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TEMPLOT 3D PLUG TRACK - To get up to speed with this experimental project click here.   To watch an introductory video click here.   See the User Guide at Bexhill West.

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 Some of the earlier pages of this topic are now out-of-date.

    For an updated overview of this project see this topic.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics 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. All files derived from Templot are © Martin Wynne.
  • The Plug Track functions are experimental and still being developed.

    For an updated overview of this project see this topic.   For some practical modelling aspects of using Plug Track see Building 3D Track.

    The assumption is that you have your own machines on which to experiment, or helpful friends with machines. Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful.

    Some pages of this and other topics 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. All files derived from Templot are © Martin Wynne.

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

Quick reply >
@Marsh Lane @Steve_Cornford

Hi Rich, Steve,

Those default dimensions are the prototype BS-95R dimensions in S scale (1:64). It's very unlikely that the code 87 BH rail matches them exactly, especially the web thickness.

This is how the rail section is dimensioned:

index.php


2_120508_000000000.png


BS-95R prototype dimensions in red. The dimensions in black relate to a sample of C&L rail from AndyB in 2016. Later batches may vary.

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.

cheers,

Martin.

Hi Martin,

I don't think I have any C&L rail (at least not as far as I can remember).

The only bullhead I have is SMP which is strictly a bit narrow for 1:76.2 although I quite like it, but we better not get into all that again 🙂

Cheers!

Andy
 
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.
I have added this note to the yellow panel at the top of this topic:

"Please do not send Templot files to commercial laser cutting or 3D printing firms while this project is still experimental, because the results are unpredictable and possibly wasteful."

It's important, because apart from not wasting your money, I really don't want the idea to get about that Templot Plug Track doesn't work. We all know how impossible it is to correct a wrong idea once it has hit the internet. Because at present of course it doesn't actually work -- it's all still experimental and not fully released.

It's also being thwarted by the present egg shortage. :)

I'm currently struggling to get the slots through the plug for the handed check-end chairs -- I've used up all my coloured pencils. Whose mad idea were these loose jaws?

Martin.
 
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message ref: 5600
Hi Martin,
Could you rotate the "peg" and "slot" by 90° and then have the slot have an open side for draining?
Slide the check chair onto stock rail and plug in.
The portion of the plug under the stock rail part of the chair is solid and therefore normal strength.
Once the loose jaw is pegged in the wedge effect will give full strength to the check rail part of the chair.
Steve
 
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@Steve_Cornford

Hi Steve,

Thanks for the ideas. I would prefer to keep the loose jaw interchangeable with all other outers on 4-screw chairs if I can. Also, the pin needs to flex outwards sightly as the key clips under the rail head. If the pin is rotated 90 degrees that might not work.

I think I shall get there in the end. It just needs a lot of code, without any silly mistakes:

plug_code.png

There are reams and reams of that stuff. :)

Eventually I shall post it all as open source as before, but I can't do that until it is all working. I can't remember how much 3D stuff there is in the original TemplotMEC code which I open-sourced in 2018. There has been some 3D rendering options in the DXF export from the beginning, but not with chairs or any thought of 3D printing.

cheers,

Martin.
 
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message ref: 5602
@Steve_Cornford

Tweezer Alert

Hi Steve,

I've noticed that if the tweezers are left with the resin tips in contact under pressure, the resin shanks distort over time, losing some of the grip.

It's a good idea to insert a spacer between the ends of the tweezers so that the tips are not in contact, when they are not in use.

cheers,

Martin.
 
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message ref: 5607
Hi Martin,
Thursday morning's silly question.
Are the tweezer tips scale related, or are they just one size at the moment like the Filing Jig?
The ones I have printed so far were produced with gauge set to EM.
I have just found my store of 8BA nuts and bolts, longest is 3/8" so might have to perform a bit of countersinking!
Steve
 
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message ref: 5608
@Steve_Cornford

Hi Steve,

At present the tips are just one size, for 4mm/ft scale loose jaws. The present code was just a try-out to see if it worked.

It's an interesting question because in the larger scales they may need to fit Mole grips! :)

https://www.wonkeedonkeetools.co.uk/mole-grips/a-brief-history-of-mole-grips

I have just found my store of 8BA nuts and bolts, longest is 3/8" so might have to perform a bit of countersinking!

I made the shanks far too thick at 6mm, the mark 2 version is thinner.

cheers,

Martin.
 
