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

[Steve_Cornford]

Hi Martin,
You always seem to be 2 steps ahead of me!
Perhaps Its because I am one year older!
Steve

 

[Steve_Cornford]

Hi Martin,
Feedback from the lasercutting service I have been talking to:-
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.

They need a line thickness of 0.076 mm (hairline in their words), but the laser burns a 0.2mm line, so to attempt to get correct size objects I am adding 0.2mm to outline(timbers) cuts and subtracting 0.2mm from inside cuts(sockets.

For timber outlines I have done this by using the real > timbering > timbering data option, and have added 0.6 inches to timber sizes, in OO-SF this gives:-

For sockets I have done this by using the [chair/socket fit..] button on the Export DFX/STL panel:-

ps, the chair plug clearance option is ignored for 2D exports as yoo explain in the [info] button.
By setting the socket side clearance to -0.25mm I should get a drawn socket 2mm - 2* 0.25mm = 1.5mm, and then half the kerf of the laser should enlarge this by 0.1mm all round. Well thats the theory.

*note to self, press the [rebuild background templates] button before the [export DFX/STL file] button!

Steve

 

[Martin Wynne]

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,

That's great, I will get on with adding that and several other layers and colour choices for the new stuff. I've been concentrating on the 3-D output recently and haven't really paid much attention to 2-D. It's hardly changed in 20 years.

I will also add some separate adjustment for 2-D laser line thickness in addition to the socket/plug tolerances, now that I know about that. For some time folks have been having timbering laser-cut from Templot's DXFs, but this is the first time anyone has mentioned to me that they are coming out undersize because of the laser kerf.

Also since it's likely you would have the timbering done before making the chairs, I will make the tweak adjustment on the plug size more flexible to use.

p.s. when entering data for the timbering (or anything else), if you prefix the figure with a letter S you can enter the scaled model size in mm instead of the prototype size in inches (if that is what Templot is asking for), instead of having to do the calculation yourself. But make sure you have set your model scale first.

Many thanks for the post. It's great to get such detailed technical feedback.

cheers,

Martin.

 

[Steve_Cornford]

Maybe the "folks" are right and I have made adjustments for no reason, other than my understanding of the discussion that I have had with the laser cutting service. So far all theory, the "proof will be in the pudding"!

I wonder what dimensions Ralph uses in his Coreldraw design for the P4 sleepers?

I have output a design including plain, B7 straight turnout and a B7 curved turnout with a minmum radius of 30.0" as a test. I know turnout sockets are still WIP, but thought it worth testing the viability of laser cutting the sockets that are angled in relation to the timbers, to check if there is burn through between the socket corners and the timber edges.

Having output the .DFX file, I then opened it in Inkscape, added a new layer named SOCKOUTL and moved the sockets from TIMBOUTL to the new layer. Then changed the socket colour to blue. I then set all the cut outlines to 0.076mm as requested by cutting service.
The plan is to get a TRACKBED sheet cut with just the sockets, and a JIG sheet cut with both sleepers/timbers and sockets.
Once cut I will measure the timbers and sockets, and adjust the pudding recipe if needed.
I have attached DXF file.

Should there be a "copyright" text legend output in the DXF as you do when printing the templates, or is it just suffiient for me to state that in the email when sending the .DXF file to the cutting service?

Thanks for the S for scale tip.

 

[ralphrobertson]

I would be careful changing Templot specifically to suit one laser bureau and one type of laser cutter. I have used 3 different types of laser cutter over the years and the software used for driving the cutter works differently in each case. The width of the laser beam can be dependant upon the type of laser used - there are different types that can cut using different technology. I am using a diode laser on my Darkly Labs machine and the thickness of the line on the drawing is really immaterial since the beam always cuts through the same width regardless of the drawing - my beam is also 0.2mm but that depends upon the material being cut and the thickness of the material.

When deciding the size of the sleeper for my example I didn't actually use the Templot output. I did say I worked differently and my need was for plain sleepers in card, a material far more suited to my cutter than anything else. Personally I see no advantage in having timbers cut in plywood which is much harder to cut so I have settled on card sleepers shellacked with easily available sanding sealer, shellac, button polish or whatever is available. I buy it in litre containers and dunk the sleepers in it and fish them out to dry giving a stable end result which is perfectly capable of serving the purpose of holding a chair plug.

