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JeffP

O Gauge: do we NEED wheel bearings?

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Looking at different kit manufacturers, there would appear to be a difference of opinion. I'm not going to name names, so don't anyone worry.

 

But what I'd like an opinion on, hopefully from someone who has mad a few models is this:

 

Can we get away with simply having axles running in a slot in mainframes, with compensating beams taking the weight/some of the weight? Or ought we to try and organise some sort of brass/etc bearing to spread the load and maybe cut down on wear?

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Errrrm. Where's the emoji for blush.?

Is there a difference?

 

Unless you are in pedant mode, (no offence meant) and mean ACTUAL bearings like roller/ball bearings, or bushes? I hadn't thought of actual bearings...yet...

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26 minutes ago, JeffP said:

Errrrm. Where's the emoji for blush.?

Is there a difference?

 

Unless you are in pedant mode, (no offence meant) and mean ACTUAL bearings like roller/ball bearings, or bushes? I hadn't thought of actual bearings...yet...

Some builders swear by the tiny ballraces now available on the net.

My only observation is that a J25 built in the early 90s had plain holes in the 3mm thick main frames and was semi retired due to the amount of slop around the axles. To be fair, it completed many hundreds of laps of my 90foot roundy roundy attic layout usually with 20+ wagons in tow. Modern kits use much thinner material for the frames than my old J25. The old girl still runs but clanks and waddles alarmingly. A bit like the real thing.

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The frames tend to be made from softish brass and being quite thin will wear very quickly. Fitting either bushes or bearing massively increases the life of the loco and when you've spent £xxxxx on the loco kit in the first place why would you not want to make a proper job of building it? The other problem would be that the holes in the chassis will have been drilled/ etched on the presumption that some sort of bearing or bush will be fitted and will in most cases be too big for the axles anyway.

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44 minutes ago, doilum said:

Some builders swear by the tiny ballraces now available on the net.

My only observation is that a J25 built in the early 90s had plain holes in the 3mm thick main frames and was semi retired due to the amount of slop around the axles. To be fair, it completed many hundreds of laps of my 90foot roundy roundy attic layout usually with 20+ wagons in tow. Modern kits use much thinner material for the frames than my old J25. The old girl still runs but clanks and waddles alarmingly. A bit like the real thing.

Hi all,

Just an observation. Could you not take out the axels of the said engine and re-drill the plate to accept bearings. thus removing the slop. As for new chassis the only experience I have with that sort of thing is 16mm narrow gauge where I believe the engines we run in plain phosphor bronze bearings. I do not build the engines I just help run them...….. :)

Edited by cypherman

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1 hour ago, cypherman said:

Hi all,

Just an observation. Could you not take out the axels of the said engine and re-drill the plate to accept bearings. thus removing the slop. As for new chassis the only experience I have with that sort of thing is 16mm narrow gauge where I believe the engines we run in plain phosphor bronze bearings. I do not build the engines I just help run them...….. :)

The chances of drilling them square is slim to nil. One day I will get round to cutting some new frames and a pair of jointed rods.  Maybe go the whole hog and try sprung hornblocks. 

The other function of bushes is to avoid the wheel rim coming into contact with the frames without the need for washers or spacers.

If we didn't need them, the budget kits wouldn't supply them.

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I was worrying that the slots in the frames, and/or the carrying arms of the compensation beams would wear on the steel axles?

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Generally the longer the bearing the less wear. As soon as you add springing you double or triple the amount of play you start with and shorten the life of the chassis.  I suspect the ball races will last much longer than plain bushings as long as they kept clean and lubricated but damp and rust will destroy them, Locating them could be challenging.  I would use bushes and rest the compensation beams on the bushes rather than directly on the axle.

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It's a lot easier to replace a worn axle bush (if ever it did wear) than to correct a worn slot in a mainframe.....

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7 hours ago, polybear said:

It's a lot easier to replace a worn axle bush (if ever it did wear) than to correct a worn slot in a mainframe.....

That was my thought.

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I had the opportunity recently to have a close up look at a rather lovely collection of O gauge locos.

 

"Pick that one up" the owner said, pointing at a particular loco. It weighed over 2 stone! I wouldn't fancy that without decent bearing surfaces.

 

i have always been a bit doubtful of the use of bearings in a beam compensated loco. All the weight is on the beam and none is taken by the frame. In that situation, I have used a bearing on the axle where the beam sits and just run the axles in slots in the frames but I reinforce the slots with a dummy hornguide/axlebox which is also slotted. I haven't built a layout yet in 7mm to see how long they last but in 4mm it has worked long term on many locos.

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11 minutes ago, t-b-g said:

I had the opportunity recently to have a close up look at a rather lovely collection of O gauge locos.

 

"Pick that one up" the owner said, pointing at a particular loco. It weighed over 2 stone! I wouldn't fancy that without decent bearing surfaces.

 

i have always been a bit doubtful of the use of bearings in a beam compensated loco. All the weight is on the beam and none is taken by the frame. In that situation, I have used a bearing on the axle where the beam sits and just run the axles in slots in the frames but I reinforce the slots with a dummy hornguide/axlebox which is also slotted. I haven't built a layout yet in 7mm to see how long they last but in 4mm it has worked long term on many locos.

At the risk of opening a huge can of worms, why do 0 gauge modellers 'generally' insist on making their locos way too heavy. Some years ago I saw a Scalefour Society recommendation of ½oz per axle. Allowing that 7mm scale is nominally 4 times the mass of 4mm scale that would suggest that 2oz per axle would be plenty of weight. Surely any decently installed bearing, hornblock or bush would be likely to last as long as the rest of the loco in most cases.

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The general 4mm finescale weighting recommendation for 4-wheel wagons is approx 1 ounce per axle.

 

For 4mm locos, a figure of approx 4g per prototype ton is a good objective,

 

7mm stuff is, volume for volume, 5.25 more massive than 4mm stuff, but I would not draw a conclusion from that on what a weighting factor should be for 7mm scale, because the inertia and momentum values do not scale linearly.

 

What strikes me most about 7mm loco builders is their bewilderment if asked what their locos weigh. Most 7mm builders don't a clue. To be fair, and unlike 4mm scale, they probably don't need to worry about that sort of thing too much - what they have tends to be 'sufficient'.

 

And in any case, good balance tends to be far more important than overall weight.

 

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I use ball bearing for coach and wagon axles in HO. Makes hauling  8 coach trains with RTR locos a snap. Lots of other friction lowering and easy assembly advantages too.

 

1344411100_amfleetrighttrucksfittedunderclose-600.jpg.633fb2b79b2e27bbabf43c405ace10c7.jpg

 

BTW the bogies shown have 100% working beam suspension and I'm using the combination of beams and BBs in  loco chassis as well now.

 

Nadal's formula for track holding essentially says the heavier the vehicle the better.  The bogies shown will support 4 oz per axle and still run free. Wonderful for realistic inertia.

 

Andy

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