Shopsmith Forums

What is the "advertised" RPM Ratio between the upper and lower Mark V Model 510 Spindles?

Working from memory here, but I believe it is 1.6 revolutions of the lower spindle to 1 rev of the upper spindle.

edflorence wrote:Working from memory here, but I believe it is 1.6 revolutions of the lower spindle to 1 rev of the upper spindle.

Yep!!!!!!!

http://woodworkingintro.com/

This link brings you to a page where you can click on "Speeds" on the menu on the left hand side and thus to the info about the relationship between the upper and lower spindle speeds.

edflorence wrote:Working from memory here, but I believe it is 1.6 revolutions of the lower spindle to 1 rev of the upper spindle.

OKAY. That agrees with the literature but it does not coincide with reality (at least not on my goto machine).

This is not an issue! It is nothing more than an observation and only becomes important if there is a time when exact speed is a requirement. I don't know when that might be.

My machine runs faster than advertised. At the lowest speed I can acquire, the upper spindle is turning 757.5rpm when it should be 700rpm.

The motor is advertised to be 3450rpm but it turns at 3570rpm. This alone explains some of the apparent discrepancy. Taking this into consideration, the spindles' low speed would become 725rpm.

That leaves me with the question: "Where does the other 22.5rpm come from?

It is not belt slippage! That would result in a lose of speed.

It is not high speed adjust! That is simply a physical stop that puts a limit on upward speed adjustment!

How did I get here? My machine has been working fine but it does seem to be a bit noisier than it was. But that is not the reason.

I was scrubbing the data files on my computer yesterday and I found a chart that I had prepared back when I first got my tachometer. The figures did not look right so I started checking. This threw me off onto the tangent where I am now.:)

I hate it when I cannot answer my own questions.

The width and length of the motor belt has a major impact to what the quill RPMs will show. Playing with various motor belt widths and lengths, I have gotten the RPM ranges from a low of around 700 RPM to around a high of 6250 RPM at the quill spindle.

Motor belt wear.

A narrower belt will ride further into the idler pulley for a given control sheave position and also further out on the motor pulley. Both create a faster speed at the idler shaft/main shaft.

A slight positioning of the idler sheave/idler bearing/eccentric outward will create the same effect.

A very small change in the belt position creates a surprisingly large speed variation.

The 3450 is relative to rated hp. At no(minimal) load it will run faster.

Bill and JPG, Thank you for the feedback. You are probably both right on.

The drive belt and the sheaves apparently account for all of the deviations that I am seeing in the resulting speeds.

But, that is sorta like saying that the Republicans are causing our Government to fail. The issue is bigger than that.

My two machines do not track (speed wise) the same way. Now I understand that they are different machines and will not perform exactly the same. Belts and sheaves and eccentric adjustments be major factors.

My Shorty, however, has a band of speeds, that peak my curiosity. From Speed L to Speed G, the Shorty spins at a speed lower than the advertised while at all other levels the Shorty is slightly faster than advertised. Curious. At least to me it is curious.

Oh, If only I had been just have as inquisitive when I was growing up.

Dusty
How accurate is your tachometer? Everything has tolerances. Some more than others!
Bill V