The laser cutting software I am using now is called Lightburn and in my opinion is the Rolls Royce of the products I have used. It allows the cutting colour order to be changed however you want so you can control how you personally want the order of the cuts to be made. Also you can change the position of the cutting lines to reflect the kerf (width) of the laser so if you want precise sizes output you can make the laser cut to a dimension plus n or minus n where n is a value you set yourself. This allows extremely precise cutting according to your machine which is very important as they do vary as I said earlier and you can end up with perfectly fitting parts.

When preparing my test piece after having roughly worked out how much boundary was needed around the socket size on the sleeper to give a suitably strong socket I then changed the 3D parameters on the Templot chair plug size and printed some chairs on my Anycubic Photon. I then measured this plug size and drew a timber in Coreldraw with a socket I thought corresponded to the size the printer had produced. Using the chair plug size as a fixed value I then adjusted to size of the socket in Coreldraw until I got a perfect match that worked using the machines and materials I was using. This is the important bit because that may be different for other scenarios. Once an accurate timber was produced it was easy in Coreldraw to produce a row of exact size sleepers in a row with no gaps, a quicker job than cutting gaps. Using a spacing jig then makes gluing all this down much easier and leaves no tabs between sleepers.

I don't know how accurate or easy it would be to do it the other way round, that is cut the sleepers and then make the 3D printed chairs fit the socket but it might work easier - I haven't tried it. Different 3D printers and resins might generate different size plugs too even though the parameter settings in Templot are the same, I don't know, I only have one 3D printer capable of creating chairs although I do have a PLA printer which just gathers dust nowadays.

I hope this helps people understand how this process works. There are a few variables here which need to be understood to achieve the result I have been able to show.

Ralph
(edited to correct typo)

 

[Martin Wynne]

I would be careful changing Templot specifically to suit one laser bureau and one type of laser cutter.

@ralphrobertson

Hi Ralph,

There's no way I would do that. Like much else in Templot everything will be an option. There will be clearance options and adjustment settings available, but they will all default to zero and have no effect unless and until you change them.

Furthermore, at present the entire 3D stuff is experimental, and it could stay that way for years. Anything might change in any program update. I do want to emphasize that.

But unless this option is set on the control template, the working of Templot will be just the same as before:

And when it is set the screen response is likely to be much slower -- look at all the extra detail to be drawn. So for most of the time when track planning you will want to have that option turned off.

Also, I haven't yet decided how much of this detail to include in the output for construction templates -- so far none of it is. That's because for a long time to come, most of the chairing will be wrong. Getting to a situation where you can do, say, make tandem, and all the right chairs are in the right place for your chosen prototype is a dream for the future. Just getting to where 3D Plug Track is doable for a single turnout is going to be a major task, and then only for REA chairing. GWR chairs will have to come later. Not to mention all the pre-group designs. Or FB.

Unless of course a whole bunch of coders want to jump into the T3 project to help out?

In the meantime I must get 228b out soon, because I forgot to fix the straight-over-straight bug in make diamond-crossing which crept into 227a.

cheers,

Martin.

 

[AndyB]

Just getting to where 3D Plug Track is doable for a single turnout is going to be a major task, and then only for REA chairing. GWR chairs will have to come later. Not to mention all the pre-group designs. Or FB.

Unless of course a whole bunch of coders want to jump into the T3 project to help out?

Hi Martin,

I passed a whole bunch of coders on the road today. I waved at them but they seemed a wee bit surly

I've no idea what your code looks like (and I'd rather not know ) but would it make any sense to construct the crossing chairs as the summation of a few bits? The difference in jaw angles over a large range of crossing angles is really very small. Could you construct most of the crossing chairs "on the fly" by adding standard jaws (rotated to align with the rails) and base-plates of appropriate length?

Cheers,
Andy

 

[Martin Wynne]

I've no idea what your code looks like (and I'd rather not know )

@AndyB

Hi Andy,

It's all open-source. See: https://85a.uk/templot/club/index.php?threads/t1-files.192/

dxf_unit.pas is at: https://85a.uk/templot/club/index.php?threads/t1-files.192/post-1739

(as it was then -- I've made many changes since)

See also: https://sourceforge.net/projects/opentemplot/

but would it make any sense to construct the crossing chairs as the summation of a few bits?

That is how they are being constructed. The tricky part is the placing on the timbers (bearing in mind that timbers can be shoved to new positions, but the chairs can't). Some chairs can move along the rails in the process, changing angle for the rail as they go (S1, L1, P slide chairs, check chairs), but switch and crossing chairs can't be moved. Some may have to swap from S1 to L1 as the timber is shoved along.

