need some advice
24 Aug 2016 03:53 #79347
by strobes
need some advice was created by strobes
Hi, as you can see I'm new here. My question is about hardware so I'm not sure if I'm posting in the right session but any way here is the story with little introduction. I'm planning to purchase a mini mill, G0704 specifically and trying to select components for CNC conversion.
So with LinuxCNC in mind, hardware selection is getting complicated. Many kits on web for this mini mill based on oversea parts priced low, and I suspect with inferior design and quality. Of course components made in US by Geckodrive, Leadshine, Automation technologies good quality but expensive. Also its on web advertise steppers for all 3 axes, about 420oz for X,Y and 960oz for Z. But may be 960 is to close to stepper limits and better to use a servo? So I'm looking for a reasonable balance between quality and price combination that works well with Linux CNC in mini mill application. I'd need 4 axes (3 for now and one for expansion later) plus two more controls ( one for coolant, second for expansion). Desirable that his setup will not hold me back and would give .001-002" tolerances with right screws and latency.
So with LinuxCNC in mind, hardware selection is getting complicated. Many kits on web for this mini mill based on oversea parts priced low, and I suspect with inferior design and quality. Of course components made in US by Geckodrive, Leadshine, Automation technologies good quality but expensive. Also its on web advertise steppers for all 3 axes, about 420oz for X,Y and 960oz for Z. But may be 960 is to close to stepper limits and better to use a servo? So I'm looking for a reasonable balance between quality and price combination that works well with Linux CNC in mini mill application. I'd need 4 axes (3 for now and one for expansion later) plus two more controls ( one for coolant, second for expansion). Desirable that his setup will not hold me back and would give .001-002" tolerances with right screws and latency.
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24 Aug 2016 09:17 #79351
by andypugh
There are many reasons to prefer servos to steppers, but they typically offer less torque than a comparably-sized stepper. The advantage of a servo is much higher speeds without the same torque drop-off.
You will get much more satisfactory stepper performance at higher voltages, so you might want to look at the mains-input drives, though those do cost a lot of money, only partly offset by not needing to buy a separate DC power supply. The new closed-loop steppers are also likely to give much better results. However, if you look at
www.zappautomation.co.uk/es-dh2306-easy-...Pb2c4CFVRsGwodamgGIg
You will see that one drive costs more than a complete kit of motors and drives would cost using standard steppers and TB6560 controllers.
Replied by andypugh on topic need some advice
But may be 960 is to close to stepper limits and better to use a servo?.
There are many reasons to prefer servos to steppers, but they typically offer less torque than a comparably-sized stepper. The advantage of a servo is much higher speeds without the same torque drop-off.
You will get much more satisfactory stepper performance at higher voltages, so you might want to look at the mains-input drives, though those do cost a lot of money, only partly offset by not needing to buy a separate DC power supply. The new closed-loop steppers are also likely to give much better results. However, if you look at
www.zappautomation.co.uk/es-dh2306-easy-...Pb2c4CFVRsGwodamgGIg
You will see that one drive costs more than a complete kit of motors and drives would cost using standard steppers and TB6560 controllers.
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24 Aug 2016 16:25 #79360
by strobes
Replied by strobes on topic need some advice
Thank you.
So I think to use this controller board and drives ( for 3 axes ) Is this reasonable choice?
qty. 1 www.amazon.com/SainSmart-TB6560-Stepper-...roller/dp/B0093Y89RA
qty. 3 www.automationtechnologiesinc.com/produc...epper-drivers/kl5056
I think to settle for steppers in all 3 axes at 420 and 960oz .in. And looking for a good balance between price and quality that would work good with stepper drivers above. I thing higher voltage is better to reduce current, heat at the same power? Any particular source should I look at? I understand that it may be just educated opinion based on personal experience which I don't have.
Of course then I can select a power supply.
So I think to use this controller board and drives ( for 3 axes ) Is this reasonable choice?
qty. 1 www.amazon.com/SainSmart-TB6560-Stepper-...roller/dp/B0093Y89RA
qty. 3 www.automationtechnologiesinc.com/produc...epper-drivers/kl5056
I think to settle for steppers in all 3 axes at 420 and 960oz .in. And looking for a good balance between price and quality that would work good with stepper drivers above. I thing higher voltage is better to reduce current, heat at the same power? Any particular source should I look at? I understand that it may be just educated opinion based on personal experience which I don't have.
