Building 3D track

[Martin Wynne]

@Phil G

Hi Phil,

Is this idea feasible? Run the laser cutter along the baseboard?

Change the playback speed to 0.75 to make sense of it.

Martin.

 

[Phil G]

Hi Martin,
I can see what your getting at here, the baseboard would need to be very flat, in fact it may not be able to get a baseboard flat enough. If it is, then yes it certainly opens up the cutting size options. It even makes much bigger and quite cheap 3 mm MDF made trackwork variable.
what was not covered in the review was any comment on a protective cover, which I am finding both for stray light and controlling the smoke/fumes, a must have feature.
It will be interesting to follow the development of this concept. As it could have some unique advantages.
phil.

 

[Martin Wynne]

.
Worth a watch: proposed 3D resin printer

Martin.

 

[AndyB]

@Terry Downes

Hi Terry,

Presumably that's a resin print with integral fixed-jaw chairs? It will be a miracle if you get that chair detail in an FDM print.

What are the extra bits of chair plug which you have included, and how did they get attached to the chairs on short spurs? Mystified.

cheers,

Martin.

Hi Martin,

Definitely not as good as resin but good enough for me.

Cheers!
Andy

 

[Martin Wynne]

Hi Martin,

Definitely not as good as resin but good enough for me.

View attachment 5943

Cheers!
Andy

@AndyB

Hi Andy,

Looks good! I have seen your posts on RMweb.

Presumably that was done with a 0.2mm nozzle? How long did it take? How long would it take to print a full turnout? FDM printing is slow anyway -- I found that with a 0.2mm nozzle you could start a job with one prime minister and have a different one by the time it finished.

Did you do the timbers with the same 0.2mm nozzle? Or change the nozzle size half-way through the print? Does your printer have a direct drive extruder? Is that ordinary PLA filament? Printed at what temperature? How much cleaning up of stringing, etc., was needed before taking the photo?

Have you actually used any of this FDM-printed track on a layout? My experiments with FDM-printed chairs in 4mm/ft scale were a dismal failure, even with a 0.2mm nozzle. It would be great if you have found a practical way of doing it.

cheers,

Martin.

 

[AndyB]

Hi Martin,

Yes, a 0.2 nozzle. I bought a roll of PLA+ (aka PLA Pro) recently. PLA makes the best prints for appearance and detail but the chairs (at 00 scale) tend to be a bit brittle. PLA+ is more flexible and the chairs do seem to be a lot more robust.

That is actually two prints each with five timbers. Each takes under 12 minutes (after warm-up), so a bit over two minutes per timber. It's all done with the 0.2 nozzle. I use Slic3r for slicing and Repetier Host drives the printer from the G-code. That sample has 21 layers, 0.15mm each. Filament temperature is 210C and the bed is heated to 50C. The inner layers are printed at 20% fill density with a rectilinear fill pattern.

Yes, direct drive extruder. Those prints are straight off the printer. There might have been a whisker or two that I pulled off with my fingers but that would be it. (The trick seems to be getting the temperature and the extrusion factor just right for the particular roll of filament, and that can take a bit of experimentation. Another trick is to now and again hit the heated glass bed with the cheapest possible hair spray. Also, the toothed belts have to be quite tight to eliminate backlash.)

It's quite a while since I printed a complete turnout but I seem to remember it took a bit under an hour. The PLA+ looks like it will allow me to make the chairs a bit more realistic and I intend to revise them yet again . I'll post again when I have done that. No real layout yet but the samples I made several years ago are holding up very well.

I've attached the STL and G-code for that print although the G-code is probably too printer specific.

Cheers!
Andy

 

[AndyB]

Hi Martin,

As you might recall I did tweak my printer to try to increase the X-Y resolution a bit. I swapped the toothed belt cogs for smaller cogs and i swapped the stepper motors for double-step motors. I'm reasonably sure the smaller cogs helped. Not so sure about the steppers. I made both changes at the same time which in retrospect was not a great idea.

I'm not familiar with the state-of-the-art for FDM printers so it's quite possible there are printers available now that could equal or surpass my printer.

One other easy tweak I made was to arrange for the vertical motion to hit the Z zero micro-switch right on top of the micro-switch's button rather than at the end of its lever arm. That makes for greater consistency.

