Pre-Project start questions and mentor advice

Hi All
Time to (re)start my 15 year old CNC project ambition which was abandoned due to "issues" - mainly my total "doffness" (stupidity) with all things electronic.
My VERY weak point is anything that has a transistor in it and 15 years ago you either had to cough up MANY US$ (South Africans will know how much pain the US$/ZAR exchange rate gives you) or you had to build it yourself.
RS Components made a fortune out of me (smoked over 30 PIC processors) - but it was my fault, not theirs.... and I eventually gave up (or rather my credit card did).
Today there are MANY pre-assembled products at what seems to be good pricing value so I am giving it a go again.
However it is still as confusing as #$% for someone like me who does not know whats going on or what questions to ask.
Before I start with the questions, here is what I wish to build:
A 4 axis mill exclusively for wood - accuracy is not an issue beyond MAYBE 0.25mm - its wood! - when the weather changes so does the wood sizing !!!
In the design, the clamp bed on the X axis is removable and can be replaced with the A Axis assembly which will be centered about 10mm above the level of the Z Axis bed.
I chose this approach so that with a Z Axis travel of 200mm I would be able to put a 400mm diameter "log" into the A axis and because half of it would be below the reach of the tool (Z Axis) but due to the rotation of the A Axis everything would be machinable.

Now for 3 Axis work there is the Arduino Uno which is (relatively) affordable and MANY people seem to be using it very successfully for 3 Axis machines.
The Uno has g-code interpreter and this does all the math to figure out what the g-code instruction line wants it to do.
This is is a far better approach than getting the PC to do the math and then just send the step/direction pulses with the required timing to the stepper drivers because as many people know, Microsoft software does what it wants to do and not what you want it to do.
So in the middle of a code execution Windows stops sending instructions because it decides that doing something else (having a look to see if there is a CD in the CD drive for example) is more important - and there is a royal screw up in the making.
Add cost of MACH and the rest it is also simply NOT affordable to me.
So the "on board path calculation" method takes care of that "little" issue - All the PC has to do is stream the actual g-code instructions which then are buffered on the Uno so that waiting for Windows to join the party becomes far less of an issue.
The g-code interpreter of choice for Arduino seems to be GRBL - many references to it all over the web !!!
However I have yet to get a "Yes/No" answer to the question "WHEN YOU BUY AN ARDUINO UNO (Amazon or wherever) IS THE GRBL SOFTWARE ALREADY LOADED?"
If it is not there are probably all sorts of costs (and dangers) involved in assembling the code and flashing it to the board yourself.

The next "issue" is that GRBL is SPECIFICALLY (as of version 0.9) a 3 Axis interpreter and I have spent many hours on Google and it seems that the guys doing the development have got the 4th Axis capability high on the list for a long time BUT quite openly tell everyone that there is no expected release date for the 4th Axis version. They do hint that it will be in version 1.0
There are a number of hacks around but there are so many disclaimers attached it seems that they are not able to "fit" GRBL onto the processor that is on the Uno - maybe it is too big, maybe it is too slow - I dont know but I think that it is probably a combination of both ...

Maybe the Uno (16 MHz speed, 32kb programming ram, 14 I/O pins) is at the end of development as far as adding more Axis (and possibly the more obscure g-code functions that are not already implemented) to the mix.

The next board in the Arduino range is the MEGA - almost double the price BUT it uses a similar processor at the same speed (16MHz speed, 256kB programming memory, 54 I/O pins) but having more "stuff" does not help much if you are already running out of processor speed in the g-code interpreter !!!

The next Arduino product is the DUO - (84 MHz speed, 512Bb programming memory, 54 I/O pins AND about US$10 less expensive than the MEGA)
The GRBL code is specifically for the UNO so what g-code interpreter will work here?
Is there one?
Where do I find it?
And a bonus would be a nice looking PC based activity monitor - We can only dream....

To be honest, I am not even going to start the project until I am sure that I will be able to mill "Hello World" into a chunk of wood.

Thank you for reading my long winded story and know that Any comments or advice will be appreciated - even if it is to tell me that I am a poephol (A$$hole).

Eish - Sorry - seems like the reference article spelled it wrong - should be DUE !!!
And to make matters worse, it is "retired" !!!
Oh Well - back to the drawingboard but any comments and / or suggestions are still VERY welcome....

