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  #541  
Old Fri 28 November 2014, 05:23
KenC
Just call me: Ken
 
Klang
Malaysia
Quote:
Originally Posted by racedirector View Post
..... in biploar parallel mode the shafts spin freely and only lock up when power is applied....
That isn't right.... the shaft should lock-up solid.

IMHO, unless broken, all brand/make stepper motors makes no different with MM.

Sound very much like a bad motor. Unlucky ....
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  #542  
Old Fri 28 November 2014, 05:27
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Quote:
Originally Posted by KenC View Post
That isn't right.... the shaft should lock-up solid.
Sound very much like a bad motor. Unlucky ....
Ken, not broken, all the motors are wired the same way and all act in the same way. When I queried the wiring with AusXMods he confirmed the the shafts would NOT lock up on these motors and I even double checked with MS Motor themselves.
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  #543  
Old Fri 28 November 2014, 05:29
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Thanks clarson66, sounds like I should just pull my finger out and get my belt drives done. They'll have to be MDF or plywood initially though, no way I could cut ali at this stage.
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  #544  
Old Fri 28 November 2014, 05:32
KenC
Just call me: Ken
 
Klang
Malaysia
24T pinion will give 25% more torque then 30T, should improve thing a tat. and cost very little time & money.

Did you do motor tuning for Z? you get loose steps?

Last edited by KenC; Fri 28 November 2014 at 05:38..
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  #545  
Old Fri 28 November 2014, 05:37
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Was just outside having a smoke and thinking the same thing Ken, will price some 24T's on Monday.

Z motor tuned the same as all the rest, no lost steps if I am very careful plunging, too aggressive and lots of lost steps.
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  #546  
Old Fri 28 November 2014, 05:58
KenC
Just call me: Ken
 
Klang
Malaysia
the "free" thing to do now is re-tune the motor to lower acceleration & velocity, write a short G-code doing repetitive up-down for the tuning purpose.
At least get you to continue cutting.

Last edited by KenC; Fri 28 November 2014 at 06:02..
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  #547  
Old Fri 28 November 2014, 16:42
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Some hybrid motors will spin free with no resistance without power, some with achieve detent torque when you spin freehand faster then turn with resistance others will not like to be turned at all. Depends on the manufacturer. As far as the Z motor running hotter while running, mine is always 10°C hotter than the other axes. Every driver is different on how they function. AMCI driver will cook eggs on 100% idle reduction but at 50 it is only a little above room temperature. Gecko 203V drive barely heat the motor at all at idle. That is how my motors are.

You said you swapped the motor drivers. Just be thorough, put the suspect motor on the Y drive and have g-code run only it (the Y axis) and let it sit idle to rule out some other hidden troubles. Lets see if the problem moves.
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  #548  
Old Fri 28 November 2014, 17:37
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Thanks for the info Pete, appreciated.

Got some rubbish to get rid of then will do the motor swap. Will report back with the results. Will also do a quick video of the Z as it currently sits basically bouncing at any resistance.

Overall I am pretty happy with the machine, its just these niggly bits that annoy me
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  #549  
Old Fri 28 November 2014, 19:26
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Found something this morning, the controller is the one heating the motor up, I connected the Z controller to the Y motor and vice versa, now the Y motor is really warm from sitting for an hour or so and the Z motor is stone cold.

The Z however is *still* stalling under *any* pushback so I will very carefully cut out a belt drive from MDF to chuck on the Z and see what happens.

Later this avo I will recheck the settings on the Z controller (now on the Y) to find out why the attached motor is heating up at idle.
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  #550  
Old Fri 28 November 2014, 20:34
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
I would recommend belt reduction for the axis. Will give it more strength. I have a PK296-F4.5A 440 in-oz wire parallel with a 4:1 reduction. I haven't had any problem. I give the spec so you can relate to your motor to see what others are using and not to tell you what to use.
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  #551  
Old Fri 28 November 2014, 21:14
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Thanks again Pete, will definitely move on the belt reduction now for the Z. I would think that 640 Oz-in/2.2Mh wired parallel would be better than it is, my drives will be 3:1 to start with until I see how it performs.

