# Gear help

#### simong93

Dec 20, 2011
28
Hi all im doing a project design and ive come up with this idea my only problum is if my canculations are right my gear should turn at 2,160,000rpm now this would be great if ive got it right but im also hopeing my lil motor can handle this.

http://www.ebay.co.uk/itm/2x-Miniat...Supplies_ET&hash=item5d33cf3580#ht_1121wt_952
this is my motor

http://www.ebay.co.uk/itm/DC-5V-40V...ultDomain_0&hash=item2a1e7cc8fe#ht_2608wt_952
and this is my speed controler

My main question is is this going to work.

thanks for all the help in advance[IMG]http://i45.tinypic.com/2gxqolu.jpg[/IMG]

Last edited:

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
2 million RPM?

I hope you have really good bearings (magnetic?) and extremely small and lightweight (and really well balanced) gears.

If the gears are 1cm in diameter, the teeth on the outside will be moving at almost 7 times the speed of sound (at sea level)

If they weigh 1g, the energy stored in them will be about 1300 joules. That's about the same energy as a .44 magnum round.

I'm seeing issues here...

#### GreenGiant

Feb 9, 2012
842
2 million RPM?

I hope you have really good bearings (magnetic?) and extremely small and lightweight (and really well balanced) gears.

If the gears are 1cm in diameter, the teeth on the outside will be moving at almost 7 times the speed of sound (at sea level)

If they weigh 1g, the energy stored in them will be about 1300 joules. That's about the same energy as a .44 magnum round.

I'm seeing issues here...

Spinning something at almost Mach 7, no big deal

I believe your math may be a little off, no promises but I have a feeling

#### simong93

Dec 20, 2011
28
i will explain how i got my answer

my first 30t motor gear will spin my 10t gear 3 times per rotation my 10t gear will now spin 1 of the other 10t gears 180 times per my motors 1 revoltuion so going by my motors full speed of 12,000 rpm per minite that should mean it should spin as 2,160,000 i hope

#### duke37

Jan 9, 2011
5,364
The belt will step up 3 times.
The gear will step up 6 times.
That is 18 times.
12,000 times 18 = 216,000
You will need a high powered motor to supply the energy lost in windage and bearings. You will also need earplugs.

#### simong93

Dec 20, 2011
28
The belt will step up 3 times.
The gear will step up 6 times.
That is 18 times.
12,000 times 18 = 216,000
You will need a high powered motor to supply the energy lost in windage and bearings. You will also need earplugs.

18 times should it be alot more then that and i just want something thats going to be dam quick but super light but is going to need to be able to take a bit of force

#### BobK

Jan 5, 2010
7,682
Why do you think you want to spin something at 2M revolutions per minute?

Bob

#### Laplace

Apr 4, 2010
1,252
These small motors don't have much torque. This one is rated at only 10 g.cm and would normally be geared down rather than up. I doubt the motor will be able to turn the belt pulley even with no gears attached. You would need a bigger motor.

#### Raven Luni

Oct 15, 2011
798
2 million RPM?

I hope you have really good bearings (magnetic?) and extremely small and lightweight (and really well balanced) gears.

That big oval one in the middle is definitely asking for trouble

2 million RPM?

If they weigh 1g, the energy stored in them will be about 1300 joules. That's about the same energy as a .44 magnum round.

That ought to make someone's day........punk..

#### simong93

Dec 20, 2011
28
ok so i can see i have a thew problems with this.

What design would everyone sujest i need something that has alot of speed that turns them two front wheels but the design needs to be super light weight is my biggest factor here.

#### duke37

Jan 9, 2011
5,364
You have not said what you want the speed for.
I would think that gears are a bad idea. How do you lubricate them?
To spin something very fast, you need very special bearings, magnetic or air and a very strong structure that will not explode under the forces.
The turning force can be generated using the principle of an induction motor with a high frequency drive.
Look up designs of high speed centrifuges.

#### simong93

Dec 20, 2011
28
You have not said what you want the speed for.
I would think that gears are a bad idea. How do you lubricate them?
To spin something very fast, you need very special bearings, magnetic or air and a very strong structure that will not explode under the forces.
The turning force can be generated using the principle of an induction motor with a high frequency drive.
Look up designs of high speed centrifuges.

