can an RC outrunner shaft be magnetic steel?

[MrDude_1]

SO long story short, chain jumped, wrapped on the gear bolts of the rear sprocket and yanked on the motor shaft with enough force to bend it.. bend the 14mm stainless steel shaft.

So now I need a new 14mm shaft. I am having issues finding non-magnetic steel rod 14mm od. I can find steel rod though.
Can I use steel inside, or will there be eddy current losses and heating from it?

 

[MrDude_1]

well I guess I will find out one way or another... I just ordered this: http://www.amazon.com/gp/product/B0050RMFW4?psc=1&redirect=true&ref_=od_aui_detailpages00

 

[bobc]

I would expect it to be OK.
1 The outrunner stator "short circuits" the motor flux away from the shaft
2 The shaft has an airgap between it and the stator
3 The shaft is rotating WITH the magnetic field (it is fixed to the can with the permanent magnets on)
14mm shaft - my that's a big one........

 

[MrDude_1]

I would expect it to be OK.
1 The outrunner stator "short circuits" the motor flux away from the shaft
2 The shaft has an airgap between it and the stator
3 The shaft is rotating WITH the magnetic field (it is fixed to the can with the permanent magnets on)
14mm shaft - my that's a big one........

Thanks for confirming my thoughts. :lol:
and yeah. 14mm is large, and I managed to bend it. Atleast it shows how strong I made everything else in mounting it.

 

[MrDude_1]

ugh. so I am dumb.
Its not 14mm.. its 12mm.
One of my older brushed motors is 14mm. Thankfully I didnt have anything shipped yet, so I swapped it for one the correct size.

So anyone reading this.. a 80-100 has a 12mm shaft.

 

[fechter]

Magnetic steel is fine for the shaft. You might look for "drill rod" from steel suppliers. This is some pretty tough stuff and is generally very straight/round.

 

[MrDude_1]

Magnetic steel is fine for the shaft. You might look for "drill rod" from steel suppliers. This is some pretty tough stuff and is generally very straight/round.

Thanks!
I ended up ordering this: http://www.amazon.com/gp/product/B002BBJ0CA?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

Linear Motion 12 mm Shaft, 13" Length, Chrome Plated, Case Hardened, Metric

Since its a linear motion shaft, It should be very straight and much stronger than the old shaft. I know I'll be cutting through the chrome and case hardening when making my flats and clip areas, but I figured the chrome would make it easier to slip the gearing on and off.

 

[fechter]

That will be good material. Hard to cut though. An abrasive cut off wheel or grinder will work. Heating the end with a torch might un-harden it and make machining easier.

 

[MrDude_1]

That will be good material. Hard to cut though. An abrasive cut off wheel or grinder will work. Heating the end with a torch might un-harden it and make machining easier.

I plan to chuck it up in my drill, clamped to the bench, then use a 4" cutoff wheel with it spinning to cut it.
then do the same drill trick with a thin dremel disc to cut the clip groove.
then do the flats freehand with a dremel disc.

unless anyone has some tips on a better way... ? :lol:

 

[Thud]

The circlip groove is the weakest point on the shaft.
I omit them & make collars to hold things in proper alignment.

The clip groove on the output shaft is textbook poor engineering practice.

 

[MrDude_1]

The circlip groove is the weakest point on the shaft.
I omit them & make collars to hold things in proper alignment.

The clip groove on the output shaft is textbook poor engineering practice.

Sounds like sound logic to me. Do you have suggestions for collars? part numbers\sources would be great
it has to fit under the cover if possible.

 

[Thud]

I use a length of 1/2" pex tube (plastic) & open the thru hole on the motor cap for clearance. The tube is captured between
the bearing & your drive sprocket.

 

[MrDude_1]

I use a length of 1/2" pex tube (plastic) & open the thru hole on the motor cap for clearance. The tube is captured between
the bearing & your drive sprocket.

Im having trouble visualizing what you're saying. Do you have a picture?
Are you saying you use a spacer, and the sprocket is what holds the bearing down?

 

[Thud]

I think you got it.

.5 blue pex tube fits a 12mm shaft perfectly
View attachment 2



on the older motors, you may need to open the pass thru hole in the end cap of the motor.(too clear the spacer OD.)

 

[MrDude_1]

cool. that looks pretty simple... I just have to drill out the end cap, and get some tube. Much easier than grinding a groove.

On a related note, where do you buy your pulleys from... Ive been eyeing some 5mm HTD pulleys, but havent bought any yet.

 

[Thud]

If you dont mind the source, the pricing &selection here is good:
http://stores.ebay.com/speed-mart/Timing-Pulleys-Belt-/_i.html?_fsub=880883719&_sid=1130292079&_trksid=p4634.c0.m322

Stock drive products has everything you'll likly ever need & a phenominal center distance calculator.
http://www.sdp-si.com
https://sdp-si.com/eStore/CenterDistanceDesigner

Enjoy.