The heated bed with its plate glass surface is now supported on a triangle of three adjusters. Four adjusters is daft because it tends to bend the glass.

While I was messing about with different types of filament I did change the extruder for one that could run at higher temperatures. That's a waste of time for printing PLA and PLA+.

My guess (I hate to say educated) is that the most important thing for what I'm trying to achieve is the extrusion factor. It's almost impossible to calculate and most of the stuff I've seen about it is pretty useless. It might be OK for printing tug-boats but it's NBG for turnout chairs. There's a common assumption that it can be calculated based on the diameter of the filament but that's nonsense. It's how the the extruder drive mechanism interacts with a particular filament and that has an awful lot of variables.

Cheers again!
Andy

 

[Charles Orr]

Hi Martin,

As you might recall I did tweak my printer to try to increase the X-Y resolution a bit. I swapped the toothed belt cogs for smaller cogs and i swapped the stepper motors for double-step motors. I'm reasonably sure the smaller cogs helped. Not so sure about the steppers. I made both changes at the same time which in retrospect was not a great idea.

I'm not familiar with the state-of-the-art for FDM printers so it's quite possible there are printers available now that could equal or surpass my printer.

One other easy tweak I made was to arrange for the vertical motion to hit the Z zero micro-switch right on top of the micro-switch's button rather than at the end of its lever arm. That makes for greater consistency.

The heated bed with its plate glass surface is now supported on a triangle of three adjusters. Four adjusters is daft because it tends to bend the glass.

While I was messing about with different types of filament I did change the extruder for one that could run at higher temperatures. That's a waste of time for printing PLA and PLA+.

My guess (I hate to say educated) is that the most important thing for what I'm trying to achieve is the extrusion factor. It's almost impossible to calculate and most of the stuff I've seen about it is pretty useless. It might be OK for printing tug-boats but it's NBG for turnout chairs. There's a common assumption that it can be calculated based on the diameter of the filament but that's nonsense. It's how the the extruder drive mechanism interacts with a particular filament and that has an awful lot of variables.

Cheers again!
Andy

Hi Both

Here is your stl file printed on my Prusa Mk3S.

PLA+, no tweaked settings, just one of the standard Prusa fine detail profiles (0.2mm nozzle)

White was in the printer already.

I will do some more without the brim

C&L bullhead rail

Fits perfectly.

Sorry the detail is not good, I will try and send a better photo in a bit.

Charles

 

[Charles Orr]

Hi Both

Here is your stl file printed on my Prusa Mk3S.

PLA+, no tweaked settings, just one of the standard Prusa fine detail profiles (0.2mm nozzle)

White was in the printer already.

I will do some more without the brim

C&L bullhead rail

Fits perfectly.

Sorry the detail is not good, I will try and send a better photo in a bit.

Charles

And another.
Sorry I have camera shake (due to me, not the camera)

 

[Martin Wynne]

@Charles Orr @AndyB

Hi Charles, Andy,

Looks good. How long did it take to print?

Have you tried doing the same with a Templot STL? It will take longer because of the deeper sleepers and flanges. You can reduce the depth and remove the flanges in the export settings.

I noticed in the STL that there are no keys to lock the rail in place. Presumably it is a friction fit -- and could be dropped/clipped in rather than threading? Is that intended Andy? Do the missing keys notice?

To make realistic ballasted bullhead track the webs will need to be reduced in thickness, but that's a simple design change.

cheers,

Martin.

 

[Charles Orr]

Hi Both,
7 minutes to print (15 layers)
I really just wanted to see what it would look like.
The rail is a friction fit, held sedurely.
Martin,
If you have time, can you post a similar STL file here from Templot. I'll print it using the Prusa and PLA+

Charles

 

[Martin Wynne]

@Charles Orr

Hi Charles,

7 minutes to print (15 layers)

Wow, that's very fast.

But at only say 9 layers for the chairs it's impossible to expect much detail. FDM can go as fast as you like if you increase the layer thickness, but the quality drops way off.

Here is a sample STL from Templot in 00-SF. It can't be an exact match because I don't know Andy's dimensions.

File attached. In addition to matching the settings you used before, it would good to see it printed at the finest standard setting your printer offers, and how long it takes.

edit: Sorry, this STL included sockets under the chairs. File deleted. The slicer wouldn't like it. See next post.

cheers,

Martin.

