• 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 Some of the earlier pages of this topic are now out-of-date.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 post.   For some practical modelling aspects of using Plug Track see The Book of Plug Track.

    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.

The Book of Plug Track

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Martin Wynne

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Assuming S1 chair plugs are designed to be 2.10mm, I suppose an accuracy of plus/minus 0.01mm is acceptable?
So my locators with adjustment of -0.20 (per side should give a target plug width of 2.10 - 2 * 0.20 = 1.70mm

Am I right in thinking that if the printers resolution is 50 microns (0.05mm), then objects produced will have nominal dimensions prouced in increments of 0.05mm (in the X and Y plane), but 0.01mm in the Z plane?

I am wondering whether it would be usefula to actually get a dark room bulb (one of those red ones)
You earlier posed question about incandescent bulbs but t'internet seems to imply that even these can emit UV
@Steve_Cornford

Hi Steve,

Thanks for the info, but something is not right there.

The design size for the S1 plugs (top part under chair base) in 4mm/ft scale is 2.0mm x 4.17mm (6" x 12.5" scaled).

I'm getting typically 1.99 - 2.01 mm. That's because I set the shrinkage to achieve exactly that:

shrinkage_3d.png


which in my case is 1.5% on all 3 axes. This therefore is the default in the program (it has to be something).

If you are using 2.5 second exposures it is likely to be printing slightly larger than my 2.2 seconds, so you would need to adjust the shrinkage accordingly to get 2.0mm plugs.

We don't know the X-Y resolution of the sliced images sent to the printer in the CTB file. But I suspect they are resampled to 2560 x 1620 and a bit depth of 1 (black/white, screen dot either off or full on). In which case achieving +/- 0.01mm is an excellent result and it's amazing we can get close to that.

Although the Z-axis resolution on the printer is apparently 0.01mm, we are slicing the model into 0.05mm layers. So all Z-dimensions will be rounded to 0.05mm increments. We don't know enough about the internal workings of Chitubox to know how intermediate Z-dimensions are rounded to the layers. I suspect on the free version it is a simple truncation at the slicing section.

I have a single 60 Watt incandescent ceiling light in my work room. It is on a dimmer, and turned well down when I'm resin printing. I believe if dimmed to less than about 75%, the UV emitted is effectively nil. I do have a darkroom safelight, but it's years since I used it and I never found it very pleasant to work under -- one of these:

paterson_safelight.jpg


When I first started photographic printing I had a 1-bar electric fire in the darkroom which served as a combined heater and safelight. Saying that now sounds like I was on a different planet at the time. :)

Sorry to hear you ran the tank empty! You have obviously been busy.



p.s. to see chair dimensions on the control template, user the ruler tool:

measure_chairs.png


Switch off timber infill (trackpad menu, above) so that you can see the ruler. Ruler at utils > show ruler.

CTRL+FULL STOP = mouse cross hairs

ALT+LEFT CLICK sets one end of ruler
ALT+RIGHT CLICK sets other end of ruler

cheers,

Martin.
 
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I will try some prints at 2.2 secs exposure so that I am matching your settings and report back. I am using elegoo abs like grey resin.
I think that it was all the locator plugs that used the resin. About 1 hour per print.
Steve
 
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Martin Wynne

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The bad news: Today's loose-jaw pins won't fit the slots.
@Steve_Cornford

Hi Steve,

I have now re-done those rafts, laid in "portrait" mode (running the short way across the build plate) as I did before.

The good news is that the loose-jaw pins now fit the slots again. :)

There isn't any bad news, although it meant fitting one fewer raft on there. They could be made a little longer.

It occurred to me that the deep vertical slots in the chairs are very tiny to wash out properly with a horizontal swirl. So I plunged the plate up and down in the wash bucket several times before starting the powered wash. I don't know if it made any difference, but the pins are fitting fine. Any residual resin left in the slots would be bad news for that.

I will post some pics later.

cheers,

Martin.
 
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Thats good news, and a useful pin slot wash tip.

I did wonder whether an ultrasonic clean would help until I researched the dangers of using IPA in an ultrasonic cleaner:(

My chitubox settings
1667291980467.png


1667292023905.png



1667292042955.png



1667292065216.png

Print in progress!
 
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Martin Wynne

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Print in progress!

@Steve_Cornford

Hi Steve,

Woah! :(

Several settings there in your version of Chitubox which I don't have.

I don't know what Image Blur does, but it sounds the very last thing we need if we are trying to get accurate engineering parts. It might be used on artistic models to soften any sharp corners.

With pixels 0.05mm apart, smearing 2 of them together is going to reduce the precision of parts significantly. On my printer it is switched off, and the Grey Level is set to zero to get maximum contrast at edges:

mars2pro_advanced.png


Some Googling needed to find out what's going on there. Is there any reference to this stuff in your printer manual? Mine doesn't refer to any of the advanced settings.

I can't remember if the above were the defaults on my printer, or whether I took one look at them and changed them.

edit: detailed article here: https://www.chitubox.com/en/article/support/indepth/technology/52

cheers,

Martin.
 
