paulmcohen wrote:My Shopsmith plywood blade has a 1 1/4" hole and I have a 510/520 version 1 1/4" arbor, my new carbide plywood blade has a 5/8" arbor hole. I have one arbor for every blade.
A new arbor with shipping is $50, shipping of a blade and arbor is <$10 and someone gets a fair blade and excellent arbor.
If shipping were more reasonable I would just get a new arbor or if Shopsmith had a carbide plywood blade I would have purchased theirs.
You might want to check shipping again. The arbor would ship separately to Montana for 8.49 so the total is a shade over $40 and I don't presume Oregon would be that much more. I had other things that were on sale Small Lathe Chisels and jointer dust retro fit kit (I like the 15% off!) and so the shipping for all the items was less than $14. Maybe shipping has dropped since you last checked.
I don't know if ShopSmith will put arbors on sale, but if they do I'll probably buy a couple, because I really like Dusty's idea of having an arbor for each blade. At at least one on each of the 4 or so that I will use the most. After blowing my entire budget (plus some!!) on acquiring 3 ShopSmiths, until I clean up and sell two along with some of the extras that I got when buying the units, some of the things I would like to have will have to wait. I understand that I "could" have utilized an existing older arbor for non-ShopSmith blades, by fiddling with the quill feed,

but I guess I am getting too old and adjust priorities to fit enjoyment.

But then that's just me.
Just curious, have you made your offer on other ShopSmith user sites?