Re: rod-mill project - "mains" electric motor advice

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Sujet : Re: rod-mill project - "mains" electric motor advice
De : null (at) *nospam* void.com (Richard Smith)
Groupes : rec.crafts.metalworking
Date : 22. Apr 2025, 08:44:18
Autres entêtes
Organisation : BWH Usenet Archive (https://usenet.blueworldhosting.com)
Message-ID : <m1r01kwsh9.fsf@void.com>
References : 1 2 3 4 5 6 7 8 9
User-Agent : Gnus/5.13 (Gnus v5.13)
"Jim Wilkins" <muratlanne@gmail.com> writes:

"Richard Smith"  wrote in message news:m1wmbd29er.fsf@void.com...
>
Hi everyone
I have been shown how to do this with power-electronics and
"off-the-shelf" gearbox, etc.  With all speed-control needed.
A friend had made a small welding positioner.  Hence adapted it:
* VFD - 1ph-to-3ph
  v
* 3ph induction motor
  v
* worm-drive gearbox
You turn a knob setting the output Hz.  Adequate speed range.
>
Having seen this - that it works and does everything wanted - will
simply do it this way.
Have friend's equipment on "unspecified loan' in my car to take home and
play with more.
>
-----------------------------------------
>
That is an excellent way to learn what works. The potential problems
are cost and custom machining. In that instance I'd look up and save
the components' data sheets and see how their max power ratings
compare to what was needed and what you intend to do. I've been burned
by guessing that something was good enough, my sawmill left a trail of
broken ball bearing innards until I switched to a more reputable and
expensive brand for the blade guides.
>
I hardly ever find the same device twice as second hand and must
decide on the spot if what I found is suitable, which may depend on
its power rating. People dispose of what they can't use, typically
because they are either inadequate or broken.
I tested that contactor for pull-in voltage and contact resistance.

I will go with "off the shelf".  Now seen what's needed.
Time si too valuable.

* have the thing working (hopefully!) and making inroads here in
  Cornwall

* free to get on with other things I have to do - would cost me more in
  what I have not done than I could save not "placing orders" for what
  is spec'd for the job.

One "blessing".
Gearbox must for sure have a torque rating.
Derive torque.
Found it's gloriously simple - relation of power, torque and revs.
P=tau.omega

P=power (Watts)
tau = torque (Newton.metres)
omega = rotation-rate (radians/s)
Latter makes total sense - well it does for me :-)  Radian is where a
radius is wrapped around the circumference.  Very often gives vast
simplifications (compared to working in angular Degrees or Revs Per
Minute, etc.).
Prompted that way, I can easily see from first principles how
"P=tau.omega" can be derived, giving total satisfaction in applying it.

So I can look through spec.sheets for "off-the-shelf" gearboxes.

I have a 30:1 gearbox on loan.
However, reckon 7:1 would make the drive "synchronous" (if ran motor at
mains frequency, would give the right drive speed).
Of course you need speed adjustment to make the mill(s) work exactly
right - but what you are asking is very achievable - say +-25% - which
an induction motor can do no problem.
[welding positioner - is so low power draw for small parts that eg. 10% of
the mains synchronous speed it is designed for is not a problem]
So going to have to get a 7:1 ish gearbox for mill.

Speed control should be wide enough to run rod-mills and ball-mills on
the same rollers-on-a-frame, no mechanical changes needed.

I calculated for the "metallurgical" part of the rod-mill - everything
which is and is within the "shell" ("drum"):
* 65RPM of shell rotation rate
* 127W of power draw