Quote:

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Originally Posted by MadAubrey

Hi All

However I have yet to get a "Yes/No" answer to the question "WHEN YOU BUY AN ARDUINO UNO (Amazon or wherever) IS THE GRBL SOFTWARE ALREADY LOADED?"
If it is not there are probably all sorts of costs (and dangers) involved in assembling the code and flashing it to the board yourself.

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Hi there the ardunio GRBL software is not loaded on the board you flash it your self depending on the application of the board, all soft ware is free and open source.
you then tweak the configuration h file to suit you machine. it is all fairly straight forward.

As for the fourth axis you can un plug you y axis cable then plug it it the A axis it behave like a forth axis then.
i am busy working my forth axis i am copying this idea.
CNC Shark Forum ? View topic - Bob's Super Simple 4th Axis
have a look at Bob"s fourth axis.

Hi Melvin
I eventually figured that out - Newbie Me !!!
Unfortunately I am one of those idiots that always seems to find a way (even if there is NO WAY) to screw something up.
But we will give it a go.
The machine that I want to build will eventually have a 4th axis rotary axis which will be mounted on the plate on the X axis.
And that is the issue - there are any amount of "driving 4 steppers with an Uno" tutorials out there BUT the 4th stepper is ALWAYS a clone of one of either the X, Y or Z axis.
This as I said is mainly because grbl (up to version 0.9) does not handle more than 3 axis - and the developers SAY that version 1.0 will be able to do it BUT are unwilling to even give a clue as to when that version will be published.
However there is some "good" news - I found (by accident) a demo that takes a 4 axis gcode command and after much begging and pleading I have gotten a copy of the uncompiled script.
So I am in the process of ordering the cards and other "stuff" so that I can run some tests to see if it works as I hope.
And if it does I will be shouting it from the rooftops as I am sure that I am not the only person looking for that sort of capability.
Thanks for the reply and have a good day.

Hi Melvin
That wont work because I need the X axis to travel while the A axis is rotating.
But I think I have a solution - see my other reply to you.
Thanks for posting and have a good week.

With reference to the CNC Shark project - it is quite amazing - really "thinking outside the box...
I think that I will be keeping an eye on that project too.
My issue is that I will have pockets to machine that will not be accessible by the tool if it is always above the center line of the A axis - trust me to want the difficult stuff.
But the material will be wood and the accuracy need be no more than 0.25mm - I'll probably be using UniStrut as my rails with driveway gate rollers running on them.
Fast axis speeds are not even featuring in the mix as yet - if it takes 3 days to machine then so be it...
Really a "boer maak 'n plan" situation - more for fun than anything else. (and to keep me busy in my retirement)
If it is successful then I may just build a bigger more accurate one to see just how far I can push it.

i am using the arduino mega 2560, my machine is a hybrid cnc/ 3d printer. the card has a fourth controller on it, but that is a singed to the extruder motor, if there is a way to configure it to operate as a A axis, would be very interesting.
i am interested in where you are going with this, keep posting the progress.

Quote:

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Originally Posted by melvinbruce

i am using the arduino mega 2560, my machine is a hybrid cnc/ 3d printer. the card has a fourth controller on it, but that is a singed to the extruder motor, if there is a way to configure it to operate as a A axis, would be very interesting.
i am interested in where you are going with this, keep posting the progress.

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Hi Melvin
The Uno and the Mega both have the same chip so as far as processing power and speed is concerned they are identical.
The Mega does have more ram and outputs but if you will not need them, why get them?
And of course the Mega is more expensive (IN DOLLARS) and I need to buy pipe tobacco....

The 4th stepper on your printer cannot be configured as an A axis (believe me, I looke all over the web) using the "normal" grbl code so that is a bust.

I have just created a YouTube channel (4 Newbies) and a domain ( 4newbies.co.za ) and I will be posting the progress there.

We are busy selling our house (with my 81 sq meter garage/workshop - not too happy about that !!!) and moving to a granny flat on the East Rand so I will not be able to really start the project until next year BUT I am going to buy the electronics and make sure that I can get them working BEFORE I start constructing the machine.

I'll probably need to find a garage or storage unit to put the project - we will have to see....

Anyway, yes lets keep in touch - should at least be interesting...