• The Plug Track functions are experimental and still being developed. Some of the earlier pages of this topic are now out-of-date.

    Some pages of this topic include contributions from members who are creating and posting their own CAD designs for 3D printing and laser-cutting. Do not confuse them with Templot's own exported CAD files.

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

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Martin Wynne

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B or C. Blades overhanging the chair screws look worse than the chair being a little too long! (Not that I model in either of the scales you mention 😀)

I think I agree. But you can write the replies when folks share chairs, and EM slide chairs don't fit in P4 sockets! :)

Martin.
 
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Hayfield

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Essex
If you look at what Len Numan did with the Exactoscale chair range, for 00 & EM gauges (4mm scale E4CH 301A) he made a slightly larger slide chair (for all P positions) and a P4 slide chair (E4CH 302A).

If anything there should be a 3rd version for standard 00 gauge, as the 4mm scale one is fine for EM & 00SF
 
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Martin Wynne

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@Hayfield

Thanks John. I was hoping someone might come up with a clever wheeze to reduce the workload, but I knew it would come down to more tickboxes* in the end:

dxf_switch_opening.png


Set automatically from the current gauge/scale, but can be changed before exporting the file.

This dialog is getting out of hand. It will need a full re-design before a full release for Plug Track. :(

*I suspect we shall have to leave behind any hope of compatibility with Windows95, 98, ME. "Out of resources" errors.

cheers,

Martin.
 
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Martin Wynne

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Now that I'm looking at the switch and crossing chairs, I have had to make a decision about something I've been pondering for ages. Should the chairing be prototypical or programmatic? I've settled on programmatic.

What do I mean by that? Suppose you have created an irregular diamond-crossing which fits your track plan nicely, and one of the V-crossings is showing as 1:7.38 angle. Now obviously no such size of V-crossing exists on the prototype -- the nearest size, 1:7.5, would be used instead. And the big 'ammer would be brought into play to make it fit -- a few days running-in under traffic soon removes any rough spots. That is also what you do if building with C&L or Exactoscale chairs, because they don't make 1:7.38 crossing chairs either, although I doubt model running-in has much effect.

To be strictly prototypical therefore, Templot should do the same, and I should implement a corresponding big 'ammer function.

Well I'm not going to -- it's just too much of a minefield of conflicting dimensions and prototype variations. I am hoping to finish this project within my lifetime!

Instead, Templot will programmatically create 1:7.38 crossing chairs for a perfect fit. Only you and I will ever know the difference, no-one else will notice. If that's not something you can live with, -- using Templot isn't compulsory. :)

Another example of programmatic chairing will be for the switch block chairs. Suppose you shove one of the switch timbers along a bit, like this:

shoved_block_chair.png


You know and I know that you should never do that. The block chairs support angled rails, and will fit the rails in one position only. You can't shove switch timbers more than an inch or so under the chairs, and the chairs need to stay put while you do it.

But Templot doesn't know that, and will happily shorten or lengthen the block chair, and adjust the rail angle, as you shove the timber along. Whereas the prototype has only a few fixed sizes of block chair, not an infinite range of sizes.

But in a cramped model design, you may need to shove switch timbers more than a bit, so this unprototypical result might be useful.

Again, I'm creating these chairs programmatically in order to have some hope of chairing the whole range of switches in my lifetime.

But this decision does have consequences. It means the 3D chairs file and timbering brick file will be a matched pair and need to be created at the same time and kept together, and not interchanged with the files for other templates or bricks, even if the templates are nominally the same size.

I'm intending that it will be possible to bunch together all the chairs from a brick for resin-printing, and print a paper chart showing which chair goes where on the templates.

cheers,

Martin.
 
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Hayfield

Member
Location
Essex
Martin

Certainly from a track builders point of view this is the correct way, I have found though when using the Exactoscale parts which are designed for P4 timber spacing, they also work well for both EM and 00 spacing, however in the case of separate chairs the next few standard chairs have their position altered (if only for a few thou), but are we talking about amounts that within normal build tolerance ?

