Slitting saw kerf question

[WobblyHand]

How much excess kerf should one expect when cutting with a slitting saw? I have a Niagara 4" diameter x 1/16" wide blade. I'm designing some screw less vise hold downs. Thought I'd mill out a long strip, drill the holes, and then cut them off individually. (Maybe not in that order, but that's the basic idea.) Assuming the blade isn't worn out and it's running true how wide would the slot be? Yes, it's a beginner question, but I'd guess this is the right place to ask?

I'd don't have a parametric CAD program, so it's not easy for me to change my drawings to widen the spacing. I like to draw out what I am going to do and machine from the drawing. That way it is more likely I don't end up with another door stop!

 

[Mitch Alsup]

The size of the slot should be the kerf + vertical_runout

 

[WobblyHand]

How do I measure vertical run out? I'm guessing the easiest way is just to cut something and measure the width of the slot. Won't be able to do that tonight, too tired to safely run a machine. Any other way that would be reliable, or just try it and see?

 

[ErichKeane]

You can put a magnetic indicator stand on one side of the saw as close to the teeth as possible (like on the spindle or table), and manually turn it a whole revolution.
The kerf will then be roughly : #OnSaw + 2 *(MaxMeasurement - MinMeasurement).

 

[WobblyHand]

To answer my own question, I made a cut in a piece of steel scrap. Used a set of feeler gauges to find what fit. 0.0635" fit freely (from summing all the shims & measuring with a mic) and 0.064" only made it half way in before getting too tight in the slot. So for my purposes, guess I'll use 0.064". Guess my vertical run out is 0.0015" today. Although everyting is tightened down, somehow the arbor/blade seems a little off, I think I feel a tiny bit of play. But for what I am doing, this value is good enough. Maybe I didn't seat the blade quite right, or there's a speck of grit under it.

 

[ErichKeane]

To answer my own question, I made a cut in a piece of steel scrap. Used a set of feeler gauges to find what fit. 0.0635" fit freely (from summing all the shims & measuring with a mic) and 0.064" only made it half way in before getting too tight in the slot. So for my purposes, guess I'll use 0.064". Guess my vertical run out is 0.0015" today. Although everyting is tightened down, somehow the arbor/blade seems a little off, I think I feel a tiny bit of play. But for what I am doing, this value is good enough. Maybe I didn't seat the blade quite right, or there's a speck of grit under it.

In my experience, thin slitting saws are pretty horrible for runout. I'm actually shocked you have one with only ~2 thou of runout Perhaps you got lucky and the runout in your arbor and the runout in the blade offset

 

[macardoso]

0.0015" of axial runout seems very reasonable. The quality of tools and holders we have as hobbyists isn't super precision, nor are slitting saws by design. Sounds like you are on the right track.

 

[WobblyHand]

In my experience, thin slitting saws are pretty horrible for runout. I'm actually shocked you have one with only ~2 thou of runout Perhaps you got lucky and the runout in your arbor and the runout in the blade offset

Sometimes the blind squirrel still gets the nut.

 

[WobblyHand]

In my experience, thin slitting saws are pretty horrible for runout. I'm actually shocked you have one with only ~2 thou of runout Perhaps you got lucky and the runout in your arbor and the runout in the blade offset

Got the Niagara off eBay, as well as the Shars R8 saw arbor. It's ok to get lucky once. Besides being ridiculously too long, the saw arbor is ok and machined nicely. Tight fit. Wish I could make my own though.

Last attempt was a doorstop. Had problems with boring. Micro100 bar snapped. Steel boring bar to finish up wasn't up to the task. Hadn't read @mikey's boring primer yet when I was trying to make it. But biggest screw up was how I machined the pieces. Somehow managed to machine the two pieces so that the lathe taper errors were opposite. Cap plug doesn't go all the way into the main piece.