P-P Questions, and Answers?

[keakap]

... Actually Wes took last week off and is back to work today - October 4, 2010.

Whew! The personification of fortitude!

Let us know when Wes has the fix for the BandSaw heebie jeebies.

[wa2crk]

Hi Gang;
Been reaqding through the posts and find a few things that have me confused. (not a difficult thing to do)
As to the tripping of the GFCI circuits: one post seems to describe a GFCI in the breaker panel and one on a wall outlet. There should only be one GFCI on a circuit. Two can cause a problem. Also some surge or spike suppressors in electronics can cause a small trickle current to flow and possibly trip a GFCI.
Capacitors can be a problem. If capacitors were used perhaps some MOV's would be a better choice.
Also could the vibration/chatter be caused by the nylon drive sleeve assembly's normal backlash? Mine always had some backlash that could cause a chatter if a load was causing a slow down in speed and the electronics was trying to overcome the lag.
Just my two cents.
Bill V

[JPG]

[quote="wa2crk"]Hi Gang]
For a 'confused' person, you summarized it all quite well!

[dlbristol]

Interesting reading, most of which goes right over my head. Where can I get more information on this type of motor and the associated computer control functions. I understand that these types control functions are done with what we once called matrix methods for simultainious solutions of polynomial equations. I am interested in the application of the math methods to the engineering. With some education, maybe I can re read this thread and make some sense of it later. Perhaps I should find a copy of " Electricty for Dummies" first.

[JPG]

Interesting reading, most of which goes right over my head. Where can I get more information on this type of motor and the associated computer control functions. I understand that these types control functions are done with what we once called matrix methods for simultainious solutions of polynomial equations. I am interested in the application of the math methods to the engineering. With some education, maybe I can re read this thread and make some sense of it later. Perhaps I should find a copy of " Electricty for Dummies" first.

I do Not think that would help.

Not sure Polynomials would be easily definable either.

This system is far more complex.

Realize the 'control' loop is trying to control the pulses to the motor 'windings' so as to maintain a near constant rpm. Also bear in mind the achievable instantaneous torque capabilities of this motor(far greater than the average delivered to the output shaft). That results in quite sharp acceleration per 'pulse'.

It may be that in order to accommodate the multitudinous load variations presented by the ss and its various SPTs that the 'gain' be reduced with a broader variation in speed tolerated. +- 5rpm is nice, but really not necessary. JMHO

[dlbristol]

Dang it! I thought I could be building my own by Christmas!!. I understand that the control loop is much more complicated than I stated, I was just wondering if there was a way to get an idea of how the two parts worked together.
Is the process used here at all similar to the kind of thing done when computers are used to model some complex function like weather, financial systems or a flight simulator? I have some very limited exposure to the last example, and that did use many matrix type sub routines to provide some of the solutions.
Keep in mind that my expertise is in teaching high school level mathematics, not in engineering. And my programming experience started with a little program called FORTRAN. I don't want to date my self so I'll just say the version of that could be counted on one hand and you didn't need the thumb!

Am I correct in thinking that the computer control is a separate unit and not
an integral part of the motor? Does this type of motor have to have these kinds of control or can it be used like a traditional motor with out this control programming? LOts of questions, I'll save a few for later.

[nuhobby]

[quote="wa2crk"]Hi Gang]

Prior to my getting the "Wes-ization" computer update, I experimented some. The nylon drive-sleeve backlash was a slight contributor to the noise but not the whole noise. I temporarily took the whole Quill out, but still had the noise when driving the Sanding Disk on the accessory hub.

[JPG]

Dang it! I thought I could be building my own by Christmas!!. I understand that the control loop is much more complicated than I stated, I was just wondering if there was a way to get an idea of how the two parts worked together.
Is the process used here at all similar to the kind of thing done when computers are used to model some complex function like weather, financial systems or a flight simulator? I have some very limited exposure to the last example, and that did use many matrix type sub routines to provide some of the solutions.
Keep in mind that my expertise is in teaching high school level mathematics, not in engineering. And my programming experience started with a little program called FORTRAN. I don't want to date my self so I'll just say the version of that could be counted on one hand and you didn't need the thumb!

Am I correct in thinking that the computer control is a separate unit and not
an integral part of the motor? Does this type of motor have to have these kinds of control or can it be used like a traditional motor with out this control programming? LOts of questions, I'll save a few for later.

When I learned Fortran, the version number needs not only a hand less a thumb, but two less fingers also!

As I understand it, an electronic module interfaces with a speed detector and the control panel(and the power source). I contains a processor(mini-computer). The motor coils are controlled by this module.

In addition to the power train, the various SPTs exhibit widely varying load characteristics not only singly, but also in combination if simultaneously 'mounted'.

The load variations are much more complex than a relatively simple lathe load(cutting action etc.). They also will have a different period(1/frequency) than the motor(not like a direct drive lathe spindle).

In short, be patient. This is not a trivial undertaking(IMHO).

[dlbristol]

I thank you for the information. I would never even try do do anything but get a very minimal functional understanding of this kind of thing, but it is interesting. Like most of the "things" in my life today, I know all I need to know about fixing it, the number of a good repair guy. I have learned the hard way not to over estimate my skills! For what it is worth, I enjoy the SS precisely because I can see what is working and what is not and with some help from the manual,forum and a good friend, I have been able to do all the tuning and the few repairs by my self. I enjoy the hands on, cause and effect, do this to get that nature of the tool. My 510 and my 66 Chev pickup are about the only things I can do that with. Perhaps some day I will get good enough at this woodworking stuff that I need more sophisticated stuff. But then I look at some of the work done by forum members on "old"machines and think probably not for a long time.

[wa2crk]

dlbristol
FYI Teknatool has a good basic tutorial on the DVR motor on their website Teknatool.com
Bill V