What is strange is Automation Technologies has a motor with the same part number but it is wired differently than the MS Motor of the same number. Don't know where Auto Tech get theirs from but must be another supplier. Anyhoo, I have what I have and will make them better by belt reduction

Cheers
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  #552  
Old Wed 03 December 2014, 20:43
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Haven't got around to building my belt drives yet but have cured the Z heating issue. The controller was set to 100% current at idle even though I had the dip switches set. A quick adjustment via software fixed that.
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  #553  
Old Wed 03 December 2014, 20:45
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
See, sometimes a break is all that is needed
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  #554  
Old Wed 03 December 2014, 20:52
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Yup, correct on that one. Still haven't got my Z to lift the Y yet though, even after swapping motors between the Z and the Y
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  #555  
Old Wed 03 December 2014, 22:32
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
I contacted the supplier re my motor woes and he thinks (as I do) there is something definitely wrong. Currently working through a few things to report back to him.
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  #556  
Old Wed 03 December 2014, 22:46
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
For reference, here's my Z being a jack hammer...

http://youtu.be/nQJ-SfYNpuU
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  #557  
Old Wed 03 December 2014, 22:58
KenC
Just call me: Ken
 
Klang
Malaysia
Could had been too strong spring for the y car. Nothing much to get concern with..
BTW,did you set the correct Max. Current for Z?
Or you should consider parallel coil for higher torque.
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  #558  
Old Wed 03 December 2014, 23:01
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
Are you sure that the stepper is not jumping the pinion on the rack. That is what it sounds like.
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  #559  
Old Wed 03 December 2014, 23:03
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Ken

does this without the Z strut on too. Yes on the amps, 6.4 on the controllers. I even disconnected all other drives and ran only the Z and it still does this. Oh, and they are already wired parallel, push comes to shove I could go serial but would need to replace my power supply as serial would be 8.8 mH
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  #560  
Old Wed 03 December 2014, 23:11
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Just went and checked that Pete, no skipping of the stepper. the noise seems to be the motor pulsing but not stalling
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  #561  
Old Wed 03 December 2014, 23:17
pblackburn
Just call me: Pete #98
 
South-Central Pennsylvania
United States of America
That is odd being weird parallel.
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  #562  
Old Wed 03 December 2014, 23:25
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Ah, yup, my supplier thinks so too.

The reason I disconnected all other axis was to see if the power supply was underpowered. I am running a 300VA 35+35 at 8.5a. Even with only 1 motor attached it still does this.

Here are screenshots of my AM882 settings, pretty stock aside from the amps.

http://i566.photobucket.com/albums/s...204_160058.jpg

http://i566.photobucket.com/albums/s...204_160120.jpg
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  #563  
Old Thu 04 December 2014, 00:17
KenC
Just call me: Ken
 
Klang
Malaysia
Even with 30T, this is odd.

Still couldn't pin point the problem but I am certain that the load is too heavy for the motor,

You also need to ensure the coils phase is correct when connected parallel. . the wrong phase will cancel off each other & reduce the torque.
check the motor drawings,1st.
or just swap the coil around, one at a time.

Last edited by KenC; Thu 04 December 2014 at 00:27..
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  #564  
Old Thu 04 December 2014, 01:18
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Will check the wiring again and I did double check when I first got phase errors by wiring them wrong.

These motors are in use by other here too I think, they *should* be OK given the specs:

Bipolar Parallel
Voltage: 50V Max
Current: 6.3A
Resistance: 0.36 ohm
Inductance: 2.2 mH
Holding Torque: 640 Oz-in

Bipolar Series
Voltage: 100V Max
Current: 3.2A
Resistance: 1.42 ohm
Inductance: 8.8 mH
Holding Torque: 640 Oz-in

Unipolar
Voltage: 50V Max
Current: 4.5A
Resistance: 0.71 ohm
Inductance: 2.2 mH
Holding Torque: 455 Oz-in

Wiring Bipolar Parallel
A+ = Red + Blue
A- = Yellow + Black
B+ = White + Brown
B- = Orange + Green

Wiring Bipolar Series
A+ = Red
A- = Black
B+ = White
B- = Green
Join Yellow + Blue
Join Orange + Brown

Wiring Unipolar
A+ = Red
A- = Yellow
C+ = Blue
C- = Black
B+ = White
B- = Orange
D+ = Brown
D- = Green
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  #565  
Old Thu 04 December 2014, 01:45
KenC
Just call me: Ken
 
Klang
Malaysia
Actually, when selected correctly, the air spring assist the motor to handle heavier load.

