# Slitting saw arbor



## trlvn (Aug 29, 2022)

I got a little shop time over the past couple of days and made a slitting saw arbor:






It is a 3/4 inch arbor as several of the saws I picked up in an auction lot need that size.  A number of Youtube videos all used basically the same design so I did too.

Here are the parts:






Both the cap and the bore in the main body need to be a good fit to the hole in the saw blades.  To do the bore, I used a tool that I picked up a few months ago:  a round-pin, inside micrometer:






It took a little practise to get accustomed to it.  I didn't realize the knurled knob on the head locks it.  It was dragging and it seemed hard to use.  Duh!  But after I got that figured out, it really is nice and accurate.  The bore came out at about 0.7505--exactly what I wanted!

I also used a kind of funny tool for the boring which is shown at left in the above picture.  The head is stout enough to hold a 1/4" HSS cutter but the shank fits in a basic '102' style tool holder.  My bore only needed to be 0.5" deep so I had just enough room get inside.  I've used it a couple of times now for shallow recesses and the like.  Works well; no flex.

So, does the arbor work?  Here is an aluminum offcut from my first test:






There is some texture left after the cut.  I think there are two issues.  First, I used a 36 tooth saw blade (3" diameter) for the cut.  I think that may have been too many teeth and swarf was getting jammed in the gullets.  Also, I know the tram on my mill needs more work.  Acceptable, nonetheless.

Finally, here is a shot with a bigger cutter installed:






I haven't tried a test cut with this one, which is a 1/4" staggered tooth slotter(?).  Not sure how well it will work.  I may not be able to get the cap tight enough with the 1/4-20 screw I'm using.  The cutter also has a provision for a key which isn't possible with this arbor design.

I think I'm going to add wrench flats to the arbor body.  That'll give me a chance to have a go with my 5C collet blocks that have been sitting unused for an age!

Craig


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## David_R8 (Aug 29, 2022)

Nice job!


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## YYCHM (Aug 29, 2022)

I like it.  Well done!


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## Dusty (Aug 29, 2022)

@trivn  what is the advantage of your Mitutoyo Round Pin Inside Micrometer to calipers?  

Never use one  so I assume the round pins center quicker and easier inside a cavity!


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## PeterT (Aug 29, 2022)

The Mitutoyo round pins are more accurate because the circles make contact tangentially & with a little bit of wiggle they find the max diameter across the span. Kind of the same contact principle as bore gages which have hemispherical ends. The Mitutoyo also has a clutch for consistency. Its a great tool. Caliper inside measuring blades are OK for quick measurements, but its not really a good bore measuring device if you want to be accurate (say +/- a couple thou). The blades are sharp but are still rectangular in section under magnification. Hope this makes sense.


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## trlvn (Aug 29, 2022)

Dusty said:


> @trivn  what is the advantage of your Mitutoyo Round Pin Inside Micrometer to calipers?
> 
> Never use one  so I assume the round pins center quicker and easier inside a cavity!


I have real trouble getting a consistent measurement with the calipers.  If I was a little mis-aligned with the bore, the measurement would be 5-12 thous small.  The two little pins seem to be much easier to get in straight and get a true measurement.

Worked for me anyway!

Craig


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## PeterT (Aug 29, 2022)

Good job on the arbor btw. Often times I've wanted a longer one. That's the great thing about making your own tools. And better quality than half the junk out there.


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## Dusty (Aug 29, 2022)

trlvn said:


> I have real trouble getting a consistent measurement with the calipers.  If I was a little mis-aligned with the bore, the measurement would be 5-12 thous small.  The two little pins seem to be much easier to get in straight and get a true measurement.
> 
> Worked for me anyway!
> 
> Craig



Just as I thought, I also have the same difficulty measuring with a caliper. Always end up doing 2-3 measurements sometimes more with none of them being the same numbers. Pricey little devils wish I lived nearer a good used market place.

https://www.kbctools.ca/itemdetail/1-808-145193


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## DPittman (Aug 29, 2022)

Dusty said:


> Just as I thought, I also have the same difficulty measuring with a caliper. Always end up doing 2-3 measurements sometimes more with none of them being the same numbers. Pricey little devils wish I lived nearer a good used market place.
> 
> https://www.kbctools.ca/itemdetail/1-808-145193


Accusize Industrial Tools 0.2-1.2'' x 0.001'' Inside Micrometer, Satin Chrome Finished, Eg00-3221 https://a.co/d/29IdWWZ


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## Dusty (Aug 29, 2022)

DPittman said:


> Accusize Industrial Tools 0.2-1.2'' x 0.001'' Inside Micrometer, Satin Chrome Finished, Eg00-3221 https://a.co/d/29IdWWZ



Reasonable ratings for the above item, apparently quality control appears to be an issue when you read the reviews.


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## phaxtris (Aug 29, 2022)

Looks good!

On to the pin mic ...
Why not just use a bore gauge if your trying to be super duper accurate ? Aren't those pin mics more for shallow hole where a bore gauge won't fit ?


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## PeterT (Aug 29, 2022)

Kind of depends on the part/application. The pin style is limited to shallow holes. But its reasonably quick & accurate. I don't recall mine having vernier on barrel so you are eyeing between the thou marks I believe. The pins kind of self align axially whereas bore gage or snap gage you swivel out & watch for maximum needle, so you kind of need a minimum depth dictated by anvils. If you are measuring a hole in a mill setup for example, the pin style body orients horizontally which is convenient, does not require the vertical height of bore gauge. Bore gage or snap gage can measure deeper into holes if that's the requirement. But depending on the bore gage set, minimum diameter might be say 0.8" whereas this pin style inside mic is 0.2". Bore gage is more accurate if you have say a tenths indicator mounted. There's also split ball gages which goto smaller bore sizes, nice but spendy even used.


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## trlvn (Aug 30, 2022)

Having little skill hasn't stopped me from buying hole-measuring stuff!






(To be honest, the bore micrometer set [LR] belonged to my late brother.)

I chose the pin micrometer this time because I wanted the most accurate sizing I could get.  I always worry with the telescoping gauges that I'll 'crush' them when measuring them with the micrometer.  Also that there are 2 chances to go wrong with them:  first when fitting them in the hole, say by swarf, and second when measuring with the mic.

I also had an end mill with a 0.750 shank that I was using to test the bore.  My slitting saw blades fit _very_ nicely on it so it gave me a nice reference.

Craig
BTW, the pin mic was just a lucky find in an auction box lot.  I didn't set out looking for one; it just kind of fell into my hands.  Now that I have it, though, I like it pretty well.

PPS, I mentioned doing some practise measurements with the pin mic.  I did that using the slitting saw bores.  I knew they were pretty exactly 0.750" so I practised measuring them and was happy to see the mic read the expected number.  Could have done the same thing with the telescoping gauges...probably should do it just to build skills!


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## VicHobbyGuy (Aug 30, 2022)

DPittman said:


> Accusize Industrial Tools 0.2-1.2'' x 0.001'' Inside Micrometer, Satin Chrome Finished, Eg00-3221 https://a.co/d/29IdWWZ


Or, skip the middleman and buy direct at less than half the price..with a few weeks wait and no returns possible.


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## phaxtris (Aug 30, 2022)

VicHobbyGuy said:


> Or, skip the middleman and buy direct at less than half the price..with a few weeks wait and no returns possible.



Stop spending my money!


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## Bruce Rossiter (Aug 30, 2022)

Excellent slitting saw arbor.


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## Susquatch (Aug 30, 2022)

trlvn said:


> Having little skill hasn't stopped me from buying hole-measuring stuff!



I have a set of these like yours and I like them.


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