Slitting saw holder for mill

[yota]

merry Christmas Eve. so far in my hobbie endeavors, I've managed to make do without a slitting saw, mostly using my vertical metal cutting bandsaw and Foredom rotary tool, but I think it's time I pony up.

my mill is R8 so should I get a saw holder with an R8 shank or are there other uses for these where I would wish I could put it in a collet? if a round shank for a collet is better, should it be a 3/4" shank? I guess I should say that I have a PM 932M mill.

next, I see saw blades that have a keyway and some with just a round arbor hole. should I get a holder with or without a key for the blades? the key would seem logical, but maybe there are more keyless blades available?

anything else I need to know? thanks for any info you can provide.

 

[ChazzC]

What do you think you are going to use it for, how wide a slot and how deep?

 

[Pevehouse]

Glad you asked the question. I’m curious as wrll

 

[IHinIN]

I prefer the 3/4” straight shank arbor. It allows you to hang the arbor out of the collet some if you need the clearance between your part and the quill. I have always used slitting saws without a key. That way, if it grabs, it will hopefully slip instead of busting off the teeth.

 

[Rob_fixit]

Why not make your own?

 

[GrifterGuru]

Why not make your own?

View attachment 515114

I was about to ask that very question as I read through the thread from the top.

Seems like a good project to work through on a lathe and would garner a decent understanding on the slitting saw arbor construction.

 

[Jim F]

Joe Pie has a video on making one.

 

[mksj]

I would suggest making your own, there are a number of different ones you can buy, many had pretty poor reviews (mostly complaints about run-out). It also depends on the size slitting saw you want to use, or you can make different size ones. I standardized on 1" bore ones, they are fairly common and I mostly use them in the 3-4" diameter size. On smaller mills I do not use a keyway for the slitting saws, no real need if you have a good slitting saw design. I also would prefer the saw to slip as opposed to something breaking should one bite off more than your mill can chew. I designed mine with a 3/4" shank, I find it a bit more adaptable vs. an R8 arbor in particular if you are making your own. One thing to be careful of depending on the design, is that the retaining screw for the saw arbor will self tighten and can get to the point where it is to tight to remove or breaks. I use a wave washer which limits the self tightening. A friend of mine drew up my design for me, and a few others have also made this design. Was very pleased with the end result and only had ~0.001" TIR indicated at the bottom of the holder.

 

[mmcmdl]

Depends . What size mill and what size cutters you'll use . Bottom clearance an issue ? Easy to make straight shank holders if you choose .

 

[bulgie]

Bottom clearance an issue ?

For the ultimate in bottom clearance, keep an eye out for a Peterson Flush Arbor. They;'re expensive new, but I got an old one ('70s I think) off ebay. The clever way they use a precision taper means that the saw will tighten right on center. Versus most arbors, that have to have a littile clearance for you to be able to get the saw onto the arbor, and that clearance leads to some loss of concentricity.

I have 2 sizes of sleeves, for saws with a 1" hole and for 1-1/4", must be keyed though.
Shown here with a thicker wheel cutter but it works for thin slitting saws too.



In the second pic you can just make out how the sleeve opens up radially as you push it further down the taper.

You use a stack of spacers to bring the saw down to flush with the bottom (top, in this pic), so you'll want to have a variety of spacers in different thicknesses. The spacer stack doesn't need to be exact though, especially if you don't need the saw to be 100% flush at the bottom.

My Peterson has an R8 shank but I think those aren't made anymore, except by special order. But 3/4" straight shank in a collet is plenty rigid enough for most slitting saws.