Starting to design out my build, looking for critique

[JAZZCNC]

Understood. I've been scouring the forum and the web, but it seems my search-fu is a bit off, since I could not really find a conclusive answer on the differences of the UC300eth, UC400eth and AXBB-E, especially since CNCDrive's web pages are kind of scarce on the matter. As far as I am able to see, the 300 just has more IO than the 400, withe the AXBB-E has the same amount of IO as the 400, but a built in Breakout in a nicer package? Judging from this post, it seems that I can use all the IO that I can get, which would tip me in favour of the UC300eth.

Also, you mentioned being locked into Mach 3/4, as a negative. What other (better?) alternatives are there, and why is that?

Yes your spot on with differences between these boards. The UC300 is the better option if you need lots of I/O. Coupled with a Good Bob that can accept 24v signals it's an excellent setup.

The alternative to Mach3/4 is UCCNC. Whether it's better or not is matter of opinion. The trajectory planner or put in simpler terms the way it creates motion is better and smoother than Mach3, can't speak for Mach4 because it's so full of bugs don't trust it and won't use it.
Now mach3 as it's advantages in that it's got massive following and is much easier to write custom scripts etc and customise to your exact needs.
What can say is both work well and will do what 99% of people want straight out the box.

I guess I just ignored the existence of 2020 Ballscrews :D I calculated it through in the motor spreadsheet, and, asuming I did all the correct modifications in terms of doubled motor RPM and doubled torque, I could actually now hit 12m/s rapids with the same motor, compared to 7.5m/s before. Thank you for the recommendation!

If by12m/s your meaning 12 meters per second then your massively off with your settings. 12 Meters per Min is more realistic figure.

To be honest that spread sheet is load of rubbish and spits out unrealistic figures. Real world is much different due to the many variables that affect machine performance.

IBuilding a PSU should be fine, for the most part, but just so I can make myself a complete picture, do you have any recommendations of AC Drivers that are worth it?

If you can find any the AM882-H are AC version. They are hard to find now thou.
If your on a budget these are not bad drives which i've fitted on several machines without any troubles and good performance.
https://www.ebay.co.uk/itm/2DM860H-2....c100148.m2813

I mostly tend to fit Closed loop hybrid steppers these days and many of them can be driven with AC or DC.

On a different note, I have seen Jog and MPG pendants mentioned and presented on shop pages. What do those things do exactly? What I have found repeatedly on the topic, is that they are used for manual operation of the machine, however I was under the impression that this would also be possible directly from the control software. Am I mistaken here, or is there a big advantage to using such pendants?

MPG / pendant is just a hand held box that lets you stand at the machine and Jog it arround rather than using the PC keyboard. On large machine this is very helpfull when setting tools or find edges of material etc as walking back to PC to make move is a pain.

[Chrono]

If by12m/s your meaning 12 meters per second then your massively off with your settings. 12 Meters per Min is more realistic figure.

To be honest that spread sheet is load of rubbish and spits out unrealistic figures. Real world is much different due to the many variables that affect machine performance.

Ah yes, indeed it is 12m/min, don't know how I have read that wrong every single time...

I have been using the spreadsheet to dimension all my motors so far. Is there a better way to do this, or will it all just come together in the final build? I am guessing there is no real way to account for all the variables the steppers will be influenced by when it comes to it, but I guess what I am asking is: Is it still a good idea to run the motors you can find through the spreadsheet to find the "best one" you can still drive?

[JAZZCNC]

Ah yes, indeed it is 12m/min, don't know how I have read that wrong every single time...

I have been using the spreadsheet to dimension all my motors so far. Is there a better way to do this, or will it all just come together in the final build? I am guessing there is no real way to account for all the variables the steppers will be influenced by when it comes to it, but I guess what I am asking is: Is it still a good idea to run the motors you can find through the spreadsheet to find the "best one" you can still drive?

Lots of things come into play, not all motors are equal for instance and same size motor can have ridicuously high inductance compared to another and the spread sheet doesn't and cannot really account for these variables.
Combine this with all the other variables and it's very much trial and error in some ways.

For instance I've helped folks troubleshoot machines with motors that would lift empire state building yet they stall and run slow because they wrongly sized components like ballscrews, gearboxs ratios etc or they did such poor job of building and allignment the machine is crippled.

The best advice I can give is to look around for similar size machine built with similar materials/components and copy what works.

Thru experience I can tell you that Single 4Nm nema23 with inductance around 2-3Mh wired in parallel running 4 to 4.5A with 68Vdc on 80Vdc Digital drives connected to 16mm Dia10mm pitch ballscrew with a Good motion controller (not parallel port) will easily and reliably reach 12M/min moving 40-50Kg.

