Hey Royce,

MESA doesn’t make the stepper drivers.? Just the interface from the computer to the stepper drivers.? So how are you creating the step/dir signals from the Pi to the stepper drivers?

With the BeagleBone Black the advantage was the co-processors that created very accurate timing and pulse trains as they operated outside of Linux.

However the Pi doesn’t have that hence the need for some sort of module that takes commands and creates accurate step/dir and can read high resolution encoder A/B+Z signals.

John

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Peter,

This is one option for a 3 or 4 axis set of drivers.? Reasonably inexpensive.? I even bought two more than 10 years ago and haven’t used them yet.

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I also have several of these picked up for much the same reason for a project that never happened but these would work for a DB200.

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or here you get the break out board and the stepper drivers.

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For the lathe that would give you a spare driver if one failed.? Then connect to the MESA 7i92 and either run LinuxCNC from your laptop using the Ethernet connection to the MESA board or use a Pi4 with an old keyboard and mouse.

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John

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Oh and BTW, I did find that the Arduino based electronic gearing required a 600 PPR encoder but apparently the encoder they recommend doesn’t have an index pulse (Z).? LinuxCNC needs an Index pulse so don’t get caught buying a $10 encoder only to find it won’t work for threading.

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A bit of Aliexpress research shows up this encoder as an example.? Available with various supply voltages and PNP or NPN outputs and encoder counts.

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Now if you set up your spindle to turn with a DC or AC servo motor and toothed belt and have a second motor on the Milling Machine expansion then you can not only use the Uniimat DB-200 as a CNC 2 axis mill but add the 4^th axis for indexing the lathe spindle.? Sky is the limit for this depth of ‘playing’.

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John

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Hi Peter,

There’s no end of stepper motors and motor drivers in various combinations.? And everyone will have an opinion on what is best so I’ll leave that to others.? On my Gingery Lathe I have these discontinued stepper drivers and a breakout board that goes to my Electronic Lead Screw which only requires a 1PPR spindle sensor.

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I was going to use a Beaglebone Black and this cape but support for MachineKit (LinuxCNC offshoot) dried up and the cape required normally open limit switches plus is discontinued too.? Here’s a link to a 6 year old video where the BeagleBone was used to run Z and Y axis of my mill.

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For the control system what can you buy that makes the least impact on your budget?? Not all laptops will work with LinuxCNC because of their internal battery saving approach.? For example battery voltage drops a bit so does the processor clock (to conserve power) and suddenly you have a response issue.

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I went a different direction for my playing on the bench and ultimately for one of my systems.

A Raspberry Pi4 4GB can always be repurposed for something like Home Assistant or any other projects.? Doesn’t go out of style as quickly as a laptop.? Keyboards, mice and monitors now often come for free.

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The break out boards come from China and run under $20 and have a standard parallel port interface connector and powered from USB or a 5V supply to isolate the Motor side from the processor.

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And finally the best and easiest way to use LinuxCNC is with the Mesa 7i92TF for example.? There are more extensive MESA products for larger CNC systems but other than the break out boards and the MESA everything else is recyclable and the MESA card can be resold.

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For the lathe the only other thing you will need is some sort of multi-line encoder on the lathe spindle to detect position and speed.?

John

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