Spindle Max Speed

[shipwright]

That’s what I thought but I can’t make it change. I tried the “saw-joint” speed setting and read the saw blade. It was almost exactly the rpm of my Unisaw, 4300.

[shipwright]

Okay, more research.
I agree it doesn’t make sense so I did some more tests. I tested both the Mark 5 (greenie) and the Mark V (510), each with a 4” faceplate and a drive hub. I added a strip of reflective material to the faceplate’s edge and the side of the hub.

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I also retested my Delta tablesaw and a Makita mini grinder. The ts is advertised as 4300rpm. It tested at 4323. The mini grinder advertises 10,000rpm. It tested at 10,160. These aren’t outside the “minor test discrepancy” IMHO, so I have to believe the tach, (even if I don’t want to.)

Here is the ShopSmith data:

Mark 5 Low/High readings ….. Faceplate… 760- to 660
Hub ………….766 to 6603
Mark V Low/High readings ……Faceplate….735 to 7365
Hub …………731 to 7380
I did catch the odd double or quad reading but they are easily spotted and aren’t a consideration.

These two pics show the dial position on the 510 at low and high speed.
The first one (that shows slow) is how far past fast high speed is.
The second (that shows fast) is how far past slow low speed is.

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I know I could set low speed to be correct on the dial and crank the high speed screw down to where it shows “fast” on the dial and maybe even have 5200 rpm there, but why would I? I don’t seem to be harming the machine. The bearings (same I presume) run 10,000rpm on the PowerPro.
I tilted the headstock under the table yesterday and ran a 1/4” router bit in some walnut. The result wasn’t bad and it didn’t bog down from low torque.
Still a mystery but I’m willing to live with it. Anyone else tach tested their max speed?

[DLB]

I measured mine to be 5759 at FAST and 6352 at the stop. The fact that FAST and the stop are not the same on mine tells us that I do not adhere exactly to the high speed adjustment procedure. That is just personal preference, I don't follow the 'standard' high speed adjust procedure any more.

Logically, to get 7300+ RPM as it compares to my machine at 6300+, you need some combination of A) more motor RPM; B) belt running deeper in Idler sheaves; and/or C) belt running higher in motor sheaves. Motor RPM can probably be ruled out because our slow speeds are comparable and that is not in the nature of an induction motor unless the AC line frequency is different. I think it is likely that you have your high speed stop set higher than mine, possibly in combination with some small differences in belt dimensions.

- David

[shipwright]

That sounds logical. I set mine back to factory spec today and the high speed setting screw is in so deep that the locking nut is only on a thread or two. “Saw” setting is now only around 3500 which sounds pretty slow for a TS. My belt is from ShopSmith and is just about exactly 1/2”, maybe just over. I think I will set it back a little higher just to get the nut another thread or two but no higher than yours.
Incidentally, my 1957 Mark 5 reads ~6600 at max too.