Arduino, GRBL, Experiences So Far

BillK
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Re: Arduino, GRBL, Experiences So Far

Post by BillK »

Ted, have you considered using the CNC shield V3 which piggy backs on the arduino and carries 4 mini stepper motor drivers? Looks like a lot less wiring.
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Re: Arduino, GRBL, Experiences So Far

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BillK wrote:
Tue Mar 09, 2021 2:05 pm
Ted, have you considered using the CNC shield V3 which piggy backs on the arduino and carries 4 mini stepper motor drivers? Looks like a lot less wiring.
Absolutely considered them. The drivers on those boards are limited to 2 Amps. At that amperage they tend to run hot and require a cooling fan. Trying to avoid that if I can. As I mentioned in an earlier post if I need to go to Nema 23 and 4amps then I would have to start reegineering the system. The other thing is that I am using a Mega board rather than an Uno. The Mega has a larger memory capacity which is not important right now, but should I decide to go with a 5 axis GRBL the program will not fit on an Uno.

Now, if I were some kind of rocket scientist electronics guy I would design up a shield that fits on the Mega to simplify the wiring. I saw a board someone designed that has the screw terminals already connected for a Uno. Frankly, I need to spend some more time figuring out how to create stuff like that. I do have some 2.54 screw terminals that fit onto the board nicely, but boy, are those screws some kinda small!

The goal is to have a system that is not too integrated, which is what happens when a shield is used. Totally integrated is not a good idea if things need to be swapped out later.

I am going really slow with this project and spending a lot of time researching various aspects on the internet. Last nite I saw a really neat idea for mounting stepper drivers. Essentially a plate that holds them all and the arduinio. Then that plate is located in the control box instead of mounting the drivers and arduino individually to the box.

By the way, the wiring from the board to the drivers is not a whole lot. Just six wires actually. The rest is jumpers and joins. The mess is from the drivers to the motors, 4 wires for each motor. I am going to order up some 4 conductor cable so that I do not have individual wires wriggling around all over the place. The other thing I need to order is a crimping tool for the DuPont connectors.

But, today I am going to mess around with a USB wireless keypad for GRBL. Think pendant. From what I have seen it is quite easy to configure. What is not easy is coming up with a good way to label the actual keys so they make sense. The keypad itself was about $12. The keypad should be in tomorrow, today I am going to clean up the configuration in GRBL so I am ready to start assigning keys.

Yesterday I spent a lot of time working with the motors, accels, max speed, number of steps, etc. With no machine connected they will need to be tuned later on, but I wanted to get a feel for how they run before ordering the lead screws. After working with them I decided on 2mm pitch 4mm lead. With no load on the motors I can get up to about 250 IPM on the motors, so with a load I am confident (famous last words, huh?) that I will be able to actually run at 150IPM. That should be fine for what I am planning on doing with this machine. The cutting area will be about 300mm X 300mm so a really fast honking rapid speed is not a big deal. Most of the work on this machine will be small 3D models. Those typically do not have a lot of rapids to begin with. Now, if those Nema 17's don't hack it I can just swap them out for Nema 23's. The drivers I have will handle 4A. So that should work.

Later today I am hoping to start designing a board to mount those stepper drivers on.

Off I go!
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Re: Arduino, GRBL, Experiences So Far

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Thanks Ted. Well, I guess I'm going to be chasing you down the rabbit hole. I ordered the board, drivers, motors, and power supply. Also wanted to make a smaller, more rigid machine for a while. I have the frame material, just will need the time to play. same work area of 12'x12" will accommodate 95% of what I do. I'm thinking of going with a fixed gantry which will have Z and X, and have the table move in Y.
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Re: Arduino, GRBL, Experiences So Far

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Excellent Bill! Let's share notes in this thread, unless you decide to start one of your own?

I am still up in the air about having a fixed gantry, I may go that way because no matter how I cut the mustard the spindle is going to be cantilevered out. Well, maybe it will be more rigid on a fixed column....hmmmm. One thing is for sure, a gantry style will take up less space. This all gets a lot easier if it is a laser hanging out there, LOL.

Fortunately I have a really good scrap yard close by so I can get chunks of aluminum and my machine will cut it.

I don't know how much experience you have with grbl but one thing I have learned is a lot of the people putting vids on YouTube don't have a lot. Watched a guy showing how to alter settings the other day, went through a big deal about copying and pasting them from the console window into NotePad and then saving the file. There is a menu selection that does just that, pretty obvious he has not dug into what is all there. But for the most part the info is decent, just scattered hither and yon.
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Re: Arduino, GRBL, Experiences So Far

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Ted, I will share here if its OK with you. I watch videos in the morning for some reason. There was this one guy I watched who is teaching a series on programming an Arduino, took 3 lessons to turn an LED on and off. The second episode was all about how an LED works, so I think I’ll skip that one for a while. This morning I saw one that was all in German, which I can follow along pretty well as long as its technical. He had a really nice GRBL interface, which was also in German. I think it was Estilcam. Not free, but not too expensive.

I think I mentioned I have a good supply of Bosch Rexroth 45x45 extrusions, so I’ll be going back to my erector set days (still one of my favorite toys of my youth).
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Re: Arduino, GRBL, Experiences So Far

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Works for me Bill. Keeping this all in one thread is probably a good idea, saves guys from asking or commenting in parallel threads.

I saw that EstilCam stuff a long time ago, I recall it looked pretty darn good.

