Helhedded's Comp Shafty

[JeremyH]

Hi. Was looking to see what you were talking about....now I see.

[helhedded]

Originally Posted by JeremyH

Hi. Was looking to see what you were talking about....now I see.

lol. No worries at all friend, I stole that look from TurboJimmy.

[JeremyH]

Originally Posted by helhedded

lol. No worries at all friend, I stole that look from TurboJimmy.

Who stole it from me!

This is like a weird mobius strip thing!

[helhedded]

Originally Posted by JeremyH

Who stole it from me!

This is like a weird mobius strip thing!

for realz? Where iz the razzing?

This is the build that I'm referring to. It sparked my interest in driving this class.

http://www.rccrawler.com/forum/axial...tsman-rig.html

[JeremyH]

I was just kidding....

[JohnRobHolmes]

Ashton contacted me about a custom motor for his shafty build, and decided to take a little gamble and let me design something out side of the box for him. His requirements were bigger power than a regular 540, but he also wanted to have lower weight. Size was not a concern. To start the build I pulled the design files from the original Puller 520 Stubby and converted them to a brushed configuration, since that is what he wanted. We start with a known Flux Gap Area (FGA) to accurately predict the power and torque from any given motor, otherwise we would just be stabbing randomly at rotor sizes. The FGA we start with on this motor is 1,588 square millimeters.


With a full 36mm of diameter to work with, we have a lot of room for a rotor when using Neodymium magnets. A 28mm rotor easily fits, with plenty of space for airgap and properly sized magnets to prevent tooth saturation. Working backwards from the FGA we get a rotor length of about 18mm. I just happen to have a tray full of 1588FGA 28mm rotors here


The next step is to determine magnet thickness, airgap, and back iron thickness to ensure that oversaturation does not occur. I use FEMM for this, a CAD type software for magnetic and thermal modelling. Because of the tooth profile and two magnetic pole design, 33EH Neo magnets were selected. Going stronger doesn't gain performance, and it reduces the operating temp of the motor while increasing cost. A different rotor or magnetic layout would be needed, and has been designed for future research.


All processes and machining were done by me on my equipment.


Here is the finished rotor, it is just a shade shorter than a regular 540 from bushing to bushing, but a bit heavier. Because of the large diameter, we have better leverage than a regular 540. Puller 520 on the right, regular 540 on the left.





The can was machined from an extruded housing. It reduces cost as compared to a fully machined design, and offers better rigidity than billet material because of work hardening during the extrusion process. A flux ring was integrated into the can design to ensure highest torque. For a few gram penalty we get an 8% reduction in motor speed, thus 8% lower resistance. Resistance robs power more than a few grams, so the consideration was a no brainer. Future revisions could save a few grams with an alloy faceplate, it will be tested and compared on a cost/ benefit analysis. Shown in the raw-






The motor is held together with retaining screws that run the length of the motor. I have been searching for over a year for a screw maker that could make the particular size I needed, with zero luck. Not a single factory had the tooling I needed, and spending 10 grand for a single screw size is foolish for even a rich man. So I made them myself with my spoke machine and some custom extruded spokes. It removes a few grams from the motor, reduces parts count, reduces labor of construction, and reduces cost almost $10 vs alloy screws and a timing ring. Win, Win, Win! The fine pitch grabs very well into plastic, just 2mm of thread engagement locks it down.





Final Specs:
5 slot 28mm diameter rotor, precision polished and dyed
13t Double wire for highest fill
High tempurature silver commutator termination
200c epoxy VOI impregnated coils
Dynamically balanced with the finest German Epoxy
Diamond trued Commutator

Steel can with Integrated Flux ring
EH33 Magnets, 200c rated
200c industrial epoxy
ABEC 7 bearings

Team Endbell
Holmes Silver Standup brushes
Holmes X springs
Holmes lightweight spring posts

Weight, 5.1 ounces
36mm diameter, 52mm length

Next I will bead blast and apply a special Ceramic low friction coating, then we will reweigh it. As compared to a regular 540 of the same speed, the Puller 520 has 38% lower terminal resistance and is 28% lighter. All in all, this motor will do the job nicely for Ashton. Have your cake and eat it too!



Next on my agenda, a Puller 510 Stumpy to increase terminal resistance to equal that of a 540.

[EGRESSor]

nice motor John

[JohnRobHolmes]

Originally Posted by EGRESSor

nice motor John

Thank you sir! Had a chance to work on your own motors we discussed previously?

[helhedded]

John, thanks for posting up the tech and pics. There are all sorts of goodies that your'e throwing in there

I also love the long screw idea.. very cool.

[JeremyH]

Man Ashton, you continue to drop the pounds.....everywhere.

[Szczerba]

Awesome.

I bet this motor could do your 2012 Federal Tax returns too.

[helhedded]

Originally Posted by JeremyH

Man Ashton, you continue to drop the pounds.....everywhere.

That's how I roll, brah

[Duuuuuuuude]

Nice!

[ittybitty]

Originally Posted by helhedded

That's how I roll, brah

Coulda "rolled" better before losing the pounds...just sayin

[Highlucks]

I just like that it looks like a beer keg


JRH I want these ones.

[JohnRobHolmes]

Originally Posted by highlucks

I just like that it looks like a beer keg


JRH I want these ones.

I could cut the keg profile, you know a painter?

[Highlucks]

haha, I also like the sound of the what you are creating motor wise. Keg shape or not. We can discuss further via email

[EGRESSor]

Originally Posted by JohnRobHolmes

Thank you sir! Had a chance to work on your own motors we discussed previously?

yes

a tuber

[Tgreer]

Nice job on the win today at state!

[helhedded]

Originally Posted by Tgreer

Nice job on the win today at state!

Thank you sir