I would never argue with Ed or Mr. Newton, but if the concern is the forces present when the blade/dado/molder is slowing down to a stop on our unbraked motor shafts will loosen the arbor nut - Why don't all arbors (including blade arbors) have a tongue washer?
If you told me the tongue washer is present because you can legitimately mount certain arbors to spin in the opposite direction, well I can buy into that.
If that was a question being directed at the class, I would say that the mass of the shaper blade is much greater that the typical saw blade making this extra precaution necessary.
I like these. I wonder how many more of these someone tried to teach to me.
Newton's first law: Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
Newton's third law: For every action there is an equal and opposite reaction.
"Making Sawdust Safely" Dusty
Sent from my Dell XPS using Firefox.
I can't believe it's morning again.... and so soon.
So without getting to much farther into this... the faster the blade is stopped and the larger the mass the more likely it would be to have the nut come loose.
A good example of how this effects things look at the requirements of EU table saws. They have to make the shaft short so you can't mount anything but normal blades... keyed washer or not.
Now I got to take a coffee break this physics stuff so early in the morning...
ed
{Knight of the Shopsmith} [Hero's don't wear capes, they wear dog tags]
I guess it wasn't clear from my post, in the previous post that was referenced they covered the fact about reverse direction, which of course is correct. It is the prime reason for needing the washer, in fact if you didn't have it you would have a loose what ever you mounted all the time. However what was never mentioned was the other reason... that is why I mentioned it.
I wouldn't be surprised if large stacked dado put on that arbor without the washer in place wouldn't loosen itself in the course of a days woodworking... I'd never try it and no one else should either but with that mass and the braking that does happen I think would be enough.
In summery, maybe 97% of the reason is for reverse direction and 3% is safety for what I was describing it is still a factor. (those are completely made up numbers, I have no idea what the real numbers are but I do know the washer is needed for more the just reverse direction).
In light of discussions about putting DC motors or AC motors with braking in posts the last few days I figured we all might want to remember that there is a bit more engineering put into things then what might first appear. So for those of you who have miter saws with dynamic braking your home work is to figure out how it is done on your saw. You need not answer here.
Ed
perryobear wrote:Hi Guys,
I would never argue with Ed or Mr. Newton, ]unbraked[/I] motor shafts will loosen the arbor nut - Why don't all arbors (including blade arbors) have a tongue washer?
If you told me the tongue washer is present because you can legitimately mount certain arbors to spin in the opposite direction, well I can buy into that.
Regards,
Dennis
{Knight of the Shopsmith} [Hero's don't wear capes, they wear dog tags]
Wow I got what I asked for! Special THANKS to perryobear for the very informative pix.
I will summarize what I think IS the straight skinny on this subject.
Arbor NUTS should have threads which will tend to tighten when a NORMAL load is applied to saw blade(sawing). The 1 1/4 arbors have the nut on the headstock side of the blade thus requiring a LEFT hand threaded nut.
If the thru bolt is the same diameter as the arbor hole in the blade, an undercut is prudent around the area adjacent to the bolt. This is to prevent any slight radius around the outside of the bolt from contacting the area around the circumference of the arbor hole. Solid large area mating of the blade to the arbor/nut is required. Also any anti wobble or stabilizing washers on the arbor should have this relief around the arbor hole...or a spacer so designed. If a spacer with an undercut is used it MUST have undercut face towards the BLADE.
If the arbor/blade may/is mounted so that the direction of rotation will tend to LOOSEN nut under load(sawing) then an anti rotation washer is needed. On SS arbors this takes the form of a 'tongued'/'keyed' washer placed between the nut and the blade/washer. The key resists the loosening action of the blade under load(sawing). Other saws may use a "D" shaped washer hole/shaft for the same purpose.
The 1 1/4 arbors have a good design feature in that the blade CANNOT slip off the arbor even if the nut is 'missing'. The domed end of the arbor is larger than the blade arbor hole.
The increase in table dimensions on 505/510/520 upgrades required a redesign of all the saw arbors.
If an arbor is being used on the left end shaft(opposite to quill end) a keyed arbor is a must since the rotation will tend to loosen whatever is mounted on it under load.
If using a DADO or other high mass(weight) device(molder) I would recommend ALWAYS using an arbor with a keyed washer. The higher mass will tend to loosen nut during coast down. The key word is TEND therefore it COULD.
I have never seen a 505/510/520 1 1/4 arbor, but from what I think are pix of them, they still have a left handed nut inside the blade. If I am in error about that please inform me!
For that matter inform me of ANY misconceptions I have said here.
Thanks ALL!!!!!:D
╔═══╗
╟JPG ╢
╚═══╝
Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
I'm new here.. lurking for the last month or so....
I have a question about arbors... Why do you need to use an arbor for the molder? Molder is a Magna vintage and has a set screw built in with a 5/8" hole. I was assuming it goes straight on the quill shaft, though I have not used it yet. Does the newer molders not have the set screw and needs the arbor?
Good question! I have only recently acquired a molder etc. and have come to the same conclusion! Why is an arbor needed. It seems to me it will add runout propensity.
If an arbor IS needed, why the set screw???
╔═══╗
╟JPG ╢
╚═══╝
Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
taquin wrote:I'm new here.. lurking for the last month or so....
I have a question about arbors... Why do you need to use an arbor for the molder? Molder is a Magna vintage and has a set screw built in with a 5/8" hole. I was assuming it goes straight on the quill shaft, though I have not used it yet. Does the newer molders not have the set screw and needs the arbor?
This is why I have become so dependent on images. Could it be that the term "molder arbor" brings up different images to different people.
The second link answers the "do you really NEED an arbor for a molder 'head'" question. SS says NO!.
The third link is obvoiusly for anything needing a 1/2" shaft.
The first link appears to be for folks who JUST HAVE TO HAVE A SEPARATE ARBOR.
I agree 1 pix is worth 1000 words, but the words CAN add information. Glad you provided BOTH!:)
╔═══╗
╟JPG ╢
╚═══╝
Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
but if the concern is the forces present when the blade/dado/molder is slowing down to a stop on our unbraked motor shafts will loosen the arbor nut - Why don't all arbors (including blade arbors) have a tongue washer? 
