Waisted bearings for Bedford sprung W irons?

Triode
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Waisted bearings for Bedford sprung W irons?

Postby Triode » Thu Jun 06, 2019 11:43 am

Hi All,

This is my first post here since joining the Society; although I’ve been lurking here for some time trying to make sense of it all!

I’m currently in the process of building my first wagons to P4 standards. I decided to spring them using the Bill Bedford W iron assemblies. I’ve found the W irons themselves simple to assemble and install; however, I’m having an issue sourcing suitable waisted bearings to use with them.

The instructions for the W irons recommend cat. no. LF4AXPW which are manufactured by Alan Gibson and available from Eileen’s Emporium. I bought some of these, but unfortunately the inner surfaces of the batch I received do not come to a true point, resulting in ‘slop’ from the pinpoint axles. This is apparently due to the tool used to produce them becoming blunted.

I contacted Eileen’s and they kindly offered to refund the bearings. I also waited a few weeks for a fresh batch of LF4AXPW bearings to become available to see if these would be any better. Unfortunately this does not seem to have been the case.

Ultimately I opted to source similar waited bearings from Wizard Models. These do have the correct inside profile, but seem to be deeper than the ones Eileen’s sell. As a result, I had to space them off the Bedford bearing carriers with washers to achieve the correct ‘back-to-back’. However, this leaves an insufficient length of bearing protruding on the outer face to guide the carrier neatly in its slot. The axles therefore have too much lateral freedom (as viewed from the face of the wheel). This sometimes allows the wheels to come in contact with the brake shoes as the wagon is pushed along the track.

Has anyone else encountered this problem before? And does anyone have any recommendations for bearings which work well with the Bedford W irons?


Many thanks,

Liam (7187)

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steamraiser
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Re: Waisted bearings for Bedford sprung W irons?

Postby steamraiser » Thu Jun 06, 2019 12:36 pm

Purchase direct from Gibson Wheels?

Gordon A

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David B
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Re: Waisted bearings for Bedford sprung W irons?

Postby David B » Thu Jun 06, 2019 12:51 pm

Yoe can also get them on Ebay.

I have not encountered problems with the BB units and the only back-to-back I have been concerned about has been with the wheels, not the units. It is an unfortunate side effect that having to spring the W irons apart to fit the wheels invariably introduces a bit of slack. There is not much you can do about this. Brian Morgan has a different approach on his underframes where the W irons on one solebar slide out on a bolt.

John Palmer
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Re: Waisted bearings for Bedford sprung W irons?

Postby John Palmer » Thu Jun 06, 2019 1:11 pm

Triode wrote:As a result, I had to space them off the Bedford bearing carriers with washers to achieve the correct ‘back-to-back’. However, this leaves an insufficient length of bearing protruding on the outer face to guide the carrier neatly in its slot. The axles therefore have too much lateral freedom (as viewed from the face of the wheel). This sometimes allows the wheels to come in contact with the brake shoes as the wagon is pushed along the track
Could the stepped outer profile of the waisted bearings be the reason you are getting too much lateral freedom? If so, might you be able to get round this by using the non-waisted bearings (Alan Gibson cat. ref. 4M63). Their parallel-sided outer profile may provide a better, constant fit in the axleguard slot for the carrier/bearing assembly. Admittedly, you have to increase the amount bored out of the axlebox rear to accommodate these bigger bearings, but I've never found this to be a problem in practice.

David B wrote:It is an unfortunate side effect that having to spring the W irons apart to fit the wheels invariably introduces a bit of slack. There is not much you can do about this. Brian Morgan has a different approach on his underframes where the W irons on one solebar slide out on a bolt.
To mitigate this problem you can file a vee-shaped groove through the bearing flange at its bottommost point. Technique is illustrated at http://www.clag.org.uk/bearing-interface.html. It's still sometimes a struggle to get the wheelset in place without unduly spreading the containing framework (W iron or coach bogie), but I find that this helps. Important to get the groove at the bottom of the flange so the wheel set can be inserted vertically, thus minimising displacement of clasp brakes. With care and a suitable file (I use a slotting file) you can avoid having to put a second groove in the opposite, 'top' position of the bearing flange, as shown on the CLAG illustration.

