Closing the loop with Linuxcnc, adding encoders to Mesa FPGA?

[Desertboy]

I have the machine connected to a DDCSV at the moment but I also I have a 5i25 can I buy a 7i85S
https://mesaus.com/product/7i85s/
and then replace my 4 nema 23's with nema's and encoders to close the loop with the (AM882) drivers I have now?

Will a 7i85s and the 5i25 plus a cheap PP BOB connected to a PP for home, MPG and limits be enough to drive a standard 3 axis router?

Am I right in thinking this board+linuxcnc enable me to close the loop with standard stepper drivers as long as my Nema's have encoders?

Where can I buy encoders without Nema's?

I found on alixpress 3nm nema 23's with encoders for ~£50 each but 2 of my existing nema's have dual shafts can I buy encoders to fit on them?

They are the 4nm one CNC4you sell.

[Desertboy]

I realised if I read this right I can't use the 7i85s for the spindle because I want 4 step/dir's but I could use a PP BOB for that function.

If I am going to set it up with linuxcnc want dual homing on the bottom axis.

[Kitwn]

If I am going to set it up with linuxcnc want dual homing on the bottom axis.

This thread will help you with this bit:

http://www.mycncuk.com/threads/12687-Auto-Squaring-with-LinuxCNC-v-2-8

[Desertboy]

This thread will help you with this bit:

http://www.mycncuk.com/threads/12687-Auto-Squaring-with-LinuxCNC-v-2-8

Thanks I have had it running linuxcnc but never got the dual homing working, I assume you still have to use the Beta for dual homing? (Was 2017 I had it running on linuxcnc)

At the moment I'm using just a cheap BOB through the PP which limits my speed to ~2m/min with the PC generating the steps but I have but the Mesa 5i25 PCI card that can generate 10mhz per axis which is enough for anything I might use.

I need a BOB for the 5i25 to connect the step/dir to, everything else connect through a cheap bob and parallel port.

I've had an issue with sizes on my machine it's a very weird problem, this is why I swapped back to linuxcnc but if I can close the loop as well that would be a bonus.

I think all I need is the 5i25 and 7i85s plus 4 Nema's with encoders and a lot of setting up lol.

The 5i25 are FPGA's which you flash a core onto so you need to get the correct cores for your application.

I'm going to buy a Raspberry Pi touch screen, 7" 1024*600 ~£40 ebay from UK seller, this has vga (and HDMI) in and usb touch screen support for linux so I can fit the screen on the front of the machine and keep everything mounted to the table the machine sits on.

[Kitwn]

Still the Beta v2.8 for auto-squaring. They're still developing v2.7 as the main thread even though the beta version is actually quite stable, though fundamentally different under the bonnet. Might be worth checking out both versions for the features you want since v2.8 seems to have been all about making radical changes to the core software in order to do new things v2.7 simply isn't able to.
Just remember to CLONE YOUR HARD DRIVE before you make any changes.

[Desertboy]

Still the Beta v2.8 for auto-squaring. They're still developing v2.7 as the main thread even though the beta version is actually quite stable, though fundamentally different under the bonnet. Might be worth checking out both versions for the features you want since v2.8 seems to have been all about making radical changes to the core software in order to do new things v2.7 simply isn't able to.
Just remember to CLONE YOUR HARD DRIVE before you make any changes.

If I'm going to linuxcnc route with encoders I really want dual homing, it just "completes" the picture nicely.

I can cut at 10m/min with great success but for some reason my sizes are out, my 3d carvings are coming out good.

I did some simple tests moving X 10mm then back to 0 1000 times same with Y not seeing as lost steps.

It also cuts the same size at 1m/min and 10m/min.

I only cut wood it's my thing, I don't even touch ply just real wood.

If I can close the loop using my AM882's with a breakout board for the Mesa step generator card I own and changing some motors I'll do it just for piece of mind.

[Clive S]

Still the Beta v2.8 for auto-squaring. They're still developing v2.7 as the main thread even though the beta version is actually quite stable, though fundamentally different under the bonnet. Might be worth checking out both versions for the features you want since v2.8 seems to have been all about making radical changes to the core software in order to do new things v2.7 simply isn't able to.
Just remember to CLONE YOUR HARD DRIVE before you make any changes.

