Experimental Plug Track - file exports for 3D printing

Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
I cut the outside sprues off prior to glueing down since it was not need for strength and would be a pig to remove.
@timbersgalore

Hi (no name),

Looking good. :)

I see that you have full-depth webs below the rails. How are you planning to remove them after tracklaying? Any sort of cutter or blade will force the timbers apart. A Dremel disc might be an option, but tedious to do. Or if you leave them in place how will you disguise them in the ballast - the top of the ballast is normally level with, or a fraction below, the timber top. Flat-bottom rail is wider than bullhead and closer to the timber, so tends to hide such webs. But for bullhead track the daylight between the rail and the ballast is a characteristic feature:

daylight_below_bh.jpg


(This question also applies to all the commercially available laser-cut timber bases -- but when I ask it the answer is always silence. :( )

For the Plug Track I intentionally placed the sprues outboard of the sleepers to make prototypical ballasting possible below the rails. I think you would do better to remove the webs before tracklaying (or not have them in the first place) and leave the sprues in place. If you don't apply any glue to the sprues they are easy to remove after tracklaying by holding a pair of flush cutters vertically (Xuron cutters, supplied with the resin printer).

For the FDM printed timber bases the sprues are omitted, but the webs and timber flanges which replace them are only 1.5" thick (0.5mm in 4mm scale) and easily hidden under the ballast.

p.s. notice the GWR chairs in the pictures. Which for pointwork are fixed with plain square-head coach screws (unlike REA chairs with tapered ferrules and bosses for the screws). But for plain track the GWR chairs use through-bolts from below with nuts on top. So ideally you need two types of GWR S1 chair -- one with plain screw-heads as above for use in pointwork, and one with a bit of bolt showing above the nut for plain track:

gwr_nuts.jpg
:)

Alternative bolt-tops will be an option in Templot for the GWR chairs, but oh my, there is such a long way still to go.

Hardly anyone will notice the difference in 4mm scale, but I have to think ahead for 7mm and the larger scales.

cheers,

Martin.
 
_______________
message ref: 2482

timbersgalore

Member
Location
England
Martin
Thankyou for you comments. I placed the web under the rail as it seemed to work on the pre made bases I have used. I assummed I could hide it with ballast but I have never got as far as balasting any track. I will give the spruces a try.

How far to go on detail when it is hard to see with the nacked eye? If I can sucessfully print it I will have a go at modeling it.

Timbers
 
_______________
message ref: 2486

Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
How far to go on detail when it is hard to see with the naked eye? If I can successfully print it I will have a go at modelling it.
@timbersgalore

Hi Timbers,

Are you referring to my note about the nuts on GWR chair bolts?

That was partly in jest, at least for 4mm scale.

But -- the bolts are 1" diameter and might typically protrude above the tightened nuts by say 1/2". That scales to 0.17mm in 4mm/ft scale.

Your Phrozen 4K printer claims a resolution of 0.035mm, so that would correspond to 5 layers in your sliced model. Even on my Elegoo printer with 0.05mm resolution it would be 3 or 4 layers. So it should be doable.

However I will let you off modelling the bolt thread. :)

In 7mm scale and above it would definitely be doable, so I must include it in the Templot export. The nuts will be generated at a random angle, and 1/2" of bolt will optionally protrude above them on the GWR S1 chairs.

You may have noticed that the screw-heads on the REA S1 and L1 chairs are also generated at a random angle:

random_screw_heads.png

(L1 chairs unfinished)

Notice how much more prominent the REA chair fixings are, compared to GWR.

GWR L1 bridge chairs have only 2 screws on diagonally opposed corners (right-hand side when looking towards the rail). Here's 4 of them:

gwr_bridge_chairs.jpg


They always look as if they have a screw missing!

Not used on plain sleepers, so they are always screws not bolts. Having written the dreaded word "always" I now have to leave some space for someone to post a photo showing GWR L1 chairs fixed with through-bolts. :)






cheers,

Martin.
 
_______________
message ref: 2487

Phil O

Member
Location
Plymouth.
That may be due to the wrong fishplates, there are rails drilled to 4 1/2 inch centres and rails drilled to 5 inch centres, there are fishplates for both, but if there's a mismatch then only the 2 centre bolts fit. More commonly is one rail has been replaced and you end up with 3 bolts.
 
