Peco Bullhead Points: in the flesh

[Pint of Adnams]

The message will get through eventually Martin...

Numerous photographs in the Windwood collection clearly show bullhead track layouts with square-on timbering as laid by the GER, and as was continued by the LNER...

 

It's a fact of history that the GWR did different whilst the other three followed the REA standards.

[Scottest]

Numerous photographs in the Windwood collection clearly show bullhead track layouts with square-on timbering as laid by the GER, and as was continued by the LNER...

 

It's a fact of history that the GWR did different whilst the other three followed the REA standards.

 

 

The above may be of value to help understand some pre-grouping challenges.

[martin_wynne]

Numerous photographs in the Windwood collection clearly show bullhead track layouts with square-on timbering as laid by the GER, and as was continued by the LNER...

 

It's a fact of history that the GWR did different whilst the other three followed the REA standards.

 

REA V-crossing:

 

[Bucoops]

Numerous photographs in the Windwood collection clearly show bullhead track layouts with square-on timbering as laid by the GER, and as was continued by the LNER...

 

It's a fact of history that the GWR did different whilst the other three followed the REA standards.

 

So for "my" line - Liverpool St to Shenfield way, I need bullhead that doesn't match the Peco points? Ugh

[gr.king]

I would have felt happier, with or without factual historical reason, had the timbering been square-on to the straight rails and I'm not especially pleased with the wide spacing of the timbers around the crossing, BUT, the fact remains that these OO BH points are a massive improvement on what has gone before and fortunately, for my currently anticipated needs almost every one will be flexed to form a curved point or a wye, helping (in my opinion) to fudge the apparent angle of the timbers. Given time constraints and the challenge of adding chairs the alternative of building by hand to try to produce exactly what I want instead simply does not now arise. Three (modest) cheers for Peco.

[hayfield]

So for "my" line - Liverpool St to Shenfield way, I need bullhead that doesn't match the Peco points? Ugh

 

 

Switch to EM then, as the society may have the orientation you require, or pop round and I will show you how to build them

[martin_wynne]

So for "my" line - Liverpool St to Shenfield way, I need bullhead that doesn't match the Peco points? Ugh

 

For bullhead you need square-on timbering for running-line crossovers and goods loops. You need equalized timbering (as Peco) for junctions, yards and sidings, and minor branch lines. Regardless of prototype location, period or company.

 

That's a gross simplification, but seemingly no-one wants to read a detailed explanation of design practice.

 

Martin.

Edited November 14, 2018 by martin_wynne

[Bucoops]

I'd love to switch to EM or even P4 but 1) It's taking me long enough to achieve anything in OO without adding in that extra complication, and 2) I want friends to be able to run stuff, or me to run stuff on friends' lines

[gr.king]

For bullhead you need square-on timbering for running-line crossovers and goods loops. You need equalized timbering (as Peco) for junctions, yards and sidings, and minor branch lines. Regardless of prototype location, period or company.

 

That's a gross simplification, but seemingly no-one wants to read a detailed explanation of design practice.

 

Martin.

 

Simplification perhaps, but it's a useful summary.

[PaulG]

I understand that Cheltenham Models has the Bullhead 4mm 00 slips and crossings in stock?

 

Paul

[Nile]

I can't see them on their website (CMC).

[Pint of Adnams]

For bullhead you need square-on timbering for running-line crossovers and goods loops. You need equalized timbering (as Peco) for junctions, yards and sidings, and minor branch lines. Regardless of prototype location, period or company.

 

That's a gross simplification, but seemingly no-one wants to read a detailed explanation of design practice.

 

Martin.

Oblate spheroids - I am looking at photographs now of sidings where the timbering remains perpendicular to the 'running' line all the way through the departure curve until the siding becomes parallel to the 'running' line. It was typical GE practice.

[martin_wynne]

Oblate spheroids - I am looking at photographs now of sidings where the timbering remains perpendicular to the 'running' line all the way through the departure curve until the siding becomes parallel to the 'running' line. It was typical GE practice.

 

If the siding is from a running line, that's what I would expect.

 

I said my comments were a simplification. What is very clear is that GER pointwork does not match the Peco geometry or its 4ft-1.5in gauge, so Peco turnouts won't be correct for GER, regardless of their timbering style.

 

Martin.

[Pint of Adnams]

If the siding is from a running line, that's what I would expect.