And then do it all again when swapping from square-on to equalized timbering style.

Some of it is working now -- try shoving some turnout timbers and watch the chairs re-position and swap to/from S1 to L1 (bases and keys only for L1 so far) at the switch heel. Note that crab shoves are not included (and won't be, the complexity goes through the roof if I try that). But nothing has so far been done to allow individual chairs positions to be tweaked on a timber. In fact I don't even have a name yet for that process ("heaving" chairs?).

p.s. switch block chairs are currently moving too, not yet fixed.

What fun! A long way still to go.

cheers,

Martin.

 

[Steve_Cornford]

Looks a bit PECO'ish to me

 

[Steve_Cornford]

Ralph, thanks for the useful information. I am beginning to see the benefits of your card timber solution.

I have received my trial lasercuts, and have attached photos:-

Timbers-and-Jig
Trackbed
I have also attached the box file from which the dfx was derived

For trial purposes I used 3.2mm ply for the trackbed rather than cork, as the cork was not available in this sheet size. from my supplier.
The idea being that the trackbed just has sockets, which use temporary locator plugs to locate the timbers.

I included a straight B7 turnout and a curved B7 turnout.

I know the experimental chairs option is not ready yet for turnouts, but I beleive I have learnt something from this trial.
The sockets on the turnout timbers on the exit stock rail are gardually angled in respect of the timber, and that makes these timbers asymetrical so when using them it will be necessary to take great care that they are they right way round and the right way up.
A bit like taking care to ensure your bullhead rail is the right way up!
So I can see that 3D printing turnout timbers with flanges and connecting webs as Martin has demonstrated is probably a better solution than ply timbers as you can't go wrong with the orientation or seuquence of the timbers.

Back to the ply trial.
Turnouts
Another thought occured to me that pending the whole gamut of turnout chairs, one could use a hybrid approach, and use the plug-track approach for those timbers that that use S1 chairs, and other means for the other timbers. For example copper clad timbers and etched chairs for the Slide chair timbers, Pre-constructed croosing vees and cosmetic chairs etc. Plastic chairs glued to ply timbers etc.
Having output the DFX file it is relatively easy to delete the unwanted non S! sockets.

 

[Steve_Cornford]

Hi Martin,
I have spare copies of the lasercut Timber-and-Jig and TrackBed sheets. Would it be ok with you if I sent you some?
I assume you have access to me email address so that you can let me know address details.
Steve

 

[Steve_Cornford]

Todays Socket Fun
I have made a crossover and used the shove timbers function to extend 2 timbers, X6-C and X7-D.
Note that these timbers do not have chairs where they intersect the background template rails.

I then stored this template in the background, and made the lower template the control.
I then used shove timbers to increase the width of sleepers E2 and E3 to 4", and shoved them along until they overlaid the two extended timbers.

We now have chairs & more importantly sockets in the right place over the extended timbers.
If I now save to the background & then invoke the Export to DXF, 2D function but opt for timbers only (with sockets.
The resultant file will have the sockets needed, but it will have a superflous sleeper outlinbe that I can delete by opening the .DXF file in Inkscape and deleting the 4 lines that make up the widened sleepers.
Before:-

After deleting sleepers E2 and E3

I changed the sockets to blue to highlight the extra sockets that are now positiond on the extended timbers.

This is a work around, but no doubt Martin will design a much better way when Heave chairs is born!

I am trying to learn something new in Templot each day in order to re-inforce what I have learnt so far.
It is quite addictive
Steve

 

[Martin Wynne]

This is a work around, but no doubt Martin will design a much better way when Heave chairs is born!

@Steve_Cornford

Hi Steve,

Many thanks for the feedback.

Instead of removing the timbers from the DXF, try shoving their length to zero. They will then be in the BOX file and not need removing from the exports every time. More about all this:

https://85a.uk/templot/archive/topics/topic_3307.php#p25295

If you look at the date on that, you will see why I keep warning folks not to hold their breath. (At that stage I was still trying to do it all by FDM printing, and hadn't invented the idea of Plug Track. None of that was in the released program updates.)

p.s. package arrived, many thanks, looks very good. Haven't had a chance today to look at it properly yet.

cheers,

Martin.

 

[Steve_Cornford]

Wow!
Thanks Martin.
One more thing I have learnt today!
And a lovely long topic to read & glean more insights!

