Many of the standard spooled freshwater casting reels have ~1-1/2" spool widths, with ~3/8" spindles. So I started with cork rings measuring 1-1/8"OD x 3/8"ID x 1/2"W. I found mine at Jann's Netcraft. Three of them glued together give a 1-1/2” width. For a tight fit, and for narrower spools, I used a fine coping saw to lop off an end, and sandpaper to square it back up.
It’s a good idea to use a waterproof wood glue, like Tightbond III.
The finished diameter of the arbor was a trial and error process for me: 50yrds of 10 to 20lb braided nylon doesn’t fill up the spool very much, so I needed a greater diameter arbor than I expected, or that originally came with some of my reels. I found about one inch in diameter (25mm) was about right for 50yrds of 15lb Mason braided nylon on a standard spool freshwater casting reel.
To sand down the diameter I used a drill press, making a mandrel from a long 3/8” (or 7/16”?) bolt, lopping the head off with a hacksaw so I could chuck it. The glued cork rings would thread onto the bolt threads firmly. Then it was a matter of sanding down the cork diameter, using a strip of medium sandpaper, being careful to keep the width even. It’s easy to round the ends, so I was careful there, and flipped the orientation of the cork half way through.
I then cut the glued cork rings in two, lengthwise. I held the glued rings firmly in a vice and cut using a coping saw, careful to keep the cut as straight as possible. Absolutely perfect is not required as the resulting two halves will fit together regardless.
Next is fitting the arbor to the spool. If it is too wide the coping saw will take it down easily. This cut should be as close to straight as possible, followed by sanding, so that the arbor will not be short, leaving a gap between it and the spool wall for line to get into. Since some sanding here will be required, cut fat! Sanding with the sandpaper lying on a flat surface makes square sanding easier than trying to use a sanding block directly.
Also, most spools have a flare or collar at the base of the spool wall, which must be accounted for. A half-round or rat-tail file makes short work of this. The arbor should fit tightly; You can hear it squeak as you press it into place. If the inside diameter is right, the two halves should come together.
One thing that must be kept in mind: If the arbor is too loose and you spool line on top of it, the pressure exerted on the arbor from a fighting fish can cause it to rotate on the spool spindle, causing the entire spool of line to rotate on the spool! It would be like having drag set too loose, but not being able to tighten it down. To be sure, I put some friction material on spool spindle before installing the arbor. I’ve been using “hockey tape”. However, masking tape might actually be better. Remains to be seen. With the hockey tape, I use a heat gun set on low that helps the tacky tape hold better.
Lastly, check for gaps between the arbor and the spool wall. If there is a gap I’ve used a strip of duct tape the width of the spool to cover. Duct tape is also used to build up the diameter of the arbor, in case the 50yrds of line I’m using doesn’t fill the spool entirely. A full spool casts better, and gives you the maximal retrieve speed for these slow older reels.
