I need super basic Help with Hardware choices

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17 Jun 2021 12:58 #212272 by Twizzlermill
I got another question, which may be considered off-topic: I stumbled upon the Protoneer CNC Raspberry Pi Hat. It seems like I can link up external drivers with relative ease. I'm assuming linking up a JMC CL stepper will be possible.

Do you guys think this is a viable alternative? I tried looking for its limitations, but I didn't find much, apart from a "limitation" of 1/32 microsteps (which still sounds like way more than I'd need…? And I'm not sure whether this only applies to the small drivers, instead of external drivers). Speed maybe?

Kind regards,
Twizzler

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18 Jun 2021 15:27 - 18 Jun 2021 15:27 #212338 by andypugh
Is the interface step/dir on GPIO pins, or does it have some higher-level interface to on-hat logic?
Last edit: 18 Jun 2021 15:27 by andypugh.

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18 Jun 2021 18:26 - 18 Jun 2021 19:06 #212351 by Twizzlermill

Is the interface step/dir on GPIO pins, or does it have some higher-level interface to on-hat logic?


Connection-wise? Yeah, it's pretty much that. It connects to the last 16-ish pins of the Pi, that's it. You can run a spindle and coolant, but stepper-wise, it's four connections (Step/Direction/enable/ground) plus endstops. Apart from that, I relly don't know (yet) what the board itself does, i.e. how much work happens on the board vs. on the Pi.

This is the thing:
wiki.protoneer.co.nz/Raspberry_Pi_CNC

I understand now that a Mesa card solution would mean using an FPGA to do time sensitive stuff and I'm assuming with the protoneer board, this will still be handled by the Pi (although I don't know, really), so I guess a Mesa card would allow higher speeds without losing as much precision – is that accurate?

According to what I found, my longest ball screw spindles (1605, 1400mm length) shouldn't go quicker than 6 meters per minute anyway, so that's pretty much the upper speed limit mechanics-wise. Honestly, I have no idea whether that sounds particularly quick.

I'm currently looking into Mesa cards, but am a bit confused, because a) there's so many and b), I don't understand whether just a Mesa card will be enough, or whether I'll need other hardware (apart from a computer, of course) because I see mentions of breakout boards…

In short, I'm almost where I was at the beginning of the thread. I guess I understand better what the different solutions do, but apart from that, I'm still undecided (except that I decided that the parallel port solution won't be interesting for me.).
Last edit: 18 Jun 2021 19:06 by Twizzlermill. Reason: Clarification

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18 Jun 2021 23:04 #212367 by andypugh

This is the thing:
wiki.protoneer.co.nz/Raspberry_Pi_CNC.


Right. That is running GRBL on the hat. GRBL is roughly equivalent to LinuxCNC and there is no way to use both GRBL and LinuxCNC in a single system (and it makes absolutely no sense to do so).

There are other, simpler, hats that would work with LinuxCNC:
thepihut.com/products/stepper-motor-hat-for-raspberry-pi
For example. That is just a pair of stepper drivers linked to the GPIO ports. However I think it will only run two motors.

You might want to search this forum for "Remora". That might be close to what you want.
Or, the docs here: remora-docs.readthedocs.io/en/latest/

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20 Jun 2021 19:49 #212508 by Twizzlermill

This is the thing:
wiki.protoneer.co.nz/Raspberry_Pi_CNC.


Right. That is running GRBL on the hat. GRBL is roughly equivalent to LinuxCNC and there is no way to use both GRBL and LinuxCNC in a single system (and it makes absolutely no sense to do so).

(…)

You might want to search this forum for "Remora". That might be close to what you want.
Or, the docs here: remora-docs.readthedocs.io/en/latest/


Thanks for the answer.

The thing is, I'm really not set either way; I'm not even super set on using as Pi as my computer, but after I fried a laptop at my shop (steelwool… bad stuff.), I'd prefer a Pi because it's cheap to replace. So really, it's not like I'm looking at something specific; I just want my machine to move (and move well) and I'd prefer a Linux-based approach.

A Pi has an ethernet port, so Mesa cards are an option.
But either I'm an idiot or I'm looking in the wrong places (or both), but I have a hard time figuring out what I'd need exactly if I wanted to go the Mesa route. As in, will a Mesa card be enough to get my steppers moving? If yes, which one? if no, what other hardware will I need? Configuration might not be a piece of cake either, but I can get through that with copy-pasting terminal commands (living the Linux pleb life).

I took a look at Remora, but it looks like it's introducing a level of complication that I don't need right now.

