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Mach 4 and 5 Axis CNC
« on: May 11, 2020, 04:35:19 PM »
Hi, I am currently a student, and am working for a university Lab that has me assisting in creating a 5 axis CNC with Mach4 software.

I am posting a few questions, if anyone can help regarding this project, I would greatly appreciate it.

1. If someone could suggest a good controller board for a 5 axis CNC (Mach4), that can control x y z and 2 rotary axes, along with spindle control.
2. We are currently thinking of using Nema 34 stepper motors, any suggestions in changing these motors or keeping them would be taken into consideration.
3. Suggestions on power supplies for both motors, and motion controller would be helpful as well.
4. finally any breakout board information is helpful as well in case the motion controller doesn't have any additional inputs for limit switches and emergency stop.

The professor basically gave the people in the lab this task, and asked us to work from scratch, throwing us in the deep-end. We understand we are complete newbies to this, so any information regarding this would be very helpful, including links to other sites or forums for help.

Thank you very much for your time in reading this,

-Starting_Anew
Re: Mach 4 and 5 Axis CNC
« Reply #1 on: May 11, 2020, 06:07:50 PM »
Hi,

Quote
1. If someone could suggest a good controller board for a 5 axis CNC (Mach4), that can control x y z and 2 rotary axes, along with spindle control.

Arguably the Ethernet SmoothStepper (Warp9 TD) is the most complete (step/direction) Mach4 ready motion controller, certainly in the value end of the market, $180. You'd
need to pair that with one or more breakout boards, the C10 ($23) is bidirectional with one port (17 IO's), the C25 ($30) with two ports (34 IO's) are simple
and cheap whereas the MB3 ($180) (CNCRoom) has three ports developed (51 IO's) replete with both differential and single ended 24V IO's, opto-isolated inputs, spindle control
features like PWM-to-analogue etc.

Quote
2. We are currently thinking of using Nema 34 stepper motors, any suggestions in changing these motors or keeping them would be taken into consideration.

Many people make the mistake of choosing 34 size steppers because of their great torque specs, say 1000 oz.in and higher. These steppers have high inductance and perform
VERY BADLY at speed. Avoid like the plague!

All steppers lose torque the faster they go and the winding inductance determines how badly the torque will roll off with speed. The lower the inductance the better.
With a 23 or 24 size stepper you want 1-2mH, 1mH preferred and reject anything over 2mH.
With a 34 size you want 2-4mH, 2mH preferred and reject anything over 4mH.

Many users have found low inductance (1-1.5mH) 23 size steppers of 350-400 oz.in outperform (overall) 34 size steppers by virtue of 34 size steppers greater inductance.

The classic means of counteracting the inductance of the windings is to use the highest possible driving voltage. The effective practical maximum at this time is 80VDC.
Gecko drivers are the gold standard for reliability but are not cheap. Leadshine AM822's for example are also 80VDC capable and half the price.

Transformer/rectifier/capacitor type power supplies are recommended over switch mode types by virtue of their superior overload capacity.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach 4 and 5 Axis CNC
« Reply #2 on: May 11, 2020, 06:50:22 PM »
Hi,
depending on your budget you might consider AC servos. There are some very cheap Chinese made AC servos but of questionable quality, support and documentation.

Delta (Taiwanese manufactured in China) and DMM (Canadian manufactured in China) are two good quality brands that won't break the bank.

Any decent AC servo of sufficient power will blow ANY stepper into the weeds. They have very generous overload ratings, typically three to four times their rated torque.

As an example I have a 400W B2 series Delta servo. It has a native 160,000 count per rev encoder, 1.27Nm rated, 3.8Nm 10 sec overload at 3000rpm rated or 5000rpm max.
The driver takes 230VAC single phase input, ie no power supply required. The programmable drive has an overwhelming multitude of control modes which makes them superbly
flexible for just about any machine for any purpose. The servo/drive/cables/shipping to the US will cost about $380 from various EBay suppliers.

Most steppers will not make 1000 rpm, the loss of torque will mean they lose steps or stall before they reach 1000 rpm. A servo has a flat torque characteristic to rated
speed, often 3000 rpm or higher.

You might be able to represent to your professor that equipping with servos IS THE  industrial solution and that your project would best prepare you for real world solutions
that servos are vastly preferred over steppers.

A slightly cheaper alternative to AC servos are closed loop steppers. You will no doubt see plenty of offerings. They are intermediately priced between servos and
open loop steppers.

The manufacturers will claim that they are faster, more powerful, never lose steps.......all pure BS. As I said above all steppers lose torque as speed increases,
a closed loop stepper is no different. A stepper will only ever lose a step if its overloaded by either excess load or the speed at which its being asked to operate at.
A closed loop driver will insert an extra step to try to 'catch up', but guess what.....the extra step suffers the same fate, it gets lost because the stepper is overloaded.

