Learning Material for someone new to CNC

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Learning Material for someone new to CNC

Postby lucidgroove » Sat Mar 17, 2018 11:42 am

Hey CNCdrive and forum members,

First off I must say thanks to the creators. I purchased the UC400ETH and a license for UCCNC and so far the experience has been great.

I am a woodworker and somehow decided I needed to build a CNC Router. I have been building since October and have the Machine, Controller Box, Control Panel all working. Everything is new to me so I have been reading all the manuals, related manuals, cnczone posts, etc.

Here is where I am at today, and here are a few things that I didn't learn about anywhere. Hoping someone can point me to a good resource to learn some of these basic core concepts so I can be less confused.
I have most of my UCCNC v1.2037 software setup.
X,Y,Z Axis Pins, EStop, Limits/Home, Hotkeys for my panel.
I can jog each axis as designed.

Before I attach actual tools to the spindle I decided to chuck up a nice Sharpie pen and laid a roll of wrapping paper over the table bed. I found a website that let me convert some text into simple gcode. The max amount of Z travel is from 2 to -1. The letters come out nice (when I get the Z zeroed), but they are huge and also the feedrate is super slow. Even at 300%. I was running it line by line so I didn't get the initial popup like when you press Cycle Start. I later noticed I could set the feedrate in that popup. So while drawing the letters it is insanely slow, but when homing or moving to another location it is insanely fast. Also the safe Z says 25 which can't be possible on this machine. What does 25 mean? 25mm? What are the coordinates measured in ?

A little more background...

I completely understand zero for the X and Y axis and where home is. Z is another story. I keep thinking I have it at zero and then it tries to go way too far into the table, bending my Sharpies. I was reading some other posts and think I may have been misunderstanding the term "Units". When I built this machine, the author of the plans explained in great detail how to determine Steps per Inch, Inches per Step, Resolution, Inches per rotation... When I use the Calibration Tool to measure for Steps/Unit it comes out to 10x lower number than if I do the math.

Here are my math figures.
Image
Thanks,
Doug

Machine/Software Specs: 3 Axis CNC Router (Modified Solsylva Design) UC400ETH, UCCNC v1.2037, 2 C10 R11 Boards, Win10 64Bit powered by i7-7700K and 16GB RAM.
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Re: Learning Material for someone new to CNC

Postby cncdrive » Sat Mar 17, 2018 12:45 pm

Hi and welcome,

The speed of the tool is called Feedrate and you define it with the F keyword in the g-code file or via the MDI.
The Fset readout on the screen shows you the actually programmed feedrate value.
So, for example you code F100 then the Fset DRO will show you the value 100.
The Fact readout on the screen shows you the actual feedrate, in other words it shows you with what feedrate the machine is moving the tool with.
The Fact ofcourse not always equals the Fset, because on direction changes etc. the machine axes has to slow down to change the direction...

So, check what is your Fset feedrate, look into the g-code file to find the F keyword and the value coded there.
The target feedrate for the path will be the programmed feedrate and if the machine is running slowly when running the g-code, but is fast when doing a gotoZero is because gotoZero is using G0 commands which command runs the tool with the maximum possible valocities set by your velocity parameter of the axes while in g-code program G1 and G2 and G3 linear and circular interpolations are used which commands running the tool with the programmed feedrate.

The safeZ is a parameter you can define in the configuration, it is set to value 25 by default. It is 25 units.

Units mean the lenght units of your axes. You can select any length units, mm, inches, feet, kilometers or whatever you want and then you setup the axes configuration's steps per value for your unit.
So, for example you select that you want to use inches as units then you have to set the steps per value of the axis to let your stepper drive run the axis one inch distance when outputing the number of pulses for the stepper drive defined by the steps per value.
Or if you select millimeters then you do the same process, but the value of the steps per then should run the axis one millimeter.
So, the steps per value and your stepper drives resolution and drive gearing (screw or belt pitch, gearing etc.) defines your unit.

What the automatic calibration do is simply makes a move with your setup steps per value and the distance you define and then let you measure it on the machine and tell the software what the moved distance in real was and then the software back-calculates the steps per value if the wanted to and the real moved distances are different.
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Re: Learning Material for someone new to CNC

Postby lucidgroove » Sat Mar 17, 2018 1:27 pm

Thanks for the quick reply! I will test this out today. One thing I forgot to mention was about a probe. Will a probe help solve my Z axis zeroing confusion? I am not really sure if this is something that is a must have? The top of the workpiece is supposed to be zero? Maybe that is my problem. The gcode is written to go to -1 but since I am using a pen for testing , I actually would want it doing the drawing at zero.
Thanks,
Doug

Machine/Software Specs: 3 Axis CNC Router (Modified Solsylva Design) UC400ETH, UCCNC v1.2037, 2 C10 R11 Boards, Win10 64Bit powered by i7-7700K and 16GB RAM.
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Re: Learning Material for someone new to CNC

Postby dezsoe » Sat Mar 17, 2018 2:17 pm

lucidgroove wrote:The top of the workpiece is supposed to be zero? Maybe that is my problem. The gcode is written to go to -1 but since I am using a pen for testing , I actually would want it doing the drawing at zero.

Usually, the top of the workpiece is the zero. If your code uses -1 to draw, find the top of the paper, click into Z DRO and write -1.
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