Meganewton

Hi all, and thanks for any help...
I'm studying the physics and structural stress of a cartesian 3d printer. So.... mass, friction... and motors... Selecting the right motors... I found in some stepper motors datasheets this two values:

Holding torque: 450mN.m
Detent torque: 37mN.m

Now mN.m means Meganewtons per meter and 1 Meganewtons = 1.000.000 of newtons.
www.casunmotor.com/nema-17-stepper-motor

If i follow the motors spec of this page:

[reprap.org]

i can clearly see that a "normal" holding torque of a stepper is:

42SHD0404-22 - 44N cm

44N cm = 44/100 = 0,44N m = 0,000 000 44

In Meganewtons / meter:
0,44N m / 1 000 000 = 0,000 000 44 Meganewons/meter

Can someone explain me what i wrong or what i have misunderstand ? Thanks... ( Google doesn't help too much in this case... )

Edited 1 time(s). Last edit at 01/23/2018 05:36AM by lucaestiva.

You are studying physics and don't know the difference between "milli" and "Mega"? Are you kidding me?

Edited 1 time(s). Last edit at 01/23/2018 02:40AM by o_lampe.

Yikes, show me where you got those meganewton steppers, I want 'em.

... same with me -- can't await to get hands on a (totally illegal anyway) blue "laser-pointer" with 2500 MegaWatts(!!!) power, how they are selled in masses at Alibaba

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

So you're telling me I could have ordered a sort-of-but-not-quite-lightsaber all this time?

A failed education system indeed !

[www.youtube.com]

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

... no, not this powers yet

Someone calculated the "real" power of a light-saber, how it was used to cut through a locked door -- he estimated some Peta-Watts to cut through the 500mm thick metal lid ... this is much, much more than Mega

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

OK, my mistake. It's like Mb ( mega bits ) and MB ( mega bytes ). Sorry for the uppercase distinction.... ( it's the first time i study seriously stepper motors )
So 1 mN or millinewtons is 1/1.000 of newtons:

1mN = 0,001 Newtons.

Thanks to all. ( Yes, the size of the measure is extremely BIG the strength be with you... )

Edited 1 time(s). Last edit at 01/23/2018 05:54AM by lucaestiva.

... so be welcome and always note the "typical error of a physicist" - the numbers are correct, only the decimal point can be a few places next to it

I'm also a physicist - so I know what I'm talking about

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I've studied physics. One thing that I always liked was dimensional analysis, and one thing I always hated was naming units after people, thus obscuring the underlying, fundamental units. Dealing with Newtons and Pascals always felt like using feet and inches. If you want to honor physicists who made great discoveries, build a statue in a park somewhere, or name a university or library after them. Don't obscure the fundamental units by slapping someone's name on top of them.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thx VDX.
Yes sometimes i made, very stupid little errors not only during conversion...

Milli, Micro, Nano, Pico and so on...

I use multiple value, most of the times in electronics so milliHenry mH, microHenry uH, micro Farads mF , nanoF nF, Ohm, MOhm, KOhm, mA milliampere, uA microampere.... and so on... Some times, i don't know, may be i run too much , i made mistakes and i have to found and correct them....

Sometimes the values are specified in the wrong way ( not if the data are given by industries for example )...

Yes i know Mega, is equal to 1 000 000, yes yes yes may be i loose my mind

Now... I'm about to evaluate the resultant forces ( vectors ) that act on two parallel rods ( rectified steel ) and 4 recirculating ball bearing. I have a new Anet E10, little money, little party, but anyway, ( i'm happy , i can 3DP ), and it has a series of problems...

1) On the Y axis - The resultant forces are not always perpendicular to the rods ( resulting in breaking forces ).

The problem gets worse when i try to align the bed to the nozzle. The springs forces tend to bend the two aluminum ( ma be low quality aluminum ) plates that support the bed itself. I can calculate the rods bending

EG:
[www.easycalculation.com]

but, may be someone have already resolved this kind of issue, if the forces are applied out of this plates... Means... Plates that support the support that support the hot bed <- Sorry

Now i have to remember and read about mass, G acceleration, Joules, Frictions [en.wikipedia.org], Kinetic energy [en.wikipedia.org] and so on.....