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message ref: 5609
1. Chairs. For these you need a resin printer. The one which we (Steve, Charles, and I, and no doubt others) are using is this one. It's currently available at a so-called "Black Friday" price on Amazon. There are more recent, bigger and better(?) resin printers available at greater cost, but the results we have been getting from this little Mars printer are excellent:
.
It seems the Mars 2 resin printers have now ceased production and are out of stock from Elegoo. Replaced with the more expensive Mars 3 Pro:

https://www.amazon.co.uk/ELEGOO-Purifier-Protector-Precision-5-62x3-5x6-8-Mars-3-Pro/dp/B0B4JN6KX4/

If you wanted a Mars 2 Pro it would be worth googling around smartish to find one still in stock anywhere -- there was just 1 left on Amazon UK a few hours ago, but it has now gone.

It's annoying because for the plug track I wanted to make it easy for beginners by saying "get one of these, and use these settings". Now I can't do that because I can't prove for sure what settings work best on a Mars 3, without getting one. I'm back at the beginning in having to rely on conflicting reports and advice from others -- invariably referring to printing fantasy figures and little boats, not track chairs.

Martin.
 
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Unfortunately I think this will be the case with both resin & fdm printers, a particular model only seems to be in production for a couple of batches before they are superseded.
However I think you have established the principal of plugtrack & demonstrated what is achievable.
Fir that I for one am grateful
Steve
 
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p.s.

Looking at DesignSpark Mechanical again set me thinking about how little non-Templot use I have made of my 3D printers in the last couple of years. Checking on RMweb to see the popularity of DSM v. Fusion360, I found this -- designed in DSM and printed on a Mars 2 Pro in 7mm scale:

52117434249_2813187b92_b.jpg

linked from https://live.staticflickr.com/65535/52117434249_2813187b92_b.jpg

See:

https://www.rmweb.co.uk/topic/17410...here-to-start/?do=findComment&comment=4926660

I must not get distracted from Plug Track. I must not get ... :)

Martin.
If only I were modelling in 7mm those wonderfully scale looking wall thicknesses would be practical!

1672344116534.png


I'm having great fun putting together a body for an Aspinal A class in Fusion 360, but I wish I had put the dimensions into context sooner. It's all well and good drawing up a scale thickness cab wall until it comes off the printer looking like wet newspaper in 4mm. Still terrifically rewarding.

I'm looking forward to having a go with the track once the new ubiqitous "railway room" is completed. Though my Saturn has developed a patch of dead screen seemingly to spite me. Oh well, good excuse for a fancier machine on the horizon.
 
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.
Here's a New Year project for someone who wants to try a bit of plug track on an existing layout. :)

A common problem is to make a track fixing at baseboard joints which is robust but invisible.

You could print something like this, to replace the last few sleepers of the track and the cork underlay:

baseboard_track_end.png


Make the base slab rectangle a reasonable thickness. Drill through and screw it to the baseboard. All to be hidden under the ballast.

The clip is optional and could be used to align with the same on the next baseboard while fixing. Saw through the clips before separating the boards.

If the rail ends ever got damaged, it would be easy to pull out the chairs and replace them, without disturbing the original base or its alignment.

Martin.
 
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message ref: 5639
.
Here's a New Year project for someone who wants to try a bit of plug track on an existing layout. :)

A common problem is to make a track fixing at baseboard joints which is robust but invisible.

You could print something like this, to replace the last few sleepers of the track and the cork underlay:

View attachment 4879

Make the base slab rectangle a reasonable thickness. Drill through and screw it to the baseboard. All to be hidden under the ballast.

The clip is optional and could be used to align with the same on the next baseboard. Saw through the clips before separating the boards.

If the rail ends ever got damaged, it would be easy to pull out the chairs and replace them, without disturbing the original base or its alignment.

Martin.
 
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message ref: 5640
If only I were modelling in 7mm those wonderfully scale looking wall thicknesses would be practical!

View attachment 4877

I'm having great fun putting together a body for an Aspinal A class in Fusion 360, but I wish I had put the dimensions into context sooner. It's all well and good drawing up a scale thickness cab wall until it comes off the printer looking like wet newspaper in 4mm. Still terrifically rewarding.

I'm looking forward to having a go with the track once the new ubiqitous "railway room" is completed. Though my Saturn has developed a patch of dead screen seemingly to spite me. Oh well, good excuse for a fancier machine on the horizon.

Nice Caledonian 0-6-0. I used to see them all the time a few years ago. Not sure about the firebox on that one. I think it should be narrower at the bottom.

