control of lathe spindle speed

can Arduino be used to control lathe spindle speed for constant surface speed machining,motor specs are 180V DC 7amp 4000 Rpm

Sure it can. You'll need an index switch (magnetic) for feedback.

You also need a suitable motor driver that can handle the voltage and current required by the motor and which can be controlled with a 5v logic signal.

...R

Zepplin: can Arduino be used to control lathe spindle speed for constant surface speed machining,motor specs are 180V DC 7amp 4000 Rpm

There is a bit more involved here than you have disclosed.

The surface speed depends ENTIRELY on the circumference of the part you are turning and the shape of that part. So that value will have to be input to the Arduino program to actually compute the surface speed.

Then as you make subsequent cuts, the diameter will be smaller, so the new diameter will have to be entered.

If your cutting tool produces "chatter" while cutting, your method of controlling the surface speed will have to decide what the "real" surface speed is.

If you are doing "interrupted cuts" on a non-round object, there is no way to monitor the surface speed.

Paul

Surface speed on a lathe depends on the diameter of the workpiece. The diameter of the workpiece depends on the position of the cross-slide. To get to a known diameter, it is usual to have tooling with either standard length, or known offsets. to the toolpost. If you want to be picky, then you will need to incorporate movement of the saddle, too, for surface speed. so, a rotary encoder for the spindle, and a couple of linear encoders for saddle and cross-slide. If it's a manual lathe, then you may as well add a couple of servo's and turn it into a cnc machine. If funds are limited, and it's purely for spindle speed, then you can get cheap digital scales (or even cheaper calipers) with a digital output for the cross-slide and not bother with the rotary encoder. Many motor drivers are analogue controlled, so you could use a linear pot instead of digital, and forget about the arduino. Have fun setting it up...

Thanks for you inputs,have already worked out the encoder requirements on the spindle and cross slide to get this to work,my main problem is the Arduino bits and pieces to get this up and running,as well as programing as this is the first attempt using Arduino.

Zepplin: Thanks for you inputs,have already worked out the encoder requirements on the spindle and cross slide to get this to work,my main problem is the Arduino bits and pieces to get this up and running,as well as programing as this is the first attempt using Arduino.

It's not clear from that what you need help with. What are the encoders to be used for?

Can you read the encoders with your Arduino?

If you have an Arduino program please post it and tell us in detail what it actually does and what you want it to do that is different.

Links to the datasheets for the parts you are using and a simple wiring diagram would also be a good idea.

...R

Virtually any arduino will most likely do what you need, that is not the problem, as I see it. To be able to help you with the code, we will need the details of the other system components that you have. The motor driver unit is the major component, inmnsho, and you've mentioned nothing about that. The intererface voltage levels will be critical. Also, how are you controlling this, touch screen, variable pot, push buttons? Are you wanting to be just able to input the material, get the arduino to go on-line to the tool website, download the recommended tool and surface speed, or do you just want to type in a surface speed, or set the surface speed through your existing motor speed settings, and know that as your diameter decreases, it speeds up. What will the speed change profile be like. Does it matter? Do you want the random variable speed rate changes to reduce harmonics/chatter?

If we spend time on this, going back and forth, asking for basic information so that a question can be answered, exactly what, in return, are you going to do for us? So, to minimise our time wasting, give the specifications/link to data sheets of what you have, or what you think you need, then maybe we can help further. If it is a case that you need to learn the basics of arduino programming, then that is another issue, relatively cheap development kits are available..

raymw

Your first post in reply is closer to the sorting CSS out than using Arduino.The original post was to see if anyone had actually used Arduino to solve this problem,there by making things a little easier.

Thanks for your input.

Zepplin: The original post was to see if anyone had actually used Arduino to solve this problem,there by making things a little easier.

That is not at all obvious from the text of your Original Post - "can Arduino be used to control lathe spindle speed for constant surface speed machining,motor specs are 180V DC 7amp 4000 Rpm"

...R

So, what is the question you really want to ask? Do you want a simple yes/no answer, and then go away and do your own further research, or do you want complete build instructions provided for a specific control system? , or something in-between? The arduino is a uP with a few auxiliary components to make prototyping easier. If a uP can do the job, then in most cases an arduino can do it, but other caveats come into play, so commercial controllers will use some other device.

You mentioned the motor type/voltage. That is not important. What is important, from the point of view of the arduino, is what the arduino is directly connected to. You've not mentioned that.

If this stuff was easy, everybody would be doing it.