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Le Corbusier
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Re: Waisted bearings for Bedford sprung W irons?

Postby Le Corbusier » Thu Jun 06, 2019 3:49 pm

Interested to know how much of a problem the slight slop is .... is it visible when the wagons are running on the track? I suppose a tad of slop it could be argued might be a good thing? I have used Gibson waisted bearings on my wagons and have not noticed a discernable problem .... I will look more closely tonight :?
Tim Lee

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Will L
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Re: Waisted bearings for Bedford sprung W irons?

Postby Will L » Thu Jun 06, 2019 4:48 pm

Le Corbusier wrote:Interested to know how much of a problem the slight slop is .... is it visible when the wagons are running on the track? I suppose a tad of slop it could be argued might be a good thing? I have used Gibson waisted bearings on my wagons and have not noticed a discernable problem .... I will look more closely tonight :?


What you don't want on a sprung chassis is the axle bearing length being over size and pushing the W iron out of vertical as this will inhibit the spring action. For this reason you should err in the direction of a little slop which should not be an issue so long as you don't over do it.

Filing a v slot in the bearing does make things easier. You can do this using a triangular file at an angle so you cut much less through the rim on one side than the other. The deep cut side goes downward. With the bearing notched like this It should be possible to get the wheels in, only flexing the W irons a little bit and without permanently bending them out of the vertical.

Triode
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Re: Waisted bearings for Bedford sprung W irons?

Postby Triode » Fri Jun 07, 2019 11:14 am

Thanks for the replies.

I’ve attached an image which hopefully illustrates the problem.

Too little of the 2mm side portion of the bearing protrudes through the slot (due to the use of spacing washers on the inside). As a result, the axle end can move from side to side in the slot instead of just up and down.

This doesn’t prevent the wagon from running, but sometimes causes the wheel surface to contact the brake shoes; thus ‘applying’ the brakes.

I did make up some other bearing carriers with parallel sided ‘top hat’ bearings. This solves the issue, but as John has pointed out, it needs a larger slot in the cosmetic axle box. So far I’ve had no success in making such a large slot without damaging the casting; perhaps the outer face of the bearing could also be filed down a bit?
Attachments
Bearings 1.jpg
Bearings 1.jpg (78.67 KiB) Viewed 1904 times

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David B
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Re: Waisted bearings for Bedford sprung W irons?

Postby David B » Fri Jun 07, 2019 12:04 pm

I don't understand why you put in the spacing washer which clearly the unit is not designed for. I have never had any need to use them.

Your brake block looks too close to the wheel and will inevitably catch on the wheel when you put the wagon body (weight) on to the unit and the spring deflects. With the brake block so close, you are preventing the springing unit from working. There has to be some compromise on the model which here, I suggest, means moving the brake block further from the wheel and perhaps even a little further out to avoid the wheel flange.
Last edited by David B on Fri Jun 07, 2019 12:08 pm, edited 1 time in total.

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jon price
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Re: Waisted bearings for Bedford sprung W irons?

Postby jon price » Fri Jun 07, 2019 12:07 pm

After looking at my wagons with these W irons and bearings I can't see the slop being an issue once the weight of the wagon is bearing down on the suspension. It just looks like it will when they are hanging in the air. The insertion of washers is going to do two bad things. The first is the issue you identify with the bearing not being held in the W iron. The second is that either the carrier or the w iron will be bent out of true on both sides of the wagon with every chance that one side is bent further than the other, which can only exacerbate the problem you are trying to correct in the first place. Leave the washers off and watch how the wagons behave in practice is my view. If they run satisfactorily then everything is fine.

Crepello
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Re: Waisted bearings for Bedford sprung W irons?

Postby Crepello » Fri Jun 07, 2019 1:19 pm

If I understand the OP correctly, the washers were introduced to counteract the over-deep cups on the waisted bearings.
Thus the axleguard verticality should not be compromised as long as the washers merely take up the slack in the cups.

