I am new to arduino and have a nano that I would like to use to control three stepper motors. 1 to raise and lower the blade in 1/32 of an inch increments, 1 to control the angle of the blade in one degree increments and one to move the fence in 1/32 of an inch increments. The fence would use a pair of machine screws connected with a chain and sprockets and the height and angle would use gears attached to the shafts in place of the hand wheels. A keypad and digital readout is how I would like to enter settings. Like I said I am new to arduino and am unsure where to start, the mechanical aspect is easy for me and I know where I can get most of the mechanical parts at a local salvage yard.
So if someone could help me out with figuring out the electronic aspect I would be very grateful.
Determine the torque need from the steppers. Than buy a driver board that handles the currents needed. Get the proper power supply.
Add a controller and create the code.
That doesn't really tell me much. The angle and blade height adjustments are done with screw feed on the shafts and don't require a ton of force and by using gear drive the amount of torque required is reduced significantly. being as I have zero experience with steppers I am trying to determine what steppers I can use from salvage(I love building from things thought to be junk by most) and how to determine how many steps per rotation would be most practical. Would steppers from say printers be able to do the job? Also, the fence movement will take even less torque due to the use of machine screws syncronized with sprockets and chain, so the number of steps per rotation is that would best serve my purpose is what I need to determine.
ANYTIME you use the word "control" that means you have some type of feedback to know you really have control and are not shooting in the dark.
I do not note any mention of how you are knowing anything about the movement you are looking for.
You cannot control the adjustments of your saw, you can only make movements for assumed distances.
Paul
Printer steppers aren't likely to be very powerful, but if you can salvage some you can use them to learn how to use them with the Nano.
Note that you will need a stepper driver and separate power supply too. I'm not convinced that those will be simple to extract from scrap printers though.
Semantics, I know that, so maybe you could come up with something constructive to share rather than quibble over my choice of words Paul.
I agree that regular printer steppers would be weak but I saw a BIG large format printer at the salvage yard and was thinking that it might contain useful steppers but gears would be useful in giving them an increase in ability to turn the shafts. Power supplies are easy, I have built several and there is always the electronics box at the local recycle center and thrift stores, there are always a good selection of power supplies in a variety of voltages and current outputs. I do like the suggestion to use printer steppers as a learning tool and will definitely do that. Right now I am in research and learn mode as well as collecting things that will be useful. Thank you for your input.
Two other things - stepper applications usually have some kind of homing mechanism that they run at startup. Microswitches are commonly used for this.
For preference, do one axis at a time. The fence seems most useful. Leave the other two until you're done learning on that one.
One question I have about the steppers is this; can the position of the fence, the blade height, and blade angle be sensed according to to0 the number of steps the individual steppers move, or do I need rotational sensors on the individual shafts? If the number of steps the stepper moves is the method to be used then I would need to choose steppers with a specific number of steps per rotation I would think, and this would also be different because of the gear ratio of the gears used, yes?
No, which is what @Paul_KD7HB was getting at.
In basic stepper applications (like a hobby 3D printers) you home them at startup and then count steps and you assume that when you asked for a step, you got one. If your stepper is powerful enough and your mechanicals are ok, perhaps this will work well enough.
If you want to be sure, you need some other way of detecting whether there was movement. Rotary encoders can be used for this.
Fence position and blade height are equally important when doing many operations, dados for example need to be of a consistent depth.; I often have to switch back and forth between a standard blade and a stacked dado set and it is very time consuming to keep the depth consistent. Is it possible to have a memory function so that I can repeat a cut depth or fence position or blade angle? It wouldn't need to be a large capacity memory, just a couple of settings for each axis should be sufficient.
Ok, that shouldn't be too difficult to manage and there are many things that have the items I would need to accomplish that. I have very little in the way of income, plus I really enjoy the challenge of finding the things I need for any project in salvaged items. I work for myself repairing things for people and have gone to the local salvage yard to find parts many times. The salvage yard is paradise to me and I will use any excuse I can come up with to go there.
Another question that I have is will the Nano be able to handle the positon sensing as well as the three steppers or would it be better to get an Uno or Mega for what I want to do?
You can certainly add a memory functionality of some sort. You could even store the data in EEPROM so it'll survive power cycling. You'll need a way to control it of course. Maybe menus shown by the LCD.
As to whether the Nano can do the job, pins will probably be a constraint. Some for the LCD, more for the keypad, two per stepper and one per limit switch. If you're going to add encoders or some other mechanism to detect movement, you're likely to run out. The Uno doesn't have any more, so you may need a Mega. You can prototype with the Nano of course while you figure out how many pins and how much memory you will need.
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