Frame spacers, washers and sideplay

[Buhar]

Using standard chassis spacers for OO gauge (eg Comet) seems to leave a huge void behind Gibson wheels and getting the right number of washers is a real pain, especially as Gibsons don't like being continually removed and reattached.  I found a calculator for the sideplay needed over a fixed wheelbase and this seemed to indicate I could use wider spacers as my minimum radius is 3ft.  However, I've end up with one 0-6-0 that is very unhappy with these curves and another where I seem to shift between to much sideplay on the front axle and jamming the thing up.

 

I am putting the sideplay on the centre axle of a six-coupled, driving the rear axle and trying to prevent the front axle wandering around much.  I think I'd like to scrap the calculations and the theory and hear what others have achieved in practice. I think the difference in the sideplay required between, say, a Midland 16'6" (66mm) wheeelbase and a Caley tank's 13' (52mm) is not going to be much of an issue, more important, I would have thought, is the minimum radius to be negotiated on the layout.

 

With 3ft minimum radius what overall width should I look for on the frames with Gibsons and what thickness of washer should I be using on the front and rear to allow sufficient sideplay without inducing duck-like running.

 

Thanks in anticipation.

[John_Miles]

I sort this out by drawing a curve of the minimum radius to be used and then drawing the chassis wheelbase on top of the curve. You can then measure the amount of sideplay needed - I then add 0.5mm as a factor of safety. This works for me. That said, when I converted to EM from OO, I converted several locos by using longer axles and putting on washers to eliminate excessive sideplay. These have run successfully for several decades with no problems. You can retro fit washers without removing the wheels by removing part of the washer so it is a tight push fit over the axles.

[N15class]

Normally with OO I would leave the front and rear drivers with just enough side play to rotate freely. The centre would have side play. With OO there is a lot of slop between the wheels and the track, with 3 foot curves there should not need very much side play on an 0-6-0. in 7mm finescale I have very little side play as there is the the same slop in 32mm gauge track and wheels.

 

As above draw an outline of track and frame to see what you need.

[relaxinghobby]

A quick look at RTR.....Hornby Jinty chassis just under 1mm of play on all axles.  Bachman Billy with it's short 0-6-0 format about 0.8mm side play on all axles.

Is that any help?

[N15class]

A quick look at RTR.....Hornby Jinty chassis just under 1mm of play on all axles.  Bachman Billy with it's short 0-6-0 format about 0.8mm side play on all axles.

Is that any help?

But for 3 foot radius it is unnecessary. They have been designed to go around tiny radii. I expect they crab down the straight with that much play on all wheels.

[Buhar]

Thanks for your attention folks, but I'm no closer on the measurements I was looking for.  I'll see if I can get possession of part of the kitchen this weekend and do some trial and error.