 

[Martin Wynne]

p.s.

Sorry, that previous STL included sockets under the chairs. The slicer wouldn't like it. Here is the same thing with solid sleepers:

edit: file now replaced with mesh-fixed version.

 

[Charles Orr]

Thanks Martin
I'm marking exam papers at the moment
I'll do it when I get a chance.
Charles

 

[AndyB]

@Charles Orr @AndyB

Hi Charles, Andy,

Looks good. How long did it take to print?

Have you tried doing the same with a Templot STL? It will take longer because of the deeper sleepers and flanges. You can reduce the depth and remove the flanges in the export settings.

I noticed in the STL that there are no keys to lock the rail in place. Presumably it is a friction fit -- and could be dropped/clipped in rather than threading? Is that intended Andy? Do the missing keys notice?

View attachment 5965

To make realistic ballasted bullhead track the webs will need to be reduced in thickness, but that's a simple design change.

cheers,

Martin.

Hi Martin,

Yes, no keys. The key side is vertical. The idea is that the top and bottom of the rail make contact with the outer chair. The inside jaw contacts the rail web to form a sort of three-point connection. I ended up doing it that way because I was having problems keeping the rail vertical. (I'm using SMP rail which is a bit narrow.)

The other thing that's going on is the jaws are not all the same. There are actually two versions. The idea is to keep the jaws a bit wide to make it easy to insert the rail and the rail is "woven" between the chairs. The amount is very small. It uses the elasticity of the rail rather than relying on a lot of elasticity in the chairs.

Cheers,
Andy

 

[AndyB]

TurboCAD and DXF files attached. 16.2mm gauge but the sleepers and and chairs are scaled at 1:81

 

[AndyB]

To make realistic ballasted bullhead track the webs will need to be reduced in thickness, but that's a simple design change.

Agreed. They were thinner but for some unknown reason my slicer kept adding solid layers under the chairs. That was slowing down the print and as I was mainly interested in testing PLA+ and the weaving idea I just made them the same thickness. The sleepers are really a bit too thin as well.

 

[AndyB]

p.s.

Sorry, that previous STL includes sockets under the chairs. The slicer won't like it. Here is the same thing with solid sleepers:

Hi Martin,

Here you go!

My printer driver complains that the model is not manifold. It did repair it but there seems to be something not quite right towards one end. This was printed using the same settings I used for my test piece. It took about around 15 minutes to print. Some of that could be eliminated if the slicer would stop being too clever.

I managed to insert SMP rail into one side but the other side didn't do so well. It might be necessary to beef-up the inner jaw a bit. The rail is also a bit wobbly but that might be because SMP rail is underscale.

Here it is alongside mine. (I should rotate the fill orientation at the printer to make the grain run lengthwise on the sleepers.)

Cheers!
Andy

 

[Martin Wynne]

.
Another source link for supplies -- 4mm wide masking tape:

https://www.arrowmodels.com/fastrax-line-tape-4mm-x-10m-masking-tape-for-rc-modelling-fast255-4

If building plug track in-situ on the baseboard, you might want to do the ballasting before fitting chairs and rails. If so a strip of 4mm masking tape along the timber would prevent any glue/ballast getting in the sockets.

Or cut your own 4mm strips from ordinary masking tape. Should be re-usable a few times if kept on a glass or china plate afterwards. Strips cut cross-wise from a 2" roll would serve for the majority of an 00/EM/P4 turnout. Use two strips on longer timbers.

But I wouldn't advise ballasting after fitting the chairs if they are for loose jaws. The slots for the pins are quite tiny, and would be easily clogged with a speck of ballast. Not easy to protect them with anything. If ballasting before railing, it needs to be before chairing too, if using loose jaws.

Also available in 7mm width from same supplier for 0 gauge.

Thanks to Nigel Cliffe for the train of thought.

cheers,

Martin.

 

[Martin Wynne]

.
The wide flanges/webs on FDM-printed plug track, and the deep timbers, makes it possible to drill and screw track into position instead of gluing -- all to be lost under the ballast. No rushing to get everything perfectly aligned while the glue is still wet; no weighting it down to keep it flat; no waiting hours for it to set before you can fix the next section; no difficulty tweaking the alignment if you didn't get it spot-on first time; no problem lifting the track for later re-use or a change of plan -- stress-free track laying.

Martin.