_______________
message ref: 2490

timbersgalore

Member
Location
England
I am amazed at the level of detail acheivable by the Sonic mini 4K. I think it is helpful to model the detail as it helps to get the big stuff right. Martin thankyou for the chair pictures. Mine arn't as good as the old track near me is still part of network rail. I have the drawings for the chair plan views but I am having to work out the cross section.

I have refined my ordinary char and made a stab at the SS chair:-
chair_OC.JPG

chair_SS.JPG

printed on a phrozen sonic mini 4K. Aqua 4K resin, XY 0.037mm Z 0.030mm.
 
_______________
message ref: 2492

timbersgalore

Member
Location
England
This afternoon I print some chairs from the templot files. I first had to fix and unsupported island formed at the bottom of the rail clip.

templot_chairs.JPG


A you can see I droped them on the floor!

Timbers
 
_______________
message ref: 2495

Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
I print some chairs from the templot files. I first had to fix and unsupported island formed at the bottom of the rail clip.
@timbersgalore

Hi Timbers,

Looking good. :)

Can you clarify which part you mean by the rail clip?

s1_inner_detail.png


In Templot terminology, the part of the inner jaw shown green is called the "stand". As far as possible allowing for model wheel flanges it follows prototype dimensions.

The part coloured blue is called the "grip" and has to match the model rail section, with no regard to the prototype.

I'm aware of a bug in the area circled, and it's on my list to be fixed.

Looking at your print, you seem to have lost the angled fillet between the jaw and the rail seat:

edit: see later posts.

s1_inner_fillet1.jpg


This what Templot generates in that area:
s1_inner_fillet2.png

which is also in the generated STL:
s1_inner_fillet3.png


So it's a bit of a mystery where it has gone, or appears to have gone, in your print? Maybe it is an optical illusion.

I'm aware that those side fillets on the jaws are a poor representation of the radiused fillets on the prototype, and they are also on my list to do something about. When I did the design originally I was thinking in terms of FDM printing. The resin printers can create higher resolution results, so need rather more work on the design.

cheers,

Martin.
 
_______________
message ref: 2496

Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
That may be due to the wrong fishplates, there are rails drilled to 4 1/2 inch centres and rails drilled to 5 inch centres, there are fishplates for both, but if there's a mismatch then only the 2 centre bolts fit. More commonly is one rail has been replaced and you end up with 3 bolts.
@Phil O

Hi Phil,

Fishplates with bolt holes at 5" centres are intended for flat-bottom rail. Do they fit ok on bullhead? They are 20" long (as opposed to 18" for bullhead) so wouldn't easily fit between the chairs at a bullhead rail joint. Flat-bottom rail fixings do not obstruct the fishplates to the same extent, and the fishplates can be longer. If an 18" fishplate is drilled at 5" centres, the end holes would be very close to the end of the fishplate.

We need the full info on this because Plug Track will need it's own 3D printed fishplates. The standard H-section locking fishplates from the trade won't work because the rail needs to slide into them. Whereas Plug Track rails are pressed home vertically. The fishplates will need to be attached to the side of the rail rather than inserted from the end. The insulator lug on the back of the fishplate will occupy only half the rail height (and can be cut off where the fishplate is on a dummy joint).

cheers,

Martin.
 
_______________
message ref: 2497
Hi Martin,

This is what I get displayed in a 32-bit version of Chitubox after uploading to the "fix" service linked on the .DXF export window.
1630876748175.png

No fillet, but as you can see I generated some deep plugs to go through to the trackbed layer.
This was before uploading to the "fix" service
1630877115767.png

Fillet appears to be there before fixing.
Hope this helps
Steve
 

Attachments

  • OO-SF-S1-Chair.stl
    4.7 MB · Views: 8
  • OO-SF-S1-Chair_fixed.stl
    2.8 MB · Views: 9
_______________
message ref: 2498
Last edited:

Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
@Steve_Cornford

Hi Steve,

Thanks for that. This is what I get back from the repair service:

s1_inner_fillet_fixed.png


So clearly that bug in the file is throwing the repair. I need to get the bug fixed.

And apologies to Timbers for suggesting he might have a problem there. I should have noticed it in my own prints, see earlier in this topic:

https://85a.uk/templot/club/index.php?threads/229/post-838

cheers,

Martin.
 