Without the washers, and the resultant play in the cups, the axles could wander out of parallel and reduce the wheel tread to
brake shoe clearance anyway, apart from the accidental centring effect of the pin points seeking the highest point of the
cup arc under the effect of gravity.

I hope the problem does not lead to discouragement, as the photo above reveals neat and careful work.

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Will L
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Re: Waisted bearings for Bedford sprung W irons?

Postby Will L » Fri Jun 07, 2019 2:31 pm

Triode wrote:... So far I’ve had no success in making such a large slot without damaging the casting; perhaps the outer face of the bearing could also be filed down a bit?


Yes you can file off much of the bearing. Think about it,the waisted bearing should have exactly the same size hole on the inside as the standard bearing, so logically you can file a waited bearing out of an ordinary one. So you should be able to file the bearing where it protrudes beyond the W iron to fit the available hole in the casting rather than visa versa. Just a fiddly job.

John Palmer
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Re: Waisted bearings for Bedford sprung W irons?

Postby John Palmer » Fri Jun 07, 2019 2:37 pm

Crepello wrote:I hope the problem does not lead to discouragement, as the photo above reveals neat and careful work.

I strongly agree with this.

I recall there being a number of posts to this forum about the variations encountered in pinpoint bearing depth. An overdeep boring of the pinpoint and/or an axle less than the nominal 26mm length seems sure to lead to excessive sideplay of the wheelset in its bearings. Whilst this can be taken up with washers, the use of waisted bearings then leads to the problem apparent from the OP's photograph: the wheelset is being displaced along the wagon's longitudinal axis until the tread comes into contact with the brakeshoe.

It does seem that use of the non-waisted bearings would prevent such displacement, but the problem then becomes
Triode wrote:... it needs a larger slot in the cosmetic axle box. So far I’ve had no success in making such a large slot without damaging the casting.
So how can this problem be overcome? Three possible solutions suggest themselves to me:

1. Mount the cosmetic axlebox on the end of a non-waisted bearing, so that it moves up and down with the wheelset+carrier. This involves no more than making a 2mm bore in the back of the axlebox sufficent to enable the box to slide up and down in close proximity to the axleguard. It may be necessary to take a little off the top of the axlebox so that there is a small gap between the box and the spring buckle above it - just enough to allow the wheelset to move up and down to the extent needed by the spring suspension.

2. Find a way of making a slot in the cosmetic axlebox such that it can be fixed to the axleguard (W iron) but still leave freedom for the bearing to move within. I can see that forming a 2mm wide slot for this purpose can be difficult, and that using a drill bit larger than 2mm to create the necessary space for the bearing to move could well damage the axlebox. Suggestions?

3. Revert to the use of waisted bearings, but find a source of such bearings having a shallower bore depth, such as to make the spacing washers unnecessary. That should make it possible for the 2mm diameter shoulder on those bearings to slide and be constrained within the axleguard slot as intended.

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David B
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Re: Waisted bearings for Bedford sprung W irons?

Postby David B » Fri Jun 07, 2019 2:54 pm

John Palmer wrote:2. Find a way of making a slot in the cosmetic axlebox such that it can be fixed to the axleguard (W iron) but still leave freedom for the bearing to move within. I can see that forming a 2mm wide slot for this purpose can be difficult, and that using a drill bit larger than 2mm to create the necessary space for the bearing to move could well damage the axlebox. Suggestions?


You ask for suggestions, John.

A drill bit is not the right tool for opening the holes in axleboxes. Use a milling bit - I use an end mill which is flat at the end. I got mine from Drill Services where a 1.5mm or 2mm carbide mill costs £6.75. I don't see mine either breaking or wearing out for many years. It fits my Dremel and being sharp, it cuts easily.

John Palmer
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Re: Waisted bearings for Bedford sprung W irons?

Postby John Palmer » Fri Jun 07, 2019 3:30 pm

Thanks, David. I would have thought that a slot drill might have been better for this application, given that a plunge cut is going to be required before you can start milling out the slot. I see that a suitable slot drill is also available from Drill Services at the same price. This leads on to the question of how you hold the job satisfactorily. Not a problem for me because I can improvise a suitable arrangement on my Unimat, but for someone who may have little more than the kitchen table at his disposal this needs some further thought. Something like a rectangular recess in which the axlebox can sit whilst being milled, maybe, and perhaps formed with suitable offcuts of wood or styrene?

