Have tech questions? Will answer.

[GTSLOW]

My understanding is the further from 0* the more torque you lose, but you gain speed and there is an efficiency gain, but it's at a certain rpm range. Since you can reduce reverse speed on the tx or esc I run mine at zero.

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I'm following. That's why I think if you're running at 0* the motor direction is irrelevant for the application?

 

[Voodoobrew]

Yes, if you have a reverse direction transmission like some axial rigs I think, you simply retard the timing 6* to advance it. If that makes sense.

I might be wrong though, it could be you just reverse the wires, but I think it's both.

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[Voodoobrew]

John, I have been studying your brushed motors and was wondering about the difference between the CrawlMaster Magnum series and the 550 size Crawlmasters. All things equal which gives more torque, extra length or larger rotor diameter?
Thanks.

This never got answered, I would like to know as well.

 

[mikemcE]

This never got answered, I would like to know as well.

Thinner stronger magnets, huge armature is the Magnum difference.
JRH dropped a Magnum video showing it yesterday .


Hang up and Drive

 

[JohnRobHolmes]

Perfect timing for this magnum vid

https://youtu.be/3mnp-NPs5t0

 

[mikemcE]

Thinner stronger magnets, huge armature is the Magnum difference.
JRH dropped a Magnum video showing it yesterday .


Hang up and Drive

Perfect timing for this magnum vid

https://youtu.be/3mnp-NPs5t0

YUP thats it!!"thumbsup""thumbsup"

 

[JohnRobHolmes]

Motor torque is linear to length and the square of the diameter (assuming magnetic flux density is not reduced). Fir example, revolver snubnose has 10mm long stator and standard 540 is 20mm stator, standard is twice the power. Comparing a motor with 23mm rotor to 28mm rotor is about 1.5 times the potential torque, assuming rotor didn't displace our ability to cram magnets in.

 

[brian.brigg]

Thanks for the information, John. One more question. Would the 540 Magnum be suitable for a TRX-4 with a 9T pinion on 3S?

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[JohnRobHolmes]

Yes, seems to handle the trx just fine.

 

[brian.brigg]

I have pored over the various brushed motor options and the higher price of the Magnum has always stood out. IME you tend to get what you pay for (your Revolver motor seems to be an exception to the rule, how do you manage to produce it with all those poles and magnets at that low price? ) from reputable dealers so the Magnum has always intrigued me. It is also the only motor on your site that the typical startup RPM is quoted on.

Is the Magnum noticeably smoother than the "normal" Crawlmaster?



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[JohnRobHolmes]

The normal cralwmaster is still a little smoother than the magnum version. But the magnum has an incredible amount of power and drag brake without weighing more. It's high cost is due to the additional cost of materials and time of manufacturing. The magnum also has custom armature tooling for the stacking process, which was costly to manufacture.

The revolver is assembled in china, thus the lower cost. We could fully wind and assemble them in house too, but they would not be cost effective. Would have to retail well over $200. The biggest pain of assembling outrunners from scratch is the rotor. Just a lot of tooling and time compared to other topologies.

 

[Voodoobrew]

Motor torque is linear to length and the square of the diameter (assuming magnetic flux density is not reduced). Fir example, revolver snubnose has 10mm long stator and standard 540 is 20mm stator, standard is twice the power. Comparing a motor with 23mm rotor to 28mm rotor is about 1.5 times the potential torque, assuming rotor didn't displace our ability to cram magnets in.

So the magnum would be (28*28)22=17,249 torque potential?
and the 550 ver would be (23*23)29=15,341 torque potential?
and the 540 ver would be (23*23)22=11,638 torque potential?
Meaning the magnum should have 12% more torque than the 550 and 32% more torque then the 540 wet magnet variants of the same motor?

 

[JohnRobHolmes]

In theory, yes. The brushes are still a choke point but the comparisons are good general guidelines of motor potential.

 

[offroad1911]

Have a radio question. Im trying to find out if a new SR515 reciever will bind with an older DX4C?

 

[JohnRobHolmes]

I dont know about that. I dont keep up on radios much.

 

[Voodoobrew]

Have a radio question. Im trying to find out if a new SR515 reciever will bind with an older DX4C?

I don't have a dx4c but the dx4c is a DSMR transmitter and I have not seen any versions of dsmr receivers that use different codings like that stupid DSM2 surface/air fiasco.

But personally I would go for the Spektrum SR415 if you can find it, because in spektrums infinite wisdom they decided not to make their new receivers water resistant...

normally it's the same price, but this unknown site has it for cheap https://www.zodbuy.com/ oddly enough there is a youtube video that's an hour old saying the site is not trustworthy so I'm listing it as a place not to buy from.

 

[brian.brigg]

Hi John, thanks for the replies, it gives me a better idea of the difference between the Magnums and "standard" Crawlmaster motors.

One other question I put out a few months back that didn't get answered concerned stand-up versus lay-down brush styles. Stand-up would have slightly less "dwell" and overlap, particularly on 5 pole motors compared to lay-down, how does this affect motor performance and start-up?

Which style gives more back EMF and how does back EMF affect motor performance? How do ESCs handle back EMF? Does it have any useful effect on drag brakes?

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[M1tch]

@offroad911. The SR515 is DSMR and DSM2 capable.

https://www.spektrumrc.com/Products/Default.aspx?ProdID=SPMSR515

The DX4C is DSMR, so should work ok.

https://www.spektrumrc.com/Products/Default.aspx?ProdID=SPMSR515

But as Voodoobrew says, you are probaly better with the SR415 or any DSMR rx.

 

[HumboldtEF]

I cant find the old generation of the Spektrum receivers so I've settled for the new version and have used the Holmes Hobbies Conformal Coating on them. Its an easy board to coat just give yourself some extra time to let it dry. Also binding first is helpful since the button used to bind becomes a bit harder to push when put back in its case, or use your fingernail to push it while out of the case.
https://holmeshobbies.com/featured-products/conformal-coating.html

 

[brian.brigg]

Does the direction of rotation, forward or reverse, have any effect on skewed armature motors?

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