2.8 IS stable 2.7 is no longer updated also it will not do auto squaring.

[Clive S]

If I'm going to linuxcnc route with encoders I really want dual homing, it just "completes" the picture nicely.
I can cut at 10m/min with great success but for some reason my sizes are out, my 3d carvings are coming out good.
I did some simple tests moving X 10mm then back to 0 1000 times same with Y not seeing as lost steps.
It also cuts the same size at 1m/min and 10m/min.
I only cut wood it's my thing, I don't even touch ply just real wood.
If I can close the loop using my AM882's with a breakout board for the Mesa step generator card I own and changing some motors I'll do it just for piece of mind.

I know you have said all this before but before you go down this route the machine should be made to cut accurately.

You are say it is out by about 1mm at 1M/min or 10M/min. That sounds like backlash or acceleration to high. I don't think changing the motors will help.

I would not attempt to close the loop until you get the gantry squaring sorted. Also closing the loop for a wood router in my opinion is a waste of time and money.

If you want to go with Linuxcnc I have a test ini file I could post that I know that works on a PP with V2.8 or 2.9 just for the that gantry squaring.

I have built a test rig for this from an old A frame type Prusa 3D printer with a motor on each side on Z running off a PP

[Desertboy]

I know you have said all this before but before you go down this route the machine should be made to cut accurately.

You are say it is out by about 1mm at 1M/min or 10M/min. That sounds like backlash or acceleration to high. I don't think changing the motors will help.

I would not attempt to close the loop until you get the gantry squaring sorted. Also closing the loop for a wood router in my opinion is a waste of time and money.

If you want to go with Linuxcnc I have a test ini file I could post that I know that works on a PP with V2.8 or 2.9 just for the that gantry squaring.

I have built a test rig for this from an old A frame type Prusa 3D printer with a motor on each side on Z running off a PP

It's a weird one Clive S, I cut a square indent it's 1mm undersized no matter what size the indent is but I move the machine 1000mm and it's spot on. I direct drive with couplings and everything is tight it's not slipping, I replaced all my couplings trying to solve this. My PSU is a Tolordial build, ~70v 1kva and 4 AM882's I'd be surprised if they're the issue here.

I've had the machine working for 2 hours doing a 30cm*40cm 3d carving with a R1 ball nose mill with 4% stepover this was spot on but the size was off.

When I cut 10 indents with a gap between them the indents were 1mm too small and the gap 1mm too large, tried with multiple tools of different sizes to be sure. I'm sure it has to be tool related but I had people check my gcode and it's good and I've had someone cut code I generated and there sizes were spot on.

I've also tried generating my code in Vcarve and Fusion to see if there was a difference, it's off, but it's repeatably off.

I definitely want the config file ;)

Not hooked it up to Linuxcnc yet, it's raining hard here today and I have the machine in a van so I need the weather to calm down a bit first.

[Kitwn]

2.8 IS stable 2.7 is no longer updated also it will not do auto squaring.

27868

True that it will never do auto-squaring but it's still where you have to start in order to then upgrade to 2.8. My recommendation is to do a clean install of LinuxCNC and use the configuration wizards to get the machine largely set up. That will populate most of the configuration files you need. Then upgrade to 2.8. Unfortunately the wizards have not been updated to fully incorporate all the new features so this is where you need to manually make changes to the config files as described in the thread referenced earlier. It's very important that from then on you NEVER use the wizards to change anything.

I'd also suggest a separate hard drive for this process, leaving the existing one completely unmolested and the machine able to revert to it's current state at the swop of a plug.

[Clive S]

Or you could go down this route https://forum.linuxcnc.org/9-installing-linuxcnc/38857-debian-10-3-buster-linuxcnc-quick-and-easy-install?start=0#164287
.
There are now quite a few iso's floating around with Linux mint that some members have made with 2.8 and 2.9 that work straight out of the box

[Desertboy]

Or you could go down this route https://forum.linuxcnc.org/9-installing-linuxcnc/38857-debian-10-3-buster-linuxcnc-quick-and-easy-install?start=0#164287
.
There are now quite a few iso's floating around with Linux mint that some members have made with 2.8 and 2.9 that work straight out of the box

2.8 has dual homing right? And I think a config for the Mesa card.

[Clive S]

2.8 has dual homing right? And I think a config for the Mesa card.

Yes 2.8 and 2.9 has it. It is a bit different than 2.7 But that now is a dead duck