 

I said my comments were a simplification. What is very clear is that GER pointwork does not match the Peco geometry or its 4ft-1.5in gauge, so Peco turnouts won't be correct for GER, regardless of their timbering style.

 

Martin.

 

But it's a siding off a siding, both dead ends in the goods yard at Hadleigh (Suffolk), which is why I put 'running' in quotes to distinguish which line was which. 

[gr.king]

I had a look at the pre-production mock ups of the crossings and slips, presumably on 3D printed (white) "timber" bases at the Warley NEC show. I was less impressed than I had hoped to be. I have a feeling that the idea of preserving the scope for direct substitution for an existing Peco slip has been taken a bit too far. The old tie-bar positions seem to have been closely duplicated, with the result that the tips of the switch blades are well inboard from the V-crossings, and hence the slip radius is just as tight as it previously was. Given that the geometry / layout of this track system has to be a bit of a fudge in various ways anyway, then whether or not it happens to be strictly prototypical practice I would rather have seen the tips of the switch blades moved out as close as possible to the V-crossings so that the slip radius could be eased. I accept that the gain would be fairly small, the tips of some blades would have to be almost touching the ends of check rails, and that the change might oblige users to move point motors or operating linkages a little if substituting a bullhead item for the old flat-bottom type, but this is one area in which I think that in the interests of good running other matters should be of lesser priority.

 

My personal impression of the overall look was also that the timber spacing had been kept a bit too wide throughout, and that doesn't help to create any illusion of length or of shallowness of angle. I didn't understand the logic of the spacing either, as there appeared to be no timber directly under each crossing nose.

Edited November 27, 2018 by gr.king

[gr.king]

In an attempt to illustrate the case I was trying to make above, here are some pictures, although I apologize in advance for the grim quality!

Peco code 75 BH slip through glass, with unsuitable camera, and glaring white base:


My "soldered on copperclad, DIY lash-up" including all sorts of things technically "wrong" and cosmetically lacking, especially the grossly overdone tie bars, but stock runs through it very nicely:

This is actually approached by points with a nominal 3ft radius curve, the angle is very similar to Peco's, the length from V to V is just a touch more than Peco's but as you can see I haven't used up every last scrap of that length with the point blades as I could have done if I really had to, and I deliberately built the slip radius to 3ft (as closely as I could manage by manually drawing / setting out the curve). The timber spacing was intended to match that of SMP plain track as far as possible, which helps to put a few more timbers in than Peco have done, without in my opinion making the whole thing look like the timber-crowded continental version of track which I was trying to avoid.

Illustrating the similarity of length compared to the Peco plan and the near-matching angle compared to one of the new BH points:

 

I feel that the advantage of setting out designs by hand and building by hand is that you can tweak dimensions here and there so that the final product still does what it should, even if the precise dimensions fail to agree with values dictated by simple theory. One is also not restricted by the limitations of what can be done repeatedly and at low cost in a factory.

 

I imagine there is no hope that Peco might think again at this stage.
 

Edited November 27, 2018 by gr.king

[Merfyn Jones]

In an attempt to illustrate the case I was trying to make above, here are some pictures, although I apologize in advance for the grim quality!

 

Peco code 75 BH slip through glass, with unsuitable camera, and glaring white base:

Single slip nec rmw.jpg

 

My "soldered on copperclad, DIY lash-up" including all sorts of things technically "wrong" and cosmetically lacking, especially the grossly overdone tie bars, but stock runs through it very nicely:

Single slip diy.JPG

This is actually approached by points with a nominal 3ft radius curve, the angle is very similar to Peco's, the length from V to V is just a touch more than Peco's but as you can see I haven't used up every last scrap of that length with the point blades as I could have done if I really had to, and I deliberately built the slip radius to 3ft (as closely as I could manage by manually drawing / setting out the curve). The timber spacing was intended to match that of SMP plain track as far as possible, which helps to put a few more timbers in than Peco have done, without in my opinion making the whole thing look like the timber-crowded continental version of track which I was trying to avoid.

 

Illustrating the similarity of length compared to the Peco plan and the near-matching angle compared to one of the new BH points:[

attachment=1081986:Single slip comparison.JPG]

 

I feel that the advantage of setting out designs by hand and building by hand is that you can tweak dimensions here and there so that the final product still does what it should, even if the precise dimensions fail to agree with values dictated by simple theory. One is also not restricted by the limitations of what can be done repeatedly and at low cost in a factory.

