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Author Topic: Jerky motion...yes I've read the other posts :-)  (Read 15924 times)

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Offline Hood

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Re: Jerky motion...yes I've read the other posts :-)
« Reply #30 on: July 06, 2008, 04:50:29 PM »
Have you tried just setting up with one axis and only the E-Stop connected to see if it runs OK?

Hood
Re: Jerky motion...yes I've read the other posts :-)
« Reply #31 on: July 07, 2008, 08:09:49 AM »
yes, failure occurs within 1 to 3 seconds now. not clear how or why but seems worse than ever.

Offline Hood

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Re: Jerky motion...yes I've read the other posts :-)
« Reply #32 on: July 07, 2008, 10:12:56 AM »
I presume thats just with one axis connected? If so try another instead and see if thats the same.
Hood
Re: Jerky motion...yes I've read the other posts :-)
« Reply #33 on: July 07, 2008, 03:47:38 PM »
doesnt discriminate between axis. doesnt even matter if motors are engaged to rack or not. problem has progressed to poing where failure growl and stop occurs within 1 to 3 seconds from command on any axis smultiples or all.
Thanks for trying, this is quite the "sticky wicket" mate!

Offline Greolt

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Re: Jerky motion...yes I've read the other posts :-)
« Reply #34 on: July 07, 2008, 07:55:20 PM »
Jhicks

I have only just read through this thread so I might have missed it but what power supply are you using?

Is it a switchmode supply?  I always prefer a linear supply.

Is the voltage staying consistent as the motors start to move?

I have heard of this symptom before with switchmode supplies going bad.

Greg
Re: Jerky motion...yes I've read the other posts :-)
« Reply #35 on: July 07, 2008, 08:55:43 PM »
Greolt, what do you mean by switchmode? I'm used to the terms unregulated, unregulated doesn't keep the same voltage, regulated keep the volts the same no matter what.

Anyway, I was having the limit switch problem tripping, so I rewired the entire CNC with shielded cable (already had it on motors), made sure no wires laid on each other and kept the PS outside the enclosure so no 120V inside, grouped only like lines together. What a difference. I honestly believe it runs smoother!! The limit switch problem went aways and it's definately quiter. Thanks for everyone's help. It runs super smooth now.

Offline Greolt

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Re: Jerky motion...yes I've read the other posts :-)
« Reply #36 on: July 07, 2008, 09:10:33 PM »
Cartierusm

Glad you machine is going well now.

I was referring to Jhicks problem.   :)

Greg
Re: Jerky motion...yes I've read the other posts :-)
« Reply #37 on: July 07, 2008, 09:19:34 PM »
I know that, but I was still curious.

Offline Greolt

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Re: Jerky motion...yes I've read the other posts :-)
« Reply #38 on: July 07, 2008, 09:58:58 PM »
Cartierusm

You will have to ask someone more knowledgable than me how they work but this is a typical switchmode supply.

In hobby level applications they are usually cheap chinese built units. You get what you pay for.

I have never had much success with them driving cnc machines. When they get flakey they do weird things.

I prefer a good solid unregulated linear supply.  Simply a transformer, rectifier and cap with some other small incidentals.

Now that was to answer Cartierusm's question. 

Jhicks just check the output when a load is applied and motors stall if using a switchmode.

Greg

Offline da21

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Re: Jerky motion...yes I've read the other posts :-)
« Reply #39 on: July 08, 2008, 03:09:48 AM »
the power supply is the likely culprit  , check your power supply output both volts and current , preferably with a analog multimeter if you can   

it is possible to be the Motors , but as you say it's on all three then it's most unlikely to be them , but not discounting them at this time

Dave