For longer than 1200mm 20mm 10mm pitch screws you'll need to use nema 34 or use method like I suggested using larger pitch with ratio.
Same for dual screws you'll need 2 x Nema 23 upto 20mm Dia, Single 4nm Nema 23 won't drive 2 screws, even with ratio.

If you go to nema 34 then for better speeds you'll need more volts.

[MartinS]

Thru experience I can tell you that Single 4Nm nema23 with inductance around 2-3Mh wired in parallel running 4 to 4.5A with 68Vdc on 80Vdc Digital drives connected to 16mm Dia10mm pitch ballscrew with a Good motion controller (not parallel port) will easily and reliably reach 12M/min moving 40-50Kg

Hi Chrono,

Dean,

For those of us who are learning and planning, could you expand on the above?

Is this 60BYG401-03 https://cnc4you.co.uk/resources/Step...1-03%204Nm.pdf an example of the stepper categorised above? or if you have another preferred source/model, what is it?

and

I mostly tend to fit Closed loop hybrid steppers these days and many of them can be driven with AC or DC.

Are those different from the above and do they need different drivers?

Thanks,
Martin

[JAZZCNC]

Dean,

For those of us who are learning and planning, could you expand on the above?

Is this 60BYG401-03 https://cnc4you.co.uk/resources/Step...1-03%204Nm.pdf an example of the stepper categorised above? or if you have another preferred source/model, what is it?

Yes those are good motors which I've used many times. The sheet say's it all really When wired in parallel the Inductance is 3.0mh which is a good value. The lower the inductance the better.

Are those different from the above and do they need different drivers?

Yes and No.
Yes they are still a stepper motor but they have encoders built into them.
No because while they are stepper motors the drives they use are more like Servo drives and designed to read the encoder to track the motors rotation.
Normal stepper drive just recieves pulses and tells the motors to rotate but doesn't actually check or know if actually rotated the commanded distance. So for instance if your axis is binding stiff or very heavy you could lose steps and neither the drives or control software(mach3) know anything about it which leads to inaccurate cuts.

Closed loop drives work differently in that they use the Encoder on the motor to check if it rotated the commanded distance. If it over shot or under shot they correct it's position so returns to commanded position. If they over shoot more than programmed distance they will throw a fault message that can be sent to the control software so can stop the cutting.

While they are Not Full Closed loop, meaning they don't feed the motor position back to controller which still takes it on blind faith that commanded position as been reached. They are a good alternative because they do correct for small positional errors inside the drives and warn the controller if large positional errors occur. Compared Standard stepper drives which have no clue where the motor ended up so can not tell the control software if errors occur. The first you know about it is when the job is finished and wrong or worse machine crashes because it's got lost.!!

So in short yes they are different and need special drives, No they are still stepper motors.
Often you buy the closed loop drives and motors together as a set. Like these.
https://www.ebay.co.uk/itm/CNC-Hybri...IAAOSwjlVcIJIb

https://www.ebay.co.uk/itm/NEW-Leads...UAAOSwqFBbvGxS

Hope that helps.

[MartinS]

Yes, thanks, most helpful.

So in short yes they are different and need special drives, No they are still stepper motors.
Often you buy the closed loop drives and motors together as a set. Like these.
https://www.ebay.co.uk/itm/CNC-Hybri...IAAOSwjlVcIJIb

https://www.ebay.co.uk/itm/NEW-Leads...UAAOSwqFBbvGxS

I guess that we still need a low inductance. I can't see it specified in the links.

[JAZZCNC]

I guess that we still need a low inductance. I can't see it specified in the links.

Yes the same applies but I've yet to find a Closed-loop drive/motor combination that uses high inductance motors and just about every set I've used gives reasonable torque at higher speeds, most reach 1500rpm before torques drops away.

Also, there are closed-loop systems that use 3 phase motors which give much better torque and smooth operation. To be honest I mostly fit 3 phase systems on larger machines.

The only thing you have to watch for with smaller closed-loop systems is that they use low voltage, often 50Vdc drives and they do not tolerate more than 50V and will be damaged if rises above. This means you need to run safe margin, 44 - 45V is recommended. That said they still tend perform very well and better than a standard stepper at same voltage. Think this must be to do with the way the closed loop drives work.!

The bottom line that I've found is that closed-loop systems tend to be slightly stronger at higher feeds and the closed-loop drive ensure the position is maintained.

That said a correctly sized and set up Open-loop stepper system is just as accurate and shouldn't lose position if tuned correctly. Thou Closed-loop systems are coming down in price and the difference in price is now such that closed loop is the wiser choice.