[JWWalthall]

I am designing a faceting machine that I would like to incorporate a digital index system for the angle and index setting. I have very limited electronic experience, (could not build my own board ) but have retrofitted two CNC mills. I am looking for advice/help on this project.
The basic design of the machine control:
Axis 1 : I will need a stepper motor to move a stop plate on a rotatory axis to a specified angle setting and hold. I would like to enter the angle in degrees from 0 (from horizontial) and the motor move the stop to that location. The head will then free pivot and touch this stop.
Axis 2: Is a motion that involves index settings (positions) based on number of gear teeth of a given diameter,ie 32,48,64,80,96,120 . Here again I would like to enter the number value and the motor index to that angle based on a home "0" setting.
I am experienced in CNC programming and 5 axis work so I know what a Gcode program would look like for the B& C axis if programmed. I don't want to have to program but it might be a possibility. I don't know if Mach 3 could be configurated so that I could use it for manual entry for each axis or if a stand alone display is what I would need.
My dream system would be a laptop or a small touch screen like an Automation Direct plc interface that would operate each axis.
Any help or direction would be greatly appreciated as I have just about got the mechanical part of the machine designed .

Thanks in advance

Jim Walthall

[vger]

Most steppers do 1.8 degrees / step, or 200 steps / revolution. Microstepping drives can get you to 0.9 degrees (1/2 step), 0.45 degrees (1/4 step, and so on. If you want exact degrees (360 / rev) you may want to use reduction gearing/belt/worm to get you there. I might suggest worm gear drive for your application. Worm drive would just about preclude you from accidently bumping the stepper out of position.
108:1 worm would give you one minute steps (60 / degree) in full step.

Sounds like a great project. Diamonds ??

Steve

[JWWalthall]

Steve,

Thanks for the reply. Yes I was going to use a worm gear for the index.
I was looking at a worm reduction of 36 to 1 because that gace me the size I needed and also it was divisional into the standard index gears that are used in facet designs. I will look into a 108 to 1 and see what I can find.
Anyone out there have any imput on the front end of the control. Is Mach 3 what I want and just configure the screen . I would really like a pendent with jog buttons for each direction of rotation and a readout of what index setting I was at. I would also need a readout for the angle setting. Any person that can do this please contact me.
Once again thanks for the reply.

No not diamonds, colored gemstones

Cheers,


Jim W

[vger]

Got my interest. Did a quick look at faceting machines and found the Ultratec site. They have index gears that have 32, 64, 72, 77, 80, 96, and 120 teeth.

A quick calculation gives 221,760 as the least common multiple of those values. That comes out to 616 steps / degree.

So if you can come up with a gear ratio that will rotate your dop 1 degree with 616 steps, you would be able to hit any angle that any of their gears will do (and a lot of points in between).

Might take a double worm as in a speedometer, but could be done.

Not sure as to which software might be best for this. Seems you might want the g-code to have several pauses in it and just index to the next successive pause.

Are you looking to automate the post height as well ?

Steve