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21 Jun 2021 01:26 #212529 by Aaroncnc
the mesa card will not drive a motor directly.
It will make the signal to go to the motor driver and that driver will drive the motor.

Best thing to do is make a list of hardware you have or are going to buy and we can try and help you with what will work or wont.

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21 Jun 2021 02:13 #212531 by BeagleBrainz
If you are going to jump the RPi route, be aware that a 2nd corporate desktop may come in at the same price point, only the RPi 4 will work, as all the previous versions have the Ethernet on the USB bus.

Whilst I haven’t looked into costs the RadPad looks like it would make a neat console for a cnc machine. Ok looks like $150 plus the cost of the RPi 4 on top.

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21 Jun 2021 18:56 #212580 by Twizzlermill

the mesa card will not drive a motor directly.
It will make the signal to go to the motor driver and that driver will drive the motor.

Best thing to do is make a list of hardware you have or are going to buy and we can try and help you with what will work or wont.


I have drivers; the JMC steppers have drivers mounte to them.
I did mention my hardware in the first post:

What I have/want:

1.: A Raspberry Pi 4 as a computer (with all the other stuff of course).

2.: 4 JMC Closed Loop Stepper motors(Model IHSS60-36-30-21-38); the y-axis will need two.


You did actually mention Mesa cards and that's what made me take a closer look, aor at least made me try to, because I feel like I'm not getting it yet.

I'm not super set on the Pi, but I have one and I thought it's as good as any old computer, so why not give it a go.

And apart from that I'm really wide open for suggestions. Someone mentioned the Mesa 7i76e, would that be a good option? And (apart from drivers) would that be all I need?

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21 Jun 2021 19:50 - 21 Jun 2021 19:50 #212587 by Aaroncnc
so with the using one of the mesa ethernet options gives you some room to change platforms.

It will work with a RPI4 and most desktops that have good latency.
some options for mesa ethernet are
store.mesanet.com/index.php?route=produc...t_id=311&search=7I96
store.mesanet.com/index.php?route=produc..._id=290&search=7i76e

The 7196 has 11 inputs and 6 outputs (there are expansion cards for future upgrades.)
And the 7i76e has 32 inputs and 16 outputs
Both can drive 5 stepper or servo motors.

Take a look at the manual for a second see page 10 in the doc (page 5 as written on the paper)
You will see it has headers labeled step 0 step 1 step 2 step 3 step 4, ect
If you zoom in you will see the pins are labeled 5V, dir0+, dir0-, step0+, step0-, gnd
www.mesanet.com/pdf/parallel/7i96man.pdf
Now if you look at your motor driver
www.jmc-motor.com/product/954.html
and look at the Connections to Differential Signal
you will see pulse signal, direction and enable.
You would hook the step from the mesa to the pulse on the driver
and dir from the mesa to the direction pins on the driver.
For the enable you would hook all the driver enable pins together and use one of the outputs found at the bottom of the mesa board.

So as long as you have power being fed to your motors and the mesa board
and you hook everything up then you will be able to move your motors around.

both mesa cards above will do a standard cnc machine but if one wants to start adding a bunch of extra features and sensors or switches the one with more IO will be better. but if not needed could be unnecessary

other things you should have are limit/home switches.
A big E stop button that can be slammed to quickly stop the machine. (this is a must trying to hit a key on a keyboard while something is trying to break itself or smoking a motor sucks!)
Good wires that can take vibrations. (this is a luxury but its nice to not chase down sporadic issue only to find a wire snapped inside the insulation and the issues only happens once every few months and you go crazy changing switches and connector ends to forget this can happen....)
maybe a few buttons to make hardkey cycle start and pause and tool change confirm. a few relays to turn on dust collection/ coolant.
Last edit: 21 Jun 2021 19:50 by Aaroncnc.
The following user(s) said Thank You: Twizzlermill

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21 Jun 2021 20:23 #212592 by Twizzlermill

so with the using one of the mesa ethernet options gives you some room to change platforms.

(…)

Take a look at the manual for a second see page 10 in the doc (page 5 as written on the paper)
You will see it has headers labeled step 0 step 1 step 2 step 3 step 4, ect

(…)

other things you should have are limit/home switches.
A big E stop button that can be slammed to quickly stop the machine. (this is a must trying to hit a key on a keyboard while something is trying to break itself or smoking a motor sucks!)
(…)


Thanks, this is very helpful.

Yes, endstops and emergency button are a must and planned. Relays for all the good stuff are definitely planned down the line, especially after I managed to ram a powered-off spindle into (thankfully soft) wood on a friends machine... No fun.

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