Please carry on :)
 
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message ref: 5641
Nice Caledonian 0-6-0. I used to see them all the time a few years ago. Not sure about the firebox on that one. I think it should be narrower at the bottom.

Please carry on :)
Hi Andy,

Not quite a Caley type in this case, though I do wish the L&Y machines had retained the wing plates between smoke box and sanders. A highlight of victorian elegance I reckon.

This one is destined to be an A class, like the real one thankfully preserved and owned quite coincidentally by a Mr Andy Booth, and accordingly has parallel firebox lower sides.
1672685878780.png

.
Here's a New Year project for someone who wants to try a bit of plug track on an existing layout. :)

A common problem is to make a track fixing at baseboard joints which is robust but invisible.

You could print something like this, to replace the last few sleepers of the track and the cork underlay:

View attachment 4879

Make the base slab rectangle a reasonable thickness. Drill through and screw it to the baseboard. All to be hidden under the ballast.

The clip is optional and could be used to align with the same on the next baseboard while fixing. Saw through the clips before separating the boards.

If the rail ends ever got damaged, it would be easy to pull out the chairs and replace them, without disturbing the original base or its alignment.

Martin.
Now there is an idea. I have often wondered about how to improve on the tried and true PCB sleeper firmly fixed at the join. My prospective layout project will need a good few such joins so i'll certainly give this a try. Could be some while though, as these things always are.
 
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message ref: 5671
Hi Andy,

Not quite a Caley type in this case, though I do wish the L&Y machines had retained the wing plates between smoke box and sanders. A highlight of victorian elegance I reckon.

This one is destined to be an A class, like the real one thankfully preserved and owned quite coincidentally by a Mr Andy Booth, and accordingly has parallel firebox lower sides.

Thanks for that James.

I should have spotted the missing wing plates :) The cover over the rods under the smokebox has a very Caley look about it.

Sorry for the distraction.

Cheers!
Andy
 
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message ref: 5677
Hi everyone,

I'm new to the forum, but not new to Templot.

I posted this yesterday on the 3D Plug Track thread on the Scalefour Society forum. I've been following this with interest because the idea of printing my own track-building components is hugely attractive, I live in Portugal so it's not very easy for me to get parts, plus I'm an advocate of radio control and although I'm not quite there with printing everything yet, that is definitely an option for me.

I've just acquired an Elegoo Saturn 2 resin printer, and after a week of setting it up and running test prints, I finally tried printing the example loose jaw chairs stl that's back a few pages in this thread. And I have to say I'm completely floored by the results.

IMG_20230104_182323199.jpg


Martin mentioned that you're putting together a catalogue of settings, which obviously I'm happy to share. I'm using Elegoo Standard Grey resin, I've switched off the Image Blur (as mentioned somewhere), and I have Exposure Time set at 2.5 with Bottom Exposure Time set at 30, the rest is all out of box but I can share everything if needed.

So I guess my next question is, can I print some sleepers?

This is all hugely exciting!

Many thanks, Nick
 
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@Nick Allport @Steve_Cornford

Hi Nick,

Many thanks for that. Welcome to Templot Club. :)

I see that you are using the Elegoo Standard resin. Most of us have been using the ABS-Like resin which is claimed to be more resilient than the standard resin and slightly flexible.

The pins on the loose jaws need to flex slightly as the key passes the rail head and clips under it. Have you yet tried assembling some rail in the chairs to see if that works ok with the standard resin?

There have also been some suggestions to mix different resins, although that seems a bit messy and unpredictable to me.

The jury is still out on using resin printing for the timbering bases (instead of FDM), and whether to print the chairs integral with them, rather than separate press-fit chairs. If you make them integral, I can see difficulties in properly washing out the slots for the loose jaw pins. When I tried some resin-printed bases, they curled up significantly after a few days and would be difficult to lay flat. That can be avoided by fully UV curing them while still on the build plate, but that makes them more difficult to remove from it. Steve is conducting some experiments on all this and can report more fully.

You mentioned battery radio-control, i.e. resin-printing the rails too. That means the whole thing could be printed in one go, no separate chairs or loose jaws needed! No doubt Chitubox will want to add some supports under the rail between the timbers. The rails might be strong enough to allow the timber webs to be omitted, which would likely solve the curling problem. It would mean I have to do some work on the DXF export to add solid ends to the rails, nose for the vee, etc. Have you given any thought to the moving switch blades and stretcher bars?

cheers,

Martin.
 
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Thanks Martin.

