Shopsmith Forums

JPG wrote:The reason for the 1 1/4" arbor nut being on the 'inside' is to minimize the extent of the arbor beyond the slot(think trunion interference). Now that incurred the extra cost of having to make it with a left handed thread.

I don't think it is trunion interference. The 5/8" arbor actually extends past the blade more than the 1 1/4" arbor. In the picture the 5/8" arbor is on the left. You can clearly see the 5/8" arbor is longer past the blade than the 1 1/4" arbor. It is in fact 3/16" longer. The 1 1/4" arbor extends past the blade 11/32". The 5/8" arbor extends past the blade 17/32".

Notice that at some point SS Changed the 5/8" arbor. The arbor body on mine is much larger in diameter than the one Paul has. I have 3 or 4 and they are all the same. They were bought in the mid to late 90's and are the same as what is being sold today. My guess is that Paul's is the original version. Another thing, if you look at Paul's 510 arbors, the blades do not register the same distance from the left end of the arbor by about the width of the blade. That is assuming the spindle holes are the same depth which I would think they should be. That dimension should be a (one) standard from which other dimensions are derived depending on the purpose of the arbor.

OK, enough! Well one more thing.

Also, in the manufacturing world why do left handed threads cost more than right handed threads?

jsburger wrote: . . .

Also, in the manufacturing world why do left handed threads cost more than right handed threads?

Economies of scale.

JPG wrote:

jsburger wrote: . . .

Also, in the manufacturing world why do left handed threads cost more than right handed threads?

Economies of scale.

Well hopefully the same machining tools can cut threads in either direction so I am not sure how economies of scale applies at the manufacturing level. For the end user, sure, someone in the supply chain jacked up the price.

OK but maybe it off sets all the other manufacturing/machining process in this case. You and I will NEVER know why it is the way it is unless we can talk to the engineer who sighed the print. It could be as simple as an engineer convincing corporate that this is the way it needs to be. After all SS 1 1/4" arbors were around long before SS 5/8" arbors. To me there is no reason why the 1 1/4" arbor can not have the nut on the right side.

I remember something about not needing blade stabilizers with the SS 1 1/4" arbors. At the time the design was made, almost all of the higher quality saws and blades required the use of stabilizers. The metal mass of the arbor is supposed to supply the same support on both sides of the blade as the stabilizers. Could this be the reason for the location of the nut on the left?

jsburger wrote:

JPG wrote:

jsburger wrote: . . .

Also, in the manufacturing world why do left handed threads cost more than right handed threads?

Economies of scale.

Well hopefully the same machining tools can cut threads in either direction so I am not sure how economies of scale applies at the manufacturing level. For the end user, sure, someone in the supply chain jacked up the price.

OK but maybe it off sets all the other manufacturing/machining process in this case. You and I will NEVER know why it is the way it is unless we can talk to the engineer who sighed the print. It could be as simple as an engineer convincing corporate that this is the way it needs to be. After all SS 1 1/4" arbors were around long before SS 5/8" arbors. To me there is no reason why the 1 1/4" arbor can not have the nut on the right side.

Well twice wrong assumptions will lead thee to never never land.

Yes the same 'tools' can be used to create left handed threads, BUT, they in turn need to be made in a mirror image from those for right hand threads. i.e. one cannot create left hand threads with right hand taps, dies etc.. Therefore the tools are more expensive because of economy of scale. On a machine lathe the lead screw needs to be either a left hand screw or run in the reverse direction.

FWIW there were no 1 1/4" arbors for the model 10.


BTW you determine the arbor-trunion clearance with a Mark 5 table tilted to 45?


As for stabilizers, tis the increased clamping area and arbor-periphery distance that makes them unnecessary.

