3D Printing - General Thread

[Hauk]

Back in April I emailed Alan at Modelu to tell him how much I liked his figures even in HO scale. I asked him what the red material was and this is what he wrote in reply:
The resin is hard though also does have an amount of elasticity to it as it has a wax content for casting.  For that reason I only use the red resin as the non-wax resins are far too brittle.
Cheers
Alan

Wonder how much wax there is in that resin? Not sure the long term stability of wax, but boy do those figures look great!

Thanks for the clarification! It never occurred to me that the resins could contain wax.
For long term stability I guess I will just have to wait and see. And keep the little ones out of the sun and UV-light!

[Rail and Tie]

Been a while since I posted here, but always lurking. Here is a detail that I have been working on. An HO Scale power meter. printed on my printer. I am finding that the resolution is holding up well in this scale. the meter dials should be raised further to show off the disks, but overall I am pretty happy with the output.

[Ray Dunakin]

Wow! That turned out great, especially considering the small scale.

[finescalerr]

The resolution really surprises me. Maybe there's hope for printing my 1:32 scale Plymouth. -- Russ

[eTraxx]

What printer did you use to print the meter? That came out very well.

[Rail and Tie]

Thanks guys, this was printed on my 3DS Projet 1200 Printer. The printer is great for small parts as it has a 1.7"X1" and 5" tall print area. I find the resolution to be better than anything I have done with shapeways and the finish is superior to what I have gotten from shapeways as well because there is no build wax residue to deal with.

[mabloodhound]

The gas meter came out very nice.
I too like the fine details better than what I get from Shapeways.

[finescalerr]

Does anyone know of a service bureau that uses the 3DS Projet 1200 Printer? I'm sure many of us could use a place offering higher resolution output. -- Russ

[eTraxx]

I posted some pics of my 3d printed 1:48 Ore bin chutes/gates the other day. Ray Dunakin asked if I could scale them up to 1:24. That .. CAN .. be done of course but I got to thinking about it and thought it would be worthwhile to show the problems/constraints etc. this process engenders. This will by the way be the most "geeky" part of this thread .. at least I hope so.

-- Sketchup --
Ok. I'm not going to go anywhere near the "this is better than that" thing. I use Sketchup .. and will address the problems that can create .. and the workarounds in a bit. I am hoping the discussion can focus on the modeling while letting what software one uses be simply their choice.

Sketchup was created by @Last Software with version 1 released in 2000 as a modeling tool for "Architects, designers, and filmmakers". The part about 'Architects' may have something to do with a couple of the problematic issues with the program – at least as far as it relates to those of us using the program to model scale objects.

— Problem —
The program refuses to create a radius below approximately .018″ – which means the smallest hole you can create therefore is .036″. To give an idea what this means .. here is what that .036″ is in various scales:

• HO scale – 3.132″
• O scale – 1.738″
• 1:24 – 0.864″

Obviously, those of us who use Sketchup for scale modeling will have a problem with this.

This same restriction comes into play when re-sizing objects as you can get glitches where you have missing polygons when resizing curves. Sketchup can throw a fit sometimes when resizing a spherical surface.

So .. what to do?

One way would be to re-size a model up x 100 .. and then re-size back down x 100 when finished. This can work .. probably works *most* of the time but not all. You can still run into problems when that reduction re-size drops radii below that 0.018" radius.

-- Pmm --
My own solution is to use what I term .. Pseudo Millimeter .. Pmm modeling. Ummmm. How to explain so it makes sense .. let's try this ...
Let's take a cube which full-size is 1ft x 1ft x 1ft. We also want to punch a 1″ dia hole though it

• In HO scale this cube would be 0.138″ x 0.138″ x 0.138″ with a 0.012″ hole
• In O scale this cube would be 0.250″ x 0.250″ x 0.250″ with a 0.021″ hole
• n 1:24 scale this cube would be 0.5″ x 0.5″ x 0.5″ with a 0.042″ hole

Note that both HO scale and O scale the holes are smaller than 0.036″ dia. To model these cubes we would have to go through re-sizing up and then back once finished. 
My Pmm method not only bypasses this problem it also allows working directly in scale .. Simply .. I set the units to Decimal Inches but model as if I were working in mm.

sooo .. back to the cubes ...
In HO the cube is 3.5 x 3.5 x 3.5 with a 0.3 hole
In O the cube is 6.35 x 6.35 x 6.35 with a 0.533 hole
In 1:24 the cube is 12.7 x 12.7 x 12.7 with a 1.07 hole
Ignore the " .. indicating inches .. or simply uncheck the [ ] Display units format in Model Info.

Happy days .. that 0.036″ minimum hole dia is now .. ummm .. 0.00014″
In addition we can model directly .. as it were .. to scale. Example, for WSF the minimum wall thickness is .7mm .. so we can measure directly on the model to ensure that any all is equal to or greater than that .7 mm minimum. In reality .. I keep to a .8mm minimum for WSF and a .4mm for FUD (even though the stated minimum is .3mm) .. makes all the difference. I have found that using minimums causes unending pain to the modeler. Just my 2¢ – ignore it at your own peril.