_______________
message ref: 2499

timbersgalore

Member
Location
England
Martin
island.JPG


The problem it shown by the Red arrow. When the chair is printed from the bottom up the pyramid tip is not supported for several layers. The easiest fix is to introduce a horozontal slab from the tip to the chair.

templot_fixed.jpg



On my version I decided it was better to go for more fill to better support the rail.
rail support.jpg




I have been trying to work out the nominal dimensions of the rail (bull head from the 4mm society). I tried looking at the " 3-D custom rail section" dialogue in templot. Most of it makes sense but could not work out fish angle. Are the initial values shown based on anything? eg the last used non custom option.


Reflecting on how much work is going to be required to get Templot to reliably generate all the chairs types needed for a complete turnout I wonder if it would be better to produce the chairs separately. Placing the sockets on the template is a tremendous step forward even if only for the ordinary chairs.

Timbers
 
_______________
message ref: 2500

Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
@timbersgalore

Hi Timbers,

Many thanks for finding that. The angle on the underside of the key is from the prototype -- the key is tapered end-to-end so that it can function as a wedge, but is symmetrical front to back so that it can be used either way up. The model key gets distorted in two ways -- I added a rail-side taper at both ends to ease rail threading, and the rail-side is further modified to match the thicker model rail web and fishing angle. There is an option to fill below the key, but as it's not prototypical I left the default to off:

fill_below_key.png


I will modify the bottom of the unfilled key so that it is horizontal, or angled a fraction the other way.

The fishing angles shown for the model rail sections are my best estimate from the samples available. It is obviously better to err towards a steeper angle, rather than risk fracturing the chair if the angle is too low. Likewise the height of the rail foot. If you have access to better info please do share it. Bearing in mind that model rail batches do vary, so it would be wise to leave a bit of leeway in the settings. I have added a rail-fit tweak (see above) which allows for small changes in the rail web thickness.

Reflecting on how much work is going to be required to get Templot to reliably generate all the chairs types needed for a complete turnout I wonder if it would be better to produce the chairs separately. Placing the sockets on the template is a tremendous step forward even if only for the ordinary chairs.

My aim is that Plug Track should be available to any Templot user who wants it, without needing CAD design skills. 3D printers can be purchased or accessed via friends, but the skills to design a chair from prototype dimensions are not so easily acquired. Anyone who wants to source or create their own chairs is obviously free to do so, but I want Plug Track from Templot to be usable as a self-contained system available to anyone.

It also needs to work in any chosen scale -- so that for example the handful of folks using 5.5mm/ft can also have chaired bullhead if they want it (and can find some suitable rail). And likewise at any desired crossing angle, and any desired flangeway gap -- crossing chairs and check rail chairs for say P4 wouldn't be usable in EM. Finding crossing chairs for a 1:7.63 or 1:9.5 crossing in S scale anywhere else seems extremely unlikely, but that might be the only angle which fits the site. On a model we can't use the prototype big 'ammer to make stuff fit, the chairs are in fragile resin, not cast iron. :)

cheers,

Martin.
 
_______________
message ref: 2501

timbersgalore

Member
Location
England
HI Martin
Regarding the rail and grip on it. I found the templot chairs quite a sloppy fit on the 4mm society rail. I would say you have overdone the allowance for rail side taper. It would be helpful the know what are the profile numbers for "C&L / EMGS/ S4Soc code 75" rail. What is "Fish centre" How is the fish angle measured (between what).

The accuracy I am achieving with the sonic mini 4K is amazing so far what I draw is what I get.

I have kept the grip parallel to the rail and find my chairs easier to thread than the plastic chairs form the 4mm society. I am using a web thickness of 0.4mm

I am in the throws of making a "test of method" track sample. It consists of a GWR 12ft heel V7 with return curve. Rather than post detail here it is probably better I start another topic elsewhere. I will be using a laser to cut the sleeper base as I get far superior results compared to the FDM printers I have (I have three!).

Timbers
 
_______________
message ref: 2502
Hi Timbers,
As you have a laser, have you thought of cutting a cork(or ply) trackbed layer just with sockets, then make the chair pegs deeper. That way you dont need to have sprues on your timbers, and you can cut the timbers with the long edge parallel to the grain. Then the longer pegs locate the timbers onto the trackbed layer.
Good luck with your "test of method"
Steve
 
_______________
message ref: 2503

Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
What is "Fish centre" How is the fish angle measured (between what).
@timbersgalore

Hi Timbers,

Tightening the fishbolts wedges the fishplate between the angled fishing faces, putting the rail web in tension. Ideally sufficient to ensure that it doesn't become unloaded under the traffic load. Otherwise the bolts would work loose:

fish_angles.png

Note that there is a space between the back of the fishplate and the rail web, otherwise the system doesn't work. The same applies to the fishwashers and spacer blocks which are used on bolted crossings.

