Slitting Saw Arbors

[ronboult]

I purchased a Sierra American 5/8" slitting saw arbor with 3/4" shank to use in my Tormach 3/4 Collet. Seems reasonably well made except for the arbor size for the blade.

Here in Australia its no longer easy to purchase Imperial 5/8 bore slitting saws. All the imported saws while they may be listed as 5/8" are really 16mm.
Well the saw blades that I ordered are really 16mm ( 0.630") but what has exacerbated the problem is that the Sierra arbor appears undersize at 0.619 - 0.620 " leaving a 10 thou gap.
What clearance does one want on a slitting saw arbor ( 10 Thou is very very sloppy)
What are my options?
Buy true 5/8 bore saws from America. This becomes expensive mainly due to the shipping costs and I would then have to do this repeatedly.
Bore out the holder to 16mm and machine a new plug for metric 16mm blades. This seems to be the best long term solution.
If the latter option, what material would I make the plug from, and how accurate would it need to be? I don't have cylindrical grinding facilities.
The plug supplied with the Sierra arbor seems to be slightly tapered presumably to make getting the saw onto the plug easier. Is this normal and is it required. I will try to measure the current bore in the arbor to see if it is also tapered
Thanks
Ron

Edit
Checked the bore of the arbor and it is not tapered. However the bore is 4 thou larger than the plug at 0.624". Also seems a bit sloppy.

 

[mksj]

I would suggest turning your own arbor, it is fairly straight forward to make one to the specs you desire. I used some drill rod to make mine. It is designed to take a 1" bore slitting saw, but you could scale it down for whatever size you want, or use a spacer to neck down the diameter. For a 5/8" bore, I would probably start with 1" rod so you maintain enough rigidity and cut the shank to 3/4", there should be no tapper to the arbor saw baled mount. The one I made, there is under 0.001" clearance between the arbor and the locking carrier, I did not opt for a key to index the saw. The sequence of boring and cutting down the drill rod is important to minimize the TIR of the arbor, mine is about 0.001" at the tip. I use a wave washer under the clamping allan bolt which prevents the clamping bolt from getting too tight, and use the same size wrench on the arbor flats as I use for my QCTP nut.

An inexpensive alternative, is there are slitting saw R8 arbors (and also straight shaft) with stepped saw carriers that fit a range a range of slitting saw sizes (these should be available for both imperial and metric size saws). These are inexpensive and also should work fine for thinner blades, or make a simple arbor shown below. As long as the blade does not wobble up/down, I do not believe it is a a problem to have some rotational wobble, I have also heard that the blades will work reasonably well even if missing a few teeth. It is important not to take shallow cuts, but a full depth cut.


R8 Stepped Slitting Saw

Basic Slitting Saw Arbor 3 inch Reach 5/8 inch shank