 

I imagine there is no hope that Peco might think again at this stage.

 

 

I understand the problem with having the switch tips further from the crossing nose. It will be more to do with a double slip where the nearer you get to the nose the less room you have for 2 switch blades with the overscale switch opening you have for 00 wheels.

[Zunnan]

That illustrates where the Peco slips aren't ideal. If only they'd lengthen the switch blades down towards the crossings so that the radius through the slip can be eased a bit, the basic geometry can remain essentially the same overall but you do have the issue with a double slip and the switch blade tips. I was waiting to see the slips before making a decision on what direction to take with the next layout, but I think I'll be waiting a bit longer to see if the EMGS expand the ready to plonk trackwork to include slips. I'm not sold on the 00 bullhead slips now that there is a 3D version to look at, it may just be the light material used for the timbers making it more obvious than with a darker moulded plastic, so I'll hold fire a bit longer until the production samples land before I jump in one direction or another.

[gr.king]

Space for the inner switch blades on the double slip doesn't appear to be lacking until their tips are little more than one timber width away from the wing rail knuckles if my dismally poor photograph of the double slip is anything to go by, so even with the wide opening used in OO that does not seem to make it necessary to have them so far away from the crossing. Maybe current factory procedures dictate the arrangement, or is it possibly the case that either not enough imagination has been used or that Peco design commandments are set in stone in this respect?

 

Does anybody have clearer photographs by the way?

[martin_wynne]

Space for the inner switch blades on the double slip doesn't appear to be lacking until their tips are little more than one timber width away from the wing rail knuckles if my dismally poor photograph of the double slip is anything to go by, so even with the wide opening used in OO that does not seem to make it necessary to have them so far away from the crossing. Maybe current factory procedures dictate the arrangement, or is it possibly the case that either not enough imagination has been used or that Peco design commandments are set in stone in this respect?

 

The blade tips must be far enough apart that there is no possibility of wheel backs touching the open blade tip, causing a short-circuit. The amount of gauge-slop in the 00 RTR settings and the variation in back-to-backs requires a significant gap between the blade tips. It is also necessary to have space on the stretcher bar for the two blade fixings, which must be insulated from each other.

 

Martin.

[dhjgreen]

Does anybody have clearer photographs by the way?

Here

http://www.rmweb.co.uk/community/index.php?/topic/139765-new-oo-bullhead-crossings/?p=3376764

[gr.king]

The blade tips must be far enough apart that there is no possibility of wheel backs touching the open blade tip, causing a short-circuit. The amount of gauge-slop in the 00 RTR settings and the variation in back-to-backs requires a significant gap between the blade tips. It is also necessary to have space on the stretcher bar for the two blade fixings, which must be insulated from each other.

 

Martin.

Understood, but the Peco design does not appear to approach the permissible limit in this respect. Whatever the case, it looks as if I will get best running through the single slip that I shall need in due course if I stick to my original intention of building another one for myself. It will at least have some cosmetic chairs this time. Although the standard right and left turnouts are a real time-saving bonus I had never expected Peco to come up with slips in time to suit my requirements anyway, so I feel no hardship - in fact I may enjoy not spending the money on a Peco slip.

Edited November 28, 2018 by gr.king

[Chamby]

The PECO slips are looking pretty much as I expected. As with the points, they are a bit of a curate’s egg, very much better than the existing streamline offering, but not quite what they could be, if they are aiming for prototypical accuracy.

 

The EMGS/PECO points in development provide an interesting contrast. The EMGS guys were quoting a price for their points that is in the same ballpark as the PECO bullhead equivalent. Makes me think it might be viable for someone to do the same thing in 16.5mm... surely they would sell at least as well as an EM gauge version?

[AJ427]

There is of course nothing to stop Peco from expanding this range and introducing more prototypical formations once they've got over the commercially logical nitty gritty of replicating the existing geometry. I'm not holding my breath though.

[Joseph_Pestell]

 

The EMGS/PECO points in development provide an interesting contrast. The EMGS guys were quoting a price for their points that is in the same ballpark as the PECO bullhead equivalent. Makes me think it might be viable for someone to do the same thing in 16.5mm... surely they would sell at least as well as an EM gauge version?

 

Well, some of us think so.

 

Problem is in finding, in the UK, a manufacturer who can (or wants to) do it. I don't know if EMGS looked for any alternative partners for this project but PECO would certainly not want to be doing this for a direct trade rival.