Of course then I can select a power supply.
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24 Aug 2016 16:54 - 24 Aug 2016 16:54 #79362
by andypugh
Replied by andypugh on topic need some advice
The Amazon price is quite high comapred to eBay. www.ebay.com/itm/262581091094
And I wouldn't really recommend the TB6560. They are rather fragile.
The TB6600 is supposed to be better, and you might prefer to use separate drives and a breakout board, for example: www.ebay.com/itm/291806175328
This might be better, 80V drives and including a small breakout board
www.ebay.com/itm/141870897819
The advantage of higher voltage is that the available torque drops off more slowly as the motor speed increases. My lathe runs on a 28V supply and can't drive the motors at more than 600 rpm. Which is OK, but if you look at what a well-designed system can do with steppers...
And I wouldn't really recommend the TB6560. They are rather fragile.
The TB6600 is supposed to be better, and you might prefer to use separate drives and a breakout board, for example: www.ebay.com/itm/291806175328
This might be better, 80V drives and including a small breakout board
www.ebay.com/itm/141870897819
The advantage of higher voltage is that the available torque drops off more slowly as the motor speed increases. My lathe runs on a 28V supply and can't drive the motors at more than 600 rpm. Which is OK, but if you look at what a well-designed system can do with steppers...
Last edit: 24 Aug 2016 16:54 by andypugh.
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24 Aug 2016 21:33 #79378
by strobes
Replied by strobes on topic need some advice
Ok, thank you.
Yes this look good : www.ebay.com/itm/141870897819
given 80V, competitive pricing. And in general people report good experience.
I'd think these drivers will work with steppers I found? Are these, based on your experience reasonably priced?
It looks like NEMA34 stepper is rated up to 80V vs. Nema 24 is 48V. Should I use different power supplies? Any suggestions for PSs?
Also Nema24 supports unipolar, bipolar, serial/parallel type connections. I'd assume the connection that takes less current is preferred if it can support required holding torque?
www.ebay.com/itm/US-Ship-Dual-Shaft-8-5N...f:g:XY4AAOSwd0BV5U1s
www.ebay.com/itm/US-Ship-Nema-24-Stepper...3:g:0~QAAOSwu4BVmzzG
yes, that Tormach video is unreal....I think spindle runs at 10k rmp prob 3-4hp, not bad for $7k but far from my budget....
Yes this look good : www.ebay.com/itm/141870897819
given 80V, competitive pricing. And in general people report good experience.
I'd think these drivers will work with steppers I found? Are these, based on your experience reasonably priced?
It looks like NEMA34 stepper is rated up to 80V vs. Nema 24 is 48V. Should I use different power supplies? Any suggestions for PSs?
Also Nema24 supports unipolar, bipolar, serial/parallel type connections. I'd assume the connection that takes less current is preferred if it can support required holding torque?
www.ebay.com/itm/US-Ship-Dual-Shaft-8-5N...f:g:XY4AAOSwd0BV5U1s
www.ebay.com/itm/US-Ship-Nema-24-Stepper...3:g:0~QAAOSwu4BVmzzG
yes, that Tormach video is unreal....I think spindle runs at 10k rmp prob 3-4hp, not bad for $7k but far from my budget....
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24 Aug 2016 21:54 #79379
by andypugh
Most stepper motors are rated at 5V or less, that being the DC voltage to drive rated current through the windings of a static motor.
However, stepper drives modulate this voltage with PWM to achieve the setpoint _current_ regardless of the motor back-emf.
I think this means that regardless of the supply voltage the motor windings only see 5V, but I might be wrong about this.
In any case, any stepper will work fine at the drive rated voltage, though a 70V supply is probably a reasonable compromise to give 80V drives a bit of headroom.
You might consider making your own PSU. A big toroidal transformer, bridge rectifier and large capacitor is all you need. A switchmode PSU might not like the load, and a big linear regulated supply is likely to be expensive.
If you do go that way, don't forget that the caps will charge to the peak voltage of the supply, not the nominal. So for a 110V supply you would have 155 volts. A 2:1 transformer will give you 78V, perhaps a bit close to the drive max voltage. Though there is probably some built-in overhead in the drives.