Or am I misunderstanding what you are saying

Another thought does the gauge alter the slide rail lengths, if so would you have to increase them up to PL2 position ?
 
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Paul Boyd

Member
Location
Loughborough, UK
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Now that I'm looking at the switch and crossing chairs, I have had to make a decision about something I've been pondering for ages. Should the chairing be prototypical or programmatic? I've settled on programmatic.

What do I mean by that? Suppose you have created an irregular diamond-crossing which fits your track plan nicely, and one of the V-crossings is showing as 1:7.38 angle. Now obviously no such size of V-crossing exists on the prototype -- the nearest size, 1:7.5, would be used instead. And the big 'ammer would be brought into play to make it fit. That is also what you do if building with C&L or Exactoscale chairs, because they don't make 1:7.38 crossing chairs either.

To be strictly prototypical therefore, Templot should do the same, and I should implement a corresponding big 'ammer function.

Well I'm not going to -- it's just too much of a minefield of conflicting dimensions and prototype variations. I am hoping to finish this project within my lifetime!

Instead, Templot will programmatically create 1:7.38 crossing chairs for a perfect fit. Only you and I will ever know the difference, no-one else will notice. If that's not something you can live with, -- using Templot isn't compulsory. :)

Another example of programmatic chairing will be for the switch block chairs. Suppose you shove one of the switch timbers along a bit, like this:

View attachment 2675

You know and I know that you should never do that. The block chairs support angled rails, and will fit the rails in one position only. You can't shove switch timbers more than an inch or so under the chairs, and the chairs need to stay put while you do it.

But Templot doesn't know that, and will happily shorten or lengthen the block chair, and adjust the rail angle, as you shove the timber along. Whereas the prototype has only a few fixed sizes of block chair, not an infinite range of sizes.

But in a cramped model design, you may need to shove switch timbers more than a bit, so this unprototypical result might be useful.

Again, I'm creating these chairs programmatically in order to have some hope of chairing the whole range of switches in my lifetime.

But this decision does have consequences. It means the 3D chairs file and timbering brick file will be a matched pair and need to be created at the same time and kept together, and not interchanged with the files for other templates or bricks, even if the templates are nominally the same size.

I'm intending that it will be possible to bunch together all the chairs from a brick for resin-printing, and print a paper chart showing which chair goes where on the templates.

cheers,

Martin.
Hi Martin

That all sounds an eminently sensible and pragmatic solution to me!

Cheers,
Paul
 
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Martin Wynne

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but are we talking about amounts that within normal build tolerance ?

Or am I misunderstanding what you are saying
@Hayfield

Hi John,

Providing you use the chairs from the corresponding STL file, and not some you had left over from a previous file, they should fit the corresponding timbering base perfectly, and there should be no need to rely on build tolerances to make things fit.

I say "should" because I haven't actually written the code yet. :)

Also, it is necessary to set the shrinkage rates correctly. At present there is a single allowance on the dialog which is used for all 3-D files, and ignored for all 2-D files. The default I have on there at present is 1.5% which is about right I think for the resin-printing, but maybe a bit too much for FDM filament printing. Indeed with the wide footprint of a typical timbering brick on the build plate, there may be very little shrinkage of the timbering brick at all, unlike when printing more bulky items having a smaller footprint. My test prints tend to confirm this. But like most plastics, some age-shrinkage may take place afterwards over time.

In addition, all machines 2-D and 3-D may need scaling adjustments to cover for any mechanical errors in the pitch of lead screws, pitch of toothed belts, diameter of pulleys, rollers, etc., on individual machines.

All this is still very much in the air and subject to trial and error when we are in a position to start making Plug Track in anger.

Another thought does the gauge alter the slide rail lengths, if so would you have to increase them up to PL2 position ?

The P slide chairs are all a single size along the rail, like the S1 and L1 chairs, but will be adjusted in length to suit the current scale/gauge setting -- see my previous reply. They should therefore be interchangeable in different templates, provided you don't mix up the P4 ones with the EM ones, etc. Beyond the P chairs are the block chairs. These will be programmatically generated to match the switch, as I mentioned, so they won't necessarily be interchangeable with any other template and will need to be kept for the corresponding timbering base if you want a perfect fit.