Date Sujet#  Auteur
7 Apr 25 * rod-mill project - "mains" electric motor advice56Richard Smith
7 Apr 25 +- Re: rod-mill project - "mains" electric motor advice1Leon Fisk
7 Apr 25 +- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
8 Apr 25 `* Re: rod-mill project - "mains" electric motor advice53Jim Wilkins
14 Apr 25  `* Re: rod-mill project - "mains" electric motor advice52Richard Smith
14 Apr 25   +- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
14 Apr 25   `* Re: rod-mill project - "mains" electric motor advice50Jim Wilkins
15 Apr 25    +* Re: rod-mill project - "mains" electric motor advice42Richard Smith
15 Apr 25    i+* Re: rod-mill project - "mains" electric motor advice37Jim Wilkins
20 Apr 25    ii`* Re: rod-mill project - "mains" electric motor advice36Jim Wilkins
21 Apr 25    ii `* Re: rod-mill project - "mains" electric motor advice35Richard Smith
21 Apr 25    ii  `* Re: rod-mill project - "mains" electric motor advice34Jim Wilkins
22 Apr 25    ii   `* Re: rod-mill project - "mains" electric motor advice33Richard Smith
22 Apr 25    ii    +* Re: rod-mill project - "mains" electric motor advice30Jim Wilkins
29 May 25    ii    i`* Re: rod-mill project - "mains" electric motor advice29Richard Smith
29 May 25    ii    i `* Re: rod-mill project - "mains" electric motor advice28Jim Wilkins
30 May 25    ii    i  `* Re: rod-mill project - "mains" electric motor advice27Richard Smith
30 May 25    ii    i   +* Re: rod-mill project - "mains" electric motor advice2Jim Wilkins
30 May 25    ii    i   i`- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
30 May 25    ii    i   `* Re: rod-mill project - "mains" electric motor advice24David Billington
31 May 25    ii    i    +* Re: rod-mill project - "mains" electric motor advice22Richard Smith
31 May 25    ii    i    i+- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
31 May 25    ii    i    i+- Re: rod-mill project - "mains" electric motor advice1David Billington
1 Jun 25    ii    i    i`* Re: rod-mill project - "mains" electric motor advice19Jim Wilkins
18 Jun 25    ii    i    i `* Re: rod-mill project - "mains" electric motor advice18Richard Smith
18 Jun 25    ii    i    i  +- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
18 Jun 25    ii    i    i  +- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
18 Jun 25    ii    i    i  `* Re: rod-mill project - "mains" electric motor advice15David Billington
18 Jun 25    ii    i    i   `* Re: rod-mill project - "mains" electric motor advice14Jim Wilkins
18 Jun 25    ii    i    i    `* Re: rod-mill project - "mains" electric motor advice13David Billington
19 Jun 25    ii    i    i     +- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
19 Jun 25    ii    i    i     `* Re: rod-mill project - "mains" electric motor advice11Jim Wilkins
23 Jun 25    ii    i    i      `* Re: rod-mill project - "mains" electric motor advice10Richard Smith
23 Jun 25    ii    i    i       `* Re: rod-mill project - "mains" electric motor advice9Jim Wilkins
23 Jun 25    ii    i    i        `* Re: rod-mill project - "mains" electric motor advice8Richard Smith
23 Jun 25    ii    i    i         `* Re: rod-mill project - "mains" electric motor advice7Jim Wilkins
24 Jun 25    ii    i    i          +* Re: rod-mill project - "mains" electric motor advice5Richard Smith
24 Jun 25    ii    i    i          i`* Re: rod-mill project - "mains" electric motor advice4Jim Wilkins
24 Jun 25    ii    i    i          i `* Re: rod-mill project - "mains" electric motor advice3Richard Smith
24 Jun 25    ii    i    i          i  `* Re: rod-mill project - "mains" electric motor advice2Jim Wilkins
26 Jun 25    ii    i    i          i   `- Re: rod-mill project - "mains" electric motor advice1Richard Smith
24 Jun 25    ii    i    i          `- Re: rod-mill project - "mains" electric motor advice1Richard Smith
31 May 25    ii    i    `- Re: rod-mill project - "mains" electric motor advice1Richard Smith
22 Apr 25    ii    +- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
22 Apr 25    ii    `- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
15 Apr 25    i+- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
15 Apr 25    i`* Re: rod-mill project - "mains" electric motor advice3Jim Wilkins
16 Apr 25    i `* Re: rod-mill project - "mains" electric motor advice2Richard Smith
16 Apr 25    i  `- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
16 Apr 25    `* Re: rod-mill project - "mains" electric motor advice7Richard Smith
16 Apr 25     `* Re: rod-mill project - "mains" electric motor advice6Leon Fisk
16 Apr 25      +- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
16 Apr 25      +* Re: rod-mill project - "mains" electric motor advice3Jim Wilkins
17 Apr 25      i`* Re: rod-mill project - "mains" electric motor advice2Leon Fisk
17 Apr 25      i `- Re: rod-mill project - "mains" electric motor advice1Jim Wilkins
21 Apr 25      `- Re: rod-mill project - "mains" electric motor advice1Richard Smith

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