Fitting a worm gear

[DavidB]

It is years since I built anything motorised. I now find myself with a motor and worm drive, the latter with a hole too small for the 1.5mm shaft on the motor. I have nasty memories of trying to fit a worm years ago and bending the motor shaft.

How does one go about fitting a worm gear - successfully? I would use a vice but the length of the motor shaft exceeds the maximum opening of the jaws unless I used my woodworking bench vice which has wooden jaw faces.

Whilst I am asking questions, what are thoughts on flywheels?

 

[simond]

David,

some context would perhaps help, scale? make & material of gears? Motor type?

the worm (the worm gear or worm wheel is the mating part that goes on the axle) should be either a slip-on fit, in which case a drop of a suitable retainer is required, or an interference fit, in which case a press of some sort will be needed. Your vice may do that, but a rigid bench drill press would be easier. If your worm is brass I doubt it is intended to be an interference fit. It could be, but you’d need a lathe or good press to get it on - probably not intended for diy.

Assuming it is a plastic worm, I’d arrange a piece of hard packing on the table of a drill press, place the motor, shaft up, on that, and a suitable stub of brass or steel clamped in the chuck to push the worm down onto the shaft. If it needs to go on further than the end of the shaft, then a suitable washer can be added once it has been started.

Flywheels - probably better than nothing, but not as good as DCC with keep-alive. As heavy as possible, and as large diameter as you can get into the loco. And balanced!

hth
Simon

 

[Bill Campbell]

Hi David

Not so long ago I used a High Level gearbox in a model. I have reproduced part of the advice included in the fitting instructions and found that the use of a smoothing broach enabled a gradual approach to getting the worm to fit on the motor shaft. Take good note of the reference to excessive force - very easy to bend the motor shaft or damage the armature.


Regards.

 

[DavidB]

Thank you both. No idea of the motor which came with the kit, but the gearbox is High Level with a brass worm. I didn't get any instruction sheet with the gearbox; I assembled it from photos.

I don't have Loctite 601, only 243 which I have had for years, never opened, so I will have to look into what these are.