I have kicked the idea around for a while now of making an HO Bilby tower.?ÿ It posses extreme challenges to additive manufacturing (3D printing), as at 1/87 scale it is wispy to say the least.?ÿ The tower I have modeled is correct to the diagram posted by Richard Leu here:
Rich Leu, post: 297759, member: 38 wrote: Since Most Model Railroads Are Of An Earlier Era
Page 9 in http://docs.lib.noaa.gov/rescue/cgs_specpubs/QB275U35no1581929.pdf&apos ;">this PDF (not page 9 in the book) has a detailed dimensioned drawing of a Bilby tower that would give you enough information to construct a scale model.
I??m afraid an accurate HO scale model (1:87.1) would be pretty flimsy. For example, the 1 3/4? x 1 3/4? angle iron that makes up the bulk of the outer tower would only be 20 thousandths in HO scale. I don??t know if you can even buy material that small. And it sure wouldn??t survive the first time the cat decided the layout was a good place for a nap.
His link appears to be broken now.?ÿ The link to my model is in the "Surveying 3D model" thread located here https://surveyorconnect.com/community/computers-tech/surveying-3d-models/paged/3/.
The issue with this print is its very nature.?ÿ The towers were built multiple ways I am sure, but, the one in the pdf was with "L" metal that wasn't very big.?ÿ I have made the tower with 1mm braces throughout, which in real scale would be 87 times bigger or 87mm square.?ÿ That is obviously way to big to be true, so, I will fudge there.?ÿ The other area I just don't know what to do is the legs and the instrument at the top of the tower.?ÿ I do have models for both a T3 and GST-30 legs, but, to get them printable at 1/87 would be a lot of work and they would end up being blobs.?ÿ I am doing the tower now in draft resin which limits me currently to a 300 micron layer height.?ÿ I may try the instrument and legs separately in a resin capable of 25 micron layers, which will allow for some detail tests.?ÿ I am very confident of success of the tower without the instrument and I will post regardless of success.?ÿ More over, it is a welcome break from printing baby Yoda's for my wife.?ÿ If this works I will display it at my office for a bit and then send it to someone with an HO train set diorama as it really is nothing more than a challenge to trainless me.
I have broken the inner tower into 9 parts and the bottom three are printing now.?ÿ With the supports they weigh in at 46ml of resin.?ÿ Wish me luck!
This is one of the aforesaid baby Yoda's to show printer accuracy.?ÿ He is 2" tall and is a slippery little bastard as just before the picture he jump from my hands ran under some furniture and covered himself in dust bunnies
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To dramatize what I mean about the instrument sizing, this is the correct scale instrument and legs placed within the 1mm framed tower.?ÿ The instrument is exceedingly small
OK, brain not connected.?ÿ No legs, ... inner tower.?ÿ The test run is complete and 1mm x 1mm printed fine.?ÿ Now to try 0.7mm square
Norm, you are probably at the limit for printing. In smaller scale (2mm finescale - N in USA - 1:152) for that sort of latticework nothing beats etched nickel silver or s/steel. It would probably need 8 thou sheet - once bent the angles are remarkably rigid, especially if you run a smidgen of solder up the inside of the fold. But the paint coat would add considerably to the size - better to chemical blue it and then colour with an ink marker.
Chris, I agree, I am pretty much at the limit.?ÿ At one point I had taken to the idea of printing as sides in FDM, but, you know what I found??ÿ The sides as designed aren't flat, basically if you lay any of the three sides down they will not lay flat.?ÿ I took this as Mr. Bilby did not have fancy CAD at his disposal and made it work.?ÿ
I have cleaned the 1mm rails off the lowest section and broke two of the rails in the process.?ÿ A combination of large hands and old eyes with a splash of lack of patience.?ÿ The 0.7mm rails printed fine, but, the sprues look bigger than the part.?ÿ Looking at the 0.7mm rails, I am thinking that it is too small to be workable and they are going to be hard not to break during the removal of the support.?ÿ Maybe if I switched to a different stronger resin, but, the 1mm rails actually don't look bad.?ÿ In the pic below is the lowest section of the outer tower with the support off and 1mm rails.?ÿ The Ariel Atom is for scale as it is also HO
Since Mr Leu's link is broken, this is page 9 from the pdf from my hard drive
Suggestions:
Bilby towers would be erected on the nearest high hill, so it would not typically be in the foreground on an HO railroad scene. I agree, steel not plastic, and since it is not in the foreground round steel springwire is thin enough and stiff enough to represent the angle shapes. While the inner and outer towers are supposed to be independent, at HO scale I would want to get some extra stiffness into them. My inner tower would only have the horizontal stiffeners and not the diagonals, since they would be visually blocked by the exterior tower diagonals. Instead I would cheat and put a horizontal stiffener from inner to outer tower at the horizontal connect points. Since this is going to be on a rise it will be viewed essentially at viewer eye height. The tower structural sections are indeed flat, the break at the top is the target light support (thinner wire) above the observation platform. Make sure the climbing ladder is facing the viewer. Closer to the edge of the scene and nearest the viewer have a USGS crew setting the azimuth marker. The whole point of a bilby tower is to be above local structures and clear of the trees. Somewhere in your distant wall scenery you will want a painted bilby tower with an actual target light. Your tower instrument should be aimed in that direction. It would not hurt to have a Church Steeple azimuth point in the scene area also.