Replied by andypugh on topic need some advice
It looks like NEMA34 stepper is rated up to 80V vs. Nema 24 is 48V. Should I use different power supplies? .
Most stepper motors are rated at 5V or less, that being the DC voltage to drive rated current through the windings of a static motor.
However, stepper drives modulate this voltage with PWM to achieve the setpoint _current_ regardless of the motor back-emf.
I think this means that regardless of the supply voltage the motor windings only see 5V, but I might be wrong about this.
In any case, any stepper will work fine at the drive rated voltage, though a 70V supply is probably a reasonable compromise to give 80V drives a bit of headroom.
You might consider making your own PSU. A big toroidal transformer, bridge rectifier and large capacitor is all you need. A switchmode PSU might not like the load, and a big linear regulated supply is likely to be expensive.
If you do go that way, don't forget that the caps will charge to the peak voltage of the supply, not the nominal. So for a 110V supply you would have 155 volts. A 2:1 transformer will give you 78V, perhaps a bit close to the drive max voltage. Though there is probably some built-in overhead in the drives.
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24 Aug 2016 22:29 #79382
by strobes
Replied by strobes on topic need some advice
I need tor read about steppers some more....Yes I can make a power supply, I have all parts.
And of course here is a new question:
www.ebay.com/itm/US-Ship-Dual-Shaft-8-5N...f:g:XY4AAOSwd0BV5U1s
it needs 60V, 5A/phase, it has two coils. does it mean it may need 10A?
And of course here is a new question:
www.ebay.com/itm/US-Ship-Dual-Shaft-8-5N...f:g:XY4AAOSwd0BV5U1s
it needs 60V, 5A/phase, it has two coils. does it mean it may need 10A?
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24 Aug 2016 23:01 #79383
by andypugh
I don't think so, I think that the drive will either run one phase at 5A or both at 2.5A (depending on where it is in the step cycle)
Replied by andypugh on topic need some advice
it needs 60V, 5A/phase, it has two coils. does it mean it may need 10A?
I don't think so, I think that the drive will either run one phase at 5A or both at 2.5A (depending on where it is in the step cycle)
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24 Aug 2016 23:17 #79385
by tommylight
Replied by tommylight on topic need some advice
power supply 60V ===>drive 80V====>motor 5V
Power supply 2A ===>drive in 2A=>out 2x 5A====>motor 2x 5A
That is simple electronics math, with lots of headroom, as even 1A power supply will work but at the very limit.
60V/5V=12
1A x 12= 12A <==== this is theoretically, when the loses are accounted for 10A output, depending on the efficiency of the system.
B.TH.W i would not go over 50V on cheap 80V drives, they tend to blow when hitting E-stop while moving heavy loads due to back EMF
Power supply 2A ===>drive in 2A=>out 2x 5A====>motor 2x 5A
That is simple electronics math, with lots of headroom, as even 1A power supply will work but at the very limit.
60V/5V=12
1A x 12= 12A <==== this is theoretically, when the loses are accounted for 10A output, depending on the efficiency of the system.
B.TH.W i would not go over 50V on cheap 80V drives, they tend to blow when hitting E-stop while moving heavy loads due to back EMF
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24 Aug 2016 23:22 #79386
by strobes
Replied by strobes on topic need some advice
Andy, found this article. Tommy, I need to seat down and think, allot of info in just few lines........thanks.
machinedesign.com/archive/stepper-phase-current-made-easy
The key relationship to remember is that amps peak = 1.41 X amps/phase (or amps RMS). Regardless whether you remember the reason behind the 1.41 constant, understanding the relationship between amps peak and amps/phase is crucial because, for most manufacturers, stepmotors only list amps/ phase while drives only spec amps peak. Understanding that difference lets you talk the same language to drive and stepmotor makers alike.
machinedesign.com/archive/stepper-phase-current-made-easy
The key relationship to remember is that amps peak = 1.41 X amps/phase (or amps RMS). Regardless whether you remember the reason behind the 1.41 constant, understanding the relationship between amps peak and amps/phase is crucial because, for most manufacturers, stepmotors only list amps/ phase while drives only spec amps peak. Understanding that difference lets you talk the same language to drive and stepmotor makers alike.
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