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Messin' With Resin - 3D printed track

Martin Wynne

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Have you got the original chair .STL without the plug and the single heavy support so that I could experiment with other methods of setting the chairs out for printing?

Hi Jim,

Sorry, no I haven't. I probably do have the DXF which I could edit. If I can find it -- I've generated 100s of DXFs in the last few days while working on Templot. I will have a look.

But here is the STL with the supports, which you could presumably edit in CAD?

I don't think scaling the CTB will work, will it? The layers were already sliced at 0.05mm, so by scaling you have increased them. I think you would do better to scale this STL, and then re-slice it.

mars_first_try.png


p.s. "scoosh" is now my word of the day. :)

cheers,

Martin.
 

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  • mars2p_s1chairs_first_try.stl
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Martin Wynne

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I don't think scaling the CTB will work, will it? The layers were already sliced at 0.05mm, so by scaling you have increased them.

That seems to be the case. Original STL for slicing:

stl_org.png


CTB rescaled -- Chitubox is attempting to re-slice this:

ctb_rescaled.png


cheers,

Martin.
 
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Martin Wynne

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Have you got the original chair .STL

Hi Jim,

Sorry, there isn't such a thing. I could generate one for you, but not just at the moment because I've got Templot in bits while I'm working on it.

I think we may be at cross-purposes. These chairs are generated by Templot on the fly, I'm not using any CAD program such as Fusion to create STL files.

If I switch the plug off, or switch the sleeper off, the chairs will be hollow. Probably the online fixer could make them solid.

cheers,

Martin.
 
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Martin Wynne

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Hi Jim,

Here you go. Sleepers deleted from the DXF in TurboCAD. Saved as STL. Fixed solid in the online tool. 4mm scale (to fit Exactoscale rail):

chairs_only_for_jim.png


You will need to rescale the STL for S. I don't know how you are going to support them and keep the base dead flat for use?

cheers,

Martin.
 

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  • exacto_chairs_only_mm_fixed.stl
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I don't think scaling the CTB will work, will it? The layers were already sliced at 0.05mm, so by scaling you have increased them. I think you would do better to scale this STL, and then re-slice it.
Martin,

I'll have another go with the .STL file.

I had another look at importing your Chitubox project file and now that I look closely at it, I see the extreme layering on the image on Chitubox after scaling - I didn't look closely the first time. :) I think Chitubox has developed quite a bit over the years and I dug up some of my project files from two years ago when I was working with a very early number version - probably around V1.2 or V1.3. I could load them and re-scale them with no problems. So it looks as though the current project files are storing the sliced .stl including sliced support stl information whereas the early versions were just storing the stl files of the part with supports. When I rescaled these early files, Chitubox removed the supports (after a warning).

Jim.
 
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richard_t

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nr Spalding
Jim,

I'd be happy to send you some of my STL files for 7mm chairs, as per the images earlier in this thread. The files are on the large side though.

Martin used WeTransfer which seem to work quite well.

The offer is there.

Richard.
 
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Martin Wynne

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Hi Jim,

Just to explain, Richard's STL files are incredibly detailed CAD renderings of prototype chairs:

richard_chairs.png


With separate keys and even including the code letters on the screw heads. I'm going to have a go at printing them when I've got a bit more time.

My chairs are simple geometrical approximations which can be generated on the fly in Templot. There is no CAD program involved:

templot_chairs.png


Two different things.

I fear I shall have my work cut out trying to get this difference across to 3D printing users when/if I finally get a Templot update released. :(

cheers,

Martin.
 
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Martin Wynne

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I'm pleased to report that Templot can now export 3D files in STL format in addition to DXF:


stl_ex_templot.png


stl_ex_templot_pad.png


This removes one bottleneck from Templot 3D printing which has been bothering me for some time. It's very difficult to find a free or low-cost CAD package which supports 3D DXF files. 3D Crafter seems to be the only one, but it's very clunky and buggy and seemingly no longer being developed. All the others are quite expensive. Now you don't need one.

It's not all good news. As far as I can find the STL format does not support nested blocks. It's a single flat fully exploded file -- unless anyone knows otherwise?

This means that STL file sizes are massively inflated compared with the corresponding DXF file:

The above in DXF: 750 KB
The above in STL: 7900 KB

More than 10 times larger.

Also the STL files from Templot (just like the ones converted from DXF in TurboCAD) are not solid objects ready for slicing. For that they first need to be "repaired" in a mesh editor program, such as this free online tool:

https://www.formware.co/onlinestlrepair (others are available).

The above trackpad shot (EM gauge) shows that full 3D resin printing of complex pointwork is not going to be very practical on a small printer such as the Mars. The purple outline is the effective size of the Mars build plate. A large formation would be a jigsaw of small pieces to be aligned and fitted together.

But I'm not planning to do that. The timbering will be either FDM (filament) printed, or laser cut from plywood. Only the plug-in chairs need to be resin printed, and they can be bunched together in a single print (STL file size permitting). For FDM printing the build area is much larger at 200mm square on my machine, but that still requires some careful planning of jigsaw pieces to create a full pointwork formation.

