Shopsmith Forums

I have an assortment of what I am referring to as spacers and or collars based on my limited knowledge and information that I've been able to glean from Ebay sellers of Shopsmith items and information on this forum. Are the collars/spacers interchangeable for dado and shaper operations? Can they be used safely for either operation? They appear to look the same except for their thickness.

I would say no. The shaper arbor is 1/2 inch, the dado arbor is 5/8 inch.
Ron

As Ron said they are not interchangeable and are for different purposes. In your first two pictures you have a combination of Machined Spacers and Washers that belong to arbors plus Shaper Collars. The spacers and washers come with hole diameters for both 5/8" and 1/2" Arbors. The Shaper Collars which go on a Shaper Spindle have a 1/2" hole and come in four different outside diameters. They do not have the machined indent around the hole like the spacers and washers for the 5/8" Molder/Dado Arbor (P/N 505506) or the old 1/2" Universal Arbor (P/N 505505). Your third picture, although blurry and hard to see, looks like a complete 5/8" Molder/Dado Arbor P/N 505506 which was previously known as the 5/8" Universal Arbor with the same part number. There have been many different Arbors made over the years since the first Model 10E's in 1947 so it can be hard to tell which part goes with which arbor. See the attached PDF for an example of many different arbors.
Besides the standard Shaper Collars there is a second style of Shaper Collars with ball bearings made for a specific Shaper Spindle.