Triode
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Re: Waisted bearings for Bedford sprung W irons?

Postby Triode » Sat Jun 08, 2019 11:26 am

Thanks for your replies.

I had another look at the wagon and tried to account for all the space between the W-irons to determine whether the spacing washers were really needed. The diagram below hopefully illustrates the measurements. (I used a set of cheap digital calipers so perhaps they’re not 100% accurate).

Adding up all the dimensions (without spacing washers) gives 23.52 mm, compared with 24.00 mm between the inside surfaces of the W-irons. There is therefore 0.48 mm of side-play without spacing washers. I judged this to be too much.

Having come to the above measurements I made up another set of bearing carriers and included a 0.20 mm spacing washer on each side. In theory this cuts the side-play to 0.08 mm. (Note that the original problematic bearing carriers shown in my previous post used two spacing washers per side).

Fitting these to the wagon gives a much better result. The bearings run smoothly in the slots and the wheels are more free-turning. There is a small amount of side-play but not too much.

I also revisited the original setup, and found that the Gibson axles I was using were somewhat under-length. This may have been why I ended up using so many spacing washers to reduce side-play. I’ve since started using Exactoscale axles and these are nearer 26 mm, so there is less need for spacing washers.
Attachments
W iron diagram.jpg
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W irons 2.png
W irons 2.png (581.53 KiB) Viewed 1748 times

billbedford
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Re: Waisted bearings for Bedford sprung W irons?

Postby billbedford » Sat Jun 08, 2019 12:02 pm

Triode wrote:Thanks for the replies.

I’ve attached an image which hopefully illustrates the problem.

Too little of the 2mm side portion of the bearing protrudes through the slot (due to the use of spacing washers on the inside). As a result, the axle end can move from side to side in the slot instead of just up and down.



Instead of spacing washers try bending the w-irons in slightly, so that the axles are held by the springiness of the brass.
Bill Bedford
Mousa Models
http://www.mousa.biz

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Guy Rixon
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Re: Waisted bearings for Bedford sprung W irons?

Postby Guy Rixon » Sat Jun 08, 2019 1:15 pm

Complicating matters, the waisted bearings from AGW have changed recently. The ones I bought at the York show this year are visibly different from those bought a year ago, at least on the outside. On the recent ones, the parallel, 2mm-OD part is deeper than before, the tuning pip on the tip is wider and the angle of external coning seems to be different. It's hard to be sure, but I think the inside coning might be slightly deeper.

PS: has anybody measured the variation in width between axleguards that is possible when folding them up?

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Re: Waisted bearings for Bedford sprung W irons?

Postby davebradwell » Sat Jun 08, 2019 3:49 pm

Now you're winning, why not buy a few more packets of the same bearings from the same batch as you have so you can use the same axleguard spacing every time and avoid going through this performance with every wagon you build. If you wish, axleguards can be narrowed with a double bend at the base like the real thing has where steel solebars are used. Plastic ones can be stuck on wherever you wish. I find the position of the bend in etched items to be very consistent (within the odd thou' or so) provided you use the same technique when forming the bend each time - ie fingers or pliers, etc.

I suggest you file the brake blocks to a larger radius than the wheels so that you get more clearance as the spring moves. There is a perfect shape of Swiss file for this job, it has a larger radius one side than the other although a quick search failed to come up with its name.

Referring to an earlier posting but outside my comfort zone, isn't a carbide cutter more likely to chip than an HSS one when used by hand? You're not even supposed to use hand feed on a machine according to some cutter websites, so perhaps choose the cheaper HSS type. I've never bought any carbide because of these warnings although I am perfectly happy to acknowledge satisfactory reports as above but why pay more? You're not likely to blunt it very quickly on whitemetal or plastic.

DaveB

billbedford
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Re: Waisted bearings for Bedford sprung W irons?

