slitting saw arbor build - R8 or 3/4" straight shank

[JCByrd24]

I'm going to build a slitting saw arbor for a 3-3/8" slitting saw (re-purposed carbide tipped trim saw blade). The arbor will extend from spindle nose by about 1.5-2". Is 3/4" sufficient or should I take the time to make it R8? I've seen nice DIY designs of both....

[old mart]

Go for the 3/4 straight shank, and make it long enough to allow some length adjustment in a 3/4 r8 collet.

[v860rich]

Exactly what old mart said.
That's how I made mine and it works a treat.

THANX RICH

[Norman Bain]

My finding is that a 3/4 shaft is fine.

I have posted this before; but here again is my spin on a slitting saw arbor that results in a low profile ... less of the holder sticking out beyond the blade.

[BCRider]

For out to about 1.5" extension you'd be fine. If you want to run it further out than that by something like 2 to 2.5" extension then I'd do something similar to the Tormac style stub arbor where there's a shoulder that runs up against the spindle nose for a larger "footprint". Tightening the collet then draws the shoulder up against the nose of the spindle with some good force for more stability. For much over 2.5" of extension I'd want to go with a large full length one piece option with the R8 shank

[Tim Clarke]

Given the nature of saws to cut on just a few teeth, I'd assume that adding the runout of a collet would be best avoided. Mine are somewhat less than perfect. Checked my 3/4" and it's got about .0004" as close as I can tell.

[CCWKen]

You'd be hard pressed to find any collets better than that. Most saws have more runout.

[BCRider]

Given the nature of saws to cut on just a few teeth, I'd assume that adding the runout of a collet would be best avoided. Mine are somewhat less than perfect. Checked my 3/4" and it's got about .0004" as close as I can tell.

Quite true. I wonder about the option of making our stub arbor in two operations on purpose with the idea of finding a combination of collet and arbor positioning that cancels out the usual collet error? Dial it in and mark the relative positions and always return it to that point

[JCByrd24]

Thanks for all the input, you've convinced me 3/4" is fine, I may design it to pull up against the spindle nose as an option. Norman your design was one that I found on a google images search that I was fond of. With regard to runout I've read the same, that it's the saw that is usually the worst offender. I planned to check my blade once mounted up and massage it as necessary.

[Norman Bain]

I think if I needed to make another, that I would do it as a weldment. That is, rather than start with, something like 35mm round stock, and carve the shaft from that, I would select a shaft from suitable cold rolled stock and, after drilling a hole all the way thru the end portion, weld it to the end portion.

Weld would only be at the intersection of the shaft and the end portion. True up the end portion to the shaft after welding. The female threaded (nut) portion for the cap screw would still be into the shaft.

If one used the weldment approach, the shaft could be left "sticking out" of the chuck by an inch or so in order to true it up with a dial indicator prior to cutting the end.

[J Tiers]

Given the nature of saws to cut on just a few teeth, I'd assume that adding the runout of a collet would be best avoided. Mine are somewhat less than perfect. Checked my 3/4" and it's got about .0004" as close as I can tell.

There is the fit of the saw on the arbor, which is usually a straight-sided fit, for which you can expect a minimum of a thou possible runout. Don;t sweat the runout issue.... runout will be there regardless.

[Tim Clarke]

There is the fit of the saw on the arbor, which is usually a straight-sided fit, for which you can expect a minimum of a thou possible runout. Don;t sweat the runout issue.... runout will be there regardless.

I agree, eventually the proud teeth will blunt, and fresh teeth will be available. I wish I had an arbor for each saw I have, that would allow the compensating wear factor, but I don't want to face the prospect of making a dozen or more holders for the saws I have! Then, there is the need to move the saws to the horizontal mill arbor. I will, I guess, continue my whining about the situation.

[JCByrd24]

Here's the final product, it works very well. The blade is 3-3/8" carbide tipped for $11 from Amazon.