Linux in the Machine Shop Hack Chat

Andy Pugh will host the Hack Chat on Wednesday, July 8, 2020 at noon Pacific Time.

Time zones got you down? Here's a handy time converter!

From the time that numeric control started making inroads into machine shops in the middle of the last century until relatively recently, the power of being able to control machine tools with something other than a skilled human hand was evident. Unfortunately, the equipment to do so was expensive, and so NC technology remained firmly in the big shops, where a decent return on investment could be realized.

Fast forward a few decades, and everything that makes the computerized version of NC possible is cheap and easily available. Servos, steppers, drivers, and motion control components can be plugged together into CNC machines that can move a tool to a fixed point in space with incredible accuracy and repeatability. But without CNC software, none of it means a thing.

Enter Linux CNC, the free and open-source CNC package. With support for realtime operation, one-step installations, and a huge range of capabilities provided by a team of volunteer developers and a supported by an active community, Linux CNC has democratized the world of CNC machines.

Andy Pugh is a frequent contributor to the Linux CNC codebase and a moderator on the forum. He knows a thing or two about Linux CNC in particular and Linux in the machine shop in general. He'll stop by the Hack Chat to share his experiences with the Linux CNC project, tell us how Linux can revolutionize the machine shop, and maybe share a few stories of from the world of CAD, CAM, and using Linux to make a few chips.

Event Logs

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Hack Chat Transcript, Part 2
Dan Maloney • 07/08/2020 at 20:18 • 0 comments

Andy Pugh1:01 PM

I suspect that the inverted board on the right could be pulled off, and step/dir pulses fed into the headers.

Axel1:01 PM
Sounds like a plan!

Axel1:01 PM
just some tracing. What would the controls of a stepper driver be?

Chris Radek1:01 PM
if you could read the number on those driver chips, we could be sure

Chris Radek1:02 PM
often just enable, step, direction

So it's the end of our hour, and we need to let Andy get back to work, or the shop as the case may be. Feel free to stay on and keep chatting, this has been hugely informative. I want to thank Andy for his time today, and everyone else for coming along for the ride.

Andy Pugh1:02 PM
Looking at the data sheets of the driver chips and tracing tracks would probably allow you to keep the existing drivers. Which are probably rubbish. But that approach leaves you the option of plugging the old board back in to return the machine to a working state during the refit. And that can be very nice.

Axel1:03 PM

Chris Radek1:03 PM
Thank you Andy!

Axel1:03 PM
Thank you Andy and Bari!

Daren Schwenke1:03 PM
@Andy Pugh Thank you, and congrats on having your random retrofit in a chat, with no prep turn out... looks like it will anyway. :)

Andy Pugh1:03 PM
I can actually stay a while longer, all you are keeping me from is wrestling with the generation of LinuxCNC documents in a language I can't even read.

Axel1:04 PM
So, I noticed from the 3D printing world there is a whole evolution of stepper motor drivers. What has changed in the last, oh, 20 years?

jeghartman1:04 PM
Where would be a good starting point on reading up on Linux CNC

Fine by me - I'll wait a bit to pull the transcript, so we don't miss anything

Dipjyoti Kumar1:04 PM
Does linuxCNC has repository for android?

Chris Radek1:04 PM
Yes, L6208 are step/direction drivers, and they are pretty decent at 52v/5.6A max.

Axel1:04 PM
They still convert pulses to 2 waveforms, no?

Axel1:05 PM
Thanks Chris!

But let me just plug next week's Hack Chat: Back to Basics with "Simplifier":

Alex1:05 PM
Thanks Andy!

Andy Pugh1:05 PM
Mainly everything now is bipolar, so you get twice the torque from a motor. And clever pulse shaping to deal with resonance, induction etc.

https://hackaday.io/event/173282-back-to-basics-hack-chat

Hackaday

Back to Basics Hack Chat

Keep it simple, Simplifier Wednesday, July 15, 2020 12:00 pm PDT Local time zone: Hack Chat This event was created on 06/19/2020 and last updated 2 days ago. Join this event's team Simplifier will host the Hack Chat on Wednesday, July 15, 2020 at noon Pacific Time. Time zones got you down?

Read this on Hackaday

Dipjyoti Kumar1:05 PM
Using circuits from old smartphones to run CNC m/c.

pink_vampire1:05 PM
@jeghartman https://linuxcnc.org

Axel1:06 PM
Ah, and the drivers can now also detect 'missed steps' due to the power response of the motor , stuff like that?

Axel1:06 PM
Might be worthwhile to fully retrofit this baby. Give it some TLC.

Bari1:07 PM
@Dipjyoti Kumar Smartphone are about the worst real time controllers I can think of. Full of blobs that you'll never be able to access and turn off to get in the way of real time. But possible useful for a GUI.

Daren Schwenke1:07 PM
@Axel Yes, and from that detection you have the ability to correct and/or fail and/or dynamically increase the current you are providing during moves that need it.

