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I can't see where you mentioned how many drives you are using. For CNC all motors are almost never running in unison and requiring full current is rarely needed. 3 motors at 2 amps = 6 amps. 6/1.4 = 4.3 amp power supply required.As I said a 7 amp power supply is probably cheaper.

If you follow my advice and run a higher voltage power supply for motors, you need a seperate 24 volt power supply for field power. Whilst you could use a buck power supply for 5 volt logic but the power supply I suggested is only about $20. Given the number of issues I've seen where people have tried to use 5v plugpacks or phone chargers for mesa cards, the extra $10 is a small price to pay for reliability.
 

 

I always run 48 volts and sometimes as high as 90 volts but on a small machine I might consider 36 volts depending on manufacturers recommendations. 24 volts leaves too much available torque on the table.
I would prefer you to use seperate power supplies with the 7i96
Meanwell MDR-10-5 for logic (5v)
Meanwell MDR-60-24 for field power (24v) MDR-40-24 is Ok too.
Meanwell NDR-240-48 (48 volts) for motors but a LRS-350-48 (7 amps) might be cheaper and is a popular choice.

I can spend that much but I feel like I'm already splurging with this card. I also feel that the NDR-240-48 might be tool little current. Just curious but why should I swap to a separate power supply for the 7i96.

I like the idea of using a capacitor. I would just put that capacitor in parallel between the positive and negative terminals and add a bleeder resistor also in parallel also between the two terminals, correct? And this would protect my PSU and stepper drivers?

I think your cheaper ball screws would be OK Look at your motor torque allow for any gearboxes. Convert 1700 kgf to Newtons = 17000 N = approx 17 kN so I doubt your motors will get anywhere near that!

In Europe A Beckhoff EK1100 with EL1008 and EL2008 is supported natively by Linuxcnc for you inputs and outputs. You can also add a encoder input (EL5151 from memory) if you wish.Check eBay too but get a price first.

If you can't add the encoder don't worry about it, just use thread milling to cut any threads you need. Its a lot easier on the machine. Because there are metric coarse and fine threads, you don't need that many thread mills initially. eg 12x1.25, 10x1.25, 8 x 1.25 can all be cut with the one thread mill.

Initially home your machine using Linuxcnc and convert to internal homing down the track as it might not be that easy.

and yes, get CIA402 compatible drives as life will be easier.

So much advice already but a coupe of pointers including from some gecko docs I read years ago.
1. Doubling the motor voltage almost quadruples available torque
2. Any power supply for CNC can be overrated by about 40% so for 3 or 4 x 2 amp motors a 5 amp power supply is plenty
3, If a drive does not have a max temperature spec, be guided by the temperature the windings start to melt which is typically around 130 deg C but your motors are silent on that too. 80-100 deg C is fine

I always run 48 volts and sometimes as high as 90 volts but on a small machine I might consider 36 volts depending on manufacturers recommendations. 24 volts leaves too much available torque on the table.
I would prefer you to use seperate power supplies with the 7i96
Meanwell MDR-10-5 for logic (5v)
Meanwell MDR-60-24 for field power (24v) MDR-40-24 is Ok too.
Meanwell NDR-240-48 (48 volts) for motors but a LRS-350-48 (7 amps) might be cheaper and is a popular choice.
 

TL431 was/is some type of low current voltage regulator of reference or ... been over 30 years, so it can not send anything to big resistors.
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Start over:
-get some cheap drives, the so called "TB6600" that do not use the TB6600 chip are very good as they are the cheapest boxed drives, i have probably over 40 in daily use
-Get a MeanWell or Delta power supply, 24V (no, not 36V nor 48V) and 200W or 8.something amps, it is more than enough for 4 or 5 or 6 drives at full current of 3.5A (they are rated at 4.5 or 5A online), never mind the math for now.
-get a used PC with parallel port, or buy an add on parallel port
-wire the drives to the PC, with no BOB (your choice, i never use them)
-start making chips.
Oh cr@p, i just went back and :
-forget the parallel port
-those drives are fine, i have them for over two years.

Logthor wrote:

Are you sure it is 4 amps per motor?

 

4 amps per motor... I was thinking worst case. In practice you won't hit that.

A TL431 Precision Programmable Reference by itself won't handle the current. It will need some form of power transistor to handle the current. My little home-built cnc mill I had for a while had simply a cheap switching PSU powering 3 stepper drives with no additional protections. If a person had to add something I would connect  a 35V 10,000 uF capacitor to the DC bus. This adds cushion to even out short duration voltage spikes from decelerating motors.

