The completed automatic coil winder.

This is my build of the: High Stepping Automatic Coil Winder project that was featured in the June 2005 issue of Nuts & Volts magazine and authored by Robert Lang.

The Automatic Coil Winder was created to facilitate the unattended winding of coils and also as a introductory learning tool in precision object positioning.

I have made some changes to the winder along the way and the biggest change is the addition of a PIC microcontroller based control unit that offers much greater control over the winding process than the original Windows based coil winder program.

If you are interested in reading the original article or building the High Stepping Automatic Coil Winder a print copy or digital version of the June 2005 issue of The Nuts & Volts magazine can be ordered from the Nuts & Volts website.


Screen Shot of the Coil Winder Program Running in Windows XP.

A screen shot of the Coil Winder program. The white fields are filled in by the user and the green fields are the calculated results output by the program based on the user inputs.

To run the winder you need a copy of the "Coil Winder" software program (you can download from the Nuts & Volts website) running on a pc with a parallel port, a parallel port printer extension cable, and a power supply to power the driver board and stepper motors.

The Coil Winder program will run in MS Windows 98, but to run in newer operating systems such as, NT, 2000 or XP you will need to download and install a driver named INPOUT32.DLL from LOGIX4U.NET otherwise you will get an error when the Coil Winder software tries to access the parallel port.


Wood cut to size for automatic coil winder.

For the wood parts of the coil winder I was able to use wood I had leftover from other projects.

The plywood I used for the sides and bottom of the winder have a 1/2 inch nominal thickness. The sides are cut to 8" X 8", and the bottom is 8" X 18". The side supports are 3/4" X 2 3/8" X 8", and the channels cut into the supports are 3/8" deep and the width of the plywood.


Automatic coil winder in the process of being constructed.

I had a difficult time understanding the placement of some of the coil winder components while referencing the original coil winder mechanical drawing, so I studied it and made my own drawing to locate the positions of the motors, and threaded and brass rods.

I have since improved my drawing and added a few more at my coil winder mechanical drawings page.

The side panels are glued into the side supports, and the side supports are fastened to base with screws from the underside of the base.

The side support screws can be loosened so you can adjust the sides of the winder. If the sides are not parallel to each other the rotating rods will bind up. Cardboard shims can be placed under the side supports as needed to make the sides vertical.


Drilling brass and threaded rods for automatic coil winder.

Stepper motors mounted to automatic coil winder.

The stepper motors the author used were surplus units from All Electronics and are no longer available.

Here is the information from the original stepper motor listing. I got this from The Wayback Machine.

New stepper motors are generally expensive to use for hobby projects.
I bought new old stock stepper motors through the Internet.

It can be difficult to find specifications for old stepper motors. I gathered as much information as I could, took a chance on these motors and I am quite satisfied with their performance.

The coil winder 28BB-H151-11 stepper motor wiring diagram & information.


Underside view of automatic coil winder carriage base.


Minebea Stepper Motor part number decoding & specifications, Circa 1999.

The underside of the carriage base with polystyrene slide tube and threaded #10-32 hex nut fitted into channels and epoxied into place.

I formed the channels in the base with a miter saw, wood chisel and a round file.


Automatic coil winder carriage wire guide.

For the carriage wire guides I used eye screws that measure 7/16" in length, have 1/8" inside eye openings, and are made with a .047" diameter wire.

A large sewing needle was used for the final wire guide and cut to length before inserting it into the wood.

I also drilled pilot holes in the wood before inserting the wire guides to prevent the wood from splitting.


Automatic coil winder spool.

The polystyrene material was purchased from a local hobby shop.

A 1.25 inch hole saw was used to cut the sheet material. The hole saw pilot bit cut the center hole just right for the .25 inch tubing.

I glued the spool together with gel super glue, but have since purchased a solvent to weld future spools together.

The foam cylinder in the photo was a sewing thread spool that I cut and sanded to use as a form to make the coil winder spools.


End view of automatic coil winder.

Coil winder and carriage rod nylon bearings epoxied into side panel. Aluminum spacer epoxied on threaded rod as inner bearing surface.


Automatic coil winder driver board.

When I first started running the coil winder I noticed the stepper motors were randomly miss stepping.

After checking into the problem I discovered that my computer's parallel port could not properly drive the IRF510 mosfets specified in the original Nuts & Volts article.

The parallel printer ports uses 5 volt logic so I replaced the mosfets with IRL540 logic level mosfets and it eliminated the random miss stepping.



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