Molder/Dado Arbor

[drl]

Oldc6,
I noticed you said that slowing down the speed helped in making the dado head make a smoother cut. I have both a SS stacked dado set and a Black and Decker stacked dado set and have not been satisfied with the quality of dado cut with either one. I haven't used the sets in awhile but I think I ran them up to the regular table saw speed--speed dial around R. I will have to try some slower speeds and see what happens. Thanks.
Regards,
Dwight

[judaspre1982]

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[perryobear]

There hasn’t been any activity on this Thread in couple of days, so I thought now that the “dust has settled” I would revisit a question that I asked earlier in the thread which didn’t get much of a response (as Dave – Judaspre1982 noted).

This time I will ask my questions more directly.

Dave asked;

...I wonder how crucial the tongue in the washer really is...

Nick's Response;

Pretty dag-gone. Unless you don't mind being chased all over your shop by whirling trimmers and chippers. The tongue in the washer and the groove in the arbor prevent the nut from turning off the arbor when in use.

Questions:

Is this concern for pieces whirling across the shop limited to the "tongue-less" mounting of stacked dados? (I don’t want to be chased by a molder head or 10” saw blade either! )

Since my Shopsmith Molder/Dado Arbor doesn’t have the tongue washer feature:

Is it OK to use with a wobble dado?
Is it OK to use with a molder head?

or

Is it now better used only as a paper weight?

I said that I would keep my questions direct, so I will just leave you to think about the other tongue-less arbors you might own and their applications (I own three, myself).

I know that times change, and we are always trying to work safer. Once again, I would appreciate any thoughts that Nick and others might have on the subject.

Dennis

[judaspre1982]

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[judaspre1982]

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[Nick]

And sometimes a glorified cotter pin is exactly what is needed. In case of a castrophic stop (i.e, a wrench falls into the lower sawguard), the tongue of the washer will deform before the threads on the shaft are damaged beyond repair. Which would you rather replace -- an inexpensive washer or the whole shaft?

As for Dennis' question, I need to expain a little engineering. There are two ways that you can keep a nut from turning off a revolving shaft. The first is to use a groove and tongued washer, as we have discussed. The second is to make sure that the nut tightens in the opposite direction in which the shaft is revolving looking from the direction of the nut. We employ both of those safety measures in Shopsmith designs.

Take a look at the saw arbor. The saw mounts on the quill and the nut is to the left of the blade (between the blade and the headstock). Looking at the blade from the left side, it turns to the right (clockwise). So the nut on the saw arbor is a left-hand nut that tightens by turning it to the left (counterclockwise). There's no groove or tongued washer because the arbor is designed to be mounted in this position only.

When mounted on the quill, the nut on the dado/molder arbor is to the right of the blades and knives. Looking at the molder or the dado from the position at which we find the nut, the blades and cutters revolve counterclockwise, so we've made the nut turn clockwise -- it's a right-hand thread. Theoretically, if you use the dado/molder arbor in this position, set up as I have described, you don't need the tongued washer. The nut will tighten as the shaft revolves.

However, unlike the saw arbor, the dado/molder arbor is sometimes mounted on the opposite side of the headstock and spins in the opposite direction. (I do this on the Academy's sharpening station, using the arbor to hold a buffing wheel.) Additionally, we have some tools out there such as the Mark VII and the Craftsman's Station that are reversible. Because of this, we add a groove and a tongue washer to the arbor just so all the bases are safely covered.

If you have an arbor without a groove, it wasn't made by us. Whether or not you can use it on you Shopsmith safely will depend entirely on how you mount it.

Aren't you sorry you asked?

With all good wishes,

[beeg]

I'm NOT sorry at all Nick, that someone "asked". Thanks for the lesson.

[judaspre1982]

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[Nick]

Thanks for the kind words, Dave, but don't think I keep all this stuff in my head. Most of the time, I simply take your questions back to the folks in the factory. They are the experts and they're happy to share what they know.

With all good wishes,

[perryobear]

Nick,

I too thank you for your input.

I think the key to the 1-1/4" saw arbor that you describe is the fact that even if the nut loosens, the blade is held captive on the arbor by the nature of its design. Certainly there is nothing keeping someone from improperly mounting this arbor on the MK 5 or MK 7 such that it is spun the wrong way.

I must say for the record that all three of my tongue-less arbors were indeed supplied by Shopmith Inc.

Here are the Shopsmith p/n's for your information.
555619 - Molder/Dado Arbor
517118 -1-1/4" Saw Arbor
555608 - 5/8" Saw Arbor

You can see them here if you are interested:

http://picasaweb.google.com/PERRYOBEAR/SSARBORS

Thanks again for everyone's input, it seems to me that direction of rotation is indeed the key to safe operation of the arbor (and I will continue to use my tongue-less arbors as intended).

Dennis