I have started drawing and 3d printing more prototype structures, and I wanted to have a Frisco and a MoPac prototype for a clinic I am doing later this year at the joint MoPac/Frisco convention in beautiful Joplin, MO October 9, 10, 11. See mopac.org and frisco.org. For 3d printing on my Afinia printer, afinia.com, I consider several things:
- Can the entire building be printed in one piece on my printer bed...this limits the size to about 4-1/2" square for the foot print, and 4-1/2" in height.
- What type of siding is on the structure? I can design and print vertical siding, but it has to be exploded in to pieces and the pieces have to be oriented to print horizontally. A good example can be seen in this post: http://nvrr49.blogspot.com/2013/07/springfield-hanger-ho-scale.html. To make lap siding print clean, it is best orient the item to print upside down.
- Overhangs and gable ends mean extra work exploding the structure and orienting it for printing, but most things can be worked around. Sometimes, however, why 3d print it, I only need one, and it would be quicker to build from wood or styrene. All options are considered.
This is the plan for a Frisco, SL&SF, section house, as published on the frisco.org web site. I was not able to read the actual dimensions, and in reality, I would need to size the building to fit on my printer, and, as such, it would be a good size for the compressed area of most model railroads. In other words, adjustments and guesses were made.
An over all view of the building to be 3d printed. With the limitations of my printer, I decided to go with Tichy windows, which are injection molded, and much finer than I can print. And, for what it's worth, Tichy products always seem to be in stock, unlike other manufacturers. tichytraingroup.com Their web site provides all the dimensions needed. The final building is about 20' x 30', i.e. the rooms are all 10' x 10'. I would assume they were larger than that on the prototype, but I really don't know.
Once the basic design is done, then I start thinking about what it is going to take to get the item to print correctly. Not to say that I don't consider what it is going to take to get the item to print correctly as I am working on it, but at this point I look at exploding the project and how it will need to be oriented. As I said above and have shown before, http://nvrr49.blogspot.com/2013/12/the-house-3d-printed-down-on-farm-5.html, lap siding is best printed upside down, so, here you can see how I have drawn the gable ends to be removed.
As I am constantly learning with each new item I print, I have figured out that if I make the walls thin to speed up the printing process, then I need to add bracing to strengthen the walls. Now, again, from trial and error, I design the bracing to be printed with the walls. Also, where two surfaces will need glued together, there really needs to be 6-8" of surface area, in HO scale. The ABS that I print with will solvent weld, but not as easily as styrene, thus it works better with a little more surface area. As you can see in this view of the drawing, I am using the interior walls as bracing, as view blocks, and I am printing the interior doors in place. The interior walls do not go clear to the bottom, so there is room to add a floor. For display purposes, I have not added a floor at this time.
Here is what the files look like I use for printing the section house. All the siding is upside down to eliminate support material and sagging...you want to see some sagging siding...http://nvrr49.blogspot.com/2014/02/farrowing-barn-down-on-farm-8-3d-printed.html. I did have to create supports under the turned upside down gable ends, but that will be cut off after the printing is done, and before assembly.
An in progress shot of the printer running. You can clearly see the support generated to create the window and door openings. Total print time, with the gable ends, is over 6 hours, with the walls taking over 5 hours. I believe, at the time I printed this, it was the longest single print I had done up to that time. This past Friday night, I did a print job that lasted over 17 hours! That building will be part of the clinic I will be doing at the Frisco and MoPac meeting.
The assembled house, with the wood porches added. In this under side view, you can see the interior walls, interior doors and the bracing, all printed in place.
I used colored paper for the roof, wood for the porches, and styrene for the rafter tails. The chimney is also 3d printed. Notice how nice the Tichy windows look, particularly when compared to the one I print on the Afinia printer, see http://nvrr49.blogspot.com/2013/12/the-house-3d-printed-down-on-farm-5.html,
The back door.
A final shot. I have a few things to do to it before planting it in a layout, but it is ready for a clinic display.