fabricating replacement electric mower bush mounting

[Ben Sharp]

I'm trying to make something to hold the bush on a qualcast lawn mower and after a few failed attempts could do with some advice. Firstly apologies, I'm not sure what it's called so I'm calling it a bush holder! I've attached a couple of pictures of the remaining one, hopefully that makes sense.





I initially tried to form something out of polymorph but I realised it melts at 60 degrees C and I was worried it might melt. Next I tried making something out of fimo but the results haven't been great:



Does anyone have any suggestions? I've got some aluminium L section that fits but I'm not sure if I can use metal against the bush and I would still have to find something to secure the other side:


It's probably time to say goodbye to the old girl, she cost £40 nearly 20 years ago and has been running on a belt spindle made out of some welded together nuts for a while now but if anyone has any advice on materials I could use I'd be grateful and it would be good to get it going again.

 

[mike 109444]

chunk of nylon from a chopping board maybe ?

 

[pedrobedro]

Stop calling it a bush, it's a carbon brush You need something that will stand the higher temperature of an electric motor, you might be able to cast something from HigHeat JB Weld. Wrap it in cling film and cast round it to give clearance.

 

[Ben Sharp]

Thanks, searching for brushes might have helped! I'll have a look for some nylon in the shed, don't have a chopping board but might be able to find something. If not the JB weld looks like it might do the trick

 

[RichardM]

If you can find out the part number you may be able to buy one:

https://www.diyspareparts.com/parts/qualcast/list/c/6/

 

[Seadog]

Nylon will melt. The original will be a thermo-setting plastic not a thermo-plastic. Metal would certainly be worth a go. You often see brush-holders made from brass.

 

[zx9]

It's probably time to say goodbye to the old girl, she cost £40 nearly 20 years ago and has been running on a belt spindle made out of some welded together nuts for a while now but if anyone has any advice on materials I could use I'd be grateful and it would be good to get it going again.

I know it is not in the spirit of things; When my ancient Qualcast was playing up last year Mrs ZX9 found me a replacement on Ebay, opening bid of 99p got me a complete working mower then a couple of hours jet washing the 'new' mower before swapping over the parts got my old mower back in action.
Only thing that went not to plan was the three hour round trip to pick up the 'new' mower, thank you Mrs. ZX9 not all of Surrey is Croydon, some of it is further away.

 

[Ben Sharp]

I'd snap up a replacement for parts if I ever found one but not come across one yet. Does anyone know what sort of temperature it could get up to? I might try and glue something to act as a guide rail on the aluminium.

 

[Gareth J]

I would be looking at getting something complete and off the shelf and cobbling that on;

Like these (or something close to the right size)
https://www.ebay.co.uk/itm/183651950091

If not that, a s/h motor from something else.

Trying to remake the brush holder will be tricky as, not only might it melt, if it's too slack, the brush will wear oddly, too tight and it might bind.

 

[Ben Sharp]

I would be looking at getting something complete and off the shelf and cobbling that on;

Like these (or something close to the right size)
https://www.ebay.co.uk/itm/183651950091

If not that, a s/h motor from something else.

Trying to remake the brush holder will be tricky as, not only might it melt, if it's too slack, the brush will wear oddly, too tight and it might bind.

The brushes are already quite knackered from being loose so that might be a better solution. Is there anything specific I need to look for or will any that fit do the same job? I take it I could just solder the wire onto the new part.

 

[Gareth J]

Think they should match or be very similar cross section/profile to the originals. Might not be that easy to find the dimensions of off the shelf units though I guess

 

[Ben Sharp]

Think they should match or be very similar cross section/profile to the originals. Might not be that easy to find the dimensions of off the shelf units though I guess

Thanks for the help. Is the sizing critical? Apologies if that's a stupid question but I don't really understand how it works beyond the basics and not sure if changing the size of the brush would have an effect.

 

[pedrobedro]

Thanks for the help. Is the sizing critical? Apologies if that's a stupid question but I don't really understand how it works beyond the basics and not sure if changing the size of the brush would have an effect.

As long as they bear on the same surface and conduct electricity the size is not critical.