Experimental Plug Track: 3D-printed, CNC-milled, laser-cut

Martin Wynne

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The correlation is pretty good in my opinion, at least for a B7 curved to 2400mm.
@Steve_Cornford

Hi Steve,

Yes, a timber in a curved template is identical to the same timber in a straight turnout. That is how Templot draws curved templates.

I already have a function to bunch template timbers together side-by-side. I haven't had any use for it since the 1990s when I was experimenting CNC milling timbers from copper-clad laminate sheets. It will be commented out in one of the earlier files -- I just need to find it again, or re-write it. It is needed to allow a set of template timbers to be resin-printed on the small build plate. If you set the timber separation to zero the outlines would coincide, but it needs some careful thought on setting the cutter kerf width.

Thanks for the feedback. :)

Martin.
 
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Martin Wynne

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I had a similar thought. Why not just put circular holes in the sleepers to accept a cylindrical pip on the bottom of the chair and let the rail align the direction of the chair?
I'm pretty sure Martin will have considered this and abandoned it for several good reasons :)
(Crossing chairs would probably need two pips)
@AndyB

Hi Andy,

I've been asked this several times, but no-one has explained what benefit accrues by discarding information which Templot already knows (the angle of the chair on the timber) and leaving it to be determined by the rail? And if you then say two pips that argument is destroyed anyway.

The intention is that the plug chairs are a firm press fit in the sockets, in most cases not requiring any adhesive, and setting the gauge in the process. Once pressed home it wouldn't be possible for the rail to rotate the chair into alignment. So with a cylindrical plug you would be relying on the chair being aligned by means of the ungauged loose rail before pressing it home. The chances of getting some misaligned chairs strikes me as very high.

Having a rectangular plug makes it much easier to adjust the tolerances for a good press fit. In comparison two cylindrical plugs would be very difficult to tolerance.

As far as I can see the only advantage to a cylindrical plug is that you could drill the holes in home-made timbers. But because they also set the gauge, it would be necessary to do the drilling on a CNC miller or jig borer for sufficient accuracy.

The edge of the chair base is very thin and fragile, so adding a rectangular plug provides support as close the the edge as possible.

cheers,

Martin.
 
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Martin Wynne

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They recommend cutting the sockets first then the timbers, in particular this service cuts blue lines first, then green, so it would be really useful as you suggested to have a SOCKOUTL layer as well as a TIMBOUTL layer, with colour choice.
@Steve_Cornford

Hi Steve,

I have added 6 new layers for the 2-D DXF so that colours can be changed or elements omitted:

dxf_dialog_228x.png


Also a 3-D option to create tall headless locator plugs for the trackbed. These are a looser fit in the timbers so that the timbers can be dropped over them, and then removed. Presumably you would make the sockets in the trackbed a fraction smaller so they are a firmish fit in the trackbed.

As you can see the dialog is getting too large and crowded. :( I need to move stuff to a set of separate tabs.

Does anyone want the template > symbols... included in the 2-D DXF? It might be useful to have pre-drilled holes in the trackbed below the rails for the dropper wires and/or the dropper ID text marked?

cheers,

Martin.
 
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Martin Wynne

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With several additional combo drop-downs the list has got a lot longer.

To make setting the colours a bit easier I have added some buttons below the list to use as a precursor to making the required settings:

combo_colours.png


I have changed the omit layer option from "none" to blank, to make it more obvious in the list.

Note that the radial centres option always defaults to omit. Otherwise the fit extents function in CAD programs will zoom out to include all the radial centres, potentially making the actual track plan a tiny smudge on the screen. If the radial centres are needed in the file, they must be explicitly turned on.

This stuff has remained virtually unchanged for over 20 years, it feels strange to be returning to it now and making changes. :)

No doubt if I was starting from scratch I would do things very differently.

Martin.
 
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20 years!
How many boiled eggs?

Plug Track
Chairs are produced as separate components from the timbers.
You have illlustrated how to produce a "raft" of S1 chairs by manipulating sleeper spacing and gauge and adding a background shape.
By "raft" I mean the small group of chairs that are able to fit as a module onto your build plate, that you then "cloned" 5 times

How about adding this as a separate function so that one could produce a raft of one particular chair type or a "set" of related chairs.
For Example
S1 chairs
L1 Chairs
Set of Check Rail Chairs (CCL,CC,CCR)
Slide chairs / Switch chairs
1:5 Crossing Chairs.
1:6 Crossing Chairs
etc
A bit like the plastic sprues we are used to at the moment

But as usual I expect your are 2 steps ahead of me already

Steve
 
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Martin Wynne

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How many boiled eggs?

How about adding this as a separate function so that one could produce a raft of one particular chair type or a "set" of related chairs.
@Steve_Cornford

Hi Steve,

You can do most of that now. Here's a raft of mostly L1 bridge chairs -- or it would be when I get the L1 chairs finished:

bridge_chair_bunching1.png


which could be cloned on the printer (with timbers omitted of course).

That's part of an E-16 template in EM with the gauge reduced to 10mm, and the timber fill spacing changed to 14":

bridge_chair_bunching2.png


Blank off and shorten the template in the usual way to get what you want.