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Welcome to the world of voxels and hemivoxels!
Am i any the wiser? Not yet, probably because I had my eggs scrambled this morning!

That article explains the theory and shows the results in a clear and concise way, but what does it mean for our application?

Probably means upgrade to a Saturn to get text onto the top of your bolt/screw heads :)

PLug track users to use same parameters that you use, then have a standard Templot exported test piece that a new user can produce and measure to check for consistent results.
I chose S1 locator plugs as with a 12mm plug they are easier to measure than just the default S1 chair.
I suspect the pegs and peg slots are the more critica, and harder to measurel.

Steve
 
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Martin Wynne

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Am I any the wiser?

Hi Steve,

The problem with all this tech stuff is that it's likely to put folks off from trying Plug Track.

I'm hoping to make it as easy as possible with videos saying get one of these, click this, do that. But I can't do that until at least I have got as far as a complete turnout. And it's difficult with the internet awash with videos shouting at you, and everyone seemingly printing ugly fantasy miniatures which do nothing at all for me -- and certainly don't involve measuring things or fitting functional parts together.

But here's a nice article about starting from scratch with the Mars2 Pro and the Elegoo "ABS-like" resin to make usable parts:

https://thetechnologyman.com/elegoo-mars-2-pro-review-resin-3d-printing-introduction/

From which this is interesting:

"I found I could go a little lower than the default 2.5s – 2s gave slightly better results. And interestingly Lychee slicer uses 2s for this printer. Lychee slicer is an alternative to Chitubox and can still export .ctb files that can be printed off the Mars 2 Pro. I found it easier to use compared to Chitubox and it has more features in its free version."

I also discovered rather late in the day that the yellow plastic scraper is for cleaning the FEP film, not removing parts from the build plate. That solves the mystery of why they give you two scrapers.

I like the idea of spraying the FEP with PTFE dry lubricant. Something to try.

Here is the same guy covering the same subject in a video. He's talking too fast for a 74-year-old brain to follow, but I solve that by clicking the Settings cog and changing the playback speed to 0.75 :




Off to find the Lychee slicer to try.

Scrambled eggs. (y)

cheers,

Martin.
 
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So that i can get away with only 1 litre in the mercury wash tank, I have mad a trial modification to the build plate bracket so that the build plate hangs lower in the wash bucket.
20221103_182324.jpg
A couple of strips of 20mm x 2mm aluminium and some brass m4 nuts and bolts.
Steve
 
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Martin Wynne

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Not a lot but they as they only have one jaw they need to be pluuged into timbers and then the stock rail with other chairs attached have to be guided past them in order to plug the other chairs in. The separate loose jaw avoids the need for this guiding process, as the loose jaws are slotted in after the stock rail is plugged using the rest of the other chair plugs.
Both methods probably need a dab of superglue to complete.
I have now printed some S1 and P slide chairs with loose jaws and am having go assembling them.
Although (in 4mm) the loose jaws are tiny they do work.
Having detached a pile of loose jaws, In practice in takes me about 15 seconds per jaw to pick up a jaw in a pair of cermaic nosed tweezers (the type sold for vape users, not that i do) and insert into the slot and then press home.
This with the aid of a cheap illumintaed magnifying glass on a stand
Some might prefer the fixed jaw slide chairs, so perhaps we can persuade Martin to add a tick box option for this?
Steve
 
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Martin Wynne

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Enjoy using Templot?
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Some might prefer the fixed jaw slide chairs, so perhaps we can persuade Martin to add a tick box option for this?
@Hayfield @Steve_Cornford

Hi John, Steve,

No persuading needed, every single thing will eventually have a tickbox or a dimension adjustment. At present for my experiments it's a single setting which affects the entire export file:

loose_jaw_option.png


But that will change when I have worked out a proper user interface for all this stuff. In the end I want to be able to select any single chair anywhere and change it to some other chair, or change something about it. Or all the similar chairs, or all the nearby chairs, or whatever. That's a process I have provisionally called "chair heaving". :) I am nowhere near getting any of that done yet, I'm still at the experimental stage of finding out what works and what doesn't work. Until we know that there is no point in doing anything else.

John, the problem with the 1-piece slide chairs is that as Steve says they are a bit tricky to install.

You can't slide them on the rail, so you have to insert them loosely in their sockets in advance. But not firm them down, because installing the plug-in stock rail causes it to move down gradually as you firm back and forth along it. That would break the jaws on the slide chairs if they were already firmed down. So you must leave the slide chairs loose in their sockets, hook the chaired stock rail under their jaws while the stock rail chairs are still loose in the sockets, and then firm down all the stock rail chairs, including the slide chairs, at the same time.

For a single turnout there is probably some wriggle room in that process, and you might prefer to slide the stock rail out of the way.

But for switches within more complex formations, such as within a slip, you don't have so much freedom. In such cases having the loose jaws would make it a lot easier. The slide chair bases can be fully installed before you do anything else. The turnout or slip is then built over the top of them, and inserting the loose jaws in them can wait till last.

cheers,

Martin.
 
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