A lost newbie in need of starting guidance

Hi everyone!

I bought a starter kit for Arduino and did 16 tutorials. Can't say I know that much more, but was fun to make things light up, noice and a motor turn.

Reason for me buying the starter kit is that I have 2 projects in mind, but I got no idea where to start. Hence, taking the courage to post on this forum. I hope that was OK.

One project is a long term, CNC, so let's not get into that. But the 2nd project is something I would like to start asap. My problem is, well I got many :) but the first one, is I got no idea where to start. Learning to code the entire project is a fun journey, but what items should I buy? That is my first problem and I hope I can get some help.

What do I want to create you might ask?

I want to create a automatic wire-stripper and cutter, or just a cutter as version 1, for AWG 16-20 cable. It should feed cable and cut them in MM-precise lengths. Preferably I would like to have a small display/input device where I can set number of cables and lengths, but could accept a computer connected for input if it simplifies things a lot.

I have found some awesome projects online that does this, but they are all old and after waiting weeks to get a reply from the makers I have given up and need to find a starting point of my own.

I thought I would share my own thoughts and a very rough sketch on how I'm thinking. Not sure if it helps.

|500x242

Green is wheels controlled by a Stepper, blue is spring loaded wheels. Lime green is the cutter blade and the black is the actual wire. I want this mounted in a chassi to keep it neat and boxed in. Inside, I can mount my PSU, Arduino, fan for cooling, engines etc. The mechanical I'm not worried about, but it's the items needed (so I can shop) for me to start to explore and learn the Ardunio code needed to pull this off.

List of items needed (all a big question mark still)

  • 3 Nema17 or 23
  • 3 stepper drivers
  • 24v power supply
  • Ardunio Uno
  • Led display with input buttons (or X number of analog buttons corresponding to separate programs)
  • 2 wheels for wire feeder
  • 2 wheels spring loaded
  • 2 180° cutter blades

My thoughts is that the Green wheels are mounted on one Stepper engine each with an opposing spring loaded wheel to keep the wire in place. Reason for 2 engines, one to pull the wire, one to control the length. Then a third engine to control the cutter blade.

My though of operation / functionality is to pick a predefined wire from a menu (the LED display or computer). The machine will then feed the predefined length of that cable and cut it and strip 3mm of each end.

From a programing stand point I'm thinking - Move forward 3mm, do a cut deep enough to strip the wire, not cut the copper, back up 3mm to strip the end, Release cutter blades. - Move forward the full length and cut the cable - Back up 3mm and cut deep enough to strip the wire, then move forward 3mm to strip, release the cutter blades This should repeat for the predefined number of wires.

Rather than use two motors on the green wheels I suggest you use one motor and have a rotary encoder on the other wheel. Use the encoder to measure distance - as it will not be driving it will not be at risk of slipping.

And, if you have a rotary encoder you might consider whether a simple DC motor would be sufficient for moving the wire.

Separately from that, I can't see that a stepper motor is needed for the cutting blade - again, a simple DC motor, perhaps driving a screw and nut mechanism would probably be sufficient.

Just my 3cents

...R Stepper Motor Basics Simple Stepper Code

There have been several forum postings in the past relating to your project. Search for them. My commercial wire measurer and cutter has one driven wheel that is knurled and has a second rubber wheel that presses the wire against the knurled wheel.

The knurled wheel is driven by a stepper motor and it is controlled by a micro-controller that measures the wire. The length is input on a key pad.

The wire cutting is done by a solenoid driven blade. The wire never stops moving. The cutter solenoid is overdriven by a charged capacitor so it moves quickly and powerfully.

Paul

The "trick" to any project is to take it one step at a time. And if you are new to programming, "develop" your program in very-small steps, one or two lines of code at a time, testing before you proceed. This take some practice because the program has to be "complete" and it has to make sense to the compiler... For example, if you chop-off the bottom half of a working program, it won't compile.

You might want to start with the [u]Digital Read Serial Example[/u]. Once you can read a button you can start to "do stuff". ...You could add an if-statement that turns-on an LED or runs the motor while the button is pressed, or make the stepper motor run for 100 steps every time the button is pressed, etc.

The two most important concepts in programming are conditional execution (if-statements, etc.) and loops (doing something over-and-over, usually until some condition is reached).

You can also test the motor separately. For example, write a little test program to run the motor for 100 steps. In a similar way, you can test your motor/solenoid/whatever that's going to cut the wire.

The Digital Read Serial Example, also uses the serial monitor which is one of your BEST debugging/troubleshooting tools. You can send-out little helpful messages like "Button pressed", or "Running motor". The serial monitor can also be sued to "watch" variable values (as with the Analog Read Serial Example).

