Author Topic: Chronos R8 Slitting Saw Arbor  (Read 1273 times)

Offline petertha

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Chronos R8 Slitting Saw Arbor
« on: November 11, 2019, 04:18:08 AM »
Just wondering if anyone has feedback on this arbor?
https://www.chronos.ltd.uk/product/r8-stub-slitting-saw-arbors/

I have one like this, its so-so. https://www.kbctools.com/itemdetail/1-449-100
The sliding collars are a good idea to fit differnt saw hole ID's but because they are nestled into one another the runout isn't all that great. I could probably tolerate it for the infrequent time I use it, but it has another irritating factors. The spring is sticky despite lubrication & cleaning. Also they didn't tap the draw bar hole deep enough. I either added a spacer or shortened the drawbar on my previous mill, but the arbor has the faint odour of cheaptoolicitus, time to cut bait.

On the opposite end of the spectrum I have some more robust holders of good quality, meant for bigger saws. But its crazy, the 1" ID saw hole requires a big toolholder with 1" boss. It has a 1" arbor, so needs to be held in a 1" bore R8 end mill holder. 4 pounds of rotating tooling & many dollars later... all that to hold a 3"x.045 width jewellers/slotting saw. I guess I could get a 1" R8 collet, but now no keyway to the shank. Why have a key in the saw & nothing on the spindle.

I suspect the Chronos's is offshore too, at least judging by the shiny surface and 'ground all over' (without a TIR spec). But maybe worth a shot?

What is it about these saw arbors? I see these delux brands for like $300USD with 0.0002 or 0.0004: runout? Thats fine but I'm skeptical the blades are going to be that spec, at least the typical HSS from my local supplier. I don't think 15-35$ is going to buy that kind of quality. Every one I have run goes Vvvt-Vvvt-Vvvt as it cuts no matter how many times I adjust it in the holder. Maybe there are some Swiss saws I'm not aware of that are meant to do this all day on a CNC?

Offline petertha

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Re: Chronos R8 Slitting Saw Arbor
« Reply #1 on: November 11, 2019, 04:34:49 AM »
I neglected to say, I am totally fine to make myself a saw arbor too. Probably not with integral R8, just plain shank. Do you think its really necessary to to have the saw & arbor keyed, or could I hold it in a plain R8 collet under friction? I just finished an operation sawing aluminum, maybe 0.025 DOC, 180 rpm. I could push it but it seemed happy there. Some folks subscribe to the 'do it in one pass' but I felt like there was a lot of prressure entering a ~ 0.250" deep slot in one shot like that.

Offline Jasonb

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Re: Chronos R8 Slitting Saw Arbor
« Reply #2 on: November 11, 2019, 07:13:20 AM »
I've had their MT3 version for a number of years and it works fine with both saws and gear cutters, did have the stepped type like you before that but it was not perfect. I have a R8 one for teh SX2.7 from ARC but that has the nut on the end which is not ideal as you have to have a lot of work above the vice when doing certain cuts that is not ideal, the CSK screw on the Chronos one means there is a lot less projection.

As you say I've never found a saw that runs dead true.

Offline jadge

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Re: Chronos R8 Slitting Saw Arbor
« Reply #3 on: November 11, 2019, 11:33:34 AM »
I had one of the stepped arbors once. Haven't seen it in ages so I probably binned it as useless. I've got an R8 arbor bought from RS. It's ok and I use it for shallow slitting on the vertical mill. Wherever possible I use slitting saws on the horizontal mill, particularly where the deep of cut is large. The saws seem much less prone to go walkies on the horizontal mill. Which arbor one uses also depends upon whether you're in the "I use keys" or "no way no how do I use keys" group. Even quality slitting saws will be eccentric, but using a rigid setup allows one to increase the feedrate and DOC to counteract the eccentricity.

Personally I haven't bought from Chronos for many years due to many misses on quality.

Andrew

Offline petertha

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Re: Chronos R8 Slitting Saw Arbor
« Reply #4 on: November 11, 2019, 06:38:09 PM »
Well apparently one can spend good money on carbide slitting saws, so maybe that explains the requirement for 'good' arbors on the industrial scene.
http://discount-tools.com/ful-2450-4.cfm

OTOH, I see a whole bunch of HSS blade offerings on the metric side of the world with metric hole ID's in which case an Imperial holder won't be a match. What are you metric folks using for slitting saw arbors?

I think its worth me making one for the time & material. I think I can achieve a decent runout within the limits of blades I am likely to buy. That would open the door for accommodating custom (metric) sizes if the need arose. The good arbors are hardened & ground which I cannot do, but again that might be more for industrial applications?

Offline Jasonb

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Re: Chronos R8 Slitting Saw Arbor
« Reply #5 on: November 11, 2019, 08:08:34 PM »
The one I mentioned above with R8 is 22mm which suits metric saws and MOD gear cutters.

I also made a simple stepped adaptor to fit my 1" arbor so that can take 22mm bore tools

 

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