Issue 0 = Siqa transport or something like that on Instagram
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Reply 1 = i have some old industrial ballscrews that you can have for very little money, and you can come see them in person in Peja.
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Reply 2 = yes and no, drives should be CIA 402 compatible to work, but not all implementations work as advertised, and some non CIA 402 work just fine
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Reply 3 = I have plenty of experience with Mesa and i can help you with that, free of charge whenever i have time
-3.1 = Mesa has a dealer in Germany, www.welectron.com
-3.2 = Mesa 7i96S with 7i73 OR 7i84. 7i73 is for panels and low level signals, 7i84 is an IO card with 32 inputs and 16 outputs, all from 8-32 or 36V (i forgot). I used 7i84 on my lathe for panel despite having 2 of 7i73 back then.
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Reply 4 = probably, but modbus is not used for anything real time, as far as i know. The new drives have encoder outputs. usually, that can be used to close the loop in LinuxCNC, but this is something you have to decide later, after figuring out ther balscrew/leadscrew situation, or just get linear scales, in your case a much better solution no matter what drives you use. This will also require a Mesa 7i85 for the encoder inputs.
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Reply 5 = depends if you want to also tap, but i would for sure.

How many stepper drives? If 3, then we're looking at 4 amps per motor * 3 = 12 amps total. Your stepper drives will draw less than that. Now, cheap PSUs tend to be overly optimistic with their current rating. I think your PSUs are easily sized double what these specs require. Which I think is a good plan. Go for it. I would buy that.
 
Are you sure it is 4 amps per motor? I thought that at most it'll draw 2 amps between the two windings (2.8 amps if it is peak). Sounds like a plan regardless. I was thinking I might just use a TL431 on the main bus and have it send all back voltage to a large resistor.

Logthor wrote:

So based upon what I'm using you don't think I need to swap out for a different PSU that has said protections?
 

How many stepper drives? If 3, then we're looking at 4 amps per motor * 3 = 12 amps total. Your stepper drives will draw less than that. Now, cheap PSUs tend to be overly optimistic with their current rating. I think your PSUs are easily sized double what these specs require. Which I think is a good plan. Go for it. I would buy that.

Your twisted pair cable looks great. I was just coming back with a suggestion 18 Gauge 4 Conductor Shielded when I noticed your post.

On your PSU: I have used a similar PSU on a similar project and it worked great. dbtayl's notes on PSU are correct, but another way to success is to use an oversized PSU. According to the specs you seem to be doing so.

So based upon what I'm using you don't think I need to swap out for a different PSU that has said protections?

CAT6A should do if you make sure it is multi-stranded. On a lot of cheap network cable each wire is solid = will break soon if it has to flex a lot. Breaking wires between your motors and drives can fry your drives. Just something to keep in mind.

I feel like this would do good.

Hello All!

More than10 years ago (at that time i just started my studies) my father found a great milling machine in a scrapyard, Prvomajska G301 D1 manufactured in 1973 , the machine seems to be almost not used at all, unfortunately it was subject to weather changes and most of the axis were locked up by rust, its spindle motor and holding bracket broken off and x axis gearbox with motor broken off. Back when he brought it home we started to disassemble, we removed some parts from its quill and then life happened we left it on the field covered with plastic sheets as there was no more space on the workshop. 
Recently we removed some things from the shop and got some place for the mill and we placed it inside, past week we were working very hard to clean up the rest of the machine and mount it back, so far the worst part is that its spindle bearing are quite rusty and once we get the rest sorted out will have to be replaced (altho, i still dont know where we could find it).

Attached are images of before and after cleanup and a picture of a machine we found online.

Couple of decisions weve come up with so far regarding the mechanical parts are as following:
Z-Axis: The Z-Axis has 36mm trapezoidal screw moved through bevel gears from the handle and the nut is bolted on the base of the machine offset by an iron piece, maybe can be seen from a picture when the saddle traverse was removed. Since we couldnt find a neat way to put a ball screw, also, were assuming the ball screw having less friction forces the z axis will just fall down, weve decided to leave the original screw and return back to it if we find any issue later on, following This Old Tony's conversion of his Maho and leaving its Z axis with trapezoidal screw, we're expecting the same...
X/Y-Axis: Both have 28mm trapeziodal screws with anti-backlash nut with pitch of 5mm. The nuts hole on the casting for both sides is 40mm which to our research matches the 25mm ballscrew so it is more or less the driving factor to chose 25mm ballscrews.

Issue #0: Throughout this project we always find it challenging to transport anything to place where we live due to some political issues and locally there is no store that sells parts. One of the solution we've found is a middleman in Germany that transports things to here so more or less we always have to check for delivery to Germany and goods that arent subject to VAT...