In the same way you could get rafts of other special chairs.

I intend to do everything you are asking for -- but not just yet. I sense that you are getting impatient for the special chairs? :)

Me too, but I dare not leave off the timbering bricks and DXF interface until I have got all I want to do done. At present there are dozens of loose ends and if I leave off now I shall be in the same boat I was in with 227a -- powerless to release an update because I had left unfinished and forgotten about too many loose ends. It took 4 program updates to sort all that out, and there is still the silly diamond-crossing mistake not yet fixed.

As soon as I can FDM print a defined timbering brick from within a track plan, with all the on-off options working, I will have somewhere to put the special chairs and will be able to test them as I create them.

p.s. boiled eggs total = +1 half an hour ago. :)

cheers,

Martin.
 
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Hi Martin,
No not impatient, just excited! :):D

As a retired programmer (54 years of coding behind me) I really appreciate the lifetime of effort you have put into Templot, and the way you are evolving the software to take advantage of modern technology.

The chips from the lasercut plywood sockets are strangely reminiscent of the "chads" from punched cards that I remember from my early days of 1900 PLAN programming!

Thanks for the E-16 EM illustration.

Steve
 
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Martin Wynne

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Posting this now in case I forget to mention it later.

There was some confusion between the tickboxes for 3-D DXF layer options, and the previous method of setting the DXF colour to "none" to omit 2-D layers.

To avoid re-writing all the 2-D stuff, I have removed the duplicated tickboxes and reverted to the drop-down method for all except stuff which can only be in 3-D files (chair jaws, keys, etc.).

To make it easier to omit a layer with a single click, you can now do that by right-clicking on the drop-down combo.

I've added a note at the top of the dialog, and to the mouse-hover hint:

dxf_right_click.png


Omitted layers now show with the colour showing blank, to make it more obvious in the column.

The layers and colours have no meaning in STL files, but elements are omitted from the file by the same means. Set any colour to include an element.

Martin.
 
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Martin Wynne

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Please do not send requests for help direct to me via email.

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@Steve_Cornford

Hi Steve,

Two more layers for the 2-D DXF: :)

kerf_layers.png


These modify the outlines to allow for the kerf width of the laser cutter (or any other cutter), i.e. outside the finished timber outline, inside the finished socket size. Also the timber extension marks are ignored, so don't need to be rebuilt in the generator.

It's intended that you would switch one or other layer off for any given file, but can have both outlines in the file if you wish (and is the default).

I didn't want to do this with a zero-able offset, so that both outlines can be on by default, as a reminder of the setting option. You wrote:
the laser burns a 0.2mm line
so I have set this as the default, i.e. 0.1mm offset (independent of model scale).

n.b. This is not intended to be used for socket tolerancing (otherwise the timber outline size might be wrong). After setting the kerf width to give the required timber size, adjust the plug/socket fit using the settings on the chair/socket fit... button.

The kerf layers are ignored in 3-D files.

cheers,

Martin.
 
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timbersgalore

Member
Location
England
Wow - just what I been waiting for.

I have been making track for a while using my laser to cut the sleapers and then building the track on top using traditional methods(2mm and 4mm scales). Using a plug and socket to locate the chair is a briliant idea. Better still I can get templot to draw the socket, thanks Martin.

I have just aquired a 3D resin print, very impressed. I model GWR trackwork so have been designing my own 3D printed chairs.

I will share below what I have acheived in a couple of days playing around, still work in progress, my goal is to tackle complex track formations. I have a lot of chairs to design.

sat1.JPG


Cut from 1.5mm ply (birch 3 ply). I cut the outside sprues off prior to glueing down since it was not need for strength and would be a pig to remove. I normally paint the ply prior to cutting but wanted to make track fast.

sat2.JPG


I successfully changed the socket width to 1.5mm. This leaves enough meat for strength. I have previously used the shadow of the rail as a sprue and it worked well even with the 1.5mm wide socket.

sat3.JPG


sat5.JPG


sat4.JPG


Martin I am looking forward to sockets appearing within the turnout section. This would be useful even if the chair are WIP. For my prospective sockets on the 2D DXF are all I need.
 

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Hi TimbersGalore,

Would you mind me asking what laser are you using?

In your pictures shown you appear to have the grain of the ply aligned with the short edge of the sleepers, or are they sanding marks?

Also it would be usefull to know what resin printer, and what resin you are using.

Steve
 
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timbersgalore

Member
Location
England
Steve

It is the grain of the birch ply. I was in and hurry and cut it will the grain going across. If it was for real I would have found another sheet with the grain going the other way.

My laser is a "TEN-HIGH" Laser Engraving Cutting Machine 400x300mm 40W CO2 Laser" which I upgraded with the Cohesion3D G code controler. I prepare the files and control the laser using LightBurn. Cutting ply I acheive better than 0.1mm accuracy.
My resin printer is a Phrozen Sonic Mini 4K using 4K resin at 0.030mm layers.
 
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Martin Wynne

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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.
 
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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
 
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Martin Wynne

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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.
 
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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.
 
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