I hope the large fonts, colors, and all caps don't indicate that I have upset you some how with my response(s) to your questions. Perhaps I misunderstood what you were trying to say aboth the saw arbor in the last phrase of your previous post - sorry if that's the case.
The thread has been interesting and certainly expanded in scope along the way, so I went back to the beginning and your original questions:
Questions:
1. How does a keyed washer enter into this?
I think the discussion by various members covered a couple possible thoughts - It allows you to intentionally operate the arbor in both directions of rotation - It helps keep the arbor nut tight when forces are applied in the wrong direction during normal operations (i.e., stopping the shaft) - It seems to be helpful in keeping multi-layer cutters in position when tightening the arbor nut.
To my knowledge no Shopmith saw arbors have a keyed washer. You probably noted that we don't all agree on the keyed washer subject.
2. Does a saw arbor require a blade bearing surface relief at the center near the bolt or whatever?
I don't know that they "require" a surface relief, but I have never seen a Shopsmith saw arbor that doesn't have one. My take on it is that the relief is there to make sure that any variations in overall blade thickness or maybe distortions around the blade's mounting hole, are compensated for allowing proper tightening of the arbor nut against the blade surface.
3. Is there any other characteristic relevant to making it a 'saw' arbor rather than some other kind?
For Shopsmith saw arbors, the arbor's length positions the blade correctly with respect to the other parts of the saw table system, most notably in my experience, the riving knife on the 510/520 upper saw guard.
4. I am really curious why certain 5/8" arbors are considered 'unsafe' for saw arbor use. Obviously all 1 1/4" SS arbors ARE for saw blades.
I guess this refers to 5/8" molder/dado arbors (I don't know of any other non-saw Shopsmith 5/8" arbors, at least today) As was mentioned in the discussions, you can mount a saw blade on a molder/dado arbor, but it can result in blade positioning problems with the standard saw table insert and upper saw guard. It can also result in the threaded end of the arbor striking the tie bar shield under the table possibly damaging both. This interference is a "near" thing and may or may not occur depending on the actual setup. This may also be true with a very narrow dado set up. Nick reminded us to build our dado stacks from the outside-in (i.e., near to the end of the arbor shaft) because of this potential interference problem.
5. How does a SS(SAWSMITH) arbor differ from a 'regular' SS(Mark 5/V) arbor?
To my knowledge Shopsmith Inc. made only 2 arbors specifically for the Sawsmith 2000, a 1-1/4" saw arbor and a 5/8" molder/dado arbor. The 5/8" saw arbor (p/n 555608) was sold to fit both the Sawsmith 2000 and the Mark V 510. My link showed photos of both and compared them with the Mark 5 510 5/8" saw arbor and the Mark V Molder/Dado arbor. The ends of the shafts are the same on the two machines and my experience to date is that the Mk 5 510 arbors can be used on the Sawsmith 2000. If you are speaking about the old Sawsmith RAS made by Yuba in the 1960's, I'm sorry I have no information to share.
6. Also 500/5x0 arbors are different lengths.
This is true for saw arbors and it relates to the positioning of the blade on the different table and guard systems as discussed in question #3.
As far as mounting molder heads (which was added to the discussion along the way). There are at least three different molder head designs that have been made by Shopsmith Inc. or its predecessors.
The earliest cast aluminum molder head and the most common steel head each have a set screw and can be mounted directly to the quill or they can mounted on a molder/dado arbor. I choose to use the molder/dado arbor on my Mk V 510 to allow me to position the molder head in my lower saw guard.
The newer aluminum molder head (p/n 555611) produced in the 1980's and 1990's for the Sawsmith 2000 and more recently sold by Shopsmith as "compatible" for use with the Mark V, has no set screw and must be mounted on a molder/dado arbor. (I note that the original instruction sheet says not to use this molder head on any machines other than the Sawsmith 2000 - times change I guess, and instruction sheets do not always reflect the latest information and advice on the subject.)
Well, I hope this info and opinion from a fellow engineer is useful. There most certainly are other possibilites and opinions in all these areas.
Regards,
Dennis
