Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: BoatBuilder on July 22, 2011, 07:31:36 AM
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Hi All,
I am finalising my setup for my new router and am having some issues with my motors randomly stopping whilst jogging from Mach3. If I run any single axis at full speed it works well, but if I run two or more axis at full speed at some point one of the motors will randomly stop and which motor is also random. I am fairly confident that my cabling is ok but you never know which sort of leaves configuration. I realise that this is all a little vague but if there is anything someone might be able to point me to or perhaps test for I would appreciate it.
Cheers
Rod
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Can you measure the power supply outpput voltage whilst jogging two axis to see if it is dropping off.
Hood
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G'day Hood - thanks for that. I'll measure the power from end to end. I'll let you know the outcome.
Cheers
Rod
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G'day Hood - I measured the voltage output of the power supplies and it was consistent across alll supplies (4 of them) and drivers (42volts) both at stand still and whilst jogging. I then slowed the motors down in Mach3 and I eventually got success but I think that the speed will be a bit slow once I hook the motors to the table and the motors are certainly capable of much more speed. I am starting to wonder if the drivers might not be big enough to drive the motors at higher speeds. Given that this is my first effort at a CNC machine I am somewhat out of my depth. Is there a way that I can test the driver for suitablity to the motors?
Cheers
Rod
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Hi Rod, Can you post any/all info (data sheets if possible) on motors, drivers, specs of power supply plus your xml please.
Cheers
Ian
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G'day Ian - here are the data sheets. The motor is the MOT-130 and the power supplies are the SPS-407's.
Cheers
Rod
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Here is the XML
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Hi Rod
what microstep setting are you using on your drivers? dip sw 5,6,7 and 8
also your driver dynamic current setting? dip sw 1,2 and 3
Cheers
Ian
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Hi Ian,
I have included a photo of the settings on the actual stepper as the switch settings are different to the doco. I have them set to 5.6A and 1600P/R and switch 4 set off which has something to do with half power at stand still.
on,on,on,off,off,off,on,on
Cheers
Rod
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Hi Ian,
I found the doco for the driver on the web. Apart from the switch settings it is the same, I hadn't realised it was different documentation until now. I had gone off the settings on the case.
Cheers
Rod
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Hi Rod, OK if my maths is correct everything checks out pretty good. The only thing that is amiss is that your kernel speed no way needs to be 100KHz. The plain vanilla 25KHz setting is more than twice what you'll ever need from the info you've posted.
Whilst a 64V supply would give the "optimum" torque/speed curve for your motors, as you never go much above 1300 full steps/sec your 42V should be fine (according to the torque curve for your motors - different driver but probably close enough). Plus of course your driver's max voltage is 50V anyway.
JFI - are you sure your steps/pers are correct for all your axes? They're slightly "funny" numbers. X is CLOSE to an inch lead, Y and Z are CLOSE to 5mm lead and A is CLOSE to 1mm lead.
Anyway set that kernel to 25KHz and see what occurs.
Ian
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Many MANY thanks Ian. I will set the the kernal back to the default of 25KHz.
The steps per for each axis
X- is driven with a belt and I have 10:1 reduction gear on the motor. I worked out the travel based on the size of the end pully driving the belt and also included the gear reduction.
Y & Z are both on an imperial screws with a 0.2" lead - which I calculated to 5.08mm travel per revolution
A - is not active so I guess I should turn it off
After I am satisfied with the reliability of the motors and installed them on the table I had intended to confirm the steps per with some distance validation. I recall something in the doco about that so I'll re-visit that for final confirmation.
The concern that I have with the reliability of the motors is that the X Gantry is driven by 2 motors - one either side - which are powered and run by independent power supplies & drivers, and I didn't want one to stall and one to keep going. You can just imagine the carnage on the gantry. Apparently there are digital drivers that can be linked to stop if the other stops so I will investigate that.
I have sinced slowed the speed of all axis down and they are now operating reliably but I'm not sure whether it will be too slow or not. I have also swapped the signal cabling from the breakout board to the drivers with shielded cable.
In regards to the speed of the axis can I ask what would be an average speed of travel? I can't set it over 2000mm/ without the motors randomly stopping. This seems quite slow for motors of this size but anything over and they stall. My table is 3000*1500*300.
I'll let you know the outcome of the kernal change - but first I'm going to find out what kernal is - haha
Cheers
Rod
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You may well be able to achieve the speeds you had set in the xml you posted. The torque curves for your motors suggest those speeds arn't unreasonable but there's so many variables it's difficult to predict. But remember that speed isn't everything, acceleration is important too. you'll just have to see when you drop your kernel frequency.
Cheers
Ian