Studio of Bill Ooms

Bill Ooms

Computer Controlled Indexer

Mounting a Stepper Motor to your lathe

View the video tutorials on YouTube: Computerized Lathe Indexer and Using the Indexer Software.

Hardware:

The timing belt and the timing belt pulleys are MXL type which are 1/4" width and a pitch of 0.08 inch (i.e. 12.5 teeth per inch). I recommend the use of plastic pulleys because it's easier to enlarge the center hole to fit on the outboard side of your lathe. I also recommend using double flanged pulleys because the belt stays on easier.

My large pulley is 130 teeth, and the small pulley is 20 teeth. For the small pulley, you'll probably want a 1/4" bore to fit the stepper motor. I bought mine from MSC, but they don't carry the plastic ones any more. Check out Plastic Powerdrive Products as an alternate source.

For the timing belt, McMaster-Carr has a good selection of various lengths. You'll want to mount the stepper motor and pulleys first, then measure for the required length.

Stepper Motor Driver:

The driver I'm using is a Phidgets 1062 board. The main reasons I chose this board is that it connects to the computer via USB, and drivers are available for nearly any language on any computer. This board can drive up to 4 stepper motors, so you have some expansion for other things if you need. Note that this board requires a 6-wire or 8-wire stepper. 4-wire steppers won't work. Also note that you can use any stepper motor in the range of 5 to 12 volts, but no more than 1 amp at the specified voltage. You need to provide an external power supply to match your choice of stepper voltage. The driver has 1/2 micro-stepping capability, which doubles the resolution of your stepper.

Stepper Motor:

The stepper motor I'm using is a Vexta PH265-04 which is a unipolar motor (i.e. 6-wire) rated at 5 volts and 1 amp. I bought mine on eBay for $15, but now the prices seem to be higher. Search the web and you can find other sources. There are other motors that will work as well. See the Vexta web site for other motor options. Other companies make stepper motors too.

You'll want a stepper motor that is at least 50-60 oz-in of static torque (more is OK). To interface with the Phidgets 1062 board, the motor needs to be a unipolar (i.e. 6-wire or 8-wire). Look for a voltage of 5 to 12 volts and maximum current of 1 amp. Either a 1.8 degree or a 0.9 degree basic step angle is OK.

Stepper motors have 2 windings. For a 6-wire stepper, you will have 3 wires per winding (one is the center tap). Wire one winding to the AB terminals on the driver board and one winding to the CD terminals. The center taps go to the + connection on the terminal block. For example, the PH265-04 motor would be wired as follows:

If you find that the direction of rotation is the opposite of what you want, simply reverse either the AB wires or the CD wires.

Power Supply:

Choose your power supply based on the rated voltage of your stepper motor. Because my stepper is a 5 volt stepper, I used a 5 volt supply from an old computer. Look on eBay for power supplies of other voltages.

Traditionally, a red wire is used for the positive (+) connection, and a black wire is used for the negative (-) connection.

Alternate option with Phidgets 1063 board:

As an alternate option, you can now use the Phidget 1063 board which only controls a single bipolar stepper motor. You can also buy power supplies from Phidgets as well as stepper motors. I bought one of their 12V 2A power supplies along with their 3308 stepper motor. This isn't the ideal combination, but it works OK. If you are buying your own stepper motor, look for one with a lower inductance value as this will allow better performance with a lower supply voltage. The 1063 board can accomodate up to a 30 volt power supply. A higher value is preferred (something like a 24 volt supply would be better than a 12 volt supply).

If you are using some other stepper motor, follow the instructions in the 1063 manual for proper connections. The 3308 motor would be wired to the board as follows:

You can see a photo of the connected board with the stepper and power supply.

Driver Software:

Follow the instructions that came with the Phidgets 1062 board or 1063 board to download the software drivers onto your computer. You can then use the Phidget Control Panel to check that everything works.

Indexer Software:

See the Indexer Software page for details on the software. This software is no longer supported. Apple, Oracle, Microsoft, and Phidgets make changes faster than I can keep up with them.

The source code for this software is available to anyone who wishes to make their own changes or modify it for their own purposes. You can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 3 of the License. It was developed using the NetBeans interactive development environment which is available for free. To download the source code, see:

https://github.com/billooms/Indexer.git (and be sure to read the README file).

This is part of the Computerized Ornamental Lathe (COrnLathe™) project.