Building 3D track

[Martin Wynne]

I cut the outside sprues off prior to glueing down since it was not need for strength and would be a pig to remove.

@timbersgalore

Hi (no name),

Looking good.

I see that you have full-depth webs below the rails. How are you planning to remove them after tracklaying? Any sort of cutter or blade will force the timbers apart. A Dremel disc might be an option, but tedious to do. Or if you leave them in place how will you disguise them in the ballast - the top of the ballast is normally level with, or a fraction below, the timber top. Flat-bottom rail is wider than bullhead and closer to the timber, so tends to hide such webs. But for bullhead track the daylight between the rail and the ballast is a characteristic feature:

(This question also applies to all the commercially available laser-cut timber bases -- but when I ask it the answer is always silence. )

For the Plug Track I intentionally placed the sprues outboard of the sleepers to make prototypical ballasting possible below the rails. I think you would do better to remove the webs before tracklaying (or not have them in the first place) and leave the sprues in place. If you don't apply any glue to the sprues they are easy to remove after tracklaying by holding a pair of flush cutters vertically (Xuron cutters, supplied with the resin printer).

For the FDM printed timber bases the sprues are omitted, but the webs and timber flanges which replace them are only 1.5" thick (0.5mm in 4mm scale) and easily hidden under the ballast.

p.s. notice the GWR chairs in the pictures. Which for pointwork are fixed with plain square-head coach screws (unlike REA chairs with tapered ferrules and bosses for the screws). But for plain track the GWR chairs use through-bolts from below with nuts on top. So ideally you need two types of GWR S1 chair -- one with plain screw-heads as above for use in pointwork, and one with a bit of bolt showing above the nut for plain track:

Alternative bolt-tops will be an option in Templot for the GWR chairs, but oh my, there is such a long way still to go.

Hardly anyone will notice the difference in 4mm scale, but I have to think ahead for 7mm and the larger scales.

cheers,

Martin.

 

[timbersgalore]

Martin
Thankyou for you comments. I placed the web under the rail as it seemed to work on the pre made bases I have used. I assummed I could hide it with ballast but I have never got as far as balasting any track. I will give the spruces a try.

How far to go on detail when it is hard to see with the nacked eye? If I can sucessfully print it I will have a go at modeling it.

Timbers

 

[timbersgalore]

I am amazed at the level of detail acheivable by the Sonic mini 4K. I think it is helpful to model the detail as it helps to get the big stuff right. Martin thankyou for the chair pictures. Mine arn't as good as the old track near me is still part of network rail. I have the drawings for the chair plan views but I am having to work out the cross section.

I have refined my ordinary char and made a stab at the SS chair:-

printed on a phrozen sonic mini 4K. Aqua 4K resin, XY 0.037mm Z 0.030mm.

 

[timbersgalore]

This afternoon I print some chairs from the templot files. I first had to fix and unsupported island formed at the bottom of the rail clip.

A you can see I droped them on the floor!

Timbers

 

[timbersgalore]

HI Martin
Regarding the rail and grip on it. I found the templot chairs quite a sloppy fit on the 4mm society rail. I would say you have overdone the allowance for rail side taper. It would be helpful the know what are the profile numbers for "C&L / EMGS/ S4Soc code 75" rail. What is "Fish centre" How is the fish angle measured (between what).

The accuracy I am achieving with the sonic mini 4K is amazing so far what I draw is what I get.

I have kept the grip parallel to the rail and find my chairs easier to thread than the plastic chairs form the 4mm society. I am using a web thickness of 0.4mm

I am in the throws of making a "test of method" track sample. It consists of a GWR 12ft heel V7 with return curve. Rather than post detail here it is probably better I start another topic elsewhere. I will be using a laser to cut the sleeper base as I get far superior results compared to the FDM printers I have (I have three!).

