Weiler E30 Lathe retrofit?

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13 Jul 2021 08:19 #214511 by andypugh
Replied by andypugh on topic Weiler E30 Lathe retrofit?
If your lathe happens to use resolvers then you can use those as absolute encoders too. It's a bit of a hack but there is code to use the stored position in the position.txt file in conjunction with the single-turn absolute position of the resolver to derive the absolute position.
(This is something I wrote for my own convenience and decided to push)
If the screws are moved with the machine off, then it gets the wrong numbers. It also gets the wrong numbers if LinuxCNC does not exit properly (power failure, for example)

But this isn't relevant to true absolute encoders, they should just need homing once (possibly manually) during machine setup.

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13 Jul 2021 10:44 #214536 by vmihalca
Replied by vmihalca on topic Weiler E30 Lathe retrofit?
I have encoders, and not one, but two per motor. Its a wierd setup..one goes to the drive, one to the controller, but at least the one that goes to the controller its just 1000ppr.
Managed to resurrect the encoder for X axis, somehow in time it dripped oil on the encoder connector, and through the encoder cable, it ended up in the encoder itself.
I had errors when trying to jog the axis, so I've opened the encoder and there were 3 spoons of oil inside. After 4 hrs of cleaning and cable repair, I've managed to bring it to life.
However I am thinking to change them because they whine quite loud when idle.
I am studying the alternatives and that's why I was thinking about motors with absolute encoders.
I know that the drive remembers the position of an absolute encoder, I was just wondering how that position gets communicated to linuxcnc in case it's changing when linuxcnc is off.
Won't be the case for me, because I can't turn the screws by hand, but I was just curious.
Also wondering how is the tunning for those motors? I know the drives will do some tunning with the motors, but I wonder if I need to do that PID tunning in linuxcnc too.
I am thinking of buying an analog mesa on ethernet (for using them with the setup I have now) and maybe later, change the motors&drives with some absolute encoder ones.
Would a Mesa 7i97 work with drives that have absolute encoders? The drives have an encoder output that can be connected to 7i97 so that linuxcnc closes the position loop.

If I keep the current drives, Mesa 7i97 is a good candidate for now. I wonder if I decide to switch later to deltas with absolute encoders, if I can still use 7i97.

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13 Jul 2021 10:54 - 13 Jul 2021 10:59 #214537 by Aciera
Replied by Aciera on topic Weiler E30 Lathe retrofit?

I know that the drive remembers the position of an absolute encoder


The point is that it's NOT the drive that retains the position but the encoder itself. As soon as the drive or linuxcnc powers up the positions are collected from all the absolute encoders over a serial interface.

I use Mitsubishi drives with absolute encoders. These require no PID tuning in LinuxCNC but these drives use an optical serial interface to communicate with LinuxCNC.
Last edit: 13 Jul 2021 10:59 by Aciera.

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13 Jul 2021 13:31 #214580 by vmihalca
Replied by vmihalca on topic Weiler E30 Lathe retrofit?
Does that mean that the position loop is not closed by linuxcnc? Can you go into more detail about what hardware are you using: serial interface, mesa boards, etc.

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13 Jul 2021 13:42 - 13 Jul 2021 13:46 #214583 by Aciera
Replied by Aciera on topic Weiler E30 Lathe retrofit?
I use Mitsubishi drives and motors with a PLC interface card from here:
yurtaev.com/
If you can get used motors and drives for a good price it's a very nice system.

There are other ways of course like using a mesa card and analog drives where the loop is closed in linuxcnc. These are widely used (although probably not very often with absolute encoders) but I have no experience with those.

So maybe somebody else will outline that path.

[edit]
The loop is closed in the drives in my setup. The position is handed back to linuxcnc over the serial interface and the PLC card.
Last edit: 13 Jul 2021 13:46 by Aciera.

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17 Jul 2021 18:35 #215166 by vmihalca
Replied by vmihalca on topic Weiler E30 Lathe retrofit?
Regarding re-threading, this is how its done by weiler:

From what I know, the threading starts after the index pulse. So I was thinking I could calculate what's the angle of the spindle relative to the index, and then based on the thread pitch, offset the Z start so that the thread will enter on the same lead.
Regarding the dummy axis is that needed? I only need the angle when I calculate the Z starting position.

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17 Jul 2021 22:35 #215182 by andypugh
Replied by andypugh on topic Weiler E30 Lathe retrofit?
Yes, it is a calculation that can be done in the GUI (and probably is in the case shown)

The system knows the current spindle angle relative to the index, so it is possible to calculate what start point will result in a thread that will pass through the current Z position at that spindle angle for the programmed pitch.

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18 Jul 2021 12:25 #215223 by vmihalca
Replied by vmihalca on topic Weiler E30 Lathe retrofit?
Thanks for the response. I saw in one of your videos that you were moving two axes in tandem for making a hole on an angle. Not sure if I need a similar setup, but is there a simple way to make a chamfer/radius by positioning the tip of the cutter in the right position then turning only one MPG wheel to cut that chamfer/radius ?

So far I did not managed to make the sinumerik 805 work, I am still waiting for the documentation, so untill then, I am analyzing the option of retrofiting it with linuxcnc.
The drivers now are analog 0-10v and with encoder inputs into the controller.
However I am considering replacing them with delta servos with absolute encoders.
I am trying to figure out which would be the right mesa board to use.
If I would go with a Mesa 7i97, I could use the actual drives and eventually I could use it with the delta drives and command them with 0-10v. But that means feeding the encoders from delta to linuxcnc and do the tunning in linuxcnc. Not sure how good is this idea...
Another option would be to use Mesa 7i95, and to command the drives with step-dir. The drives will close the loop with the motor and I could feed the encoders from the drive to the mesa board so that linuxcnc is aware of position.

Another option would be to use modbus, ethercat because these new drives are supporting these protocols. For the sake of experimenting I would be curious to try this version, but I am not sure how this setup would pair with a mesa board, and what mesa board should I use for IO, spindle encoder, mpg wheels, etc.

Any advice/idea is appreciated

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29 Jul 2021 19:22 #216255 by andypugh
Replied by andypugh on topic Weiler E30 Lathe retrofit?

Thanks for the response. I saw in one of your videos that you were moving two axes in tandem for making a hole on an angle. Not sure if I need a similar setup, but is there a simple way to make a chamfer/radius by positioning the tip of the cutter in the right position then turning only one MPG wheel to cut that chamfer/radius ?

I think that it could be done, but I am not sure that it is worth the bother...

I cut chamfers with a macro. Jog to the corner, type in the chamfer size, press go. 
forum.linuxcnc.org/41-guis/26550-lathe-macros?start=150#82743

 
The following user(s) said Thank You: vmihalca

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11 Aug 2021 17:06 #217563 by vmihalca
Replied by vmihalca on topic Weiler E30 Lathe retrofit?
I am looking at this mesa board for retrofitting my lathe:
store.mesanet.com/index.php?route=produc...t_id=344&search=7i97

On the US store is out of stock for a few months now, but it still appears to be in stock in europe.
I was wondering if this board is supported by linuxcnc pnconf and how come on the mesa page, it doesn't have the firmware files?
Is this product discontinued or something? Is there a reason I should not go further with this board?

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