Brass gears: what are your thoughts?

[Bob Tidbury]

As Kev said Never had a brass gear split but admit they are noisier ,a dab of graphite quietens them down for a while but  does wear off .
I think the white nylon gears were also very good I have never had any problems with them ,I have no idea what type of nulln Farish used but was told that those gears were very expensive compared to the black plastic .
I havnt had a problem with the thick black plastic ones yet but I have heard some people have ,time will tell .
Bob

[Steven B]

Just my personal opinion on this - I have never had a brass gear split!

I've never had a Kato or Dapol gear split...


The 2mm Scale Association offer worm gears in Acetal or brass. Their spur gears are all brass. They also offer skew cut gears for meshing with the worm gears which will help reduce wear. As would helical cut worm/spur gear but perhaps that's going a bit too far?

@Will_J I've not seen what your motor bogie will go in. Care to share?

[Mr Sprue]

As already mentioned the 2mm Association sell brass gears, in fact they actually make them!

The problem that's been with the Acetal/plastic gears is that the axle hole is too small, so when these gears are fitted they are immediately under stress!

[Will_J]

Just my personal opinion on this - I have never had a brass gear split!

I've never had a Kato or Dapol gear split...


The 2mm Scale Association offer worm gears in Acetal or brass. Their spur gears are all brass. They also offer skew cut gears for meshing with the worm gears which will help reduce wear. As would helical cut worm/spur gear but perhaps that's going a bit too far?

@Will_J I've not seen what your motor bogie will go in. Care to share?

I'll have a chat to them about it, the helical gears would be a nice mark of quality.

The motor bogie will be 17.5mm wheelbase so the common 8'6 wheelbase on prototype. The idea is that this common bogie (or two of them if you need more grunt) will fit into a large range of plastic body kits including several Type 1 and 2 units and a large number of MUs. Yes you'll be able to see it through windows in models where it can't be hidden in a guard's compartment, but I am hoping that the value and performance will mitigate this small compromise. I have yet to decider whether to go with coreless or can motor, I will test both and go with what seems best.

I will be testing this concept in a limited production of Class 21/29s in the near future, and offering them to those who are happy to build what is essentially a live beta test of future products.

As already mentioned the 2mm Association sell brass gears, in fact they actually make them!

The problem that's been with the Acetal/plastic gears is that the axle hole is too small, so when these gears are fitted they are immediately under stress!

Yes I think that may have bee an isolated supplier issue for several productions of Farish loco unless I'm mistaken. Modern machining tolerances and POM gears should never suffer than kind of issue. Perhaps the ideal would be a POM work onto a duplex with a helical outer gear. If the gear axles themselves were mounted in phosphor bronze bushing with occasional easy servicing with PTFE grease, that should result in a pretty bomb proof mechanism.....at least one hopes!

Will.

[Mr Sprue]

Yes I think that may have bee an isolated supplier issue for several productions of Farish loco unless I'm mistaken. Modern machining tolerances and POM gears should never suffer than kind of issue. Perhaps the ideal would be a POM work onto a duplex with a helical outer gear. If the gear axles themselves were mounted in phosphor bronze bushing with occasional easy servicing with PTFE grease, that should result in a pretty bomb proof mechanism.....at least one hopes!

Will.

Assuming these gears are moulded from POM, which is likely. If so I cannot understand why they were not moulded in POM-C! 

Dave

[Will_J]

Assuming these gears are moulded from POM, which is likely. If so I cannot understand why they were not moulded in POM-C! 

Dave

It would be interesting to know! I could be mistaken, but I believe that gears can also be laser cut in POM-C sheet. That's certainly interesting! The simplest solution as it stands, would be to get my current supplier to make brass gears and then buy in acetal worms if I can get them. Though the 2mm society ones are approximately M0.25 which is curious.