Slitting Saw Arbor

[GrahamC]

Ade's post on "How do I....bore out a hollow section leaving the centre intact? " got me off my behind to take a couple of photo's and post a just finished little project that was long over due.

I don't have a mill but I do some light milling using my lathe. The lathe has a spindle that takes 4mt fittings but I generally make tooling using 3mt blank end arbors and fit them to the lathe using a 3mt to 4mt adapter. I do make some that are 4mt but 3mt blank end arbors are by far the easiest to get and less expensive.

Slitting and slotting saws come with a variety of mounting holes - 1/2" 5/8" and 1" seem to be the most common. The ones I have been using have been 1/2" but I did buy a few that are 1".  I had made a couple of 1/2" arbors years ago and have served me well but now I needed one to take saws with 1" mounting holes.

The typical 3mt blank end arbor that I get have a 1" diameter large end. How do you make an arbor to take a saw blade with a 1" mounting hole out of a piece of metal that is already 1" in diameter?  Simple - add a piece!

Basically what I did was make a up larger end piece bored out to 1" and nice fit on the blank end arbor that would allow me to then create a mounting piece to allow me to mount the saw with the 1" mounting hole. The big chunk that was bored to fit the arbor was fixed in place with Loctite 609, the whole affair then placed in the lathe (with drawbar of course) and turned to size (about 1-1/2" diameter) tap drilled for an M6 socket head bolt, the end then drilled out to 1/2" and then bored to 1.000" about 1/2" deep. The small hole was then tapped M6.

The piece that fits through the saw blade and into the end of arbor was then made. The stub end was turned to .999 inches so that it was a nice fit into the saw blade and into the bored hole in the end of arbor. The stub was then parted off, flipped over, faced off and clearance drilled and counter bored for the M6 socket head bolt.

The M6 socket head bolt is long enough that it threads into the added on bit of metal and also into the blank end arbor. I fully trust the Loctite 609 will hold this together in any use I will put it to on my lathe but the added insurance of threading into the 3mt arbor didn't cost anything and only makes good sense. If I was push this tool to the point that the Loctite 609 failed I would be pushing this thing past the limits of my lathe. Same reason I chose an M6 bolt - normally I would have used some a bit larger for something this size. The M6 is large enough that I can tighten everything up but no so large that will provide a bit of "give" if I happen to push the tool too far and too hard.

Total time was about 2 hours. I did wait over night for the Loctite to cure.

First photo show what I used to start with - a 3mt blank end arbor and two lumps of 1-1/2" leaded steel from the cutoff bin.

Second photo shows the arbor mounted in the lathe after having been drilled, bored, and tapped M6

Third photo shows all the parts and the fourth photo shows it all put together.

I must apologize for my description and lack of "in progress" photo's. It is not really a step by step nor was it meant to be. I take pictures when I working only when I remember to and that isn't often enough. I also tend to not work from drawings or sketches when I make something like this - I just jump in with an idea and remove those bits that don't belong until I end up with what was in my head.

cheers, Graham in Ottawa Canada

[Krown Kustoms]

That looks nice.
I have a MT3 that went to a drill chuck that was sloppy I think that is what I will use it for. Thanks

[John Rudd]

 Yay....kewl job...Nice use of a blank end arbor

[Darren]

The next time I make one of these it will be like yours ... a better solution methinks 

[AdeV]

Graham - that's a nice piece of kit - and, like Darren says, I think it's the one for me too! If I get my boring bar mounted up, I should be able to make this one 

[GrahamC]

Thanks for the kind words.

The basic design is not my idea; the basic concept has been around for a very long time. I first saw a picture of a similar arbor in a tool catalog long ago and simply copied the idea to suit my needs.

I found a couple of online diagrams of similar arbors that while show a better graphical representation of the tool:

http://littlemachineshop.com/Projects/Drawings/sawarbor625.pdf

http://www.metalwebnews.org/mr-tools/slitting-saw-arbor.pdf

Seasons Greetings!

cheers, Graham

[Bernd]

Graham,

I like the picture of that second link of the boy (teenager?) cutting a piece of stock in the lathe with the verticle milling slide at an angle. Something you don't or at least won't see much of today.

Nice links bt the way, thanks.

Bernd

[Ned Ludd]

Hi Guys,
Call me stupid, I'm used to it, but why are you all making the female recess in the arbour, rather than making a male shaft with a female cap to hold the blade. To my mind it would be more rigid and accurate the second way around, the saw blade would only have one sliding fit to provide "wobble". It is also easier to make with a male stub, because the cap does not need to be a good fit, it only has to hold the blade to the arbour.
Ned Ludd

[GrahamC]

Hi Ned,

I don't think the way you describe it that it would be any more rigid, least not to my thinking (but that may be faulty). This style of saw arbor can provide a great deal of "clamping", I have never had on slip yet.

Accuracy?  This type of arbor is dead easy to make, at least to me - perhaps because I have made several like this. Make the button (or cap or whatever it is called) a nice fit in the slitting saw mounting hole - I usually aim for about -.001" from mounting hole dimension. Then when you drill and bore (or ream if you like and have one the right size) the corresponding hole in the arbor main body you can offer up the button from time to get a good - again, I aim for about +.001" from the button. But your dimensions don't need to be absolutely that precise. I don't have a single slitting saw that runs true - the saws don't wobble but they almost always never run quite true in the circumference. (hope that makes sense)

Biggest benefit by far is the small projected extension beneath (beyond) the slitting saw. Meaning you can get the saw down very close to the work, vise, or whatever.

cheers, Graham in cold wet (freezing rain) Ottawa Canada

[andyf]

I vote with Ned - the register will locate the saw better if it is on the body of the arbor rather than on the end cap. I agree with Graham that the tooth tips of the saw may not be perfectly concentric to its central bore, but it must be better to avoid two small errors adding up to a larger one, where possible.

Though the recess in the end cap doesn't show up well, here's one I made a few months back out of a 2MT blank end arbor to fit my old Dore Westbury mill and cope with some 5/8" bore, 1/16" thick slitting saws:



The bolt head hasn't hampered me so far, but if it does I'll put a thread on a bit of round stock, leaving one end plain to braze into the end cap, and put a couple of flats on the cap for tightening down purposes.

One incidental spin-off of the item is that the 5/8" register just fits in the back of my diestock for small (13/16") dies, so I sometimes get a thread started with the arbor, minus cap, in my tailstock, pressing on the back of the die to get a thread started more square than I can manage without guidance. That takes a bit of juggling to keep the pressure on, so a proper tailstock die-holder is on the round tuit list.

Andy