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Coaltrain
Fireman
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 Posted - 02/03/2021 : 07:59:30 AM
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made a little more progress on the Shay, this time it was the rear sandbox and the fireman side running boards. One big issue I have is that the California State Railroad museum did not have the cab or the exact tender drawing. I have a tender drawing that is close that I have been able to learn details of construction but I did not have the exact width measurements. The frame drawing I have is what is called a "tabulated drawing", meaning that it was used to create several different size frames using a table of dimensions depending on the plan number, and I do not have a way to link the Plan drawing number to the order number. The only way I know is to guess at the plan number date and compare it to the order number date. The MC shay 8 was a special shay that had some modifications to it and I could not get some dimensions, one being the width of the tender, from the tabulated drawing. To solve the mystery I used Sketchup and did "photo match" to get the best guess I could, turns out that #8 is 6" wider than the plan calles out.
I am really confident in the 6" width compared to the standard width because I have used several different photo angles measured against known dimensions. I also had the drawing of the running board support and it was sticking out farther than the standard tender drawing showed, so that is how I knew something was different. When you look at photos of the real #8 there is just something different looking to it than other shays, part of it is the huge stack, but there is a more bulky look to it, which I now am sure is the combination of the large diameter boiler and the 9' wide cab/tender.
with the recent discover of the wider cab I am going to have to build a new cab, but that is ok because I have learned a better way to build parts for this type of modeling that makes the parts more stable and flexable.
As you can see this is just as hard and time consuming as actual modeling, just in a different way. I was thinking maybe there needs to be a name other than 3D modeling for this kind of work, maybe digital scratch building or something like that.
one detail to point out that often gets missed is that on shays the running boards on the fireman's side hang out past the side of the tender and form a toe board to allow the fireman to go from the cab to the rear of the tender without climbing down from the locomotive. this "bump out" also extends along the side of the cab for the same reason. my running boards do not stick out as far because my digital model's running boards are what I am calling "sub running board". Another detail is that the MC shay had metal running board, which you can see how bent and dented they are. I am not sure I would want to slide alongside that tender on a rainy day while crossing Glade Creek on those running boards
rear view of sandbox
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Philip
Fireman
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Posted - 02/03/2021 : 11:01:28 AM
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Good stuff! The building end is symmetrically perfect!
Philip
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Country: USA
| Posts: 3494 |
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Coaltrain
Fireman
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Posted - 02/06/2021 : 11:45:17 AM
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big day today, the cab main parts were developed and checked against the original Lima drawing. now that I have the parts all worked out I can move forward with all the final detailing, and then let the resin flow!
I have to make the cutout in the cab side for the cylinders and then correct the cylinder shield yet.
here is the CAD model laid over the actual Lima drawing.
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Coaltrain
Fireman
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Posted - 02/15/2021 : 08:09:27 AM
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I started printing parts for the frame. so far I have the firebox and the ashpan printed, and as I type this the front portion of the frame is printing.
the normal procedure for resin printing is to design the part, import it into a slicer program, add supports to hold up areas that are "floating" and then print. I tried printing the firebox and ashpan a few times using the standard procedure and I was not getting good enough results. I decided that I needed to also design my own supports and not use the slicer program supports. The slice supports work fine for your average details but I needed the parts to be more accurate because the need to be assembled with tighter tolerances. The slicer supports are good for supporting what they call "islands", or small patches of the part that are floating for part of the printing process, once the islands attach themselves to the main model then the part will continue to print fine. in the case of a random detail there can be some deforming of the part caused by sagging in the "islands" and it really does not matter. I am supporting large flat edges so I designed supports that would support over an entire edge rather than small points. I designed the supports so they would break away with just a small amount of material to sand away, and I am putting those areas on non-visible surfaces.
the other benefit of modeling my own supports is that the supports are in the model, and if I need to make small adjustments to the model I do not have to go through all the effort to put supports back on the model. For example, normally after you import into the slicer you may spend a considerable amount of time adding supports, then print the part. After the part is printed it is not uncommon for a part of the model to need to be adjusted to get it to print better or you just forgot a part. If a part needs adjusting you have to go back to the part modeling software, fix the issues, export again, import into the slicer and then redo all the supports that you put in the first time. by having the supports in the 3D model they will export with the part and all I have to do is just import into the slicer and print.
I can see the day coming that 3D modeling software will have an option to design supports for all these reasons I stated above.
here is the firebox and ashpan print. I threw on some gray paint on the firebox and did a quick grime wash. I am going to add some rust this week.
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Coaltrain
Fireman
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Posted - 02/22/2021 : 07:22:20 AM
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to say that printing the frame has been a challenge might be an understatement. I am trying plan C at the moment.