Andy Pugh1:08 PM
I think that they might be able to, but I don't know any that do.

The hot new thing now is closed-loop steppers, where there is an encoder on the motor. That basically makes a stepper into a real brushless servo motor, just a wierd 2-phase one with an lot of poles.

Daren Schwenke1:08 PM
(and be quiet for the rest)

Connor1:09 PM
That's one thing LCNC lets you do is dual closed loop. Closed loop to the stepper/servo, and Then linear scales too.

pink_vampire1:09 PM
@Axel if you are using just open loop step / dir drivers, then no.

but for example on my milling machine I'm using the...
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Hack Chat Transcript, Part 1
Dan Maloney • 07/08/2020 at 20:17 • 0 comments

Welcome all! We'll get started in about 15 minutes. Feel free to chat away

morgan11:46 AM
I hope to figure out how all this works...

Daren Schwenke11:46 AM
*cough* Machinekit *cough*

morgan11:46 AM
isn't it the same things?!? already confused

Daren Schwenke11:46 AM
:)

tyeth11:47 AM
Ok quick question, how does one ask a question, and if it's like this then:

Can I use linuxCNC to hook up a two stepper motors and RELATIVELY easily make a cnc dremel?

Andy Pugh11:47 AM
Yes, that is exactly the sort of thing that LinuxCNC is for

tyeth11:48 AM
Exactly my hope, thanks, I'm planning to attach cheap steppers to threaded rod (with nuts for the "trolley") and just have a go

jeghartman11:48 AM
What is the best information place to start learning from scratch

thejordan joined the room.11:49 AM

Andy Pugh11:49 AM
For the next hour or so, here. Then possibly the Linuxcnc forums

jeghartman11:49 AM
good answer, like a politian ;

Andy Pugh11:50 AM
It has to be admitted that, to an extent, the LinuxCNC docs kind of assume that you know what you want to do before telling you how to do it.

Adrian11:50 AM
Will you be talkinng us through the config approach for Lcnc

Axel11:50 AM
So, I'm looking at the https://www.linuxcnc.org website now. It seems I can put that on a controller board to drive my --existing-- CNC machine. I have a commercial CNC with an HPGL controller which I don't really like (only Windows support). So I can replace it, or I can simply find better linux driver software (CAM?) which outputs HPGL and can control the machine manually. Zero-ing etc.

There are some pretty good YouTube videos of complete CNC builds that could give you a good overview

Andy Pugh11:50 AM
LinuxCNC is very extensively documented, but that comes with the penalty of it taking more than an hour or so to know it all.

designbybeck11:51 AM
Greetings all!

Hello, welcome! Getting started in about 10 minutes

jeghartman11:51 AM
I am sniffing for a "start here" url

Andy Pugh11:52 AM
@Axel Both ways work. One thing about LinuxCNC is that it's free software. That means that neither I nor any other developers care if you use it. We want you to use what is best for you.

Andy Pugh11:52 AM
G-code to HPGL seems like it should be do-able with simple software.

designbybeck11:53 AM
Beck from 10BitWorks Makerspace in San Antonio, Texas. We just got a used 4x8' CNC at our space and it uses LinuxCNC, or a version of it Control Commander?

tyeth11:53 AM
@Daren Schwenke what're the main differences between MachineKit and linuxCNC, is the latter just more low level and machinekit more a highlevel management app or something?

anfractuosity11:53 AM
machinekit looks to be archived looking at their github?

Axel11:53 AM
Of course, but I am here to learn if it is useful for me. Perl is free as well, so is C, but that does not mean it is handy to drive a CNC machine :-)

Daren Schwenke11:53 AM
I'll let Andy field that one later.

tyeth11:53 AM
Cool.

Andy Pugh11:54 AM
Machinekit is a fork of LinuxCNC. The folk on that project got annoyed by LinuxCNC emphasis on stability, and wanted a faster-moving project.

tyeth11:54 AM
Fair, bleeding edge useful but dangerous

Daren Schwenke11:54 AM
basically. :)

Axel11:54 AM
haha

Andy Pugh11:55 AM
Fundamentally Machinekit and LinuxCNC look much the same and work much the same. There are differences under the hood that only programmers would care about.

dgarrett joined the room.11:55 AM

morgan11:55 AM
I'm still so confused over that, where LinuxCNC looks like a gui frontend for controller a CNC and MachineKit looks like..... I still dunno

Andy Pugh11:56 AM
But if you are starting from scratch with a PC to dedicate to the job, then LinuxCNC is easier to get going, as we offer a monolithic install image.

Bari11:56 AM
Someone got the integrated microcontrollers in the Allwinner ARM SOC's working with LCNC. So you can do what machinekit did with the Beagle Bone Black and software step using the internal micros.

Alex11:56 AM
I'd...
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