I understand the right hand / left hand threads on an arbor. I once bought a home made sawmill where the thread was wrong for the application. It loosened a couple of times. The thought of that big blade coming completely off and crossing my path prompted me to drill and tap the big nut for a setscrew. I cushioned the threads of the arbor with a split shot fish sinker down in the setscrew hole.
I explained that and a few other short comings very carefully to the new owner when I sold it. He was a pretty shrewd machinist and tinkerer and was going to make a lot of changes to it.
The one I never really understood was the use of left hand threads on the lug bolts on one side of some of the older cars. I don't know off hand of anyone making them like that these days.


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paulrussell wrote:I am sifting through an accumulation of Shopsmith parts and noted I have a huge collection of arbors, including two 5/8 arbors. These have a short screw shaft and appear to be for the mounting of a single blade -- not a dados/shapers or "universal" arbor.

In the attached photo, the arbors are (from left to right)
Old 500 arbor
Newer 500 arbor
5/8 arbor in question
510/520 arbor
5/8 "Universal" arbor

The thing I don't understand is the length of the middle 5/8" arbor -- it mounts the blade further from the headstock than a 500 arbor, but closer than a 510/520 arbor.

Why is this?

(When mounted on the Shopsmith, the 5/8 arbor aligns the blade on the arbor to the left, the 500/510/520 align the blade to the right.)

Excluding the Universal Arbor on the far right, I see only one 5/8" arbor (third from the left) in this picture. Am I wrong?

dusty wrote:

paulrussell wrote:I am sifting through an accumulation of Shopsmith parts and noted I have a huge collection of arbors, including two 5/8 arbors. These have a short screw shaft and appear to be for the mounting of a single blade -- not a dados/shapers or "universal" arbor.

In the attached photo, the arbors are (from left to right)
Old 500 arbor
Newer 500 arbor
5/8 arbor in question
510/520 arbor
5/8 "Universal" arbor

The thing I don't understand is the length of the middle 5/8" arbor -- it mounts the blade further from the headstock than a 500 arbor, but closer than a 510/520 arbor.

Why is this?

(When mounted on the Shopsmith, the 5/8 arbor aligns the blade on the arbor to the left, the 500/510/520 align the blade to the right.)

Excluding the Universal Arbor on the far right, I see only one 5/8" arbor (third from the left) in this picture. Am I wrong?

There is only one 5/8" saw arbor in the initial pix. The consternation is the different length.(shorter than a 1 1/4" 505-520 arbor)

JPG wrote:

dusty wrote:

paulrussell wrote:I am sifting through an accumulation of Shopsmith parts and noted I have a huge collection of arbors, including two 5/8 arbors. These have a short screw shaft and appear to be for the mounting of a single blade -- not a dados/shapers or "universal" arbor.

In the attached photo, the arbors are (from left to right)
Old 500 arbor
Newer 500 arbor
5/8 arbor in question
510/520 arbor
5/8 "Universal" arbor

The thing I don't understand is the length of the middle 5/8" arbor -- it mounts the blade further from the headstock than a 500 arbor, but closer than a 510/520 arbor.

Why is this?

(When mounted on the Shopsmith, the 5/8 arbor aligns the blade on the arbor to the left, the 500/510/520 align the blade to the right.)

Excluding the Universal Arbor on the far right, I see only one 5/8" arbor (third from the left) in this picture. Am I wrong?

There is only one 5/8" saw arbor in the initial pix. The consternation is the different length.(shorter than a 1 1/4" 505-520 arbor)

That was exactly the point in my post. It seems to me that the only way that will work and stay centered in the saw table insert with the fixed spacer on the way tube is if the spindle bore depth of the 5/8" arbor is less than the 1 1/4" arbor.

Paul, can you measure the depth of the bore in these arbors. The third and fourth ones from the left.

This was something to keep me out of the shop for a while.

I show a 3/32" gap for the blades.

I don't understand the reason for all the mass in the 5/8" arbor.

The bore in my 5/8" arbor is 1 9/32" measured at the wall of the bore.. It is not flat bottomed