Closed loop steppers do have two advantages, namely interpolation between steps for increased resolution, and following error alarms. These advantages are bought at
a significant price increase over open loop steppers. Any well specified open loop stepper used within its limitations will never lose a step an so my recomendation
is either:
1) Open loop steppers of lowest possible inductance with highest possible voltage drivers and power supply....or
2) AC servos

Don't mess with Mr. InBetween, closed loop steppers.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach 4 and 5 Axis CNC
« Reply #3 on: May 12, 2020, 12:51:21 PM »
100% agree with everything Craig said. I'll add that which setting them up isn't terribly difficult, AC servos are more complicated than steppers. Choose a brand with really good manuals and technical support.

I am helping a guy who bought the bottom of the barrel Chinese AC servos and the manual is 1/3 Chinese, 1/3 Russian, and 1/3 English. Even translating all those pages didn't answer most of the questions we had. I like DMM Tech, have heard great things about Clearpath (but have never used them), and would recommend Delta or any high end name brand (AB, Seimens, etc). Automation Direct also has a line of entry level servos with good technical support.
Re: Mach 4 and 5 Axis CNC
« Reply #4 on: May 12, 2020, 01:37:47 PM »
Thanks for all the information, I really appreciate it. Unfortunately the AC servos are a bit too pricey for our lab so were gonna have to go with the steppers.
Re: Mach 4 and 5 Axis CNC
« Reply #5 on: May 12, 2020, 04:49:36 PM »
Hi,
I find it hard to recommend Clearpath, its not because of quality, support and documentation, all of which is very good.

Its price and IO.

For a given sum of money a DMM or Delta servo can be had that has twice the power of a Clearpath.

The Clearpath has a built in driver which you may consider an advantage however you lose IO capability.

My Delta servos for instance can have (programmable) three alarms say, for example 'following error', 'overheat', 'overvoltage' and can have two analogue
outputs, say rpm and current. Additionally I can have digital input/inputs which select the mode, for example position verses velocity mode.

Clerapath have elected to make a device that is a 'drop in replacement' for a stepper motor and have done a good job, but has cost a great deal of
flexibility, and especially IO, and a hefty price increase.

I would do your research thoroughly before getting steppers. Yes, steppers are cheaper, but thats only the initial purchase. Good AC servos will last twenty plus years
and have the flexibility of control to survive generations of students and ever increasing demands made of the machine.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach 4 and 5 Axis CNC
« Reply #6 on: May 19, 2020, 07:30:32 PM »
Hi,
depending on your budget you might consider AC servos. There are some very cheap Chinese made AC servos but of questionable quality, support and documentation.

Delta (Taiwanese manufactured in China) and DMM (Canadian manufactured in China) are two good quality brands that won't break the bank.

Any decent AC servo of sufficient power will blow ANY stepper into the weeds. They have very generous overload ratings, typically three to four times their rated torque.

As an example I have a 400W B2 series Delta servo. It has a native 160,000 count per rev encoder, 1.27Nm rated, 3.8Nm 10 sec overload at 3000rpm rated or 5000rpm max.
The driver takes 230VAC single phase input, ie no power supply required. The programmable drive has an overwhelming multitude of control modes which makes them superbly
flexible for just about any machine for any purpose. The servo/drive/cables/shipping to the US will cost about $380 from various EBay suppliers.

Most steppers will not make 1000 rpm, the loss of torque will mean they lose steps or stall before they reach 1000 rpm. A servo has a flat torque characteristic to rated
speed, often 3000 rpm or higher.

You might be able to represent to your professor that equipping with servos IS THE  industrial solution and that your project would best prepare you for real world solutions
that servos are vastly preferred over steppers.

A slightly cheaper alternative to AC servos are closed loop steppers. You will no doubt see plenty of offerings. They are intermediately priced between servos and
open loop steppers.

The manufacturers will claim that they are faster, more powerful, never lose steps.......all pure BS. As I said above all steppers lose torque as speed increases,
a closed loop stepper is no different. A stepper will only ever lose a step if its overloaded by either excess load or the speed at which its being asked to operate at.
A closed loop driver will insert an extra step to try to 'catch up', but guess what.....the extra step suffers the same fate, it gets lost because the stepper is overloaded.

Closed loop steppers do have two advantages, namely interpolation between steps for increased resolution, and following error alarms. These advantages are bought at
a significant price increase over open loop steppers. Any well specified open loop stepper used within its limitations will never lose a step an so my recomendation
is either:
1) Open loop steppers of lowest possible inductance with highest possible voltage drivers and power supply....or
2) AC servos

Don't mess with Mr. InBetween, closed loop steppers.

Craig


Hi Craig

How do you go about deciding what size servo you require, my current stepper motor spec is attached. These are on a 3ft x 3ft bed machine. If I were to move to a 8ftx4ft size machine specifically for cutting timber, plastics and soft metals how do you determine your servo sizes?

Mark
Re: Mach 4 and 5 Axis CNC
« Reply #7 on: May 19, 2020, 09:44:16 PM »
Hi,
given that you have 34 size steppers currently I would look at 750W Delta B2 series or A2 series servos which are also 34 size.
I suspect the shaft size will be bigger but a Delta servo should bolt in the existing mount.

A 750W servo rated to 3000 rpm has a continuous rated torque of 2.4Nm and an overload of 7.2Nm.
Your existing steppers have a holding torque of 7.5Nm. Servos have very generous overload capacity and seem to punch
above their weight, and I would expect 750W to be plenty.

