Help Me Find This R8 Arbor...

[CarlosA]

I have searched high and low and cannot find a source for a r8 7/8" stub milling arbor. Does anyone know where I can find one? Maybe have one to sell?

I have a 1" version, and a 22mm version ... just need the 7/8" in order to dial in my gear cutting efforts. I currently use a slitting saw arbor for the 7/8 but I don`t like the runout and general operation of it - I want a keyway type arbor.

Now of course there will be responses like: Get a 1" and make it smaller! Make your own! Just use the slitting saw arbor! ... But I am tired of making common tools before I can spend my very limited time making actual parts for my project. I have a 3 ft bar of 12l14 and can probably make a pile of these arbors-- it just wont be easy or quick in my apartment machine shop, with my lathe that hates to be setup for turning between centers, etc. I want this thing to have no runout, and be ready to go if possible.

 

[Bob Korves]

Forget the R8 and get one with a 3/4" straight shank. Drive it with a collet. And, no, the tolerances do not add up, if you check them and mark the runout high spot on each component. You can use their individual runout to cancel each other out, usually better than either alone.
Example:
http://www.shars.com/3-4x7-8-stub-milling-machine-arbor

Edit: Also, the R8 shank makes the tool machine dependent. The straight shank is a more universal mount.

 

[CarlosA]

Good idea .. I was trying to just avoid a straight shank entirely - but for no good reason except that my mill is small and it could get in the way. I do like what you mean on cancelling out runout.

 

[Bob Korves]

Straight shanks also require less headroom to change tools than R8 shanks do, and do not typically require more headroom as mounted than R8 tooling does. Just about all the R8 tooling I have I now wish I had purchased with straight shanks. They are just more universal and user friendly tools...