I've actually just printed six of the test_slotted_resin_brick_fixed stl just to see what would happen, I'm just drying them now, then I'll cure them and see how they do over the next few days. I fear that you're right though and they won't stay flat. So I guess next purchase is going to be an FDM printer...

To be honest I'm not keen on the idea of printing everything including the rail as I really enjoy the process of building track, but I'm happy to try it.

Personally I love the idea of separate timber bases and the plug-in loose jaw chairs.

The question on resin, I've cured the chairs for 1 minute and attached six of them to a piece of rail with no problems or breakages, the loose jaw just snaps in. But the next resin order I do I'll get the ABS-Like. Does this require different exposure settings?

IMG_20230105_155927773.jpg


Any recommendations on an FDM printer? I've been looking at the Anycubic Kobra Max, which has a 400 x 400mm print area, seems ideal for timbering bases.

Many thanks, Nick
 
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message ref: 5692
You can flatten resin printed bases by putting them into a cup of very hot water, flattening them and then putting them in a cup of cold water to fix. I printed a few bases on my resin Anycubic Photon using Anycubic standard grey resin directly on the baseplate without any curl but I have used this flattening method with other things I have printed.

The quality of the Mars shines through with those photos, my Anycubic is nowhere near as sharp as those images.

Ralph
 
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message ref: 5693
Any recommendations on an FDM printer? I've been looking at the Anycubic Kobra Max, which has a 400 x 400mm print area, seems ideal for timbering bases.
@Nick Allport

Hi Nick,

Congratulations on your hi-res photo of the chairs. I find it extremely difficult to photograph the translucent material and capture detail, but you have managed for the first time to show the random rotations on the square screw heads in 4mm/ft scale:

nick_chairs_photo.jpg


Many thanks for posting that. :)

The rail seats do look rather angular, but they get mostly hidden under the rail, and a good scoosh of paint will fill the corners to replicate the fillet radii on the prototype castings. The paint is needed to protect them from long-term UV exposure which may cause them to become brittle. This might be another reason to prefer the ABS-Like resin, although no-one has been doing this stuff for long enough to know for sure. Yes, that resin uses the same print settings as the standard resin (as far as I know).

Regarding FDM printers, it is a constantly moving feast of new printers as the various manufacturers try to leap-frog over each other. I can't make a recommendation because I can't possibly buy them all to try! In any event all the latest printers appear to be currently out-of-stock in the UK after the recent Black Friday frenzy, and are quoting deliveries into February.

But a few of the relevant points which we have been discussing here.

1. For a timbering brick we must be able to create a flat print of constant thickness all over. Which is not a typical use for these printers, so doesn't feature much in the specs. It relates to the levelling of the build plate.

Some printers claim to be "auto-levelling", but are no such thing -- nothing gets changed. All that happens is that the Z height of the nozzle is adjusted while printing the first layers to compensate for any variations in the surface of the build plate. Which itself tends to be a flexible tin sheet with nothing to hold it dead flat. This "auto-levelling" ensures that the first layer adheres properly to the build plate, but does nothing to ensure the dimensional accuracy of the finished part over a wide area.

For the test timbering bricks I have been using a rigid glass build plate with manual screw levelling at the corners (on Neptune 2S). By this means I have managed to produce timbering bricks which are a constant thickness within about +/-0.025mm (+/- 1 thou) all over, and repeatable.

It seems that Elegoo have recognised the need for manual levelling by re-introducing it as an option on their latest Neptune 3 Plus and Neptune 3 Max printers, having removed it on the previous Neptune 3 and Neptune 3 Pro printers. They call it "Auxiliary Levelling":

"Auto Bed Leveling + Auxiliary Leveling: The non-contact high precision sensor automatically scans 63 points of the hotbed to compensate for any unevenness and inconsistencies of the printing platform. You can also use the hand-twist knobs under the build platform for auxiliary leveling to achieve a nice first layer."

I can't find whether other manufacturers are or will be doing the same, but if not that would be a definite vote for the Neptune 3 Plus and Neptune 3 Max printers from me. On a printer without screw adjustments it's possible to level a rigid build plate by using card packing under the corner clips, but a screw adjuster is much easier to use and repeatable.

2. Z-precision. For accurate Z thickness dimensions it needs a twin Z-screw. The Neptune 2S has only a single Z-screw and I have had to modify it to be sure of getting consistent results.

3. Extruder. The Neptune 2S has a bowden-tube extruder, unlike my older BIBO printer which has a direct-drive extruder. I was expecting that the bowden tube might cause problems with stringing from the nozzle, but I have found that by using an aggressive retraction setting it produces results just as good as the BIBO. The snag is that this stresses the bowden tube end fittings, and I have already had to replace one of them. I wondered why there were 2 spares included with the printer!