There are some calculations that would help but you need fairly detailed numbers from you machine before the calculations
offer any real insight. You need the ballscrew diameter, length and pitch, the axis mass and any gear or belt reduction you want to use.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach 4 and 5 Axis CNC
« Reply #8 on: May 20, 2020, 03:54:26 PM »
Hi,
depending on your budget you might consider AC servos. There are some very cheap Chinese made AC servos but of questionable quality, support and documentation.

Delta (Taiwanese manufactured in China) and DMM (Canadian manufactured in China) are two good quality brands that won't break the bank.

Any decent AC servo of sufficient power will blow ANY stepper into the weeds. They have very generous overload ratings, typically three to four times their rated torque.

As an example I have a 400W B2 series Delta servo. It has a native 160,000 count per rev encoder, 1.27Nm rated, 3.8Nm 10 sec overload at 3000rpm rated or 5000rpm max.
The driver takes 230VAC single phase input, ie no power supply required. The programmable drive has an overwhelming multitude of control modes which makes them superbly
flexible for just about any machine for any purpose. The servo/drive/cables/shipping to the US will cost about $380 from various EBay suppliers.

Most steppers will not make 1000 rpm, the loss of torque will mean they lose steps or stall before they reach 1000 rpm. A servo has a flat torque characteristic to rated
speed, often 3000 rpm or higher.

You might be able to represent to your professor that equipping with servos IS THE  industrial solution and that your project would best prepare you for real world solutions
that servos are vastly preferred over steppers.

A slightly cheaper alternative to AC servos are closed loop steppers. You will no doubt see plenty of offerings. They are intermediately priced between servos and
open loop steppers.

The manufacturers will claim that they are faster, more powerful, never lose steps.......all pure BS. As I said above all steppers lose torque as speed increases,
a closed loop stepper is no different. A stepper will only ever lose a step if its overloaded by either excess load or the speed at which its being asked to operate at.
A closed loop driver will insert an extra step to try to 'catch up', but guess what.....the extra step suffers the same fate, it gets lost because the stepper is overloaded.

Closed loop steppers do have two advantages, namely interpolation between steps for increased resolution, and following error alarms. These advantages are bought at
a significant price increase over open loop steppers. Any well specified open loop stepper used within its limitations will never lose a step an so my recomendation
is either:
1) Open loop steppers of lowest possible inductance with highest possible voltage drivers and power supply....or
2) AC servos

Don't mess with Mr. InBetween, closed loop steppers.

Craig


Hey Craig,

I was able to convince my professor to use the servos you suggested. I was wondering if there is any wiring guides to them, with the power supply and the breakout board and smooth-stepper? Also any suggestions on the power supply to use?

Thanks very much for all your help,

Regards,

Start_Anew
« Last Edit: May 20, 2020, 03:59:07 PM by Start_Anew »
Re: Mach 4 and 5 Axis CNC
« Reply #9 on: May 21, 2020, 02:52:36 AM »
Hi,
good news, you won't be dissapointed....they really are light years ahead of any stepper.

I personally use two MB02's from Homann Designs in Australia. As I live in New Zealand its near enough to be
local....after all its only 2500 km away......no more that a brisk swim for a Kiwi...LOL.

A cheap and effective breakout board is the C25, at only $30.00. It has two ports developed (34 IO's).
Note however they are TTL level, that is 5V. The inputs to the Delta drivers are 24V, being the norm in industrial
equipment. Thus you will need to add a resistor and a transistor/mosfet to effect the level translation. I can help
with cicuit diagrams if you need.

Another alternative is to use a MB3 breakout board from CNCRoom at $180. It has all three ports developed (51 IO's)
and its outputs are 24V tolerant. You are (somewhat) constrained to the architecture that the manufacturer has provided
but is a well balanced mix of inputs and outputs and a mix of differential and single ended. It require but one 24V power
supply and supplies (on board) 5V to the ESS.

Modern AC servos are quite complex to set up and a vast array of parameters that you need to consider.
In most cases the manufacturer offers a way to plug the drive into a PC so that you can program the drive using
the manufacturesrs software, and is highly reccommended. You can program a Delta drive by button pushing
(four buttons) on the drive itself, a bit like programming a watch. It will drive you up the wall!!. Get the required
communication cable and use the software. The tuning aids alone make it worthwhile. I promise you....you will
be amazed by the flexibility and control that can be achieved with a modern AC servo.

Delta drives are programmed using an IEEE1390 plug, which can be wired in two ways, one of which can damage the
drive. I elected therefore to buy a genuine Delta accessory cable, of course you need only one cable and can program
many drives with it.

https://www.ebay.com/itm/NEW-ASDA-B2-AB-A2-rs232-ASD-CNUS0A08-PLC-Programming-Cable-HJ54-YD/173788498397?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

This is a USB to IEEE1390, there are cheaper RS232 to IEEE1390 cables. Either way using the cable and the free software
is the correct way to get the best from your servos.

Craig
My wife left with my best friend...
     and I miss him!