I asked Chuck Burrows that question a little while ago and got this answer from him.
Mike
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But as for working the leather spacers: well I've done plenty over the years and here's how I do it.
1) Cut the spacers oversize - I generally make them sort of octagon shaped (you can also buy them pre-cut from some of the knife suppliers) - I prefer 7/8 oz veg tan, but 5/6, 6/7, or 8/9 will work - FWIW you can buy 6/7 single sides fairly cheap from Tandy/LF. Of course I just use scrap - just make sure it's veg tan. Also cut your center slots/hole for the tang.
2) Once cut - you can dye if you so choose, I use Fiebings Spirit dyes. I soak the pieces thoroughly for an hour or two so they are well saturated - after I let dry completely. If they start to curl lay them out flat and weight them with a piece of 3/4" plywood and a brick or some such. Once dry - I figure a couple of hours, rub off the powdery dye residue from each piece.
3) A choice on the next step - you can glue them direct to the tang or use a piece of threaded 1/4" rod with a couple of large washers on each end and a nut to tighten - all of the latter of course will need a good coat of release agent. The rod is especially helpful if you are not using a threaded tang.
4) Thin some long drying epoxy (needs to be at least 1 hour so you have enough working time) with acetone or denatured alcohol. Apply glue liberally and slip each piece onto your tang or rod. Be sure all pieces are aligned properly and tighten your nuts as much as possible - the object is to compress the leather as much as possible without bending your tang or rod.
5) Rub in/wipe off any excess epoxy and let dry about half way - loosen your nut if on a rod and make sure it is still removable - if it is, re-tighten and let dry completely.
6) Wait 24 hours and shape as need be - they should be thoroughly saturated with the epoxy but if by chance not, thin some more and rub it into the missed spots.
After assembled I buff with a good carnauba based wax. The object is to "stabilize" the leather, if not over time the leather can absorb moisture and begin to rot - I've "repaired" a bunch over the years due to moisture - it's why I also why I like to glue the handles solidly to the tang whether I use the rod or not.
Hope this helps,
Chuck