Timbers

 

[Steve_Cornford]

Hi Timbers,
As you have a laser, have you thought of cutting a cork(or ply) trackbed layer just with sockets, then make the chair pegs deeper. That way you dont need to have sprues on your timbers, and you can cut the timbers with the long edge parallel to the grain. Then the longer pegs locate the timbers onto the trackbed layer.
Good luck with your "test of method"
Steve

 

[timbersgalore]

Thankyou Martin
Than helps me a great deal. I can now see that the sample in fornt of me is undersize. My web is 0.40mm (measured by filling off the head/bottom then micrometer).
Timbers

 

[timbersgalore]

Martin

I did mean undersize compared to the nominal values for the C&L track. I estimate that my rail is between 10 to 20% undersize. I think I could have fixed the problem using the presets you have already build in. I don't think the taper on the key was causing the sloppy fit.

After adjusting my CAD to describe the rail profile it terms of fish, I have done a lot of experiments to get the rail grip right. I started of with daylight under the key and adjust the prints to get a good grip of the web. The rail was still sloppy in the sense it was easy to roll the rail from vertical. Rather than fill completely below the key I have tried only filling below the key at the centre of the key, shown purple below.

The is still a bit of roll. I printed this with FootWidth set to 1mm, My rail is 0.9mm.

I think this demonstrates the benefit of customising the 3d print to the actual profile of the rail to hand. The other option is to deliberately make the rail a tight fit but I that is not an option if using a brittle resin.

I think it will take a least another iteration to get something I am happy with.

Steve: my sub layer already has the sockets cut in it.

 

[Steve_Cornford]

Hi Timbers,
Can you confirm that the concept of sockets in the sub layer works ok for you, and that it is practical to do away with any timber sprues?
If it does we can bunch the timbers up and get the most economical cuts of timbers.
Steve

 

[Martin Wynne]

I did mean undersize compared to the nominal values for the C&L track.

@timbersgalore

Hi Timbers,

Those are not "nominal" values for C&L rail. They are just random test data. Please ignore any dimensions you find in the current program release. It is all just dummy data used to test the programming and the process. I grabbed just any data that I had to hand. It is almost certainly wrong. My big fear in releasing unfinished stuff is always that someone will regard it as definitive info and start using it for real. Or worse still post it elsewhere on the web.

It is all utterly experimental at this stage. I will let everyone know when Plug Track has reached a stage where it can be used for actual models, but it won't be for some time yet.

I think you have your key too small and your outer jaw too low, which probably explains why the rail is not being firmly held upright. The key should completely fill the space between the rail head and foot, and the top of the jaw should be level or fractionally below the outer face of the key:

Also the rail seat/platform should extend across to the jaw, so that the rail can be dropped into the chair before being keyed across into place.

Making the rail vertical does affect the dimensioning to some extent. But check rails are always vertical, so the jaw dimensions from the inside of check rail chairs can be a reference. For REA chairs all outer jaws are 5.11/16" above the underside of the chair (except 2-level chairs and thick-base chairs).

Here is an actual GWR / BR(W) 2-bolt S1 chair. The top of the outer jaw is 5.5/8" above the underside of the chair. The jaws are 4" wide at the top:

cheers,

Martin.

 

[timbersgalore]

Martin
Don't worry I am taking very little form the templot chairs. My height comes from measurements of the plastic chairs from the 4mm Soc. The only reason I looked at the stl from templot was to provide you with feedback.

On the other hand the pictures of the fullsize chairs are gold dust to me. Plus your written feedback has been most helpful. Are the close up of the chair casting from your own private collection or are the available on the internet?

 

[Martin Wynne]

Are the close up of the chair casting from your own private collection or are the available on the internet?

@timbersgalore

Hi Timbers,

That chair has been in my garden for about 40 years.

I dragged it into the sunshine and took the pictures this afternoon.

cheers,

Martin.

