The selvedge rollers are beams in addition to the warp beam. The warp for the selvedge is wound on the rollers instead of the warp beam. This allows the tension for the selvedges to be maintained seperately from the rest of the warp. (ie. keep the selvedges tight).
They are again being made by one or two loom makers but it's easy and cheap to make your own by gluing three wooden thread spools together, use two small ones for the selvedge warp and a third larger one for a brake band.
Use a cotton strap for the brake band, secure one end low down, bring the band up and over the larger spool from back to front and tie on about a 12-16 oz. of weight, then let it hang. Leave the spools unfinished. The spools will be on a waxed steel rod which can be supported in many ways. I use a wooden framework but a pair of common angle braces attached sideways to the back beam will work too. Angle braces are used for holding up shelving, they're shaped like the letter L , so attach them with the lower legs pointing at each other like this : |_ _| . This points two or more holes at each other so the steel rod can fit into them.
The front of the back beam is under the warp-line and it's normally not used for anything so it's a good place to attach sel. rollers. You need a selvedge roller beam at each side of a loom, positioned at the edge of the main warp.
Another way to do it although not as elegant, is to put the sel. warp onto weighted bobbins and hang them over the back beam, we do that on two other looms.
|(They are again being made by one or two loom makers but it's easy and cheap to make your own... )|