need help with ethercat vs mesa

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Hallo all,
im planning and building my own cnc from ground up with zero experience. Im in the final stages of planing but like many times before Im rethinking some basic descisions. 
Issue right now is I was planning on using linuxcnc with a mesa 7i96s and send commands to the drivers via step/dir. I plan on using stepper-online a6-series servos for my cnc and am aware that this is a kind of suboptimal setup as its not a fully closed loop system. I have ran into an issue connectiong the servo drives to the mesa, all options are eighter expensive or create a mess in my electrical box. I am considering switching to ethercat as the pricedifference is negligible. Rather it would actually save me money since the wiring is much cheaper and I don't need the mesa anymore. Problem is I already have the mesa (unused) and don't know what the best option would be.
1. Go full ethercat and sell mesa. 
2. Deal with the wiring issue by throwing money at it.
I hope someone with experience with eighter system or both can give me some help deciding or maybe give me pointers that I may not have considered before.
Many thanks in advance.

A6 Ethercat servos are not step-dir compatible; pick one or the other.
Step-dir with Mesa will be easier to configure than Ethercat, but more wiring

What is complicated or expensive about connecting the step-dir drives to Mesa?  Buy a DB44 cable from Stepperonline and connect to Mesa - maybe I'm missing something?

Only headache I know is that the DB44 cable connector is HUGE, and sticks way out when plugged in to the drive.  If you have a tight enclosure you may not be able to shut the door on a standard 8" deep enclosure.

You can buy DB44 right-angle cables (no adapters I can find) to shorten the package a bit, or you can cut a hole in the enclosure door for the cables to stick out.  And 3D print a raised cover for the new hole...

The cables are kinda expensive(relative to others), the bulky part will be an issue too. Also played around with the thought of db44 breakout boards, most expensive because I need a cable and a board for 4 servos but it would reduce the wiring headache (~34 bouncing cables per servo)

Im trying to keep everything on a tight budget as the cnc kept growing and now Im at twice the planned budget. Im trying to future proof what I can and keep the system as adjustable as possible. 

 

The ethercat A6 use a HDB15 connector on the front for the built-in IO.  Not quite as large as an HDB44, but still need to consider cost of cable and stickout/packaging.  If you plan to use a brake on one (or more) servo, you'll need at least one drive to have the IO cable connected.

OTOH, HDB right-angle cables, extensions, and adapters are much more available less expensive than HDB44's.

I mentioned before I want to future proof. To claify: its not a what if but a kind of fixed advancement plan:
1. ATC toolchanger
2. 4th possibly 5th axis
3. Alternating size/ tooling.
4. Laser/Mill hybrid 
5. possibly multiple machines of the same build.

I have a small business and depending on how I expand I want this cnc to be able to grow with me. Once I have a system running there will only be minor changes doable as downtime would cost me double.

Since you mentioned price sensitivity, you might think about IO - both current and future needs.

Ethercat drives generally have onboard IO available which can be used as general purpose, but these aren't directly expandable without adding more drives.  Nor can drive onboard IO drive high-power outputs directly - you'll likely need some relays (or similar) to turn on pumps, air cylinders, etc.

If you need more IO than the drives offer you'll need to add an IO module, such as a Beckhoff or other vendor.  Or go with non-realtime IO based on some USB solution.

I haven't priced Ethercat IO modules, but I suspect they are more expensive per IO point than Mesa.  It might be instructive to set up a spreadsheet with all your current and future IO requirements and price out an Ethercat solution vs. Mesa.

Or perhaps both Ethercat and Mesa - this is also an option.

Another consideration is your (future) ATC - have you thought about how to control it?  Will it be a 'dumb' motor using a geneva mechanism, or a servo-controlled thing with a reudcer?  Or something else?

Reason I bring this up is that it might be helpful to find an example of an LCNC configuration which matches your intended hardware...are there any examples of an ATC using Ethercat available, or will you need to break new ground?  Same goes for your possible laser.

It all gets rather complicated, doesn't it?

I looked into ethercat options for i/o and found many different modules at many different price points. Because there is so much aviable prices are not too bad. Its also easy to connect more i/o to the ethercat chain.

With the 7i96s I have a smart serial aviable for expansion cards but its only one port. Multiple boards, I think need to be daisy chained, dont know how to tho. 

The atc will be controlled by pneumatics. If you mean the rack/magazin I will try to design a semi active one, similar to what Marius Hornberger built for his hammer cnc. There will be a rack that moves out of the way when not in use. I plan on making mine not purely mechanical tho.

I hope people already did similar builds and I just need to connect the dots, basicly taking parts I need to make a build out of it. Playing around in the dark is not exactly my aim. 

Just a general question. Does a mixed system work? Put the basics on the Mesa card and, if needed, extend with Ethercat?