This is really going to sound crude but i need a quick suck and then push the idea is when the wheel is at the bottom it would have pushed all out and then when its at the top it would have sucked back in and the other wheel will do the exact opposite.

Im currently toy with the idea of just putting 2 little dc motors in the run each wheel individually and just hope its not to heavy.

#### GreenGiant

Feb 9, 2012
842
This is really going to sound crude but i need a quick suck and then push the idea is when the wheel is at the bottom it would have pushed all out and then when its at the top it would have sucked back in and the other wheel will do the exact opposite.

Im currently toy with the idea of just putting 2 little dc motors in the run each wheel individually and just hope its not to heavy.

from the sound of it you are trying to make something like a piston? (push then pull --> up then down in a tube)

its not going to get you the super speed RPMs that you want but you may be able to use a small engine from an RC car (gas powered obviously) just modify it so that you drive it with an electric motor and remove as much load (gears for the wheels) as possible

#### KMoffett

Jan 21, 2009
723
ok so i can see i have a thew problems with this.

What design would everyone sujest i need something that has alot of speed that turns them two front wheels but the design needs to be super light weight is my biggest factor here.
It would help if you explained what you're trying to do...the end goal of the project.
It may be easier for us to help solve your problem, than help solve your solution.

Ken

#### simong93

Dec 20, 2011
28
It would help if you explained what you're trying to do...the end goal of the project.
It may be easier for us to help solve your problem, than help solve your solution.

Ken

Ok you got me i will explain a bit more ive been trying to keep it close to my chest as ive been designing and redesigning the idea over and over again for a year now.

My idea is there will be a large piston/plunger sort thing and what will happen is as the wheel moves up a rod connect to the plunger will move the plunger up and open the inlet valve and close the outlet valve this will then draw the substance in then as the wheel goes down it will shut the inlet valve and at a certain pressure will open the outlet valve and expel the substance out.

i want to have 4 engines like this as part of one bigger engine like say 1 engines down then as soon as its going back number 2s on then so on and so forth.

I hope this helps out a bit more and also it must be light weight and must run off electric

#### KMoffett

Jan 21, 2009
723
So, what is the viscosity of the "substance", what is the desired delivery rate, and what is the stroke-volume of the "pump" you envision.
The more details you provide, the more practical the solutions you are likely to elicit here.

Ken

#### simong93

Dec 20, 2011
28
So, what is the viscosity of the "substance", what is the desired delivery rate, and what is the stroke-volume of the "pump" you envision.
The more details you provide, the more practical the solutions you are likely to elicit here.

Ken

The Substance is air, delivery rate bit confused but the piston is going to suck in as much as it needs when its on the suck cycle,the volume is im not sure it will be in a box that will be a rectangle off 45cm by 45cm by 55cm height.

Sorry for all of the off calculations i just scribble things on paper put them together and see if there work .

#### KMoffett

Jan 21, 2009
723
The Substance is air, delivery rate bit confused but the piston is going to suck in as much as it needs when its on the suck cycle,the volume is im not sure it will be in a box that will be a rectangle off 45cm by 45cm by 55cm height.

Sorry for all of the off calculations i just scribble things on paper put them together and see if there work .
The "stroke volume" is the cross sectional area of the piston times the stroke length...how much air the cylinder holds when full. The delivery rate is the volume of air expelled by the pump over a period of time. You will also have to take into consideration back-pressure if you are exhausting into a closed container. Still too many variables/unknowns.

Ken

#### simong93

Dec 20, 2011
28
The "stroke volume" is the cross sectional area of the piston times the stroke length...how much air the cylinder holds when full. The delivery rate is the volume of air expelled by the pump over a period of time. You will also have to take into consideration back-pressure if you are exhausting into a closed container. Still too many variables/unknowns.

Ken

I think we have gone a bit of my question all i need to know is would i be better off having 1 motor doing my original set-up or a motor on each piston and what sort of motor would be best for what i need

#### KMoffett

Jan 21, 2009
723
I think we have gone a bit of my question all i need to know is would i be better off having 1 motor doing my original set-up or a motor on each piston and what sort of motor would be best for what i need
Without specific details that will relate to your needed speed, torque,and power source, which relate directly with delivery details, it's anybody's guess as to a motor selection.

Ken

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