Fixing plastic wheels to motor shafts

[skybadger]

Hi all 

I have a dome with dome drivers using 4 motors and a set of drive wheels on each. They use wheels mounted to the shaft of the motor by grub screws  to do the driving of the dome.

Unfortunately the wheel treads are quite soft and need to be replaced. I've found an easy replacement using some harder plastic wheels with a harder rubberised tread but they are plain bores. My question is - is there a best way to fasten them to a steel shaft so they are reliably fixed ? The shaft is an 8mm d- profile . I can get the wheels in 8mm plain bore or 6mm plain bore and drill them out to a snug fit. The plastic is PU.

My thoughts are

Interference fit + red loctite ?

Araldite/epoxy glue

Metal hub inserts  but space is tight and has the same fixing problem

Spline/key cutting using d profile as flat surface for the key 

Since the current wheels are bane bits using hex centres, is there a way to push the 12mm hex hubs into the pu plastic without splitting ?

Anyone done this and have wisdom to share ?

Edited June 12, 2021 by skybadger
Added option

[Peter Drew]

I think I would try red loctite in the first instance, less chance of damaging the wheels.    🙂

[skybadger]

Hi Peter

I don't have experience with red loctite - does it bind well to metal and plastic ? I'll look it up as an option. Thanks 

 

 

 

[michael8554]

An image of a wheel would really help.........

If the boss protrudes you could drill through the boss and drive shaft, and nut-and-bolt the wheel onto the shaft.

I think the motor torque will unlock any Araldite or LocTite connection.

Michael

[skybadger]

The wheel I'd like to use.  

https://www.bilcastors.co.uk/product/bza60wgr/

The wheel I am replacing because they don't make the hard tread variety any more. 

https://www.robotshop.com/uk/rb-ban-91-orange-wheel.html. It solves the attachment problem by using a 12m hex hub and grub screws to the 8mm shaft but the tread does pull itself apart over time. They have stopped making the harder tread variety. 

The bogies these wheels have to go on look like this: 

The space is very limited due to having to fit between the walls of the dome. 

 

I should add pinning the wheel on the shaft as an option. 

ie using a drilled hole through the motor shaft ( across the long axis, near the end) and either drilling and pinning the hub on the axle or cutting a slot in the plastic for the pin to register into. 

Those hubs are 0.8" when using two wheels ie 20mm , so you can see from the picture that the motor shaft doesn't extend the entire width of the wheel. The grey wheel above is 28mm wide, 

[Rusted]

I think you could get away with drilling, tapping and fitting a grub screw in the hub.
Probably slanting? Askew? Inclined? To bed onto the flat on the motor shaft.
A coarse thread might be best. Metric is too fine to have much meat to bite into.

Your worn tires remind me how the solid variety used to look in my youth.
You've been using the back brake too much.

[skybadger]

There's a good story to that inclined grub idea. Lots of thread path and more force at the surface. I'll look into that some more. Ta.