Nema 17 - vibrate, spin both sides in pronterface

Hi everyone,
I am totally newbie in electronics so I would apprecite some help from experienced ones.
I connected my stepper motors nema17, two of them to Ramps 1.4 board. Uploaded Sprinter to Arduino board and then turned on Pronterface.
When I click on 0,1 step, motor is just whistle, on 1 step it turns only once per two clicks (sometimes), on 10 it turns but randomly, sometimes left, sometimes right. Motors trough spinning vibrate, is it normal ?
I merged voltages on steppers drivers and its around 0,7, I tried to rise it up and down, but it was the same.

My nema 17 is 8wired, so I merged it with ressistance and found pairs, from these pairs I picked one wire and connected to one from oposite pairs, the second one with second one from oposite pairs till I have 4 wires.

As I said my motors now vibrating, spining random direction, whistling.

Any idea what I do wrong ?

Thanks

Try change the pairs you made to from the two coils. You might have for example half 1st coil in series with half 2nd coil.

Hi NoobMan,

you mean like that ? :

if I have Pairs

A1 A2
B1 B2
C1 C2
D1 D2


to make:
1wire / 2wire / 3wire / 4wire
/ A1 B1 / A2 C2 / C1 D1 / B2 D2 /

?

The 8 wire is just like a 6 wire, but instead of just taking out 1 middle tap, it takes two separated ones, and breaks the big coil in two smaller ones, unconnected. If you short the medians back together, you end up with a 6 wire and you can ignore the middle tap and use only extremities.

For those name wires you may need to short A2-B1 to make first coil A1-A2-B1-B2. Then short C2-D1 which gives second coil to be C1-C2-D1-D2.

Now because each have certain position inside motor, cant just link the coils any way we want to, the pairs have to be correct ones, and with correct direction each. So it is important also the direction to which the current travels into each half coil, so using A1-A2-B1-B2 is not the same as A1-A2-B2-B1. Because the spin rotation of the coils have to be consistent. There is just only one way to form correctly the bigger two coils from the 4 smaller ones. At which point the motor datasheet helps.

Ok, thank you, I will make some try then I will tell result. I dont have datasheet and no brand sign on motors.

Ok, no result I am at the same and really dunno what exactly Iam doing now, my maximum was to make motor shaking not more.
Isnt there any manual how to make it work step by step ?

Ok if datasheet is missing thats a bumer and you have to tackle little by little. For testing, on the driver make sure you have a low current setting.

So far we identified there are 4 halves of coils, all independent from each other.

For a first step, lets identify which halves form which coil. And which halves are opposite to the other. Try pairs (halves) only, while ignoring the remaining 4 wires. For example using your labels, use A1-A2 and C1-C2 and simply not use any of the 4 others, leave them open. Try issue a move command. See what happens.
a) If motor seems to move at all, these halves belong to opposite coils.
b) If the motor does not move, then they belong to same coil.
If neither a nor b happens or is not very distinguishable between them, rotate the rotor by hand in other position and try again.
Again and same with B and D, etc. The point is to identify which halves form same coil. This way we can figure which belong together and which dont.

Last step is to check the halves coils direction. Lets say that from each coil, the top half has a direction whatever that is, and the bottom half could be reversed. If A12+B12 form a pair and still things dont seem to work, then reverse it to A12+B21. Same with the other coil. Beside the starting combo there will be other 3 possible combinations.

Ok, so I used first two pins on stepper driver and tested half pairs of wires. The result it that I have now two groups of pairs which react by shaking from Pronterface.

Lets say I have group A(4wires) and group B(4wires), so how continue ?

Or better to say I have A(2a,2b) and B(2c,2d)

Huh, no, the stepper driver always connects to 4 wires which form 2 pairs. No point to connect only 2 wires from the stepper driver.

Connect to half coils first, use 2 of the half coils ( 4 wires) and ignore the remaining 2 halves (the other 4 wires).
You have motor
A1 A2
B1 B2
C1 C2
D1 D2
Then try use A1-A2 as a ("full") coil and C1-C2 as the other ("full") coil. The B and D remain unused and open (not connected). For the moment we ignore the fact that they are just halves. Put the stepper driver on low current setting and if possible to full step because it will be easier to see things in full step, and order a move.

Edited 1 time(s). Last edit at 02/23/2014 11:15AM by NoobMan.

WOOOW, nice, I tried it, now I have connected 4 wires, one half and it does exactly what it should do in Pronterface, so now how to connect the rest 4 wires ? Should I put the rest with with working combination like first tested one and then just combine wires together ? I mean the same wires on same pins together.

Ok, I tested second 4 wires and they are not working correctly, the first 4 wires are ok. On the second 4 wires I tested every possible variation, but it turns unpredictable.

So many many testing now I have 2 pairs working (2x 4wires)

According to the initial numbering, say which wires you tested and worked and which didnt. Will figure it out from there.

Ok so I tested A1 A2 and C1 C2, then I tried changing of positions on pins till I have correct move. Then I did the same with B1 B2 and D1 D2. Both of them, you call it coils I think are moving to the same sides when I test it in Pronterface.

So now I just connect cables on same pins and its done ?

Ok, so I put them together and it works perfectly. Thank you very much for your time Noobman, it was very helpful. Thanks.

Yes the A1-A2 for example i called that "half" coil because it needs to be in series with another one, like B1-B2, and together they would form something of a "full" coil.

Glad to hear it works, btw which was the wiring that worked.

Edited 1 time(s). Last edit at 02/23/2014 02:20PM by NoobMan.

It was luck that I pick the first combination, I wanted to give it up The right combination were A1 A2 and B1 B2, on the board A1 B2 A2 B1. Same at other one.
I have read many times what you wrote and kept trying till good results. I just wonder that I didnt destroyed the board or motors

If the driver pot is set for low current, you should be safe testing, with care to avoid driver shorts and such.

I am under the impression that you are using half coils e.g. have not combined halves to make a full coil - sort of speaking. Dunno for sure coz its hard to get past the labels which we are using, so perhaps pictures are better. So i was looking for a diagram of 8 wire motor and came across this thread which provides some pictures better than i expected so its nice to have in the context: [forum.sparkfun.com] The colors will probably not match as i think everybody use anything they want, but its a good read nonetheless. You are using full coils if you use 4 wires (abcd, one from each) to the driver and you have 2 wires shorted together but otherwise not used, and again another 2 shorted but otherwise not used. Anyway, hope its all fine now.