At some stage all this stuff will need to be written up, with all the ifs and buts, and I'm not looking forward to it. But that's jumping a long way ahead, because I'm still at the more fundamental stage of making stuff work.

cheers,

Martin.
 
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Martin Wynne

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@Hayfield

p.s. John, apologies if my previous post appeared in bits, I think I've found a bug in this forum editor related to the Tab key.

I have posted a bug report on the XenForo site.

cheers,

Martin.
 
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Trevor

Member
Location
Morecambe
Hello Martin,
With regard to the switch blade over hanging chair bolts.
Could one not simply file a couple of slight hollows in the bottom of the switch blade to clear the bolt heads?
Trevor.:)
 
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Hats off to Martin.
By providing four more radio buttons, Martin is allowing you (the builder) to choose which solution best suits you.
Having used the 301A Exactoscale slide chairs for OO-SF turnouts I don't think you really notice that they are longer once laid.
ps time to get my eyes tested again then!
pps must save a 20p piece before they go out of circulation in this cashless society!
 
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I'm intending that it will be possible to bunch together all the chairs from a brick for resin-printing, and print a paper chart showing which chair goes where on the templates.
In the far off future, please can we have a template timber bunch facility for the 2D export for use when Laser Cutting but in this case with the timbers adjacent. ie sharing a cutting line. This makes the laser cutting more economical when outsourcing.
Obviously when 3D printing the timbers need to be discrete and the bunching is just to maximise the use of the print bed area.
Steve
ps but don't let this request distract from chair production ;)
 
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Martin Wynne

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In the far off future, please can we have a template timber bunch facility for the 2D export for use when Laser Cutting but in this case with the timbers adjacent. ie sharing a cutting line. This makes the laser cutting more economical when outsourcing.
Obviously when 3D printing the timbers need to be discrete and the bunching is just to maximise the use of the print bed area.
@Steve_Cornford

Hi Steve,

The timber separation will be adjustable to whatever you set. If you want them to share a common cutter line it will be up to you to set the separation accordingly, allowing for the laser kerf width.

If the timber kerf lines end up coincident I will find some way to omit one of them, so that the cutter lines are not duplicated in the DXF file.

If you don't have any waste between the timbers, how do you hold it all together while cutting?

cheers,

Martin.
 
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If you don't have any waste between the timbers, how do you hold it all together while cutting?
Don't know.
They cut the sockets first, then the timbers.
LaserCutSleepers.jpg

This is what I got back. There is what appears to be masking tape on the back.
I can only assume that it is gravity.
They do offer a "taping" service as an option, but this is to alleviate the burn marks on the surface.
I did not opt for the "taping" service, as I was not too worried about burn marks, as sleepers(or timbers) will be stained with indian ink etc
Most of the sockets that are missing have fallen out with my handling.
Just like punched cards chad from my early programming days.
Miniature bricks anyone?
The cost depended in part upon the total length of lines cut, hence request for "bunch".
The sample I sent you of the turnouts etc was just as output by Templot, the above was as a result of the cutting service editing one of the files I had output from Templot.
I will ask the cutting service about duplicate lines. They might have some utility that removes them.
Steve
 
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richard_t

Member
Location
nr Spalding
Probably a question for Martin, but do you think your CNC mill would work with 2mm thick Walnut or Mahogany? i.e. work as in "work as you're intending to work with MDF". I can send you some once my order from Cornwall Model Boat arrives if that helps.

Thanks

Richard.
 
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Martin Wynne

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@richard_t

Hi Richard,

I'm fairly confident the machine is capable -- it is advertised as suitable for engraving hardwoods, and for this plug track application holding a precise cut depth is not necessary. What I'm not so sure about is the amount of splitting and raised burrs which might occur with natural woodgrain. The same applies to plywood of course. So far I have experimented only with MDF. I intend to get some "downcut" end mills for further experiments with natural wood. Both solid wood, and applied as thin iron-on hot-melt veneer on an MDF base.