The fish angle on all UK REA bullhead and jointed flat-bottom track is 1:2.75. Here is the way the rail is dimensioned:

2_120508_000000000.png


BS-95R prototype dimensions in red. The dimensions in black relate to a sample of C&L rail from AndyB at the time that drawing was made, and taken from this old 2016 topic:

https://85a.uk/templot/archive/topics/topic_2734.php#p29639

You can see that the all-important fishing faces are dimensioned from their intersect on the rail section centre-line. The head and foot depths can then be derived if needed.

n.b. the dimensions in black are NOT metric equivalents of the dimensions in red.

Here is a bit of Exactoscale steel rail, and you can see why I estimated the model fish angles to be much steeper than the prototype:

2_111752_390000000.jpg


I found the Templot chairs quite a sloppy fit on the 4mm society rail. I would say you have overdone the allowance for rail side taper. It would be helpful the know what are the profile numbers for "C&L / EMGS/ S4Soc code 75" rail.

Thanks for the feedback. The chairs which I printed here are a nice close fit on the Exactoscale steel rail and maybe a fraction loose on the C&L nickel-silver rail which I have here. But in both cases the rails are from old stock which I have had for many years, so feedback about current production rail is valuable.

I want to emphasize again that everything related to 3D track which I have released so far is utterly experimental. There is no guarantee that any of it is correct, or workable, or will remain unchanged in a final release. I released it only so that folks could see my direction of travel, maybe join in with some experiments, and provide valuable feedback. There was no intention that it should be used for any actual modelling, because almost certainly it is wrong. The object is to first prove the concept of Plug Track, and if successful only then go back and make it an accurate model of anything. :)

If/when the whole thing works, I will then make fresh drawings as above showing how everything is dimensioned and provide some recommended settings. The settings in the program at present are not a recommendation of anything.

cheers,

Martin.
 
_______________
message ref: 2504

Derek

Member
Location
UK, Midlands
Hello Martin

I'm sorry to ask this slightly o/t question, but regarding the fishplates- why does it need the gap behind to work properly? I accept what you are saying and that it does, I'm just trying to understand from an engineering point of view why that is. I can understand the web being put under tension as an aid to locking the tapered edges together, it's just the space at the back that puzzles.

Many thanks
Derek
 
_______________
message ref: 2505

timbersgalore

Member
Location
England
Thankyou Martin
Than helps me a great deal. I can now see that the sample in fornt of me is undersize. My web is 0.40mm (measured by filling off the head/bottom then micrometer).
Timbers
 
_______________
message ref: 2506

Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
Hello Martin

I'm sorry to ask this slightly o/t question, but regarding the fishplates- why does it need the gap behind to work properly? I accept what you are saying and that it does, I'm just trying to understand from an engineering point of view why that is. I can understand the web being put under tension as an aid to locking the tapered edges together, it's just the space at the back that puzzles.
@Derek

Hi Derek,

No need to be sorry about asking questions. :)

The space behind the fishplate allows for routine maintenance -- the fishplates need to be tightened up (move inwards) as the fishing faces become worn. Which they will do under heavy traffic -- it is interesting to stand close to a fishplated rail joint and watch what happens as traffic rolls over it.

If the fishplate were to bottom against the rail web, there would be no means to tighten it further, and no way of knowing that the correct tension force had been applied to the rail.

cheers,

Martin.
 
_______________
message ref: 2507

Martin Wynne

Admin
Location
West of the Severn UK
Info
Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add helpful replies.
Than helps me a great deal. I can now see that the sample in fornt of me is undersize. My web is 0.40mm (measured by filling off the head/bottom then micrometer).
@timbersgalore

Hi Timbers,

I think you mean oversize? The prototype rail web is 3/4" thick, which scales to 0.25mm in 4mm scale.

All model rail tends to be oversize in web thickness -- although C&L have recently introduced a new code 131 bullhead rail for 7mm scale which has a commendably thin web.

cheers,

Martin.
 
_______________
message ref: 2508
Top