Postby billbedford » Sat Jun 08, 2019 4:18 pm

John Palmer wrote:2. Find a way of making a slot in the cosmetic axlebox such that it can be fixed to the axleguard (W iron) but still leave freedom for the bearing to move within. I can see that forming a 2mm wide slot for this purpose can be difficult, and that using a drill bit larger than 2mm to create the necessary space for the bearing to move could well damage the axlebox. Suggestions?


Fix the axle box to the w-iron first, then use a 1.5 or 1.8 mm ball fraizer in a Dremel type mini drill. Place the cutter in the slot while it is stationary, then pulse the drill at a slowish speed until you have removed enough of the axlebox without cutting into the w-iron. A foot control for the drill will help here.
Bill Bedford
Mousa Models
http://www.mousa.biz

Andrew Ullyott
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Re: Waisted bearings for Bedford sprung W irons?

Postby Andrew Ullyott » Sat Jun 08, 2019 6:30 pm

billbedford wrote:
John Palmer wrote:2. Find a way of making a slot in the cosmetic axlebox such that it can be fixed to the axleguard (W iron) but still leave freedom for the bearing to move within. I can see that forming a 2mm wide slot for this purpose can be difficult, and that using a drill bit larger than 2mm to create the necessary space for the bearing to move could well damage the axlebox. Suggestions?


Fix the axle box to the w-iron first, then use a 1.5 or 1.8 mm ball fraizer in a Dremel type mini drill. Place the cutter in the slot while it is stationary, then pulse the drill at a slowish speed until you have removed enough of the axlebox without cutting into the w-iron. A foot control for the drill will help here.

Never thought of that. Might give it a go.
I've always filed a groove in the back of the axle box with needle files before attaching to the W iron with superglue.
Your suggestions sounds less hassle!

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Le Corbusier
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Re: Waisted bearings for Bedford sprung W irons?

Postby Le Corbusier » Sun Jun 09, 2019 6:16 pm

billbedford wrote:Fix the axle box to the w-iron first, then use a 1.5 or 1.8 mm ball fraizer in a Dremel type mini drill. Place the cutter in the slot while it is stationary, then pulse the drill at a slowish speed until you have removed enough of the axlebox without cutting into the w-iron. A foot control for the drill will help here.

I followed this advice and found it worked very satisfactorily ... both on Bill's axle boxes and the 51L white metal offerings. :thumb I don't have afoot control ;)
Tim Lee

Triode
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Re: Waisted bearings for Bedford sprung W irons?

Postby Triode » Wed Jun 12, 2019 2:18 pm

billbedford wrote:Fix the axle box to the w-iron first, then use a 1.5 or 1.8 mm ball fraizer in a Dremel type mini drill. Place the cutter in the slot while it is stationary, then pulse the drill at a slowish speed until you have removed enough of the axlebox without cutting into the w-iron. A foot control for the drill will help here.


Is it necessary to do this while the W-iron etch is still flat (i.e. before the ends are folded up)?

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Guy Rixon
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Re: Waisted bearings for Bedford sprung W irons?

Postby Guy Rixon » Wed Jun 12, 2019 5:11 pm

Triode wrote:
billbedford wrote:Fix the axle box to the w-iron first, then use a 1.5 or 1.8 mm ball fraizer in a Dremel type mini drill. Place the cutter in the slot while it is stationary, then pulse the drill at a slowish speed until you have removed enough of the axlebox without cutting into the w-iron. A foot control for the drill will help here.


Is it necessary to do this while the W-iron etch is still flat (i.e. before the ends are folded up)?

I've done it when the etch is already folded and it worked. I was holding the assembly by the axlebox with my fingers.

billbedford
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Re: Waisted bearings for Bedford sprung W irons?

Postby billbedford » Thu Jun 13, 2019 7:51 am

Triode wrote:Is it necessary to do this while the W-iron etch is still flat (i.e. before the ends are folded up)?


Yes, you need the axlebox in its ultimate position, so that you can use the oval cutout in the w-iron as a 'pattern' for the hole in the axlebox.
Bill Bedford
Mousa Models
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