Polaris

[Functional Artist]

So, I'ma thinkin' I'ma needin' 30mm OD x 13mm ID bearings

Does this sound right?
...& do they make such a thing?

For reference, I looked up to see if 30mm x 13mm bearings were even made or available
...but, didn't find much

Then I searched for 29mm x 13mm bearings
...& found a bunch of options, like this:

PEER 7R8 Radial Ball Bearing 13mm x29mm x 8mm 1/2"id, 1-1/8"od, 5/16"w, SHIELDED
https://www.ebay.com/itm/1662935503...u/UkceHh+acnXZJeiP7iH3NvsQ==|tkp:BFBMzpSJlMhi

They list a size conversion chart

Size (conversions)

• 13mm x 29mm x 8mm
• .51 x 1.14 x .315"
• 1/2" x 1-1/8" x 5/16"
• Bore: 1/2"
• OD: 1-1/8"
• Width: 5/16"

 

[Master Hack]

Where l’m from .510 x 1,14 and 1/2 x 1 1/8 are NOT the same size! Must be a china thing?
Will the 1/2 x 1 1/8 (.500 x 1.125) fit your wheel?
if thats the case then an R8 is what ya need.

 

[Functional Artist]

I had to go to (3) stores to find that stupid (LR44) battery

They couldn't make that compatibility list any bigger?

Well, we have power now

Hub measurement

Hub depth measurement

For reference, Bearing Race measurement

 

[Master Hack]

Decimal please! Yeah l can convert it, but l want to see it. I think we’re dealing with an inch series.
actually all i really need is the ID of the hub socket.
We already established the axle/spindle is a 1/2 bolt, correct?

 

[Functional Artist]

Here is what I got (in inches)

Hub ID

Bearing Race OD

 

[Functional Artist]

The drive wheel, has a freewheel unit, that threads onto the hub

The outer hub on the freewheel unit has a sprocket for use with bicycle chain (1/2" spacing) & a ~2 1/4" OD
...& we need a bigger sprocket & for use with #35 chain

I picked up a 72T - #35 sprocket (~8 1/2" OD)
...but, the center hole is only ~1 1/4" ID

So, I set up a drillin' station (with a 1/4" hole in the middle)

Then, used a 1 1/4" hole saw ta center the sprocket (with the 1/4" center hole) on the drillin' station

After centering, I, clamped the sprocket "in place", on the drillin' station
...& removed the hole saw

Then, I used a 2 1/4" hole saw, ta drill/saw, a bigger center hole

After a bit of clean up & deburrin', it fit pretty nicely, over the freewheel hub

Here's the other side

 

[Functional Artist]

I used a caliper ta help "fine tune" the centering of the sprocket (on/with the freewheel unit)

From every direction (a couple of times) just ta be sure

Then, drilled bolt holes, in the sprocket, to align with every (3rd) tooth) on the freewheel unit

Then, used (6) 5/16" x 1" bolts (with loc-nuts)
...& bolted 'er together good-n-tight

 

[Functional Artist]

We already established the axle/spindle is a 1/2 bolt, correct?

Yup,

I would rather have the front wheels mounted standard go kart style (only supported on one end)
...which calls for a minimum axle diameter of 1/2" in the Electrathon America rule book

6. Axles supported at both ends must have a diameter of at least 3/8"(10mm).
7. Axles supported only on one end must have a diameter at least ½"(12mm)

 

[Functional Artist]

Here is our drive wheel (with tire mounted)

I'doubt these Fenix (China-cheap) tires are gonna last very long (especially under racing conditions)
...but, we'll see

The green tire on the black rim, looks pretty kool

 

[Functional Artist]

With Master Hack's assistance, it looks like I'ma B needin' some R8 bearings
...so, got 'em on order & they should be here, next week

Now, lets move on to another delima

I need to add brakes to both front wheels (as per the rule book)
...& I'd like to use disc brakes
...but, how do you install brake rotors onto bicycle wheels?

