Seeking help sourcing 20" or 24" N scale metal wheels

[randgust]

One of the other 'issues' is the design of the wheel itself.    For instance, on the 27" wheels from Kato (stealing from their chassis) you've got a very nice wheel that is an end-axle pickup design with a center plastic insert for the gears.

That's fine if you've doing outside bearings, but for inside bearings you're in trouble.  You either need wheel wipers for contacts, or frutz around with modifying the axles for an inside bearing arrangement.

So not only are the sizes an issue, but bearing design - outside bearing, inside bearing.   Split wheel designs are great and preferred but they need to be interchangeable with either a plain axle insert or a drive gear insert.  That insert should also be designed to accommodate N vs. Nn3/Z.  Having the insulation only on one side at the axle really limits your pickup options on a design.  You can always cut off outside axle points on a split axle design if you have to IF the wheel was also designed for inside bearing use as well.   Kato wheels shove the wheel back right up against the split axle insert and use that for gauging.   Even a very mild shoulder on that axle pin on the inside would let you use the wheel for inside bearings and get electrical pickup from it without resorting to wipers.

The other thing is spokes.   No, you can't machine them, you're pretty much stuck with molding or casting.   But that's another big hole in the N/Z collection.   Some of the overseas 2mm guys have some nice material, but it's rather difficult to locate and get specs on.

As far as for wheel measurements, I won't be the dog in the manger on flange depth, just tread width.   I've experimented on all kinds of wheels, and the only ones that have failed miserably are the first-run BLMA metal wheels that had the narrow tread.  Pretty much everything since has worked on a wide variety of track as long as the tread width isn't so narrow to completely drop in the frog and stick in there.

[narrowminded]

Hopefully this can add to the conversation in a general way by telling the deliberations I am currently going through with wheels. On the prototype chassis I've been working with the wheels are the split axle style with the gear muff internally shouldered for wheel gauging.  Not having to add wired and insulated pickups saves a lot of space which is at an absurd premium in a package this small.  I have also entertained making the wheels and axles one piece as well as making the wheel assembly from tungsten for additional weight although for the testing unit I have just cut axles from 1.2mm music wire and used one non insulated wheel each from a Fox Valley 33" N scale axle set.  From the couple of wheel brands I've seen, 1.2mm seems to be the standard size that presses into the wheels so sticking with that seems logical and affords relatively easily customized wheel options for an application yet to be envisioned.  The attraction to tungsten is that it's almost exactly twice the weight of brass and addresses the second problem in a device this small, the problem of weight for reliable electrical contact as well as traction.  One concern about using tungsten is material cost and machinability (although totally doable) but even more importantly, the potential for a problem you have alluded to in a recent post about traction and old wheels once the plating has been worn away.  I fear that the tungsten might be too hard and act as a better bearing material than friction material.  Possibly a surface treatment that roughened the tread finish could help with this and being tungsten, might not wear too readily and wind up polished anyway, but those are all experiments for another day.  They might actually make better rolling stock wheels than driving wheels for just those reasons but also may not be needed, not warranting the added expense.  In my limited testing with a few cars for effect as well as pulling power, brass wheels were nice and didn't demonstrate any problems that would seem to justify any further attention.  They seemed just about right in weight and reliable action.  I suspect that tungsten in this instance might very well be a solution for a problem that doesn't exist.   I am also aware of the tread width problem you speak of which is why I tested with FVM "wide wheels" and am entertaining using them as standard as they are not really visible in my application, only contribute to weight, have the best chance of reliable performance on various qualities of track work, and yet can relatively easily be narrowed for someone who has issue with that.  And this is what happens when I start thinking out loud.

[SandyEggoJake]

Interesting add, narrowminded. 

I wish you the best of luck with your project.  My needs are likely more urgent and I'm now convinced by Bruce and others that the Z scale 33" from several sources may satisfy my needs for a N scale 24", especially at this price point. 

But if I can offer suggestions, the market seems to be lacking an N Scale 20" wheel.  If I was to produce a mining wheel, I would suggest you consider the classic six spoke (http://www.shutterstock.com/pic-2759938/stock-photo-wheels-of-the-old-mine-cart.html)  also saw duty on a broad range of trams and other industrial carts.   If spoked, I suspect you would find willing buyers at the $10 - 12 for sets of 4, no problem.   Technically more challenging to make the stock, but once the rod is sliced and the flange / tread / face profile is cut, the effort is much the same.   If considering making such a wheel, please PM me with your timeline, as I would consider placing a bulk order in the 200 - 400 wheel range.   

[SandyEggoJake]

The other thing is spokes.   No, you can't machine them, you're pretty much stuck with molding or casting.   But that's another big hole in the N/Z collection. 

Fully agree spokes is the "hole".  But they can be machined...it is just more a challenge.  But not impossible.  One would need to create their own stock. 

Three options for this.  First on to a rod or tube to act as a suitable hub, braze barstock to act as spokes, tinning such and the inserting this assembly into another tube for the tread & flange material.  A second and perhaps better way is to start with a solid rod or tube to form the stock for both the hub & spokes.  Spokes would then be milled longitudinally along the stock, and after the result is then affixed into a 2nd tube for the tread & flange material.  In both of these, you then slice the stock to the wheel width and then profile the face, tread and flange profile to suit.  Or if you really want the best detail, cast the wheels individually, and then machine each with face, tread and flange profile

But yes, it is more work than a solid wheel, no doubt, but if you want to be able to charge a premium price, you need to produce a differentiated product.