As you can see, I still have a long way to go. Only the ordinary S1 chairs are finished. The L1 bridge chairs so far have a base and keys, but no chair jaws. All the other special chairs are also unfinished.

But with STL exports done I can now see the way forward to a usable system. Threading chairs one at a time, and then plugging the rail vertically onto a base, has got to be so much easier than feeding the rail into a base from one end. Especially for complex slips and crossings. And with Wayne Kinney's new cast crossings likewise plugged straight onto the base, we should have a new trackbuilding system which anyone can use.

Dream on -- still a long way to go. :)

Martin.
 
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Charles Orr

Member
Location
Leicester UK
Hi Martin,
This is excellent news.
For some reason I've been holding back building the bulk of the the track on my magnum opus layout.
(I've just got a small terminus built at the moment using copper clad).
Now I know why :) .
Perfect, I can print the sleepers on my Prusa I3 Mk 3S and now the chairs on the Elegoo Mars.
I can't wait. :):)

Charles
 
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I printed the chairs stl last evening and printed them directly on to the plate and they all stuck using the standard settings for the Phrozen printer and the Phrozen resin.

TemplotChairs-04.jpg


Not the best of shots but I had to fiddle around to stop too much light reflecting off the plate and still get a reasonable image of the chairs.

They have come out quite well but are a bit of a handful when working with them during the washing and curing phase - three have disappeared already. :)

TemplotChairs-05.jpg


For the same reason, they have not had the aerosol spray treatment so they have that slightly off focus look of cured 3D resin. They also don't appear to have acquired a noticeable elephant's foot after printing on the plate.

TemplotChairs-06.jpg


...and just a check that they fit the S scale rail.

I think if I was going to print a large number of them, I would print them on the plate but add a sprue between them to keep everything together during the post-printing handling. If the sprue made contact with the chair base under the rail then you wouldn't need to be too fussy about cleaning up sprue pips when you break the chairs off.

Richard

I would be interested to experiment with one of your chair files to see what I can do. I'm up to my eyes with getting an N scale layout (actually FS160) ready for an exhibition in November and that's taking up most of my time at the moment. Optimism reigns down in the West Country. :):) So I don't want to get too involved in chair making - I've just been following Martin's adventures over the past year or so and thought I might have a try at printing some of his output, mainly to try out my new mono printer to see what it can do.

Jim.

Jim.
 
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Martin Wynne

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Martin Wynne

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Thinking about gauge widening and angled chairs on points, would this be dealt with on the sleepers?

Hi Tom,

Yes, the individual chairs will be matched to the standard REA drawings as far as possible. The sockets for them in the timber will determine the angle and position of them, and thus also set the gauge.

I haven't given any thought to gauge widening at this stage -- one thing at a time. :) It could be done as part of the shove timber functions. It can't be set from the turnout size alone, because it depends to what extent they are curved, and in which direction. Also the track standard plays a part -- P4 needs gauge-widening where 00 doesn't. So it's difficult to see it becoming fully automatic.

cheers,

Martin.
 
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AndyB

Member
Hi Tom,

For me the big change was the realization that I could at last afford to buy a resin printer for the cost of a few Shapeways prints :D

Cheers,
Andy

PS Anyone want a mark one plywood and string (no kidding) FDM printer?
 
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AndyB

Member
I rediscovered the attached track panel(s). I think I was going to have Shapeways print them but my forgetory is such that I don't know if I ever did or not :giggle: The S1 chairs are quite good but IIRC they are designed for SMP rail which is a bit narrow.

The edge filleting on the chairs was done in TurboCad Pro which is a bit spendy but I'm tempted to buy the latest version because of the detail that the resin printer can produce.

The attached file is a DXF which you might be able to edit.

Andy

RATS! The file is too large. Where should I put it?

But here's a screenshot.

Screenshot (1).png
 
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Paratom

Member
Location
Cardiff
Interesting reading all these threads on 3d printing chairs. I have been 3D printing printing for a number of years now and acquired my second printer a few months ago. The printer was a fraction of the price I paid for the first printer and can print down to 10 micron layer thickness. I model in EM and planning on building a Midland Railway layout. I have noticed that nobody makes some of the chairs that are required to make a prototypical point and they have to be made up from sliced up chairs. Exactoscale do a check rail chair but only for P4 with a .8mm flangway gap. In EM it should be 1mm so I decided to make a MR one. I haven’t printed it out yet but looking forward to seeing what the results will be like. I was planning on making some of the other chairs for various crossing angles but if anyone have already done these and would like to share their results in return for printing them I would be interested. Below is an example of some coach parts I have printed and my 3D MR check rail chair. These coach parts were printed straight onto the build plate and did not require supports under them contrary to what some modellers do.

Thomas
 

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Martin Wynne

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This afternoon's entertainment was to get the chair plugs into the 2D:

plugs_2d.png


I have put a 1/2" break across the plug corners for a clear fit in the sockets. For the bridge chairs I have increased the base overlap, so that the sockets do not get too close to the edge of the timber.

The plugs and screw centres aren't really needed in 2D, but the only way to check that the code is putting every one in the right place is to draw them on the screen.

One more tiny step on what is going to be a long journey.

Martin.
 
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