9 replies to this topic

[Rotorranch]

Where are 36D ball bearings available from?

 

Rotor

[Bill from NH]

Jeff, check with John Havlicek. He has used them in the past, but I don't know where he sourced them.

[gas]

Professor Motor has can end ball bearings.

[havlicek]

In all the years I've looked, I've never found a ball bearing that actually fits the Mabuchi 36D bastard size shaft.  They are all more like 3/32" and the bore is oversized by enough to make for a sloppy fit.  I actually pressed a few 36D armatures using 3/32" drill blank axles to get past the problem, which makes boring the pinion necessary.  These sloppy bearings make for very quick bearing failure.

 

 

Professor Motor has can end ball bearings.

 

Those bearings (*even when packaged and say they're for the FT36D) are 3/32".  Professor motor also has/had FT36D can with the bearings installed, same thing, and they blow pretty quick.  Not only is the bore oversized, but they are fragile as well.  You can try using one if it's for a "shelf-queen", but for a motor that will be run hard, the best solution I've found is to use a fixed oilite by removing the caged bushing and adapting the can bearing pocket.

Even finding a properly-sized oilite is no small thing for the same reason as why the bearings don't work.  Other than turning and boring your own out of (expensive!) oilite stock, you can salvage correctly-sized oilites from the modern Mabuchi full-round "360" motors, and you can get two out of each motor.  These also have to be turned down on the O.D., but have a nice snug fit to the 36D shaft since Mabuchi has kept using that same odd-sized shaft.

There are details scattered-around in the various "Arm Winding" and "H Power" threads/forums...where exactly?  Beats me, but there's a lot of info in there!

[havlicek]

I should add that *I think* there was one motor, a version of the "Pit-can" that I seemed to remember had a properly-fitting and sturdy bearing for the 36D shaft size.  It's all a bit fuzzy, but even that (*from what little I remember) wasn't a straightforward solution since it had no flange.  In any case, even if that bearing was a good fit (a big "if"), those motors are pretty danged scarce.

Anyway, I'm not sure if the original poster saw this, but anyone looking-in who is also interested in bearings for the 36D shaft can double-check for other sources.  I'm pretty sure I've hit most all of them over the years, short of having 100,000 custom bearings run-off by a manufacturer. 

[Bill from NH]

I wonder what Champion used on their BB 707's? I had one in the late '60's that I put two(2) 12-hr. endurance races on in addition to 2 yrs. of weekly racing without any bearing problems. Unfortunately, I don't still have that motor, nor are the Champion people still around.

[havlicek]

I wonder what Champion used on their BB 707's? I had one in the late '60's that I put two(2) 12-hr. endurance races on in addition to 2 yrs. of weekly racing without any bearing problems. Unfortunately, I don't still have that motor, nor are the Champion people still around.

 

Those were the rare unexistium bearings, made for a short time only during a full moon by Nepalese monks under contract in a shrine outside of Katmandu.    Maybe they were a larger version of the Mabuchi bearings found in the 16D and 26D, which were themselves a comic book version of a ball bearing, having loose balls, no inner race and had a housing made of thin aluminum.  Those same type bearings were also found in some of the slightly later FT160 motors made in Hong Kong.

[Bill from NH]

The bearing in the 707 weren't Budweiser bearings like those you speak of.

[slotbaker]

Would it be feasible/practical to sleeve the shaft up to 3mm, and use 3mm x 6mm bearing?

K&S list brass tube @ 3mm OD x 0.45mm wall = 2.1mm ID (0.0827")

I measure 3 x 36D arm shafts @ 0.0905" Dia. (2.2987mm)

It would be possible to drill the tube out with a 2.3mm (0.0906") drill.

So, how keen would anyone be to go to this sort of trouble???

[havlicek]

The bearing in the 707 weren't Budweiser bearings like those you speak of.

 

 

Maybe, I don't remember but as I said, it was a guess...got a picture?

 

Would it be feasible/practical to sleeve the shaft up to 3mm, and use 3mm x 6mm bearing?

K&S list brass tube @ 3mm OD x 0.45mm wall = 2.1mm ID (0.0827")

I measure 3 x 36D arm shafts @ 0.0905" Dia. (2.2987mm)

It would be possible to drill the tube out with a 2.3mm (0.0906") drill.

So, how keen would anyone be to go to this sort of trouble???

 

There'd be a couple of ways to have at it Steve, and I've done far more ridiculous things over the years.    Still, if you sleeve the shaft to 3mm, it can only be the part that rides in the bearing, otherwise pinions ain't gonna work.  The other "fix" I've done in the past is to press the stacks onto a 3/32" drill blank and use readily-available axle bearings, then your pinions need to be reamed to fit.

Anyway, and as per the original post, I know of no "true-fit" off the shelf bearings made for those shafts.