. Preferably I would like to have a small display/input device where I can set number of cables and lengths, but could accept a computer connected for input if it simplifies things a lot. ..

...Led display with input buttons (or X number of analog buttons corresponding to separate programs)

This can be a bit of a trade-off. If you use a computer you can skip the buttons & display, but you'll have to write a companion computer application as well as an Arduino application. And, writing a computer (or phone) application is another "project".

Paul_KD7HB: There have been several forum postings in the past relating to your project. Search for them. My commercial wire measurer and cutter has one driven wheel that is knurled and has a second rubber wheel that presses the wire against the knurled wheel.

The knurled wheel is driven by a stepper motor and it is controlled by a micro-controller that measures the wire. The length is input on a key pad.

The wire cutting is done by a solenoid driven blade. The wire never stops moving. The cutter solenoid is overdriven by a charged capacitor so it moves quickly and powerfully.

Paul

I found a few, but most of them, if I didn't completely missed the right posts, was for heavier cable or not answered. I also looked at commercial products, but I'm a hobbyist and 1000€ products, isn't going to happen :D

Not sure what a solenoid driven blade, but new words to Google, thx m8

It's the stripping part that worries me the most. I got 0,5mm tolerance on my cables. If I input 300mm it has to come out exactly 300mm with 3m stripped on either end.

DVDdoug: The "trick" to any project is to take it one step at a time. And if you are new to programming, "develop" your program in very-small steps, one or two lines of code at a time, testing before you proceed. This take some practice because the program has to be "complete" and it has to make sense to the compiler... For example, if you chop-off the bottom half of a working program, it won't compile.

You might want to start with the [u]Digital Read Serial Example[/u]. Once you can read a button you can start to "do stuff". ...You could add an if-statement that turns-on an LED or runs the motor while the button is pressed, or make the stepper motor run for 100 steps every time the button is pressed, etc.

The two most important concepts in programming are conditional execution (if-statements, etc.) and loops (doing something over-and-over, usually until some condition is reached).

You can also test the motor separately. For example, write a little test program to run the motor for 100 steps. In a similar way, you can test your motor/solenoid/whatever that's going to cut the wire.

The Digital Read Serial Example, also uses the serial monitor which is one of your BEST debugging/troubleshooting tools. You can send-out little helpful messages like "Button pressed", or "Running motor". The serial monitor can also be sued to "watch" variable values (as with the Analog Read Serial Example). This can be a bit of a trade-off. If you use a computer you can skip the buttons & display, but you'll have to write a companion computer application as well as an Arduino application. And, writing a computer (or phone) application is another "project".

Awesome help, thank you so much. Will check those examples this weekend. I bought a less qualitative starter kit (as I learned) so I miss a lot of the stuff included in many tutorials. I would like to reach the point where I ca buy the real stuff needed and learn on them. Will be cheaper in the long run, rather then first buy a new starter kit, then buy a DC motor, then buy a new Stepper motor etc.

The programming bit I'm not that worried about. I worked with web programming for many years (I know it's not the same) and very familiar with objects, passing variables, conditional statements etc...

IMO, a DC motor wire drive idea is a non-starter, it will be far more difficult than using a stepper motor since you need to integrate motor speed with a high degree of accuracy to turn that information into length. This would require an encoder to have any reasonable accuracy.

A stepper, along with a knurled drive wheel of a certain diameter, will have a direct relationship between the number of step pulses issued and the resulting length. A two hundred step motor with 15.91mm diameter wheel will yield 0.25mm wire length per step. You can increase that resolution by microstepping, using a higher step count motor or a smaller diameter wheel. There will be a balance required between maximum speed desired, motor torque, measuring wheel size and resolution.

Stripping can be any number of ways. The obvious is a hinged set of notched blades similar to a basic hand stripper that cut the insulation then with the blades still closed, pull the insulation off in the downstream direction with the blades. You'll need a set of secondary pinch rolls downstream of the stripper to hold and eject the wire after the cut to length and then strip the newly exposed end of the cut wire in the upstream direction. Eject the cut and stripped wire and the process repeats.

The mechanism to strip the ends of the wire is what you are paying the big money for. Both ends of the cut wire must be stripped. And many times the insulation is cut and not completely removed to keep wire strands under control. The distance from the end and the amount of insulation movement are both adjustable.

I have a pneumatic stripper to do just that, but the workers say it's easier to just do it by hand when they need to use the wire piece.

By the way, my wire cutter came from Ebay.

Paul