Slitting saw arbor tolerance

[Sonic EscapeParticipant @sonicescape38234]

I want to make a 22mm slitting saw arbor. The idea is simple. Just two pieces and one screw.

The most critical part is the 22mm diameter segment. And of course despite my best efforts it has 21.75mm instead of 22mm … I was never able to make precise diameters so far. Because of this there is a small play, as you can see here:

How bad is this? I suppose that means that not all teeth will cut? I can give it another try at the other end to try to make it exactly 22mm.

 

[JasonBModerator @jasonb]

Just take a mm or two off the face leaving 22mm in the middle

[Clive FosterParticipant @clivefoster55965]

+1 for Jasons fix. I’d make the step a bit longer with a shallow slope at the entry. Getting a shallow saw on dead straight onto a barely wider step will be challenging. Almost certain to want to wiggle.

However my commercial one bought from ArcEurotrade “not telling you how many years ago” isn’t perfectly on size either.

But neither are the saws themselves.

One is sufficiently tight that I seriously doubt that it would go on a dead nuts holder. The others go from a tage slack to a couple of tages slack if you see what I mean. I did measure the diameter when I first noticed the differences but exactly what the error was I no longer recall. I want to say around 5 thou, anything seriously more and I’d most likely been on the phone “OK I know economy range won’t be dead nuts but this is going a bit far.”.

So mine is a bit better than yours but same ballpark.

Slitting saws aren’t a commonly used tool for me but I don’t recall ever having issues attributable to a slack fit. Important thing is to get the workpiece set up nicely with appropriate feeds and speeds dialled in. For some reason my instinct has always been to want to run them too fast. So I always check the numbers. Lubrication really helps.

0.25 mm / 10 thou difference in cut as the saw goes round will make no noticeable difference unless the operating settings are way, way out.

Clive

[Sonic Escape]

On 18 September 2024 at 11:16 Sonic Escape Said:

I suppose that means that not all teeth will cut? I can give it another try at the other end to try to make it exactly 22mm.

 

Does anyone ever get a slitting saw to cut on all teeth?  Always been elusive to me.

Mike

 

[Sonic EscapeParticipant @sonicescape38234]

Thank you for advices. I made a 3mm long segment with 21.98mm diameter. Now there is a perfect fit! Absolutely no play.

Next I started to cut the opposite part of the arbor. The one that will go into the collet. I’m using the chuck for roughing and later I’ll make the final cut between centers to maintain the concentricity.

This is the most serious roughing I did so far. The swarf was blue, so around 570 degree. Also I created these monsters:

I used an ISO1 tool with P10 grade carbide, one of the hardest I have. I like the brazed tools. Here they are super cheap and are easy to grind.  After removing 20mm from diameter the tip of the tool was still as sharp as in the beginning!

 

[Nigel Graham 2Participant @nigelgraham2]

Every time you change the saw then change it back again, different teeth will be taking the deeper parts of the cut.

You say you have problems turning diameters to within 0.25mm / 0.01″. It’d be worth while taking some time to investigate why if you’ve not already done that.

Looking at the set-up for roughing out the arbor, presumably you finish-turned it between centres to ensure the two ends are concentric with each other? Or perhaps a collet and centre. Both methods should be more accurate than a three-jaw chuck.

[Nigel Graham 2]

On Nigel Graham 2 Said:

Every time you change the saw then change it back again, different teeth will be taking the deeper parts of the cut.

You say you have problems turning diameters to within 0.25mm / 0.01″. It’d be worth while taking some time to investigate why if you’ve not already done that.

Looking at the set-up for roughing out the arbor, presumably you finish-turned it between centres to ensure the two ends are concentric with each other? Or perhaps a collet and centre. Both methods should be more accurate than a three-jaw chuck.

I used the three-jaw chuck because I don’t think my dog has enough grip to allow deep cuts. But the last 1mm I will cut it between centers. So it should be fine.

I did some experiments and I figured out how to make precise diameters. My mistake was that I was trying to touch the tip of the tool to the workpiece and use that point as a reference. This of course is not precise. Now I move the cross slide only to one direction, never back. When I’m close to the final dimension I make one diameter measurement, divide the difference by two and increment the cutting depth with this amount. The results are usually within +/-10µm.

[Sonic EscapeParticipant @sonicescape38234]

I finished the two diameters. Also I deviated from the original plan and I made a tapered section. The cutting tool could not make a square surface there. But I like it more in this way. I have to make a better finish for that surface.

I saw that there are quite a few companies around here that can do all sorts of heath treatments. I have no idea how much it cost and I’m not sure what to ask for. I know only that nitriding doesn’t change the dimensions. Are there other similar treatments?

I suppose a case hardening with Kasenite will distort the arbor? The material is most likely some low carbon steel.

 

 

[DiogenesParticipant @diogenes]

Will the topslide swing around to finish the tapered part?

EDIT; I haven’t hardened any of the saw and cutter arbors I have made, the clamp holds the blade and the spigots aren’t showing any wear because they don’t get used daily..

 

 

[Diogenes]

On Diogenes Said:

Will the topslide swing around to finish the tapered part?

EDIT; I haven’t hardened any of the saw and cutter arbors I have made, the clamp holds the blade and the spigots aren’t showing any wear because they don’t get used daily..

 

 

Yes, but I would need a smaller dog. I didn’t planed very well the operation order. So I cheated with some sandpaper 🙂

Here is the complete story of this arbor:

 

[DiogenesParticipant @diogenes]

👍 ..sequence of operations is always easier to see looking back!

Does your lathe have slower rates for power feed? ..maybe experiments with ‘roughing’ and ‘finishing’ cuts and tools will help make less sanding work.

..In the sense of doing bulk metal removal with heavy tooling first, then switch to ‘finer’ tooling and slower feeds to clean up – I thought the insert tool left a much better finish on the facing operation, maybe a final light finishing pass with that at lowest feed & higher speed on the ‘siding’ work might be worth a try..

Maybe you know all this already, apologies if so..

[Sonic EscapeParticipant @sonicescape38234]

Yes, the lathe has slower power feed. But in the video I was using the lead screw feed, and this is faster.

But I discover that after the fast feed rate roughing the surface feels very nice to touch. I like more that very fine shallow thread. Everybody who touched the arbor agreed on this.

For the the tapered section it was a different story. Apparently in my collection of a few dozens cutting tools I don’t have a suitable right hand tool! That is why the sanding.

That insert tool is indeed nice. Especially if you consider the price, ~2$ for 10pcs. But the best one I have for finishing is this kind of brazed tool:

I can ground it as sharp as a knife and the resulting surface is like glass. Unfortunately it can’t go close to a square edge without rotating the tool post a few degrees.

Did I mentioned that one center drill snapped and the tip remain embedded in the workpiece? I didn’t noticed first. I couldn’t understand why no drill was working after! I thought it must be some form of work hardening. I found a small conical stone for my Dremel tool and I was able to grind a few mm inside the hole.

 

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