( Creality CR10... like.... )

All the parameters that are required to made a cartesian 3D printer..... i don't know, again, how many and which...

Thx again for the help...

Sincerely Luca

PS: Thx to the_digital_dentist ( ma be i can 3DP something )

Edited 5 time(s). Last edit at 01/23/2018 10:11AM by lucaestiva.

Quote
lucaestiva
Thx VDX.
Yes sometimes i made, very stupid little errors not only during conversion...

Milli, Micro, Nano, Pico and so on...
...

These are NOT CONVERSION ! You CONVERT inch to yard, feet etc... because they are different UNITS ! In metric, you have ONE unit and uses base 10 prefixes to make it easier. [en.wikipedia.org]
For computation, use scientific or engineering notation. [en.wikipedia.org].

Difficult to make more logical and organized.

And forget about the kind of link you gave: [www.easycalculation.com], in fact FORGET about US customary units, from there comes the confusion. Confusion costs and kills !

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

Quote
the_digital_dentist
I've studied physics. One thing that I always liked was dimensional analysis, and one thing I always hated was naming units after people, thus obscuring the underlying, fundamental units. Dealing with Newtons and Pascals always felt like using feet and inches. If you want to honor physicists who made great discoveries, build a statue in a park somewhere, or name a university or library after them. Don't obscure the fundamental units by slapping someone's name on top of them.

dimensional analysis, indeed a good way to check we didn't screw up badly. But I don't think to just use the fundamental units would be better. a Pascal or kg/(m.s²) ?

Statues crumbles. Language evolve, come and go, their words come and go, their meaning change. Not these units and these people will be honored for ever in every languages.

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

To me it just feels like having to convert physicist-named units to more basic units isn't really any different than converting inches to yards, and I hate that BS... it's just one more layer of crud that obscures the meaning.

If a statue deteriorates, we can just print another:

[www.thingiverse.com]

Edited 1 time(s). Last edit at 01/23/2018 11:22PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

True:

1 meter is equal to 10 dm or 100 cm or 1000 mm.

1 dm ( tenth ) is 0,1 meter
1 cm is 0,01 meter
1 mm is 0,001 meter

The dm is the tithe part of 1 meter
The cm is the hundredth part of 1 meter
The mm is the thousandth part of 1 meter

1N/m = 100N/cm

Because, in this case, a class 3 lever ( the pulley for example ) scale the force applied to the fulcrum proportionally to the distance of the load ( radius of the pulley ) from the fulcrum ( the motor shaft )
so at 1 meter we have 1 N at 1 cm 100 N

[en.wikipedia.org] ( this is physics , that become mechanics )

so, because we scaling the force from 1 meter to 1 cm ( means at 1 cm the force is bigger than the force at one meter, the arm of a lever in this case... ):
1N/m * 100cm = 100N/cm

and the base is 10. ( not hex 16, not oct 8, not bin 2 )

Seems to be a semantic problem... Scaling is ok ? ( yotta, zetta from 1991 ) ah... and.... 112MB

Edited 2 time(s). Last edit at 01/24/2018 04:37AM by lucaestiva.

Sry... Moderated forum.... This message is made to read better...

Another example:

Lead screw

See: Angle of friction

[en.wikipedia.org]

cos 90° = 0 , cos 45° = 0,7
sin 90° = 1 , sin 45° = 0,7
ecc...

[en.wikipedia.org]

Multiplying ( scaling ) the force by this unit vector give the force ( quantity ) in that direction ( angle )

This, more or less, is how mechanics explain the force around a threaded screws, thread. Physics become mechanics


We can use matrices or vectors math or other type of calculation but the root... Do you not think ?

Edited 2 time(s). Last edit at 01/24/2018 04:27AM by lucaestiva.