Messing with FB

AndyB

Member
For a variety of reasons I've been mucking about with printing FB track and turnouts. This is supposed to be a Pandrol baseplate.

Screenshot (28).png

It's quite experimental and intended to be FDM printed. The missing Pandrol clips will be bits of wire, maybe :)
 
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AndyB

Member
Thread starter
And here is a test print (00). No clips I'm afraid. I might be able to apply a squiggle of filament but I'm not sure it's worth it. Other than a blast of grey primer both sections are identical. These are 12" timbers and the baseplates are the wide ones used in turnouts. The timbers are really thin to speed up the print process.

The outside screw heads have merged into the clip holders. I might be able to expose them a bit better. These were printed with a 0.2 mm nozzle on a Folger printer with tweaked resolution. The image is not magnified so it represents how it might look from normal viewing distance.

DSCN5391.JPG
 
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Martin Wynne

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@AndyB

Hi Andy,

That looks good. :)

Is that standard PLA, or toughened, or something else? I found that standard PLA gave better detail, but the rail fixings were too fragile in 4mm scale.

Which slicer software are you using? What settings and temperature? How long does it take per timber using a 0.2mm nozzle?

cheers,

Martin.
 
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AndyB

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@AndyB

Hi Andy,

That looks good. :)

Is that standard PLA, or toughened, or something else? I found that standard PLA gave better detail, but the rail fixings were too fragile in 4mm scale.

Which slicer software are you using? What settings and temperature? How long does it take per timber using a 0.2mm nozzle?

cheers,

Martin.
Hi Martin,

It's pla/pha and I agree regular pla gives better results with small details. I'll try a pla print for comparison.

I might have found a solution to the lack of strength with pla. The idea is to make the jaws a loose fit on the rail and offset them slightly alternately in and out. The rail is effectively weaving between the jaws.

Slicer is Slic3r and I'm dictating the layer heights.

Temperature is 205. It should just start to run out of the nozzle just before it reaches temperature.

I'll need to take an accurate time. I think its around six minutes for four timbers but they are only 0.45 mm thick. I would print them 1.2 mm with a very low density fill for real turnouts.

Cheers,
Andy
 
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AndyB

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Thread starter
This is actually bullhead. The rail weaving method seems to work well with flat-bottom rail and I wondered if it could also be applied to bullhead rail. Based on a sample of one :) it seems to. The rail is gripped well and it is vertical. Of course all the other bullhead cosmetics bit would have to be added. The advantage with this method is that the chair jaws are not required to flex to support the rail (it's the rail that's flexing rather than the jaws.) Flexing the jaws can break them.

This is printed in PLA/PHA but I think it should work just as well with regular PLA.

DSCN5424.JPG


This visualization might give a better view of what's going on.

BHtest.jpg
 
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AndyB

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This is the flat-bottom version above printed in PLA. As usual the camera is very cruel but without any magnification it could easily pass for an injection molding, even more so after a coat of paint :)

The rail-weaving thing seems to work quite well. I have not detected any tendency for the chairs to break when the rail is inserted. I should really make some turnouts now to see if it all works in practice.

BTW, I'm happy to share any of my models if anyone wants to give it a shot.

DSCN5435.JPG
 
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Location
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Builder of Finescale Signals in 2mm scale to 7mm scale, Trackwork, Turnouts and Layouts.
Hi,
No, I'd be looking at either Karlgarin code 82 or Peco 83
 
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Location
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Builder of Finescale Signals in 2mm scale to 7mm scale, Trackwork, Turnouts and Layouts.
The Karlgarin 82 has a slightly wider foot than Peco 83, just enough to make it difficult to fit to Peco Pandrols. I think I've detailed the dimensions of the Karlgarin rail before, Martin said it seemed quite close to prototype.

Head is 1.10mm, foot is 2.00mm, web is 0.70 (I think)
 
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Martin Wynne

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Martin said it seemed quite close to prototype.

Head is 1.10mm, foot is 2.00mm, web is 0.70 (I think)

@Stephen Freeman

For what prototype is that? For what scale? If 4mm/ft it looks like some American heavy rail. If 7mm/ft it might do for some narrow-gauge.

If you quote me, please include the context. :)

For UK BS-113A FB rail in 4mm/ft scale the dimensions are these:

Head width: 2.3/4" == 0.92mm (same as bullhead)

Foot width: 5.1/2" == 1.83mm

Web thickness (at mid-height): 25/32" == 0.26mm

Rail height: 6.1/4" == 2.08mm = 0.082" - code82

cheers,

Martin.
 
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Thanks Stephen.
Foot width for FB-109, BS-110A, BS-113A rails is all 5.1/2" which scales to 1.83mm in 4mm scale, so 2mm is not too far out.
The problem with existing supplies of Code 82/83 is not the height (code number) but the head width. Do you know the head width of the Karlgarin rail?
cheers,
Martin.
 
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Martin Wynne

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Matt M.

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Australia
Head width is 0.044" for 82/7.
0.053" for 100/7
0.056" for 125/7

They were designed for 7mm scales and are very accurate for those.
The profiles are a good match for NSWGR rails.

Matt M.
 
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Location
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Builder of Finescale Signals in 2mm scale to 7mm scale, Trackwork, Turnouts and Layouts.
Head width is 0.044" for 82/7.
0.053" for 100/7
0.056" for 125/7

They were designed for 7mm scales and are very accurate for those.
The profiles are a good match for NSWGR rails.

Matt M.
I know they were intended for NG but there isn't (IMHO) a good enough code 82 otherwise. I normally use code 83 C&L code 82 used to have a very thin head, good if he's changed it but doubt it. Code 83 has a head comparable to Bullhead 75
 
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Matt M.

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Location
Australia
Hi Stephen, I can't comment on the 82/7 as it wasn't what I needed at the time but they are
the widths listed by Karlgarin.

The 100/7 and the 125/7 were decent compromise for most the 31 flat bottomed rail sections
in use in 1936 on the NSWGR when modelling in 7mm. The 125/7 is a little narrow on the foot
when you get to 100lb rail but not badly so.

Back in 2010 when I was corresponding with Richard McLeish he did point out that one
of the reasons for having these sizes of track produced was to overcome the narrow heads on
a lot of what was available when used in 7mm.
Also using the high-Ni nickel silver as the material of choice.
But they were the best compromise of head and foot widths for height that would cover
a good number of prototype rail sections that he could come up with.

Matt M.
 
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AndyB

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Thread starter
The depth of the base is also an important dimension and it's not so easy to measure, and then there are the tolerances in the rail itself. Typically the available values are only nominal. There can be significant variations between samples. Another thing I've noticed is a certain amount of asymmetry which can alter the track gauge depending which direction you feed the rail into the clips.

Weaving the rail helps to accommodate some of these variables and prevents the clips from being over stressed but the clips really have to be designed for a specific rail supplier and that's likely to require a bit of trial and error with the clip design using actual rail samples.
 
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Martin Wynne

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Another thing I've noticed is a certain amount of asymmetry which can alter the track gauge depending which direction you feed the rail into the clips.
@AndyB

Hi Andy,

That also applies to the Plug Track chairs and bullhead rail. I suggest making a note of which way round you are using the rail and keeping to it. Then after testing, a final gauge adjustment can then be made if needed:

chairs_gauge_adjust.png


There is always more to everything than meets the eye. :)

cheers,

Martin.
 
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AndyB

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Hi Martin,

That's a good idea.

I'm also tempted to make go/no-go gauges. I could try printing them but I suspect they would really have to be in steel and that could be a bit tricky :)

Andy
 
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