Well, the rear wheel that I'm gonna use, has 34mm fine threads, on the outside of the hub, for mounting the freewheel unit

...& now, upon looking around, noticed that many mountain bikes use this same method for mounting rotors like this:
https://www.ebay.com/itm/175716099348?var=475102205451
...using a threaded on adapter, like this:
https://www.ebay.com/itm/194966693368

OK so, the front wheels, that I'm gonna use, have some fine groves
...but, don't have any threads on the outside of the hub, for mounting an adapter
...but, it looks like I could, maybe, put some there
Another view

The threaded hub measures out to be 34.95mm

From doing some research, it seem that the threads for these freewheels & disc brake adapters are 34mm
...but, not sure exactly what pitch

Then, looking at available Threading Dies, it seems like they are available in 34mm x 1mm pitch, 1.5mm pitch & 2mm pitch

Whadda you'alls think?
...does there seem like there is enough "meat" on that hub, ta add some threads to?

 

[Master Hack]

Takes a LOT of torque to turn a 34 mm threading die. You need to look at thread depth also. What material thickness will remain? Theres charts out there…
Ya need to be sure to get the die started straight. Thats a tough job without some mechanical assistance.

 

[Functional Artist]

Takes a LOT of torque to turn a 34 mm threading die. You need to look at thread depth also. What material thickness will remain? Theres charts out there…
Ya need to be sure to get the die started straight. Thats a tough job without some mechanical assistance.

Discouraging reply
...but, honest thanks

May be better & easier to get a couple more of the rear wheels (with the outside threaded hubs)

Thinking it thru, this concept should work, for adding a brake disc to the left front wheel
...but, not for the right front one

Because when the brakes were applied the left front would tighten the adapted, on to the threads
...but, the right one would just unthread itself from the hub

So, the right side would need left handed threads (another $30.00 tap)
...but, I havent seen LH threaded brake disc adapters

More thinkin' required
...we'll get back to it

 

[ezcome-ezgo]

Fortunately aluminum is pretty soft. You might be able to turn a new thread, really you're just trying to get a more depth in it right

 

[Master Hack]

but, the right one would just unthread itself from the hub

Red loctite would work for that. You’re not stopping a truck. A machine shop could cut some threads on there without the agony of hand threading, possibly.

 

[Master Hack]

Egor has been busy polishing R8s. They were REMed then he tossed em in the vibe with walnut shells. I told him this was a clasified project. He’s thinkin Mars rover or sumpthing. He doesn’t need to know….
anyway looking good! I hope you negotiated a good deal….

 

[Functional Artist]

Fortunately aluminum is pretty soft. You might be able to turn a new thread, really you're just trying to get a more depth in it right

They are just fine grooves on there now
...& I was just thinkin' about addin' threads

 

[Functional Artist]

Red loctite would work for that. You’re not stopping a truck. A machine shop could cut some threads on there without the agony of hand threading, possibly.

IDK about Loc-tighting a brake rotor on

I've always been kinda leery about adhesive bonds
...& have way more faith, in mechanical bonds

My local machine shop raised their minimum fee from $40.00 up to $75.00 about a year ago (like everything else)

Did them bearings come as a DIY kit?

 

[Functional Artist]

Workin' on a CAD rear fender

Another view

I designed it to cover the entire area (inside of the frame) which should help protect the motor & electronics from any moisture (wet track or puddles)
...&/or road debris

I made 'er out of some 20g steel (from a metal box, that was the housing of an old dishwasher)

Bended the sides up first

Then, worked on the shape

Turned out kinda like this

Another view

That front "lip" will tuck under & bolt to, the motor mounting plate

 

[Master Hack]

IDK about Loc-tighting a brake rotor on

They make some purdy tenacious s**t

Did them bearings come as a DIY kit?

IKEA bearings….
ummmm no!

 

[Master Hack]

Position race A inside race B and assemble with 8 Si3N4 balls to a radial clearance of .0006 to .0001 inch bla bla bla
Used to be able to do this s**t in my sleep.