• In HO that 0.138″ is 3.5mm (ok .. 3.5052 but .. that extra bit is not worth worrying about)
• In O that 0.250″ is 6.35mm
• n 1:24 that 0.5″ is 12.7mm

-- Exporting for printing --
If I design a cube 25.4 on a side and export as a DAE file, I can then import it into MeshLab do what 3D stuff I need to do and export a STL file which will contain a cube 25.4 UNITS on a side. I upload to Shapeways and simply tell them that the model is in millimeters .. and the model is exactly the size I need it to be.

[eTraxx]

Strong & Flexible Plastic Material Information

The following is the data for White Strong and Flexible from Shapeways. This is important *stuff* .. in that we have to work with (and around) these limits when working in 3D

Strong and Flexible plastics from Shapeways are sintered nylon .. meaning layers of nylon powder is fused with a laser beam. What you end up is a product that is similar in some ways to derlin plastic but with a rough surface. To me this works well for things like cast iron for 1:48 and larger scales. The material is strong .. much more than the higher detail frosted detail plastics.

Price
$1.50/part
$0.28/material cm3
$0.21/machine cm3

• Min supported wall thickness (A supported wall is one connected to other walls on two or more sides.) - 0.7 mm thick
• Min unsupported wall thickness (An unsupported wall is one connected to other walls on less than two sides.) - 0.7 mm thick
• Min supported wires (A wire is a feature whose length is greater than five times its width. A supported wire is connected to walls on both sides. If you must use sprues, use them sparingly, use 2mm thick wires, solid connections, and attach every part in at least two places) - 0.8 mm thick
• Min unsupported wires (A wire is a feature whose length is greater than five times its width. An unsupported wire is connected to walls on less than two sides.) - 1.0 mm thick
• Min embossed detail (A detail is a feature whose length is less than twice its width. Embossed details stick out from a surface.) - 0.2 mm high & wide, 0.5 mm for readable text
• Min engraved detail (A detail is a feature whose length is less than twice its width. Engraved or debossed details go into a surface.) - 0.2 mm high & wide, 0.5 mm for readable text
• Min escape holes (Escape holes allow unbuilt material inside hollow products to be removed.) - 4.0 mm diameter for one escape hole, 2.0 mm diameter when there are two or more escape holes. Required for products bigger than 50 × 50 × 50 mm
  
• Clearance (Clearance is the space between any two parts, walls or wires.) - 0.5 mm clearance

[eTraxx]

Frosted Detail Plastic Material Information

The following is the data for Frosted Detail Plastics from Shapeways. Again .. this is important information which is necessary to get good designs for 3D prints. FUD and FXD are great for detail .. but are weak and brittle.

FUD (29 micron layers)
Price
$2.50 handling fee
$1.00 /part
$0.75 /material cm3
$0.38 /support cm3
$0.09 /machine ((Footprint cm2) x (Height cm)1.25)

FXD (16 micron layers)
Price
$2.50 handling fee
$1.00 /part
$1.00 /material cm3
$0.50 /support cm3
$0.20 /machine ((Footprint cm2) x (Height cm)1.25)

•   Min bounding box   X + Y + Z = 12 mm. At least two axes must be = 2.49 mm
•   Min supported wall thickness (A supported wall is one connected to other walls on two or more sides.) - 0.3 mm thick
•   Min unsupported wall thickness (An unsupported wall is one connected to other walls on less than two sides.) - 0.6 mm thick
•   Min supported wires (A wire is a feature whose length is greater than two times its width. A supported wire is connected to walls on both sides.) - 0.6 mm thick
•   Min unsupported wires (A wire is a feature whose length is greater than two times its width. An unsupported wire is connected to walls on less than two sides.) - 0.8 mm thick, 1.0 mm if bearing weight (like a sprue)
•   Min embossed detail (A detail is a feature whose length is less than twice its width. Engraved or debossed details go into a surface.) - 0.1 mm high & wide
•   Min engraved detail (A detail is a feature whose length is less than twice its width. Engraved or debossed details go into a surface.) - 0.1 mm high & wide
•   Min escape holes (Escape holes allow unbuilt material inside hollow products to be removed.) - 4.0 mm diameter for one escape hole, 2.0 mm diameter when there are two or more escape holes
•   Clearance (Clearance is the space between any two walls, wires, or separate parts.) - 0.05 mm clearance

[Greg Hile]

This is really important information to have. Much appreciated and looking forward to more!

[eTraxx]

As many know, one of the great resources for we modelers is Google Books. A trade book published in 1916 was my source for designing my chutes and gates.

S-A Labor-saving Machinery - "A Reference Book of Information Relating to the Design & Application of Conveying, Elevating, Screening & Transmission Machinery & Accessories"

The Stephens-Adamson Mfg. Co. produced a vast array of conveying, elevating, screening and transmission machinery and accessories. Stephens Adamson (SA) was founded in 1901. Sold to 1964 to Borg Warner for their Morse Chain Division. In 1970 sold to Allis Chalmers. When Allis Chalmers went bankrupt in the 1980's it was sold to a Swedish company.

From this book I used a couple of their rack and pinion gates to create my own design. Their Style No. 9D and Style No. 10D.

[finescalerr]

Thank you, Ed. That was a lot of work to write and an extremely valuable reference for any modeler using SketchUp. We owe you lunch! -- Russ

[eTraxx]

Here's Version 6 of the chute. This was uploaded to Shapeways as a test upload .. and it failed. Everything passed except for one small place .. on the backside