2 seperate MPG handwheels for each axis - CNC Lathe build

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12 May 2020 10:00 - 12 May 2020 10:02 #167493 by denhen89
Hello Guys,
i think about 2 years ago i created a topic where i asked if its possible to use a spindle encoder with a cheap breakout board and i got a lot of help from you and i do now know that it depends on the Latency, but i also asked about use 2 seperate MPG handwheels for each axis and it seems its not a problem with software encoder.

Since over an month i started with the build of the CNC Lathe, but right now i have not a lot of time to do the mechanical work, but i bought already a PC, Monitor and also i do got the MPG Handwheels: 5V-6pin-100pulse + 80mm - ALIEXPRESS LINK
The BOB i use: SSK-MB2 Breakeout Board (in case you would say i should not use a cheap breakeout board if i do want to use 2 MPG + spindle encoder, then of course i am ready to order a MESA 5i25 + 7i76, but i have to admit that i would like to save some money and do the update maybe later in case i would know that it will make a big difference between a cheap BOB and the Mesa cards)

Yesterday i started to wire up one MPG handwheel same as shown on the 2 pictures from this topic: https://www.forum.linuxcnc.org/27-driver-boards/29169-mesa-5i25-and-7176-getting-started?start=40
*I have added 2 pictures from my setup to this topic*

It seems to work, because i measured 5V signal when turning the handweel and measuring on the A and B wire.

Right now i have to admit that i have no clue how to do the HAL setup. I tried to find a topic where someone did the same with a cheap BOB, but i can only find topics for the setup with MESA cards.
I feel a bit bad to ask you to tell me how to do that, but i have that feeling that it would take me weeks to get it done without any help and it would be like a trial and error.

I did not change anything on the HAL or INI files or any other files, because i just do not know how to start and i currently just want to test the MPGs, so that i will later know how to get it to work, because i see that as the biggest problem, but also i would like to have e.g. 3 buttons next to the MPG Wheels to change the resolution (0.01mm, 0.1mm, 1,00mm), but i also do not want to ask for too many things at once.
I have build already a CNC Router with slave axis and got the homing setup done, but the MPG Handwheels setup seems to be a bit too much for me.

I really hope you can help me out. I am not that much in hurry, but as soon as i get the Power Supplys from China, i would like to start with the electrical box setup.

PS: I really tried to find a way to do it by my self. :)

Thanks in advance and best regards.
Denis
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Last edit: 12 May 2020 10:02 by denhen89.

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12 May 2020 10:42 #167494 by tommylight
Some info on parallel ports and their capabilities:
forum.linuxcnc.org/38-general-linuxcnc-q...ontrol-boards#167456
forum.linuxcnc.org/30-cnc-machines/39061...-and-firmware#167371
Beware that when using the 9/8 mode, the 4 additional inputs draw more current than the other 5 so some encoder will not work with it without adding some resistors. Also those modes work on built in ports and some PCi/PCI-E cards, not all.
The painful truth is that using parallel port for spindle encoder is not the best solution by any means, it works just fine for MPG with low count encoders, but spindles use high count encoders and you run out of reliable bandwidth at very low RPM's.

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12 May 2020 11:04 #167497 by denhen89
Thanks Tommy for your reply and help.

So, should i just buy a 7i76E (or 5i25 + 7i76) and be 100% sure that it will work properly? :)
If so, would you recommend the 7i76E or the 5i25 + 7i76 plug & go kit ?
I have spend a lot more already than i have planned to do, thats why i wanted to safe some money, because i had a BOB already from a other build, but to be honest, the 275€ might be a good investment. I would just need to know if i should order the 7i76E or the 5i25 + 7i76 Plug & Go kit :)
Thanks in advance

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12 May 2020 12:09 #167507 by tommylight
Yes it will work properly, i have a big router working with a 7i76E for several years, never missed a beat, and there are plenty more in use every day all over the world. It is a very good investment, it has terminals for everything so wiring it is easy.
Given the choice i would always choose the 7i76E.
You can also get a 7i92 (eth) or 5i25/6i25 (PCI/PCI-E) and later get the 7i76, but not worth the wiring and changing stuff later on. Without 7i76 you would have very limited spindle controls or would need to add some relays and stuff.

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12 May 2020 12:20 #167509 by denhen89
Again, thanks a lot for your help and the explenation.

Ordered the 7i76E just a minute ago and hope it will come soon.
Until then i will have no questions and i think when it comes i will be able to find a lot of informations here in the forum to get it to run, at least i will try it.

Thanks again :)
The following user(s) said Thank You: tommylight

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12 May 2020 21:10 #167557 by rodw
If you search the forum here, for my Spaceship plasma build thread about 3-4 pages in there is a step by step illustrated guide on how to set up a MPG on a Mesa 7i76e. Just do it again for a second control.

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13 May 2020 08:24 - 13 May 2020 09:11 #167623 by denhen89
Thanks a lot! I found the HAL files and you even eplained most steps or maybe even all (i will find out as soon as i get the 7i76E). This should help me a lot when setting up the MPGs and also use some warning lights.

I did not read everything to be honest, because i have now a bit work to do, but i saw that you used 3 different scales (0.01mm, 0.1mm, 1,00mm), as i want to have it too, but how do you change them, with buttons?

Thanks in advance:)

EDIT: Sorry, i found on the same page (page 3), that you explained how you installed a switch to change the scale. I am currently on the Aliexpress page to find buttons for the scale change. I would like to use seperate buttons for each scale. Am i right that it would be easier than use that kind of switch as you have used? (due to the binary logic that is required)

I am not that good with with those programming stuff, so i would like to make the setup as easy as possible.

EDIT Nr.2 : I will do it as you have done it, with the 2 pole 6 position switch: Just ordered that one: www.aliexpress.com/item/4000687267288.ht...1.0.0.27424c4dhpJbs6
Hope you will help me out if i will have any problems setting it up :)
Last edit: 13 May 2020 09:11 by denhen89.

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13 May 2020 09:25 #167634 by rodw
Looks like you are good to go now. You will only need one scale switch but you can do the same thing for an axis select switch. There are docs to guide you on that but essentially its the same. I since have a wireless MPG that I use all the time and its wired in exactly the same way but it includes a 6 axis select switch. I enabled all the axes when I configured it and I have thought of using the unused selections to do speed overrides and the like but I have never found a need for it.

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13 May 2020 09:50 #167636 by denhen89
Thanks again :)
I think i dont need a axis select switch if i have 2 seperate mpg wheels for the Z and X axis (Lathe), correct?
Do i understand it correctly, that i dont need to activate the mpg wheels in jog mode, just turn and the axis will move? E.g. i turn both MPGs at same time and both axis will move, right?

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13 May 2020 12:13 #167641 by rodw
Yeh, you have to be in the right mode for it to take affect. work eg jogging need to be enabled.
My pendant has a yellow button on it that is a safety lock that must be pressed and held to enable the jog wheel. Its not a bad idea, I have that button set up so it selects the correct mode. Otherwise I had to walk back to the screen to enable jogging. IN gmoccappy, the GUI jog buttons are on a seperate tab which has to be on top.

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