So I would definitely go for a direct-drive extruder if possible. Again this is a change for the Neptune 3 range from the Neptune 2S. In theory the heavier direct-drive extruder head means a slower printer, but it's hardly relevant when printing precise parts. It might make a difference if printing large chunky parts as fast as possible. FDM printing is slow regardless, but runs unattended for hours while you get on with some modelling.

4. Build plate area. The bigger the better, but it does increase the cost! The larger printers are also taller, which might be a nuisance and you may not have any use for the increased model height in 4mm/ft scale.

cheers,

Martin.
 
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message ref: 5694
Hi Martin,

Yes, direct-drive extruder, dual Z-drive steppers and a thick, heated, glass plate. The leveling on mine had four screws, one at each corner which is daft when you are using plate glass. A three-point attachment is much better (I did modify mine.)

And if the Z-limit uses a lever-arm microswitch, remove the arm and arrange for the motion to hit the button on the switch. That improves repeatability quite a bit.

Cheers,
Andy
 
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You're right there don't seem to be any Elegoo Neptune printers on Amazon anywhere at the moment. I've been trawling through reviews overnight and the Creality Ender 3 seems to tick a lot of boxes. And I have an Amazon voucher from my Dad for Christmas that would cover more than half of the current price :).

However I'd like to persevere with the resin printer a little bit more with timbering. Is there an stl of an S4 plug sleeper on it's own? I'd like to try printing it at 25 degrees with supports and seeing if that then stays straight.

Cheers, Nick
 
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message ref: 5700
However I'd like to persevere with the resin printer a little bit more with timbering. Is there an stl of an S4 plug sleeper on it's own? I'd like to try printing it at 25 degrees with supports and seeing if that then stays straight.
@Nick Allport

Hi Nick,

It's only a few clicks to create whatever you want in Templot.

Here are a couple of STLs for single sleepers in S4/P4. One solid, one with sockets under the chairs. I have done the Formware mesh fix on them ready to print.

These are both 3.24mm thick (to contain chair plugs). If intending to use them with integral chairs, you could obviously make them thinner.

With sockets, you would normally want to add the side flanges to stiffen the sides of the timber.

Or did you want a short section of timbering base? Everything is optional, you just need to decide what you want to do.

s4_sleeper1.png


s4_sleeper2.png


cheers,

Martin.
 

Attachments

  • s4_sleeper_solid_fixed.stl
    1.3 MB · Views: 57
  • s4_sleeper_sockets_fixed.stl
    1.5 MB · Views: 63
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@Nick Allport

Hi Nick,

Here is a short timbering brick:

s4_short_brick.png


n.b. these files have been exported as the 3D for CAD option, i.e. no shrinkage allowance included. To get your chairs to fit, and to get the track gauge exactly to S4/P4, you will probably need to make a scaling allowance in the Chitubox slicer.

cheers,

Martin.
 

Attachments

  • s4_short_brick_fixed.stl
    1.2 MB · Views: 56
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message ref: 5702
You're right there don't seem to be any Elegoo Neptune printers on Amazon anywhere at the moment.
@Nick Allport

Hi Nick,

Amazon seems to remove items which aren't available for immediate delivery, and suddenly re-instate them when they are. This makes it difficult to browse and compare the different designs when you are just looking for what's on the market.

This Austrian supplier allows you to order in advance, and has some Neptune printers listed. They are saying the Neptune 3 Pro will be available in a couple of weeks:

https://www.3djake.uk/elegoo/neptune-3-pro

Portuguese site: https://www.3djake.pt/elegoo/neptune-3-pro

On past experience, the printers will reappear on Amazon UK on exactly the same day they are shown as back in stock on the above site (I don't know about Portugal).

This will presumably be new stock from China, and it's possible the next batch of Pro printers will have sprouted "Auxiliary Levelling Screws" to match the Plus and Max versions. If not, it would need card packing for levelling (if you get a rigid glass build plate for it).

(The Ender 3 printer has a single Z-screw and is not a direct drive extruder -- but less expensive of course.)

cheers,

Martin.
 
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Thanks Martin. I'll hold out for the Neptune 3 Pro then. Doing a bit of workshop remodelling to make room for this stuff at the moment. Then I'll be back in action and can try the timbering bases again in resin.

Thanks, Nick
 
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.
I'll just leave this link here:


Martin.
 