Question #1: We plan to travel to a nearby country that has ballscrews however im a little bit confused by Dynamic load rating and Static load rating related to price. A low price offers C(dyn) ~ 1100kgf and C(0) ~ 2700kgf, while a 5 times the low price C(dyn) ~ 1700kgf and C(0) ~ 5000kgf, but a 6 times the low price we can get a C(dyn) ~ 14900kgf and C(0) ~ 41500kgf... I'd appreciate a suggestion if going with the low price option is sufficient, as the 5 times the price seems to not gain much for the added cost and the last option seems like a straight up overkill.. 

Question #2: For the Motors to drive the axis of the machine, were planning to place stepperonline servo motors rated at 1kW ( link ) but interestingly they seem to have EtherCAT servos as well so im  kinda on a edge here.. I was originally planning to go with mesa cards prior to seeing the EtherCAT options, but now i kinda dont mind the added cost for EtherCAT, however, my father hopes to use the machine as a manual mill but he isnt very technophile so we will have to add quite some buttons and dials rather than use the keyboard/mouse to control the machine manually and for this we will need some IO, so, is there any EtherCAT IO that i can daisy chain to the system? I have no experience with EtherCAT so i dont know what im getting into... does LinuxCNC need to support the mentioned drive? Do we have to expect support from the manufacturer for the application? Is it doable?

Question #3: If i was to go with normal drives, i cant really decide on the loop's of the system and therefore the cards. I dont have any experience with Mesa cards, but i do have some experiences with parallel port LinuxCNC and Raspberry GPIO LinuxCNC. Should i go straight to position loop on mesa cards and velocity loop on the drive (hence analog mesa cards) or shall i take it slow and get a step/dir card and later on get an analog card if im happy with it?
Question #3.1:This leads to does Mesa official store shipment to Germany include VAT and complicated transportation or is it simple drop off?
Question #3.2: Can you suggest a good card match up for 4 Axis movement + Spindle + Lots of IO for control panel?

Question #4: Since Servos offer modbus and you can read the position of its absolute encoder im assuming that you can skip the homing procedures on LinunxCNC and fetch position from drives directly, am i correct? 

Question #5: How important is spindle encoder for a milling machine? I cant seem to find a proper place to seat it...

Any suggestion, question or comment welcomed! 

Thanks in advance!
 

On your PSU: I have used a similar PSU on a similar project and it worked great. dbtayl's notes on PSU are correct, but another way to success is to use an oversized PSU. According to the specs you seem to be doing so.

CAT6A should do if you make sure it is multi-stranded. On a lot of cheap network cable each wire is solid = will break soon if it has to flex a lot. Breaking wires between your motors and drives can fry your drives. Just something to keep in mind.

Edit:
Amps and motor drives: I think your choice is just fine.

I see, thanks for this info. I'm probably going to contact either Sherline or the manufacturer of the stepper (if they are still in business) to confirm the amps needed. Just to confirm though, those stepper drivers should work, right?

I plan on just mounting all the hardware on a piece of MDF so I don't think I really need to worry about space just yet. I really just need to get it working, then I can worry about bells and whistles.

Is there a cheap way of acquiring tools for the mill (e.g., cylindrical edge finders, collets, drill bits, end mills, etc)?

Logthor wrote:

I have a question about my servos. From the data sheet, it says that each motor is 2 amps per phase. The data sheet doesn’t seem to mention whether or not this is 2A phase RMS or peak current. The stepper drivers I’ve picked out are 2.1 amps peak for the closest dip setting. Is this fine to drive these servos? I just want to make sure I’m not going to burn up my servos.


 

Setting your drivers at 2.1 amps for your 2 amp motors sounds like a good "starting point" Then once you get it powered up, you can keep an eye on the motors to make sure they're not getting too hot as that is often the final rule whether an amp setting fully fits the motor/application. I don't see the rated operating temperature on the datasheet, as a general rule I like to keep them under 82C (180F), some are rated hotter. The cooler you run them the longer they last.

A stepper powered up and parked at 0 RPM has way more torque than it has while rotating. As a consequence, you can reduce its amps during 0 RPM, greatly reducing its heating. This reduces its holding torque some, so might take experimenting to find whether it is worth that trade-off.
I see your drives list function of sw4:OFF = half current, ON = full current. I suspect that is this feature, might be worth confirming.

@dbtayl on using a big enough enclosure: That is one detail I find too easy to get wrong. Countless times I think I started with a plenty big box. As the project evolves I find it is getting crowded.