Bill Bedfords Sprung W Irons and Parkside Kits - Questions for 4mm gurus

[Guest WM183]

Hi folks.

 

I know a popular way to add springing to wagon kits is Bill Bedford's nice little sprung W iron kits. However, I have a few questions. The Units themselves are about 1.5 to 2mm wider than the distance between the solebars on a parkside kit! Now I guess thinning the solebars a bit isn't too bad, but... do I also need to replace the cast on plastic springs and axleboxes? If I have to do so much butchery it is probably just better to use a complete underframe kit, which is often my choice. However, most Parkside kits have rather nice underframes - brake levers and guards aside, easily replaced - and I'd like to use some of them. So... how do you go about modifying the parkside kit to use these things?

 

With a spring in my stride,

Amanda

[Mark Forrest]

I tend to file away at the rear of the sole bars until I get to the point where the moulded axleguards have gone, just leaving the springs and axleboxes.

 

[Miss Prism]

File recesses on the insides of the solebars. (Before fitting to chassis of course.)

 

 

Plastic springs and axleboxes can snipped off the moulded kit W-irons and filed (on the rear) to a more reasonable thickness.

 

Attaching springs and axleboxes - there's lot of ways of doing it:

 

 

 

 

See also: http://www.clag.org.uk/bb-w-irons.html

 

 

Edited January 20, 2021 by Miss Prism

[Guest WM183]

Thanks guys! Solutions so simple they were too smart for me. Thank you much!

[Grovenor]

Note these are not rocking W-irons so the axle box is not usually fixed to the bearing (it coupld be if you preferred that but you would need to make sure its only fixed to the bearing and not the w-iron) The usual way is to elongate the hole in the back of the axlebox so the bearing can move up and down within it. Use a burr in a dremel or similar. Best to use the 'waisted' style bearings so the amount of enlargement is minimised.

[Guest WM183]

Hi Keith,

 

Mine are not rocking either; I don't like the rocking ones because then I cannot fully detail things like add tie bars, lever guard supports, and so on. Mine are the ones that use little bits of guitar spring, clever design! I really like these!

Amanda

[Captain Kernow]

3 hours ago, WM183 said:

Hi Keith,

 

Mine are not rocking either; I don't like the rocking ones because then I cannot fully detail things like add tie bars, lever guard supports, and so on. Mine are the ones that use little bits of guitar spring, clever design! I really like these!

Amanda

Hi Amanda,

 

You can certainly add tie-bars to rocking W irons, provided they are sufficiently flexible. You don't really need the rocking W iron (or the sprung W iron, for that matter) to move very much up and down, to cope with minor imperfections in the top of the rail.

 

[Guest WM183]

1 hour ago, Captain Kernow said:

Hi Amanda,

 

You can certainly add tie-bars to rocking W irons, provided they are sufficiently flexible. You don't really need the rocking W iron (or the sprung W iron, for that matter) to move very much up and down, to cope with minor imperfections in the top of the rail.

 

I didn't realize that. It doesn't interfere with them?

[Guy Rixon]

Hollowing out the axleboxes to allow the bearings to move inside: I do it with a 1.9 mm router bit in a mini-drill ("electric adze") , and the drill spins fairly slowly to reduce the risk of melting the plastic. You need room for about ±0.5 mm movement about the actual position at which the suspension settles when you make the wagon up the desired weight and pack out the axleguards to get the buffer height correct. Since it's tricky to estimate this position to tenths of a millimetre, it's best to hollow out for as much movement as possible. This is easy enough in plastic and no fun at all in whitemetal. Therefore, I avoid replacing the moulded axleboxes with castings.

 

Usually, the axleguards need about 0.5 mm packing to make the buffers right with a weight around 45g.

 

It only works well with waisted bearings, as noted above, and you need to file down the pip on the end of the bearing as far as you dare. It's probably worth making one into a wasted bearing to find out the depth at which the conical cavity breaks through.

 

The waisted bearings reduce the required width of the cavity at its bottom, of course. But you need the rim of the cavity to be opened out to clear the 2.0 mm width of the bearing where it runs in the axleguard.

 

You may need to get bearings from a few different suppliers to find ones in which the cone depth is right for the axleguards. Or get relatively deep ones (e.g. Markits) and shim them to the right depth.

 

You'll need a way to align the axleguards in the chassis. The jig in the Bedford range does the job well; buy some 2.0mm drill bits to use as jig axles if you get this jig. There are also baseplates that help with the alignment. Palatine do etched ones. Or you can find printed ones in my Shapeways shop. But you absolutely don't need the baseplates if you have the jig.

[Enterprisingwestern]

10 hours ago, Guy Rixon said:

The jig in the Bedford range does the job well; buy some 2.0mm drill bits to use as jig axles if you get this jig.

 

In Bills defence, the one I bought last year has 2mm rods included.

 

Mike.

[Captain Kernow]

13 hours ago, WM183 said:

I didn't realize that. It doesn't interfere with them?

Movement is slightly impeded, as you might imagine, but not enough to prevent the rocking W iron from doing it's job. Flexible (and sufficiently thin) tie bars are essential, however.

 

Having said that, my preference for wagon compensation these days in P4 (assuming I'm not just building the wagon rigid, without any springing or compensation at all), is internal rocker compensation, which means you don't have to disturb the RTR axle guards at all, if you're happy with them.

 

[Guest WM183]

Hi Captain,

 

How do you put bearings on the internal axle? Do you need to remove one of the wheels from its axle then? I'd like to see more about this!

Amanda

[Miss Prism]

7 minutes ago, WM183 said:

Do you need to remove one of the wheels from its axle then?

 

Yes.

Edited January 21, 2021 by Miss Prism

[Guest WM183]

7 minutes ago, Miss Prism said:

 

Yes.

 

I have a hard time even regauging wheels at times and not getting a wobble in one. I imagine there's a trick to removing a wheel and reinstalling it so t's all straight and true?

[Miss Prism]

No trick. Sometimes it's a right pain, but it's always good practice to check the BB of any wheelset, and adjust if necessary.

 

Twist and move, twist and move...

 

 

[Captain Kernow]

6 hours ago, WM183 said:

How do you put bearings on the internal axle? Do you need to remove one of the wheels from its axle then? I'd like to see more about this!

Here's a photo of a Bachmann 16t mineral that I converted to P4 for a friend, showing the internal rocker assembly.

 

[Guy Rixon]

On 21/01/2021 at 13:02, WM183 said:

 

I have a hard time even regauging wheels at times and not getting a wobble in one. I imagine there's a trick to removing a wheel and reinstalling it so t's all straight and true?

There is a technique with a drill press to hold the axle vertical while it is pushed in.

 

My experience is that if a wheelset is true as bought, it's likely to remain true after tweaking the gauge. However, if I take one wheel off and push it back on manually I'm about 30% likely to put it out of true. Once an axle has been been driven in at an angle I've never had much luck bending the wheel straight. Hence the trick with the drill press (which I did not invent).

 

Then there's Exactoscale wheels which naturally go on true because they are fitted with retainer, not interference fits.