Plan A = Resin veneerse with brass reinforced I-beams
Plan B = All Resin
Plan C = Resin print veneers and laminate on PLA
Plan D = Brass skeleton with resin veneers
Plan E = all brass
Plan A failed because of the thickness of the I-beams over resin were very thin and the attached running boards warped. however I may be able to try this again with a new curing method that seems to be warping less.
Plan B failed because of warping of the I-beams. I also got some warping in the running boards but the biggest issue is the frames are hump backed.
Plan C (the current try) is that I am printing a PLA subframe on a FDM printer that I will laminate veneers of resin over them. I wanted to try full 3D printing before I give up on it because there are advantages of all 3D printing if it works. Why I think this will work, because my FDM printer has a 12" bed and I can print the subframe in one piece, the resin printer will only do 4" max and the resin frame would have to be in three pieces. I got this idea because my original test frames that were printed in PLA are very straight and strong. PLA is not good for details but it is strong, and if I make highly detailed resin veneers I can laminate the sections over the PLA. The PLA will give the print the strength and the resin will give it detail. This is an adaption of Plan A, which was a good plan but when I tried it the resin I-beams were too thin. I could try it again but I like the idea of a completely printed frame because the accuracy of the frame will not be dependent of my fabrication skill and the printed frame will exactly match my 3D digital model and any parts I design for it will fit perfectly.
here is what print testing looks like
here you can see the warping frame rails
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Dutchman
Administrator
Premium Member
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Posted - 02/22/2021 : 08:34:16 AM
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The firebox and ashpan looks very good, Jeff. Hopefully one of your plans for the frame will work out.
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Country: USA
| Posts: 33527 |
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Philip
Fireman
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Posted - 02/23/2021 : 11:13:22 AM
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Easy getting sidetracked in the 3d world. Awesome work!
Philip
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Country: USA
| Posts: 3494 |
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Chris333
Engine Wiper
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Posted - 02/23/2021 : 8:01:07 PM
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Would even shorter pieces printed separately help the warping?
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Edited by - Chris333 on 02/23/2021 8:01:26 PM |
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Coaltrain
Fireman
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Posted - 03/03/2021 : 09:00:47 AM
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Well....progress IS being made on the shay. This has been much harder than I would have thought it was going to be and I am wondering if building in brass would actually be easier. The CAD part is not hard because I do it for a living and I have for 30 years. The hard part is breaking parts down for best printing and then getting them orientated on the printer and supported so they print as desired, then cured without warping, then assembled into a model. There are lots of parts that are printed, check for flaws, then checked for fit, then adjusted and printed again, and sometimes again. However, in the end there will be the ability to just print parts as needed.
The frame is assembled but it was not easy, building the trucks were easier. There is just a very slight back bow that I believe the boiler will straighten it out when mounted.
I made lots of progress on the boiler details and I am just a few moments away from being able to print it for the final time.
here are images of where the frame is at, sorry for all the sanding dust and poor images, it is really hard to show it in the unpainted stage.
here are the images of the boiler CAD model. one detail that I wanted to include was the seams that run down the lagging, which I have not seen on any production models yet I see it all the time on real locomotives.
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Michael Hohn
Fireman
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Posted - 03/03/2021 : 09:35:01 AM
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It’s always a pleasure seeing progress here.
You seem to be testing the limits of technology. It will be a big help to those who follow.
Mike
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Country: USA
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Chris333
Engine Wiper
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Posted - 03/03/2021 : 3:24:15 PM
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3D grease bucket for the win!
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Coaltrain
Fireman
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Posted - 03/04/2021 : 7:25:35 PM
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thank, the grease bucket was used to get proportions of the air tank, i just forgot to take it out, but I will print some and decal them for Esso
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Coaltrain
Fireman
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Posted - 03/09/2021 : 2:13:34 PM
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The printer has been running around the clock. All I have left is to detail out the cab and tender and I will have all the parts that were planned to be printed done and I can move forward to the assembly of the model. The images of the model below are NOT assembled, they parts are just placed in their location, I will glue it together when all parts are printed.
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us-okrim
New Hire
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Posted - 03/26/2021 : 1:20:52 PM
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Jeff - eagerly awaiting your next update on your shay #8 project, what a fantastic build. Mirko
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Country: USA
| Posts: 25 |
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us-okrim
New Hire
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Posted - 03/26/2021 : 1:21:41 PM
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Jeff - eagerly awaiting your next update on your shay #8 project, what a fantastic build. Mirko
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Country: USA
| Posts: 25 |
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