Shopsmith Forums

danr wrote:I agree. Any current programming would sense speed and direction then make adjustments based on what it senses. A sanding disk would act like a damper or flywheel when hooked to the other end of a bandsaw.
Maybe some future device could be programmed to react to different attachments. But then the motive force would have to monitor what devices are attached. Programming becomes like a trip to Mars, huge:rolleyes:
Dan

So how/why does the PowerPro alter rpm when a heavier load is sensed or does it?

I was under the impression that if the load varied during an operation or from that which was programmed that the PowerPro made rpm adjustments to compensate. Example: I program to rip a piece of pine but I cut a piece of oak or maple instead.

danr wrote:I agree. Any current programming would sense speed and direction then make adjustments based on what it senses.

A sanding disk would act like a damper or flywheel when hooked to the other end of a bandsaw.

Maybe some future device could be programmed to react to different attachments. But then the motive force would have to monitor what devices are attached. Programming becomes like a trip to Mars, huge:rolleyes:
Dan

I'm WAY above my head in talking about alogrithims, but I can understand critical path flow charts.

Reference the underlined sentence above::)
Sometimes flywheels or dampers do help the existing programming of the PowerPro. When conversing with Jim McMann, about bandsaw banging and jumping, he told me that mounting the sanding disk solved the issue for some users. This told me three things! 1) Others have reported bandsaw jumping issues, 2) there have been efforts to resolve the issue - and 3) Shopsmith is aware of the problem.

dusty wrote: I was under the impression that if the load varied during an operation or from that which was programmed that the PowerPro made rpm adjustments to compensate. Example: I program to rip a piece of pine but I cut a piece of oak or maple instead.

You're right, Dusty!:D

dusty wrote:So how/why does the PowerPro alter rpm when a heavier load is sensed or does it?

I was under the impression that if the load varied during an operation or from that which was programmed that the PowerPro made rpm adjustments to compensate. Example: I program to rip a piece of pine but I cut a piece of oak or maple instead.

I would imagine the 'load' sensing is done through speed monitoring. Indirectly that is also done by it's stingy power routine(decreasing power and observing any speed deviation).

It is (my conjecture) likely that at the slow bandsaw speeds with the relatively light band saw torque 'load' that the stingey power routine has to suddenly respond(large error signal) and 'over shoot' causing repeated speeding up and slowing down(underdamped). That is what creates havoc on any slop in the drive train.

It is likely that the control program does not vary feed back parameters based on speed.

I have also come to believe the changing of those parameters is NOT done by selecting the operation for speed selection and that this was a misinterpretation of the load/speed marketing blurbs.


Be nice if that was the case and it really does alter parameters that way.

After reading this discussion, I wonder what kind of Pandora's Box will be opened for Shopsmith as more DVR motors are sold (with their configurable systems).

My logic progression thinking (or wild haphazard meanderings of the mind -take your choice) follows.

+Apple warns that if the iPhone is tampered with, the warranty is void, yet jailbreaking that phone is common place to allow modification of the "Innards".
+Tekna has already released a wrist watch controller for the lathe and with it the interface board. Ergo a direct connect to the brains of the beast.
+As more DVR motors are sold, more "experimenters" will begin exploring what makes it spin (yes I was going to use tick)
+Many of the members on this forum are tweekers (though sometimes I suspect that JPG is also a "twerker")
+Tweeking the code inside the PP becomes prevalent, possibly mainstream
+As the warranty runs out on older PowerPros. even those more timid begin to experiment and start playing with the code.

A guess is that someone will begin working in making the motor react as the SawStop. Without the destruction of the blade or the blade stopping device.

No it is not linear nor probably cogent and possibly not even cognizant, just how my mind work when I bored!
Too far fetched? Not as I envision the "rise of the PowerPro" (yes a shameless reference to Terminator 3)

Be well,
Ben

benush26 wrote:After reading this discussion, I wonder what kind of Pandora's Box will be opened for Shopsmith as more DVR motors are sold (with their configurable systems).

My logic progression thinking (or wild haphazard meanderings of the mind -take your choice) follows.

+Apple warns that if the iPhone is tampered with, the warranty is void, yet jailbreaking that phone is common place to allow modification of the "Innards".
+Tekna has already released a wrist watch controller for the lathe and with it the interface board. Ergo a direct connect to the brains of the beast.
+As more DVR motors are sold, more "experimenters" will begin exploring what makes it spin (yes I was going to use tick)
+Many of the members on this forum are tweekers (though sometimes I suspect that JPG is also a "twerker")
+Tweeking the code inside the PP becomes prevalent, possibly mainstream
+As the warranty runs out on older PowerPros. even those more timid begin to experiment and start playing with the code.

A guess is that someone will begin working in making the motor react as the SawStop. Without the destruction of the blade or the blade stopping device.

No it is not linear nor probably cogent and possibly not even cognizant, just how my mind work when I bored!
Too far fetched? Not as I envision the "rise of the PowerPro" (yes a shameless reference to Terminator 3)

Be well,
Ben

I can guarantee that if I had a PowerPro with an expired warranty I would be seeking means to read and possibly tweak the code.

As a matter of fact, if I had a PowerPro I might not wait for the warranty to expire.

BTW: The DVR that initiated this thread has a top speed of 5500rpm; not quite the same as the PowerPro.

[quote="dusty"]

BTW: The DVR that initiated this thread has a top speed of 5500rpm]


I think the DVR motor tucked inside the PowerPro is about like that. But there is a speed-up factor due to the pulley size ratios, so that's how it gets 10,000 rpm on the upper spindle (and more rpm's yet on the jointer-output / idler shaft).

Add a 3:1 speed increase ratio between the motor and the idler shaft and ya got 10k.

I believe the equipment and coding for what I call "instant stop" feature already has existed for some time for the DVR motor. I spend a lot of time playing with solutions similar to SawStop for the Shopsmith but could never get the saw blade to stop until a few teeth had passed the triggering point. Any time a belt is involved, some flexing will occcur. I could not find a sensor system that would detect human flesh 100% of the time so question the SawStop as a perfect solution. Only seizing the saw blade can this possiblity be achieved but I would not stick my finger into the blade to even try this one. The GRR-Ripper appears to me to be the best solution I have seen for dealing with fingers, body parts and table saw blades.

billmayo wrote:I believe the equipment and coding for what I call "instant stop" feature already has existed for some time for the DVR motor. ...

The only thing I have seen to provide an "instant stop" was a mechanical device that sensed a connection between a saw blade and a finger. It dropped a steel pawl into the blade and stopped it dead within one tooth. The demonstrator actually used his finger. The pawl destroyed itself and the blade but it saved the finger. I seem to remember that it was on Discovery channel, that high speed camera show. Name escapes me...

Dan