 

[timbersgalore]

Hi Timbers,
Can you confirm that the concept of sockets in the sub layer works ok for you, and that it is practical to do away with any timber sprues?
If it does we can bunch the timbers up and get the most economical cuts of timbers.
Steve

Steve
I haven't explicitly tried, though it is an idea that appeals to me. Even though I made the spruces only 1mm wide and took precaution to get no glue under them they were remarkable resistant to being removed(but achievable). The sockets cut by my laser have a taper. I set may laser up (kerf offset) so that I get my nominal dimensions at the bottom. I put at taper on my plugs but slightly less (room for glue). I would need to re jig this so that the sub layer provides the positive location for the chair (provide clearance on the sleeper sockets). That done it stands a very good chance of working out OK. I would recommend using birch ply for this layer.

I would still want to attack a spruce to the timbers so that I did not end up with a bag of match sticks.

I would still want to atach a spruce to the timbers so that I could lift them from the cutter.

Timbers

 

[Martin Wynne]

Laser cutters are capable of understanding shapes. What it means is that when presented with a nested set of rectangles they work out what is inside and outside. The result is that the cut planner can works out which bits to cut first. It also means that the laser can provide the Kerf offset. It would be worth checking whether a cutting service is automatically applying it own kerf offset to closed figures. That said it would be usefully to have the timber outline and chair socket layers on there own layers. Here is a screen shot showing the cut layer from my recent test:-

View attachment 2154

A little shape manipulation is required to join the spruces to the timbers.

@timbersgalore

Hi Timbers,

Thanks for the screenshot. Is that from a Templot 2-D file or 3-D file?

For 2-D the timber outlines and sockets are on separate layers:

In the 3-D files the timbers and sockets are all in one layer because they form a single solid object.

Laser cutters are capable of understanding shapes.

There are no rectangles or other area shapes in the Templot 2-D DXF files. Everything is a simple Line entity. The files are, or were originally, intended primarily for import into a CAD program for further track and layout design purposes.

For use on cutting machines there are other types of machine in addition to Laser cutters -- blade cutters, photo-etching, CNC milling machines, presses, stamping and blanking machines, etc.

I want to provide as many options and settings as possible to make the Templot DXF useful, but ultimately it is down to the user to know their own machine and how best to use the Templot DXF on it. If the kerf adjustment is not wanted, the layers can be switched off or the kerf width set to zero.

At present home laser cutters are much more expensive than an FDM printer, so the latter is more likely to be available to many Templot users. At least for the present my main focus is on the FDM timbering bricks for Plug Track. There has been a lot of recent discussion in this topic about laser cutting, but I suspect the majority interest will be in FDM printing for the timbering. I may be proved wrong as machine prices change, but I still feel that FDM printing will be the most user-friendly option for home pointwork construction, and is capable of excellent results comparable with injection-moulded track:

Also, an FDM machine can be used to make the rail filing and bending jigs needed.

cheers,

Martin.

 

[timbersgalore]

Very much the 2D dxf. I am still basicly using the same work flow as for 227. I have descovered it is very straighforward to place my own socket outlines using the track edge and timber centre line. Is everything you mentioned in the live version of 228 or is it unrealeased?

You track sample looks good, is that 7mm scale?

I have just completed another iteration of the GWR 95 chair. I used no fill below key but with the key heights fixed. I have also switched to ABS like resin. The Phrozen stuf as very little smell. Even able to use it in the house! I still have a small tweek to make the jaw height the same. The good new is that with a close fitting key the rail is firmly held.

Timbers

 

[Steve_Cornford]

Hi Timbers,
Thanks for sharing all that useful information.