 

[Martin Wynne]

@Steve_Cornford

Hi Steve,

I have now had a chance to look closely at the laser-cut parts you sent me. Many thanks for those. They do look good with clean accurate cuts and dimensions. I'm tempted to make some matching chairs and start track building.

Your idea of using socket slots in the trackbed to align separate timbers is also inspired -- but it surely adds a lot to the cost? I'm wondering if cork was used for the trackbed it would be possible to cut the socket slots on the Silhouette cutter. With the advantage that it can be any length. The "kraft" blade is claimed to cut up to 3mm in "soft" materials, in addition to cheese slices. Cutting only the sockets rather than the timber outlines at the same time is obviously a much easier task. If it works it might be a way of using resin-printed timbers without needing to create a timbering brick to align them.

cheers,

Martin.

 

[Rob Manchester]

Hi Martin,
Apologies if I have missed something on this thread - I have to confess to not really paying attention to all the posts but is there a major reason to have holes in the sleepers rather than using the Exactoscale "NewTrack" method ( circa 2004 ) method of round dimples on the sleepers and a matching recess in the base of the chairs ? Would it not make the sleepers/timbers stronger.....and the alignment of the chairs would be set by the rail to chair jaw interface.

Rob

 

[Martin Wynne]

@Guinea_Pig_Tester

Hi Rob,

I tried that 3 years ago, see:

https://85a.uk/templot/archive/topics/topic_3307.php#p26312

Of course with "exactopips" on the timbers we don't need to make our own chairs and can use the Exactoscale chairs. In the Exactoscale system the chairs have an easy clearance on the pips, it is intended to use gauges in the usual way for assembly.

The downside is that you are restricted to the chair prototypes provided by Exactoscale and their continuing availability. But the main reason I threw them out of the window is because the rail is canted in the chairs (an utter no-no in my book below about Gauge 1) and the extremely poor fit on the currently available rail sections -- see various topics on the Scalefour forum.

If you then decide to make your own chairs for the exactopips system, you have the difficulty of supporting them with a flat base for printing, and without the plug base in 4mm scale they are much more fragile and difficult to handle. The plug base solves all that. Also of finding a suitable adhesive -- ideally the Plug Track chairs are a press fit and any adhesive is only a backup.

But no doubt I will add an option to add exactopips to the DXF export -- I want to add all possible options that anyone might want.

cheers,

Martin.

 

[Steve_Cornford]

Having produced a straight B7 and a curved B7 turnout in templot, I exported to 2D .DXF file, opend the resultant file in Inkscape, then grouped all the components of timber 1.X9(straight turnout) together as one object, changed stroke to black ink, 0.076mm wide, then took a copy and overlayed the copy onto the green timber 2.x9 of the curved (2400mm radius) turnout.

This was in order to check the corelation of the sockets, and whether it will be practical to just produce "standard" laser cut sheets of straight turnouts of a given size/angle (advantage being all timbers can have grain alighned with long edge of timbers) and use these to assemble curved turnouts.

The corelation is pretty good in my opinion, at least for a B7 curved to 2400mm.
The laser cutting service recomended closing up or perhaps concatenating is a better description of the timbers for a most economical cut. Cost is dependent on sum of the lengths of all cut lines, so by sharing timber outlines we can reduce the total cost, see their .pdf attached example.
So could have a "bespoke" trackbed layer cut in cork just with sockets to suit the track layout.
Then for the sleeper/timber layer cut in ply, use some standard "plain" sleeper sheets, and standard straight turnout sheets. Then just produce a "bespoke" extended timber sheet of ply for all the non-standard timbers relationg to the track layout.

If you have time to print some S1 chairs with longer narrower pegs to try them out that would be great.
Steve



Steve

 

[AndyB]

Hi Martin,
Apologies if I have missed something on this thread - I have to confess to not really paying attention to all the posts but is there a major reason to have holes in the sleepers rather than using the Exactoscale "NewTrack" method ( circa 2004 ) method of round dimples on the sleepers and a matching recess in the base of the chairs ? Would it not make the sleepers/timbers stronger.....and the alignment of the chairs would be set by the rail to chair jaw interface.

Rob

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)

Andy

(Personally I think it would be a much better idea to print timbers, chairs and rails all at the same time and simply stick a conductive cap on the rails but I'm a well-known heretic )

 

[Martin Wynne]

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.