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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.

Thanks for the info.

Nomenclature nitpick: Unless you've got encoders on there, those are stepper motors, not servos. And even steppers + encoders are typically referred to as "closed-loop steppers", not servos.

I meant to say steppers my mind just slipped I guess.

PSU: If you're going to use a switch-mode PSU, make sure you get a big (uF rating, voltage rating) capacitor to put on it. Motors dump energy into the PSU on deceleration, which can lead to voltage spikes and blown stepper drives and/or PSU. A toroidal/transformer based supply is often recommended instead for this reason.

Noted. The geckodrives are a bit too expensive for me to consider. If you have an recommendations for a good PSU I'm all ears. Additionally, regarding the drivers I have picked out, I assume it is RMS current right in that documentation?

Wire: You may want multi-conductor wire. If that's for the steppers, 4-conductor would be good. Running 4 separate wires to each motor seems unnecessarily obnoxious.

If I use a CAT6a cable will the shielding on it provide enough insulation to avoid being influenced by EMI?

-Coolant/air blast control
-MPG
-Spindle encoder
-Touch probe
-Toolsetter
-Hardware feed hold/single-step/pause/resume/etc. buttons
-Rotary axis

I'm probably just going to use a spray bottle with coolant for the mean time. Not sure what you mean by MPG, the machine I have has manual lead screw handles built in to jog it. I'm going to control the spindle with the 7I96S and hope it spins at the speeds I want while cutting. Touch probe's seem expensive unless there is a cheap one on amazon. Regarding a toolsetter, buttons, and rotary axis, all that seems quite far away atm. I'm going to worry about making it work first.
 

Nomenclature nitpick: Unless you've got encoders on there, those are stepper motors, not servos. And even steppers + encoders are typically referred to as "closed-loop steppers", not servos.


PSU: If you're going to use a switch-mode PSU, make sure you get a big (uF rating, voltage rating) capacitor to put on it. Motors dump energy into the PSU on deceleration, which can lead to voltage spikes and blown stepper drives and/or PSU. A toroidal/transformer based supply is often recommended instead for this reason.

This may also be useful: www.geckodrive.com/support/power-supply-basics/


Wire: You may want multi-conductor wire. If that's for the steppers, 4-conductor would be good. Running 4 separate wires to each motor seems unnecessarily obnoxious.


Missing from your list: buttons, switches, fans, terminal blocks, enclosure, mounting hardware, connectors. Specifically, you'll probably want to put your parts in a box of some kind, and at the very least an e-stop is a good idea. Generally you want that wired such that it hard-cuts power to the motors+spindle of the machine or otherwise renders it in a safe state.

Drawing out everything you'll use and the connections between them can help identify gaps- eg, making sure you have enough terminal blocks. It's shockingly easy to run out of those. Ditto for enclosure space- a little planning goes a long way there, and also getting a bigger enclosure than you think you need.


Finally: I'm not familiar with all the mesa offerings (I've got a 7i76e on my mill, IIRC), but try to think about what you might want in the future and then you can decide whether it's worth buying something with spare I/Os to support it now or accepting you may need to upgrade the card later to add things. Things you might consider:

-Coolant/air blast control
-MPG
-Spindle encoder
-Touch probe
-Toolsetter
-Hardware feed hold/single-step/pause/resume/etc. buttons
-Rotary axis

IIRC you've got a Taig, and IIRC those use ER collets or equivalent... my experience is re-zeroing tools with ER collets gets old fast. I more than once trashed a tool and/or workpiece forgetting to do so... a toolsetter IMO would be worth planning for.

Hi again, smart people! I was wondering if you could check over my shopping list and make sure I am purchasing everything I need and that everything I am purchasing will work with each other.

• Servos (SST57D3201) (came with the machine; they are quite old, but they should still work)
• Prox Sensors
• 7I96S
• Buck Converter for 7I96S
• PSU
• Stepper Drivers
• Shielded Wire

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.

Yes. you need a separate supply.

You can often use a 12V supply and scale the PWM so that full RPM = 10V
 

Hello,

I've been using the 7i96s potentiometer function to control a DC driver board on my mill, 

I'm replacing that motor with a Chinese servo that requires a 0-10v signal to be driven in speed mode, 

The drive itself does not have a +10v that I can feed the digital pot on the Mesa card 

Would I require a separate 10v power supply to feed the Mesa card digital pot to output the proper signal for the servo drive?

Attached are the wiring diagrams form the servo drive, and the link to the servo kit:

www.omc-stepperonline.com/fr/kit-de-serv...p67-a6-rs750h2a1-m17 

Thanks for your help! 






 
 

"A big machine can kill you."

That's why we have licenses to drive automobiles, and a pretty steep barrier to entry for machine tools of this size

I don't want anyone to get hurt, but if someone does get hurt because they were being stupid, no amount of words or safety meetings will prevent it.

Truth does not depend on being proven.
The truth is the truth even when everyone shouts at you and laughs at you.
That's why I have no intention of proving anything.
But I will tell you something very important.
A CNC machine is not a toy.
Even a small desktop machine can waste your time, spoil expensive material, or injure you.
A big machine can kill you.

rodw wrote:

I don't know why this conversation got down to swap drives and building LinuxCNC from source. None of that is necessar. LinuxCNC only requires 4-8 gb RAM but I think I'd lean towards 8 gb today.
 

The author of topic asked for the latest version of LinuxCNC.
The latest version of LinuxCNC is compiled from latest sources...
Compilation of LinuxCNC is easy, easier than many things you have to do after.
Where see you problem?  

I agree, many things are not neccessary, for example PC computer is not neccessary, and LinuxCNC is not neccessary, you could use GRBL  controolled from smartphone, but this is not the subject of the topic.

Modern Linux needs 2 (two) gigabytes of RAM.
Some programs needs more, but LinuxCNC not belongs to them.
My computer I use to write this post (Ryzen 5 with 16 GB of RAM running Firefox on Debian 13.6 with xfce4) uses now 2 GB of RAM, and believe me, this may be less if less memory is installed.

I see, we are on different levels of using Linux...
For me copying whole partition to other disk is normal and often used procedure. I don't need unwanted dependiences, like system not starts without swap partion leaved on old disk. I not need any swap partition, because Linux can use for swap file placed on any mounted partition, and you can turn on/off swap when you need (swapon/swapoff).
Swap file is correct solution, swap partition is a prayer for troubles...

You may use defaults installation settings, and it should works, but why you deny talk about how do it better?