The Motor Construction Thread aka What Motor should I Get?

[dirtman]

What are FB9 wet magnets in the P-94 motors? Specifically, what do you mean by "wet" magnets?

[JohnRobHolmes]

It is the industry name. Ceramic manget have a grading system, FB9 is the strongest that is easily made and available. I don't know why they are called "wet" magnets. I always wondered myself but have never asked.

[crazycallbo]

is it the way how they mold the magnets if i remember i thought i saw there was a dvd rom that had fb5 magnets dry-molded

[Manning]

dry vs. wet magnets.

Supposedly the magnetic material is pressed into shape.

Dry magnets are pressed using a dry powder.
Wet magnets are pressed using a wet slurry.

Supposedly that makes the finished magnet more dense, therefore stronger.

something like that anyway...

[dirtman]

Good enough for me. thanx fellas

[EddieO]

It's a slang term for the process of how they are molded.....

Fb-9 is not the strongest.....but is up the chart. It is the best balance of price, strength, heat resistance, etc for our little motors. Others were tried in testing, but didn't perform better, just cost more. Some motors use the cheaper Fb series magnets....

Most of the integy motors use a real cheap magnet, thats not even as good as the cheap magnet in trinity stocks (its cheap to meet price point, plus fb series stuff is too strong).

Later EddieO

[axial-aaron]

think i'm going to get a 40 t motor! the 90t is good enough for the homemade rig i'm biulding my son. wierd though, it would'nt even make the slipper clutch go!

THANX for the gd info

[BMFOTP]

Maybe I missed the information on Cobalt Puller motors. If the information isnt in this thread would someone please explain these motors to me in relationship to other motors? Thanks in advance. Or tell me where I missed the information.

[JohnRobHolmes]

The cobalt puller has a larger diameter and longer armature, stronger magnets, and a 7 segment comm/ arm. For the same speed you get lower phase resistance, so more torque.

[Terranaut]

JRH, in the first posts you touched on "flux ring". I have a microheli with a Mabuchi 400 in it, and it came with a flux ring. I took it of to install a heat sink, then found that the heat sink has very little effect anyhow, and also learned that the ring should improve motor performance. So I put the ring back on.

Can you expand a little on flux rings? How much difference do they make to a 55T crawler motor? Is it worth the effort to make and install one?

Cheers.

[BMFOTP]

Originally Posted by JohnRobHolmes

The cobalt puller has a larger diameter and longer armature, stronger magnets, and a 7 segment comm/ arm. For the same speed you get lower phase resistance, so more torque.

So a 7T cobalt puller motor is equal to a 45-55T brushed motor only with less phase resistance which equals more torque? Thanks for helping me understand these concepts.

[TLTRyan]

Originally Posted by BMFOTP

So a 7T cobalt puller motor is equal to a 45-55T brushed motor only with less phase resistance which equals more torque? Thanks for helping me understand these concepts.

I would say the 7t has the same if not more wheel speed than a 35t, but still having the slow speed control of a 55t.

I always show this pic when someone asks about a puller vs standard 540. Cobalt 7t on the right

[WarMachine]

Figured I'd dust this off....LOL

Any hints suggestions on flux ring thickness?
Been thinking back a few years to racing days gone by....we used to tear down and rebuild our motors between each heat, without fail.
Cleaning, polishing, and turning comm's were common place, seems a lost concept.
On certain motors I used to run a flux ring, but for the life of me, I can't recall how to size them (thickness) for magnet strength. I still have a few solid slugs around and was thinking of turning out a couple of rings to see how they effect today's motors.

Is it even worth it these days?

[JohnRobHolmes]

Just make sure steel can't stick to the outside of the motor. Thicker will just be weight or protection.

[Tommy R]

John, thanks so much for taking the time to post this info. Thanks also to EddieO for his contributions.