Personally, I don't know if I am ready to attempt it in N-scale, bridges and signal structures are already small enough. But then, in N-scale, I could build two bilby towers on N-Trac modules many feet apart.
Paul in PA
Suggestions:
Closer to the edge of the scene and nearest the viewer have a USGS crew setting the azimuth marker.
Some good suggestions from Paul, but I would want it to be a US C&GS crew, not USGS, and the station and azimuth marks were probably both placed well before the tower and observation crews arrived.
I keep trying to be as authentic as possible, but, you are correct, tying the towers together would help a lot.?ÿ It would also be hard to see since the towers are so close to each other.?ÿ You mention a ladder, but, in the pictures I have seen, I see people just plain climbing the tower.?ÿ I have never even seen a real tower, so, thank you for the incite.?ÿ If you build one from the math you will see that they are not flat, ... close but not flat
If someone were dead set on making a tower out of metal, the printed version would be very helpful. It would give you a dimensional accurate base which you could replace a piece at a time on. Hadn't thought of it that way
I don't think USGS ever built any towers - that was all USCGS/NGS. All the marks were set by the recon/mark setter typically several months before the builders and observers came to town. It was the job of the recon/mark setter to determine how tall each tower needed to be so the building crew could have everything planned before they got to the mark site.
Three sections done for the outer tower.?ÿ Way too many support nibs and I will have to change the support.?ÿ I broke the actual ribs I wanted to keep too many times.?ÿ Paul's idea of tying the towers together will help and changing away from a draft resin to a tough or durable resin will also help.?ÿ
Trying to replace bit by bit with metal is a non-starter. As you try and add one bit the previous bits will probably unsolder unless it is all hung in a jig - in which case you might as well put it all together in one go. the other problem with wires is at the ends. Unless you file miniscule flats on the ends they will tend to "stack-up" at the joints where several meet (there isn't enough hidden space behind the main uprights to hide the joints).
If I was etching it I'd do it as a flat for each side with fold down flanges for the horizontals - just leave the diagonals as flats - to give shape and body to the main structure. The verticals form angles as the sides are soldered together (in a jig). Once finished (!!) you can simulate the angle shape of the "flat" diagonals by highlighting the top edge when painting, using a dry brushed very light grey. As long as the tower isn't so close to the front edge as to get much scrutiny nobody will ever notice. What they would notice is the overweight appearance of the printed resin.
For something this fine don't use brass - use nickel silver or s/steel - much easier for very fine solder work, and with all that line detail, use a powerful iron, say 50W, with a fine bit; then you get the heat in very quickly to make the joint, with a small iron you have to dwell too long and the heat spreads, distorting all that thin detail.
Footnote: looking at Norm's picture of the tower section below, you might be able to reduce the apparent bulk when painting by dry-brushing the very edges of each section with the background scenery colour (green, yellow, brown??). That would confuse the eye into thinking that the edge was part of the scene, hence viewer would perceive the "steelwork" to be thinner than it has actually been modelled.
Chris, I think maybe you missed the point of what i am trying to do. I don't actually want one, it is more of a "can I do it?" thing. Think of setting a goal post and then taking a bull in a China shop method of goal achieval. Going in, I was 99% confident and that has dropped considerably now. It can be done by my printer, no question, but, at what cost? The cost as I see it is a lot of rework of flimsy plastic, fixing breaks in parts and other annoying things old eyes don't like to focus on.
Other than the only method that I will go forward on is printing, your points are well taken. I started a different print last night, but, did play with the slicer to see if I could make it printable and made some progress splitting the model and changing orientation. An SLS printer where the support medium is omnipresent during the print and then just falls away would have no trouble with this print. Shapeways has an SLS, but, they charge based upon volume, so, yikes! I am trying SLA and FDM is a complete non start and those are the two printer types available in my print room right now
Turns out I did upload at least the outer tower to Shapeways and condensed it into a blob. https://www.shapeways.com/model/upload-and-buy/3088071?mg=6&c=1&f=1 it is not as expensive as I thought, but, still not what i am trying to do.
I am still struggling with how to print this, but, in the interim I found another waste of time.?ÿ Placing 3D models in Google Earth.?ÿ I have known for a long time that you could do this, I just never tried.?ÿ It is so easy, just convert your 3D printing file into a dae and bring it directly into GE.?ÿ Attached is a dae file of a Bilby tower and it will center itself on your view in GE
The site would not let me attach a dae file, so, I re-named it pdf.?ÿ Just change it back to Bilby.dae and you can insert into GE
Inner City Bilby.?ÿ On top of the Columbia Center downtown Seattle
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I also made some QuikFAT target dae's for looking at drone pathing.?ÿ They both look small as one would expect, even the large 32" across one
You win some and you lose some.?ÿ I was sure that i could print this and it just isn't possible with what I have for printers.?ÿ I am sure that somewhere is a very expensive machine that can do it, but, this was just to see if i could do it.?ÿ On to other stupid projects!?ÿ
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I did print it as sides on the resin printer, although it did mangle the instrument portion into a squiggly mess