# R-8 Stub Milling Machine Arbor



## sjr (May 2, 2012)

I purchased this stub arbor
http://www.grizzly.com/products/R-8-Stub-Milling-Machine-Arbor-1-/G9307
and use it without the key with slitting saws, the nut is left hand thread, are there right hand ones or is it possible left hand so if a saw sticks it loosens and slips rather than shatter ? I'm baffled.
Thanks
Steve


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## 8ntsane (May 2, 2012)

Hi Steve

All the slitting saw arbours I have are home made. They are all RH threaded, and none are keyed. I allways have mine set up to tighten up if it jams. It all depends on what way you have the teeth on the blade going. I used to worry about jaming up and the blade breaking, and I used to flip the blade over, and run the spindle in reverse. But, I have found with just a light snag, it will un screw the fastener on the arbour. So, I have stopped doing it that way. Over the time, I have found that it does take a fair bit to bust a blade. I have done it in the past, but its rare these days.

You wil probably find slow spindle speed is much safer than trying to run the spindle fast, the slower the better really. The feed rate should allso be very slow, and if your mill is on power feeds, this makes it easy for you. If not, then its easy to want to rush through the job and feed to fast, and that will usually be the root of trouble. The other main thing is keep the cutting oil handy, and dont let the blade run dry, it can heat up and jam on you.

You can run the slit saw either direction, but I perfer to have the arbour bolt tighten, rather than loosen. They loosen to easy on a light snag. Being I dont run them with keys, thats my prefferance. I have used keyed arbours, way back when, but in my opinion, the key help to break the saw blade when it does snag.


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## sjr (May 3, 2012)

Hi Paul
I've only used the arbor once or twice , I fell the same way that I would rather have the nut tighten but it seems fairly robust when wrenched down. I was just wondering what the logic might be in that it is manufactured left hand rather than right , whether it is intended to be run in reverse.
Along those lines I've also heard of running a boring head in reverse to do an outside circumference which on a snag might also unscrew the head.
My best take is like with  many machining operation slow speed and extra caution is a necessity.
Steve


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## 8ntsane (May 3, 2012)

Steve

I dont know how others feel about a tool unscrewing on a snag, but Id rather have it tighten up under load personally. I guess its much like running a lathe with a screw on chuck in reverse, you can, with light cuts, but why risk it.

I would try to avoid running anything in a direction that could unscrew the tool. A boring head weighs in enough that I would hate to see the mess that would make if it suddenly decided to depart from a arbour. Speaking of that, I needed to swap the arbour on one of my boring heads back on monday. I couldnt get the arbour to unscrew. So I suppose there is a down side once in a while.

On a side note, my mill has a VFD, and when I do any saw work, I use the VFD to slow things way down. Doing so, the slit saw can snag, and the machine has very little torque available , and will stall the spindle. The VFD does help in that situation, and when tapping on the mill as well.


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