Sometimes, the wiring diagram can be wrong too... that would be the last thing we should suspect.

OK, one more test.
remove the spindle. & see if the problem persist.

Without load, the motor should stop jack-hammering. If it still does... I'm out of ideas at least for now.
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  #566  
Old Thu 04 December 2014, 01:53
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Will do the removal and test.

One thing... in this screen grab from the MS-Motor site it says the resistance per phase for this motor is 0.36 (3rd column):



The drivers are bog standard aside from the amps and the microsteps and while looking again I noticed the resistance is set to 1.2 Ohms. I am wondering a) is this the same thing and b) if it would make that much difference....
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  #567  
Old Thu 04 December 2014, 02:12
KenC
Just call me: Ken
 
Klang
Malaysia
never used AM882 before, but I do know it is a DSP driver and you can tune it for best motor performance. did you went through the tuning procedures?

I'm using a very similar stepper motor for my work in progress plasma table.

The resistance is good for sanity test, the number is not precise, +/-20% should be ok. i.e. as long as your measured resistance is within the ballpark, you should be ok. at least we know its not bad coil.
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  #568  
Old Thu 04 December 2014, 03:01
2e0poz
Just call me: Paul
 
Swindon
United Kingdom
Ok not often i post but that motor number reads that it is a nema 34. 280 steps and runs up to 4.5 amps. The 8A is reference to the motor type and not max amps.

I have similar motors that read the same. Hope that helps

Last edited by 2e0poz; Thu 04 December 2014 at 03:04..
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  #569  
Old Thu 04 December 2014, 08:28
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Here's some theories (which have been explored above in most cases):

1) The motor is bad. I think you've said you swapped and got the same behavior. That tends to rule this out.

2) The driver is bad or misconfigured. You've looked hard at this, also unlikely now.

3) The motor is miswired - you mentioned that you had some trouble with this and then corrected it. The specific miswiring that seems possible is that one of the two pairs of
wires coming into either the A or B phase is backwards, thus negating that phase and making the motor run rough or weak. However, when not hitting the table, it seems normal, so this also seems unlikely.

4) That's not actually MDF, it's a piece of stone and you're messing with us (grin)

5) The counterweight spring is way too strong, and the motor is fighting it to get the axis down. Or, the axis isn't moving smoothly, perhaps binding in some way. When you power off the machine, does the axis float down, up, or stay in place? If you pull the motor pinion out of the rack does it float up or down?
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  #570  
Old Thu 04 December 2014, 19:12
racedirector
Just call me: Bruce #122
 
New South Wales
Australia
Paul: Not too sure what you mean by 280 steps. The numbers in the above image, from left to right, are 4.5 Nm (647 Oz-in), 6.3 amps, 0.36 Ohms resistance and 2.2 mH (for parallel)

Brad:

1) Ruled Out (as mentioned) I swapped Y and Z to no change
2) Ruled Out, I manually tuned all controllers, now have exactly 6.3 amps with 10 Microsteps and all resonance settings at zero.
3) I will be checking this, I wired all motors exactly the same so they all react in the same way at the moment
4) Hahahaha.... disguised granite Nah, plain ole 12mm MDF from a big box store
5) Counterweight spring has been replaced already, first one I thought was too strong but now I think the motor was incapable of moving it It was the recommended charge. The replacement is lower charge and *just* holds the Z in place on power down.

The supplier has suggested my power supply may be undersized, a 300VA 8.5 amp toroid self built as he usually uses a 48V 15amp supply with these motors under Geckos. It would be cheaper for me to replace the toroid with a 500VA one than replace all the motors so that is something to think about. I was going to buy one motor off another supplier just to see if it made a difference, that one would be 4 wire instead of 8 but has the same power, 640 Oz-in. There is also the belt drives that I have to build that may help the issues I am having, more parts and work on them required but with Christmas so close my budget is restricted.

I can cut, its just I have to do it really carefully so not to stall part way through - slightly depressing given I built this monster to cut better than my last machine. I have learned a lesson though, I should just buy what everyone else has and not have the hassles of different/cheaper gear to deal with.

Thanks everyone for their help and suggestions, I *will* get there one day....
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