Shopsmith Forums

No one has challenged that "fact".

The question is whether or not that has changed for the PowerPro (Mark 7).

If not that - what. Run the numbers!

This pony keeps getting resurrected.

There is no reason that the introduction of the power pro motor etc. would include altering a basic design parameter such as the main/idler shaft speed ratio.

Indeed it would dictate that the redesign would adhere to that basic parameter. The idler shaft is intended to drive higher speed SPTs than the main shaft. The obvious example is the jointer and less so the compressor.

So IMO the pertinent question is: Where has anything been said that indicated that it has changed?

If none, let us accept the fact and move on.

P.S. Measurements indicate the motor:idler speed ratio is 1:1.6. Not only the inverse of the idler/main but also purely coincidental. The design intent I assume was to keep the DVR motor speed within a tolerable range while providing the main shaft speed of 250 - 10,000. Keep in mind the pulley on the drive sleeve has not changed either.

For those who might wish to measure poly-v pulley diameters, note that the pitch(effective) diameter is consistently 0.030" greater than the actual OD. I believe that dimension only applies to "J" section belt pulleys. That 0.030" is the same all the way through the entire chart for all diameters.

So this simply means that the raw measurements taken on the poly-v pulleys must be corrected before calculations can be made.

Does that "fix it"?

How does it achieve 10000rpm with a motor that tops out at 5500rpm (maybe only 5000rpm)?

everettdavis wrote:I will paraphrase my late uncle;

"A man with a tachometer can tell you how fast a shaft is rotating. A man with two is often unsure."

Everett

If your uncle's original quote was about a watch, that's one of my favorites.

dusty wrote: . . .

How does it achieve 10000rpm with a motor that tops out at 5500rpm (maybe only 5000rpm)?

I believe SS is pushing it to 6250. A possible reason for over heating at 10000 rpm for extended period.

I will deal with the rest of he question later after I carefully measure a couple of M5/V pulleys.

I don't have the paper work for the meter I have but looking at others that at least look like it they seem to be pretty accurate.

As an example :"Accurate to +/- 0.05 percent and capable of measuring at a distance from 2-20 inches; RPMs measured over 1 second sampling time"

Now granted they expect the reflective tape which doesn't seem to stick anymore but I would think a white strip would work so that has be wondering if the powerpro really gets to the 10000 rpm. Or if the .05% is not a real thing.

I got mine off ebay quite a few years ago for I think less then $10.

I'd like to find a source that I could use to verify readings just not sure what that might be right now.

Anyone else with at powerpro and tach???

Ed

I got mine about the same time. The event was discussed here on the forum. Several of us got them as a result of the discussions. Mine was the first item I personally ordered that was delivered to me directly from China. It has been bounced around the shop for years and still works well.

White electricians tape works as does Scotch (white) from my wife's gift wrapping supply closet.

For what I am doing with it - I trust the numbers.

Forget to mention: I apply the tape in three different locations around the spindle thus the tachometer reads much higher but gives a more staple reading. To determine the actual rpm simply divide the reported rpm by the number of tape segments used.

My motor RPM is rock solid at 3580rpm. ??