Laser Cutting
For my experiments the laser cutting service I used (4D model making materials) did not mention that their laser cutter understood shapes nor did they tell me what software they used to control the laser cutter.
When I asked them about the difference between their meaning of an inner cut(blue) and and outline cut(green) they just stated that the laser cut all the blue lines first then the green lines.
The principle being that if the timbers were cut before the sockets they could not guarantee that the sockets would be in the right place.
They required artwork with 0.076mm line width.
They also stated that if i wanted timbers 4mm wide and 32mm long I should add half the kerf (in their case 0.2mm) to the dimensions all round, and as far as the sockets were concerened (inner cuts) that I should subtract half the kerf all round.
Using Templot 228a, Martin suggested a work around to achieve this as far as the timbers were concerned, and he had already suggested a method to Ralph for adjusting socket size which I used.
I then used Inksape to open the resultant .DFX file so that I could copy the sockets to a separate layer and change their colour.
Martin has kindly added this experimental ability in to his next Templot release, together with the enhancement of putting the sockets in a separate layer thus making it easy to also produce a cutting file for a trackbed layer that the acts as a jig for the timbers layer, thus obviating the need for sprues holding the timbers in the right position.

The chairs I produce ( using an Elegoo Mars 2 pro, arriving in next 3 hours) will have longer pegs so that they go through the timbers and into the trackbed layer.
Also in my experiment I output both a straight B7 turnout and a curved B7 turnout, as I wanted to see whether there was any difference in the socket poitions on the timbers between a curved and a straight turnout.
Martin has since confirmed that there is no difference.
This means that I can get all the timbers cut as straight turnouts, and get the grain oriented parallel to the long edge of the timbers, also bunch them together to minimise cutting costs.

Rail Profile
I have just measued the web thickness (without filing head or foot) of some of the rails that Wayne Kinney has provided in 4 OO-SF B7 turnout kits with my cheap(powerfix) digital caliper and they appear to be 0.39mm. I checked the accuracy of the calipers using a 0.40mm thick feeler gauge (draper).
I believe Wayne sources this rail from the E.M.G.S.
I then tried measuring some rail lengths purchased from Scalefour Society a couple of years ago and these had 0.39mm thick webs.

Steve

 

[timbersgalore]

I got stuck on the idea of modelling Camborne station, prior to lifting the goods yard. It has two slips, a crossover, and 3 turnouts in an impossibly small space. Until I got of copy of David Smiths book I thought it was impossible. I have now almost got a templot track plan, I have the rails placed but timbering is a worry.

I made this to prove I could join laser cut sections together (The main line is at the top, bay on the right, good on the left)

I have been given new hope that I can do it, if I use plugs on the chair and socket on the timbers. In the short term the only place I can get GWR chairs with plugs on is if I design and print them myself.

Timbers
To be continued ...

 

[timbersgalore]

My short term goal is to find a way of reliably making a GWR loose heel switchs. I got on reasonably well following the Morgan Designs Instructions but I hope that with computer controlled machines I can do better. The 3D printer enables me to print my own chairs and my current hope is that I can make functional 1S, 2S & 3S chairs to better support the heal.

There are may challenges to overcome one being how to assemble the switch on the trackbase. The is where I hope plug in chairs will help.

This is just a trial assembly to see how I am going. The SS* chair has a functional stud block and it is my intension that the switch rail ricks in the 1S chair. I am working on the 2S chair and this will provide firm support for the end of the turnout rail. (The switch rail is junk from my desktop and not quite the right shape.)

 

[Phil O]

Hi Martin,

Loose heel switches only have 2 bolt fishplates, see my photos of special chairs in the show and share section of the old forum.

 

[Martin Wynne]

@Phil O

Hi Phil,

It's Timbers building the GWR switches, not me.

Here are links to your topics with the GWR chair photos:

topic: 182 - GW special chairs
topic: 184 - GW special Chairs
topic: 186 - GW special chairs
topic: 187 - GW special chairs
topic: 188 - GW special chairs
topic: 189 - GW special chairs
topic: 190 - GW special chairs
topic: 191 - GW special chairs
topic: 192 - GW special chairs
topic: 204 - GW special chairs

To find them again, put "GW special chairs" (with the quotation marks) in the Full Templot Search.

cheers,

Martin.