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And it's available for less than $40,000!
Think I wll be spray painting the plug track prints for a while longer!

$40,000 today, $400 tomorrow. But what price the ink?

And does it need spraying to protect from UV? Oh, hang on ...

Martin.
 
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So I've had a few days reorganising my office/workshop so I can have a dedicated 3D printing area (I hadn't appreciated the height needed for the Saturn 2, especially when you need height to lift the lid off - I had to remove a shelf). Anyway I'm back up and running now.

Previously I had printed some of the bases with the integral chairs flat on the build plate, but they haven't stayed flat.

Yesterday I printed the short timbering brick with slots that Martin attached above, but at 25 degrees and on supports. I cured that for 1 minute and it's remained flat, and the base is quite flexible still (this is still with Standard Grey resin).

Adding a rail to it and clipping the chairs in is so satisfying (although I broke one of the loose jaws in my haste). But it's remained flat and looks really nice!

IMG_20230113_082016279.jpg


IMG_20230113_082000545.jpg


I'm still staggered by the quality!

What glue do you use to stick these bases down?

I'm pretty much decided that I'll order a Neptune 3 when they come back into stock at Amazon ES so that I have all the options, but at the very least I'm certain now that this is definitely the way forward with track-building.

Cheers, Nick
 
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What glue do you use to stick these bases down?
@Nick Allport

Hi Nick,

Looking good!

We still need to experiment with different adhesives.

But you might decide not to glue them down. With the deep timbers it's possible to drill through the webs and pin or screw the bases to the trackbed instead. This avoids the issues of having to get the alignment dead right first time, weighting the track down, and waiting for the glue to set.

If you drill the screw holes a little oversize, you will have a bit of wiggle room to tweak the bases into perfect alignment. Or if it's too far out you could re-drill and have another go. It all gets lost under the ballast.

Then at a later date if you decide on a re-design you can lift the track easily, dismantle it and re-use it. Just don't put the screws directly under the rails!

The brick connector clips have a 1mm hole in them. If you print the corresponding target marks on the paper templates, you can use 1mm veneer pins to align the bases to the templates.

cheers,

Martin.
 
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I just use Gorilla wood glue to stick the resin bases down. So far no problems.
I print the bases flat on the build plate of the Mars 2 Pro, but I do reduce the web thickness to 0.5mm, seems to work for me, but Mars 2 Pro has a smaller build plate than he Saturn I think.
Steve
 
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.
I regret to announce yet another tickbox:

loose_check_option.png


I said previously that loose jaws would be the only option for the check rails. I have changed my mind on that -- you can now select either or both or neither of the jaws to be loose on check rail chairs.

loose_check_option1.png


cheers,

Martin.
 
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.
When I did the 2-part switch block chairs I mentioned that I wasn't entirely happy with them and might return to them at a later date. At that time it was before I discovered that the loose jaws option was entirely feasible, and even preferable in some cases. With solid jaws the chairs need to be bash-fitted with the rail in place. Which made it necessary to split the block chairs into 2 parts, each to be fitted separately.

This is the result, the current export from Templot (with the chair bases and rail seats omitted for clarity):


two_part_heel_chairs.png


pink = inner gauging jaws
blue = outer jaws
dark brown = keys
green = plugs
white = sockets

As you can see there are several places where the design is wrong, and differs from the REA drawings. At 1 the rib is not central between the chair screws. At 2 and 3 the middle jaws do not align properly.

This all seemed acceptable, if undesirable, and unlikely to be very evident in 4mm scale. But it is evident in 7mm and larger scales. With the chairs split in 2 parts it was difficult to do much about it.

But now with the loose outer jaws option there is no need to split the chairs into 2 parts. They can be one-piece chairs (as the check rail chairs). Even the unkeyed support jaw at A can be loose (although it doesn't really need to be), if the plug is in one piece.

So I have decided to revisit these chairs and redesign them as one-piece chairs with loose jaws. One step forward, two steps back -- which is frustrating, but I would rather do it now than get the crossing chairs done and still have the full design unfinished.

For those who don't like the loose jaws, the chairs can be printed all-solid. But in that case it will be necessary to slide the switch rail into the chairs after fitting them. Which might be tricky in some situations, such as within slips.

I'm writing this now, partly to explain the delay in progress. But mainly as advance warning that this design will change in the next program update -- if you have printed switch chairs or bases from the current version, you need to have printed sufficient matching chairs or bases, or at least exported the files for them, before updating.

cheers,

Martin.
 
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