Yup, I watch vids when I am having my coffee out in the shop and in the evening.
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Re: Arduino, GRBL, Experiences So Far

Post by jimandi5000 »

Hi All,

Just my 2 cents... I would not pull the 5VDC off the Arduino Mega to power the stepper drivers. I found the Arduino Mega 20mA falls short. I had to add a 5 volt power supply to the mix for my projects.
Thanks,
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Re: Arduino, GRBL, Experiences So Far

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jimandi5000 wrote:
Wed Mar 10, 2021 5:02 am
Hi All,

Just my 2 cents... I would not pull the 5VDC off the Arduino Mega to power the stepper drivers. I found the Arduino Mega 20mA falls short. I had to add a 5 volt power supply to the mix for my projects.
Neither would I. The 5 volts is the signal voltage to the steppers. I did not show the power supply connection to the stepper drivers in the schematic. The connections are shown on the individual drivers but I did not add in the PS. The idea was to show how the drivers are connected to the arduino.

As I am working with this the 5V is coming from the USB. It has not had any issues.
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Re: Arduino, GRBL, Experiences So Far

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While I’m waiting for the electronics, thought I’d make a concept model, rev1. I have all the structural components, not the linear rails. Fixed gantry, this will be rock solid. Thinking of being able to adjust the gantry cross bar vertically in case I want to carve on something other than a flat board. I was fortunate to work for a place where we made our own assembly equipment. When the equipment’s useful life was we took it apart, we made most of it from this Bosch Rexroth extrusions. If you know a company like that, sometimes they give it away, a lot is sold on eBay. You will have structural aluminum extrusions that you will not see on any CNC machines currently manufactured.
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Re: Arduino, GRBL, Experiences So Far

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The keypad thing went well today. I was a bit surprised (but I should not have been) that not all keys can be used. But all the essentials are there so all is good.

Spent some time on mechanical design too. I tend to work from the inside out. For instance, it needs a lead screw and nut. So I drew those up. Then it needs bearings on either end. Added those. Added the shaft coupler for the motor. Once I had those all drawn up I could see how long the screw needed to be to get the travel I want.

Doing it that way also tells me where the table needs to go, etc. That is from my very, VERY early days working on a real drafting board with real paper, real lead, real eraser, etc. I did own an electric eraser in those days, LOL.
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Re: Arduino, GRBL, Experiences So Far

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TReischl wrote:
Thu Mar 11, 2021 2:28 am

That is from my very, VERY early days working on a real drafting board with real paper, real lead, real eraser, etc. I did own an electric eraser in those days, LOL.
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Most of my early engineering days equipment has gone , including my slide rule :mrgreen: However I still have my electric eraser and use it for Engine Turning finish on small metallic projects. Guess I’m telling my age......wonder how many know what a slide rule is.....

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Re: Arduino, GRBL, Experiences So Far

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rtibbs wrote:
Thu Mar 11, 2021 1:06 pm
......wonder how many know what a slide rule is.....
Shall we call you "Slipstick Libby"?

I still have one, I know where it is, and on occasion I take it out and try to remember how to use it. Then I put it away and go back to my HP 11C, either the real one or the simulation on my phone. My HP 35 and 41 still work too, if I plug it in. Oh, and my uncle's Nester drafting board and machine act as my side table beside the CNC. Most of the components in several generations of Beaver gum vending machines were designed on that board.
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Re: Arduino, GRBL, Experiences So Far

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rtibbs wrote:
Thu Mar 11, 2021 1:06 pm
TReischl wrote:
Thu Mar 11, 2021 2:28 am

That is from my very, VERY early days working on a real drafting board with real paper, real lead, real eraser, etc. I did own an electric eraser in those days, LOL.
Ted
Most of my early engineering days equipment has gone , including my slide rule :mrgreen: However I still have my electric eraser and use it for Engine Turning finish on small metallic projects. Guess I’m telling my age......wonder how many know what a slide rule is.....
I took Mechanical Drawing, Engineering Drawing, and Architectural Drawing in High School over 3 years. I won an award for best in class that led to some scholarship money for college that was sparse in those days. I used a slide rule for freshman year of college then Texas Instruments took over. When I went to work I got to use a drafting machine for the first time, no more T-squares. Still have my rechargeable eraser too. My pencil pointer still sees some action.

Those drafting skills always served me well, a course in descriptive geometry was a course I did great in Freshman year in college, and while working for a company building missile guidance systems, I used descriptive geometry to solve a problem in 2 hours that another department had a whole room full of engineers working on for a week.

I got to use AutoCAD there, and went on from there. I still refuse to get rid of the drafting table with sliding straight edge that my Dad got when his job was selling off excess equipment. The pencils 2H, 4H, 6H mostly served me well.
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Re: Arduino, GRBL, Experiences So Far

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I am always impressed by the amount of talent we have on this forum. Folks who know Windows inside and out, engineering skills, artistic talent, software skills, etc. I have been active on this forum for about 14 years now, the amount I have learned by making it a regular stop is staggering. Sometimes I have learned by seeing someone post with an issue. Whatever it was intrigued me and motivated me to see if I could work it out. Way better than working crossword puzzles, LOL.

Here is what really, REALLY amazes me. 45 years ago there was no internet, today, if I want to learn about something all I need to do is type in a few words and the information just pops up. If I need parts, all I need to do is order it and a few days later it is sitting on my front porch. And it is not just this sort of thing, my better half does glass, clay and jewelry. She started out knowing nothing about any of it. Thanks to the internet she is now quite good at it and improving all the time. When she decided to buy a kiln she researched kilns on the internet, watched videos, read reviews and then made her decision. Try that 45 years ago. . .
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Re: Arduino, GRBL, Experiences So Far

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Ted,
I too embrace technology today. Take this for instance, sure beats waiting for snail mail to receive a response.
After all what you read on the internet is factual :mrgreen:
Just takes a little due diligence on ones part to separate the wheat from the chaff.

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