My planning so far has been for 3mm material -- the current default settings for the plugs require a socket 2.5mm deep. For 2mm material the plugs will need to be reduced (unless you laminate it with an MDF sub-base). My experiments so far for the "plug-in" method have found it necessary to have a good location depth on the plugs so that the chairs can be reliably located loosely in the sockets before pressing the rail home. Otherwise assembly gets too fiddly. For the "slide-in" method with the chairs fixed in place first one at a time, the plugs can be less deep.

The "slide-in" method is more applicable than it first seemed when you realise that not all the other chairs need to be in place on the timbering base before sliding a piece of rail into position, only the actual chairs being slid into are needed. Adding subsequent chairs to the base may then trap the rail so that it couldn't be slid out again. This differs from the situation where all the chairs are integral with a timbering base from the start (as in turnout kits). As I've mentioned a few times there is still a lot of learning and trial and error to work through before this project is done.

I'm happy to receive some offcuts of your wood if you have some to spare. It doesn't need much to make a few trial cuts. What panel size have you managed to obtain in 2mm thickness? Are you planning to build panels by gluing stripwood side-by-side?

cheers,

Martin.
 
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richard_t

Member
Location
nr Spalding
Hi

Cornwall Model Boats sell sheet in 1m by 100mm, which I've ordered a few of Walnut and Mahogany, along with some 2mm x 4mm of each strip. My original plan was to cut down the 1m x 100mmm into 3.3mm strips for "normal" sleepers using my Proxxon table saw (the cheaper of the 2 available - the fence is rubbish, so might be something I "upgrade" using the 3D printer).

Happy to send you some - 1 of each letter size? (240mm x 165mm, perhaps a little bit smaller).

Richard.
 
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Martin Wynne

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More buttons.

Testing the MINIBO printer has shown up a significant difference in the PLA shrinkage compared with BIBO. In fact on the MINIBO there doesn't seem to be any shrinkage at all, and it actually needs a slight negative adjustment to get accurate results. This must be due to the cold work plate instead of the heated glass bed on the BIBO. It's difficult to separate shrinkage variations from errors in the machine resolution, but now that I know how much difference the backlash correction makes, I shall be re-testing the settings for the BIBO.

Whatever, it means using different adjustment/shrinkage settings for FDM and resin printing, and to avoid having to change the settings between exports that means yet more buttons:

dxf_3d_options.png


The CAD option means zero adjustment, any changes wanted being made in the CAD program.

If the export is intended for 3D printing it will be important to click the right option before exporting the file (and to have set the right amount of adjustment for your printer).

More about the MINIBO:

https://85a.uk/templot/club/index.php?threads/another-fdm-printer.340/

cheers,

Martin.
 
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richard_t

Member
Location
nr Spalding
Hi

Cornwall Model Boats sell sheet in 1m by 100mm, which I've ordered a few of Walnut and Mahogany, along with some 2mm x 4mm of each strip. My original plan was to cut down the 1m x 100mmm into 3.3mm strips for "normal" sleepers using my Proxxon table saw (the cheaper of the 2 available - the fence is rubbish, so might be something I "upgrade" using the 3D printer).

Happy to send you some - 1 of each letter size? (240mm x 165mm, perhaps a little bit smaller).

Richard.
Eventually my order from Cornwall Model Boats turned up this morning - the walnut and mahogany strips and sheet have survived but I also ordered some MDF sheets as well, and each one of those are damaged in some way, and also they are now out of stock on some of the MDF and so didn't fulfil my order. I noticed my local timber merchant/DIY* place sells a variety of pre-cut MDF (I suspect for picture framing/backing) so I suspect that might be a better route.

Anyhow, if still you'd like some of the Walnut/Mahogany sheet, I'm sure I can organise that over the next few days (he says... ha ... ha ... ha ...)

All the best

Richard

* Along with offcuts of various bits of plywood, that I can't help getting ... sigh ...
 
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Martin Wynne

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