,000 just like the directions for my servo's sais. but when I do. I can only turn the max velocity up to 75 ipm. when I should be able to do about 120. I thought it was a problem with the kernel speed but I turned it up to 45000 Hz and still can only turn the velocity up to 75ipm.
any thoughts?
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Hve you confirmed it is actually doing 45Khz, should be on the diagnostics screen, but as I dont use a standard screenset it might have changed.
Also without knowing your ballscrew pitch and if you have reduction I cant say what max you should expect to get.
Hood
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Hi, guynamedbathgate
Have you increased / Adjusted the Velocity and Acceleration settings under, Config., Motor Tuning, with 20000 steps you probably need to.
Hope this Helps, Chip
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You have to restart Mach3 after changing the kernel speed for it to take effect. You also need a licensed copy for the higher kernel speeds.
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yeah I figured out that i need to restart the program after changing the speed. but now my axis are going nuts with interfearence from the higher kernel speed. is there a way to reduce this. because Id hate to have to run my machine at a slower speed.
my motor wires are all in close proximity to the cntroller and my computor. should they be further apart or what.
thanks
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My wiring all runs pretty close to each other but all my signal and motor wires are shielded and the power wires have ferrites.
Hood
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shielded how and what are ferites
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Shielded wires have either a braid or a foil that surrounds the actual wires, one end of the braid is connected to ground in the control cabinet. Ferrites are these ring like things that wires are sometimes looped through, you may have seen them inside your computer case, the front LED and Switch wires often have one.
Hood
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If you look at the pic below you will see the ferrites on the power wires to my Geckos (yellow things, can be any colour though) Also you will see the braid on my motor wires through the clear top layer.
Hood
Edit
Actually I dont have them on the power wires :-[ its the motor wires I have the ferrites on.
(http://mysite.wanadoo-members.co.uk/hoodsmachiningpages/BOSScomplete/ComuterandDrives.jpg)
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hmmm. it apears that my encoder wires have the foil shielding. so i should ground them to the enclosure? what about at the encoder end. do i do anything there? my motor wires themselves do not apear to have any shielding. will ferites help if i put them on even without shielding or should I pursue some other solution.
thanks
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You only ground the shield at one end and the control end is best from what I gather, I am certainly no expert. Ferrites could well help and certainly wont do any harm. If you have any old computer power supplies, just snip the wires from the torroids(?) and you have the ferrite rings ;) but if you dont then they are not expensive.
Hood
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thank you sir. I will report back tommorow to tell how it went.
chris ;D
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well I wish I had good news to report but. I hooked the shielding threads from the encoders and the limit switches to ground in my enclosure and i put ferrits on the servo motor wires and still my axis go nuts whenever I enter a move into the MDI screen. If Im just jogging using the keyboard the run smooth as can be. but if I enter anything through the MDI It sounds like a cellphone on vibrate siting on a countertop. and I get movement from all 3 axis even if I enter a single axis command. also aparently even when I set the controller to 25kHz Im losing steps when I tell it to move say an inch I get about .875 of movement. although it seems to be different every time. I tried to configure the steps per increment in the wizard but that didnt seem to help. plus I got some wierd ass step count number so Im definately having issues. but I guess I should get the motors moving smoothly before I tackle the rest of the problems. any further suggestions.
chris :-\
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I know its a pain but try starting from scratch entering all your settings again, might be worth making a new profile and leaving the one you are using alone. Just set up the step/ dir pins and your e-stop and test it out, then if its OK start adding the rest of your hardware (limits etc) into the equation.
Hood
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yeah I started doing that I took everything out except the motors and the encoders for them and still didnt get anywhere so now ive decided to take even my breakout board out of the equation. so i started soldering directly to my parallel cable and now i got no movement at all. Its gonna be a long weekend. :-[
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:(
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Hi, Chris
Are you talking about entering G-code on MDI input line or a external MPG encoder, you stated arrow keys work fine.
If its external input MPG encoder has it been calibrated and pins set properly.?
Thanks, Chip
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no Im talking about the MDI line. I can jog my axis around with the arrow keys smooth as day. then I enter in a move on the MDI or try to run a program and wammo. everything is moving and the motors sound like hell. Im not sure why that is.
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Press the Tab button and see what your jog % is set at please... Also try testing a jog by pressing the Shift key then Jog an axis (this will make it move at 100%)
How is that?
Thanks
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yeah I can jog at 100% fine. its just when I try and make a programed move.
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Post your XML and we will see what is going wrong here...
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how does one do that. i guess what i mean is where in mach can i find the xml file.
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Under mach3 there should be a Mach3Mill.xml file. please post that file
Thanks
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How fast is your machine. My mill did the exact thing. Jogged just fine, but when I stuck in code it went all wonky at 45khz. I turned down to 35khz and ran perfect. I then changed the PC to a 2.4ghz p4 with 512m ram with a Lava dual PCI port card and it runs perfect at 45khz. My mill (Full size knee mill bit bigger than a Bridgeport) Now does full rapids at 180ipm X and 150 Y and runs the roadrunner file pretty darned fast. Before the new computer/card the fastest rapids I could get were 120 ipm each axis.
My feeling is it is a computer problem, not interference.
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hmm yeah that may make sense. right now I can only run at 25KHZ and the fastest rapids I can get at that is 75 ipm . I noticed though that if I switch screens in mach while my machine is doing a rapid. my motors make a similar sound for a split second while it is switching. The computor is pretty old. its a windows 98 dell that I inherited so that may be the problem. if I could run at 35 KHZ I think Id be fine but its a nogo with this setup for now.
anybody else agree with this theory.
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Sounds like the computer is right on the edge of not running mach.. Keep it at 25KHz :)
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Yep. Get a faster computer.
Heck, I have seen P4s at goodwill!
Or Frys has some pretty good deals on no frills computers.