I saw that you mentioned electric motor brake cleaner to clean the motors. What are your thoughts on using automotive brake cleaner instead? When I was racing back in the early '90s, people used them interchangeably and the brake cleaner was way cheaper. But was it/does it cause damage to the motor that maybe we're not aware of?

Thanks!

[Grabby544]

Thank you for the AWESOME amount of info!

I do have some questions though...

I'm building a Timberwolf (X-mas gift, my wife kicks ass) and I know that it's going to be a heavy beast. I run Integy 35T and 45T in my other two trucks with no problem, but I want to splurge on my scaler.

I've been debating brushless... while they feel awesome for overall power, I don't like the way they feel at low speed. (I'm starting to rant)

Can you compare the Cobalt puller 7T, 10T and torquemaster pro? I definitely like brushed, and I want one stought MoFo.

Thanks!

[Olle P]

Pretty informative thread this!

I've been investigating the subject of motors a little bit for myself, both by reading posts like this one and by conducting a few experiments.

The results so far (applying to brushed motors):
For a given single wound motor design (and temperature)...
- The zero torque speed is proportional to the voltage.
- The zero torque speed is inversely proportional to the number of turns in the winding.
- The torque is proportional to the current.
- The maximum current is inversely proportional to the number of turns in the winding.

What I'm very curious about is the relationships between single and double winding motors, and would appreciate any help to fill in the blanks.
- Double winding motors are (about) the same zero torque speed as single winding motors.
- Double winding motors are supposed to have more torque, but I don't know how much more.
- The relationship in power and current consumption is totally unknown to me.

[EddieO]

A. Depends on the Circular Mills of copper
B. Again, Circular Mills of copper on the arm effects this. If your double uses two wire sizes that are LESS circular mills than the single, then it will change the torque rating. If its more, then more torque in theory.
C. Power takes amps...there is no perfect linear rate of it though, as there are always variables that effect it.

Later EddieO

Originally Posted by Olle P

Pretty informative thread this!

I've been investigating the subject of motors a little bit for myself, both by reading posts like this one and by conducting a few experiments.

The results so far (applying to brushed motors):
For a given single wound motor design (and temperature)...
- The zero torque speed is proportional to the voltage.
- The zero torque speed is inversely proportional to the number of turns in the winding.
- The torque is proportional to the current.
- The maximum current is inversely proportional to the number of turns in the winding.

What I'm very curious about is the relationships between single and double winding motors, and would appreciate any help to fill in the blanks.
- Double winding motors are (about) the same zero torque speed as single winding motors.
- Double winding motors are supposed to have more torque, but I don't know how much more.
- The relationship in power and current consumption is totally unknown to me.

[Olle P]

I think there needs to be a little bit more said about the concepts of torque and power. (Posts #2 and #3 of this thread skip too lightly on it, IMO.)

I assume that most of you know what torque is. That's the mechanical force used to turn the motor axle and in the end the wheels.
The force given to the drive train (gearbox through wheels) depends not only on the motor torque, but also on the pinion size.
A relevant measure of the force provided by the motor can be given as the torque divided by pinion size (number of teeth).

Power is used both in the concept of electrical power fed to the motor and mechanical power provided by the motor.
Electrical power can be calculated as voltage times current.
Mechanical power is calculated as torque times motor speed.
Thus when the motor is stalled or operating at no load it doesn't provide any power at all!

So, when do you need what in crawling?
- Starting from standstill in a harsh location requires lots of force.
In such a situation you want a motor/pinion combination that provide lots of force while using not so much electrical power. Here it's the more winds the merrier, since those motors provide more stall torque at less current consumption.
- Accelerating to speed, and wanting more speed, is what takes (mechanical) power in order to overcome all drag imposed by the drive train and terrain. (Goes extra for rigs running worm drives, since these suck up lots of power by themselves.)
Less wind motors provide the extra power required for running faster. (But will get hot if/when more torque is required.)

[bowtie11]

In in in