Motor torque March 09, 2014 08:28PM |
Registered: 10 years ago Posts: 20 |
Re: Motor torque March 09, 2014 08:55PM |
Registered: 13 years ago Posts: 1,352 |
Re: Motor torque March 10, 2014 10:49AM |
Registered: 10 years ago Posts: 20 |
Re: Motor torque March 10, 2014 09:49PM |
Registered: 13 years ago Posts: 1,352 |
The Vref can theoretically go a long way, lets say up to 4.0v. But do NOT rush to get it all the way up because you get a chance to burn your driver. There is a relation between the Vref and the Peak current, you need to look up this exact relation, on the driver seller website or on the chip manufacturer website datasheet. This relation involves Rs which is sense resistors, two resistors on the driver chip that you must know the exact value, and depending on their value the overall relation can change dramatically. So look this up before making any changes. Also you could have some motors that are rated like 12v or so, which have high coil resistance like 30 ohms instead of 3 ohms, and if that is the case, after some point increasing vref wont help. So who knows what you got there, you need to look things up first, starting with that vref to peak current relation.Quote
tyscof
Hello it looks like some of what I said was not very clear, When I was adjusting the pot on the driver chip I had to put it all the way to around maximum power around 1.2v vref to get the shaft to turn but even when I put it all the way up the motor still had no torque so I can't go any higher with the pot. I was saying this is weird because the motor has a lot of torque when it is not rotating but as soon as it starts to it loses all torque.
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tyscof
When I was talking about steps per mm I didn't mean that it gained torque but rather that the motor was using it full torque. For example if I set the values really low on #define _AXIS_STEP_PER_UNIT {80, 80, 3200/(1.25),700} like down to 20 the plate moves with a lot of torque but the plate as expected will move farther than it should so this won't resolve the issue. Also when I set it really low the .1 and 1 jog need to be pressed multiple times to get the plate to jog anywhere.
I hope this clear up some of my miscommunication, I'm sorry about that!
Re: Motor torque March 10, 2014 11:00PM |
Registered: 10 years ago Posts: 20 |
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The "axis step per mm" does not affect torque in any way. This setting only determines the length of the move. If you set it to 10, it will move some distance, if you set it to 20 it will move double that distance, if you set it to 30 then it will move 3 times the initial distance, etc. Ofc if you set it to 0.1 then you will have to click it 100 times to move that same initial distance because 10=100*0.1. That is all. Nothing to do with torque really.
This is what is really weird, if I set it super low all of the larger values like 1,10, and 100 will work(and like before it has the torque that the motor should) but the lower value like .1 will not move the plate... well it will but the plate wont move at all until I hit .1 like 3 times and then it budges once the same distance as the 1 jog. But if I set it higher then the motor will either not move at all or will only move on the .1 jogs and make high pitch noises for all the other values increasing in pitch the higher you go in jog vale 1,10,100. weird right?Quote
If smaller moves seem to be better, perhaps you have too high setting of acceleration or jog speed, and at long moves when it reaches the peak settings it fails, while at short moves it may not have time to reach the peak settings so it may seem better, but this scenario is already some kind of a stretch.
Re: Motor torque March 10, 2014 11:54PM |
Registered: 13 years ago Posts: 1,352 |
No, the motors are supposed to be any value 4-5 times lower than 12v. For example motors labeled 2.56v, 3v or 4v will be ok when supplied with 12v. If the stepper motor label says 12v and you supply them also with 12, thats not good: it may work, but poor performance.Quote
tyscof
I get that it doesn't effect the torque but when I set the values really low like 20 the motor will move and I wont be able to stop it like I could before. It has the torque that it should instead of the puny barley moving nonsense. Which is weird I don't see how it makes a difference, maybe has something to do with the motor needing more steps or the steps are screwy? Could this be a problem with my ramps or mega board? My motors are 12v aren't they supposed to be?
No, not weird, actually its normal, if you set steps per unit small values like 0.1 and you order small moves, it will move an imperceptible distance or wont move at all. Because said value is supposed to be bigger. Thats normal.Quote
tyscof
This is what is really weird, if I set it super low all of the larger values like 1,10, and 100 will work(and like before it has the torque that the motor should) but the lower value like .1 will not move the plate... well it will but the plate wont move at all until I hit .1 like 3 times and then it budges once the same distance as the 1 jog. But if I set it higher then the motor will either not move at all or will only move on the .1 jogs and make high pitch noises for all the other values increasing in pitch the higher you go in jog vale 1,10,100. weird right?