Sewer request

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jchunick
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Re: Sewer request

Post by jchunick » Mon Dec 19, 2016 12:17 am

All I've ever heard about that piece is that due to its size and material composition (PVC) it warped.

The molds are made of 200 lbs. of solid steel. I'm guessing that there's no 'gently manipulating' it. :)

Here's a link to all you ever wanted to know about injection molding:
https://www.3dsystems.com/quickparts/le ... ics#stress

The part about stress outlines what likely caused the warping:
Turning hard or sharp corners exerts more stress on the molecule than taking gentle turns with generous radii. Abrupt transitions from one feature to another are also difficult for the molecules to fill and form to.

As the material cools and the molecular bonds re-link the resin into its rigid form, these stresses are in effect locked into the part. Part stresses can cause warpage, sink marks, cracking, premature failure and other problems.
Remember, it's not a hard plastic like ABS, it's a more flexible PVC material.

Here's some good information on how to fix warping in injection molded parts:
http://www.paulsontraining.com/injectio ... ects-warp/

Further reading:
http://www.simcoeplastics.com/wp-conten ... elines.pdf
A whole series of videos on the subject - https://www.google.com/webhp?sourceid=c ... nd+warping+
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Re: Sewer request

Post by jackattack » Sun Dec 18, 2016 7:54 pm

I thought it had more to do with the shape of the sculpted piece, and the ability to pull the tile out of the mold (or to pull the multiple pieces of a complicated mold off of the tile) without "catching" on the details of the sculpt.

A soft mold can be gently manipulated to remove the tile, but a solid mold can't. I thought this was why Stefan remarked on the challenges of sculpting for steel molds.

Note how the cavern passages are sculpted. Although they form a U in cross section, both walls taper towards the top. This should allow them to be cast in a single solid mold, just pour in the liquid PVC and pop it out when it hardens. If the walls widened or flared at the top, the tile wouldn't come out of a single-piece mold, because the larger portion of the tile wouldn't fit past narrower portions of the mold.

(Not-so-fun fact: Dental fillings used to work the opposite way. Dentists would drill to remove the decayed portion, then expand the "chamber" to be larger than the hole in the surface of the tooth, and then force malleable metal into the chamber. The shape of the chamber was what kept the filling from falling out.)

If Dwarvenite works differently, I'd love to know. Understanding the capabilities and limits of the medium and the process allows all of us to make better suggestions.

(Or does it give all of us the same set of assumptions and rules to subtly encourage us to think similar thoughts and lose our creative diversity? Hmm...)
Favorite Pieces: Chasms, 45 Degree Passages, River & Lava Banks, Ledges, Large Curved Walls, Elevation Arch

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Re: Sewer request

Post by kodiakbear » Sun Dec 18, 2016 2:44 pm

jchunick wrote:
HeroQuestFrance wrote:Then you didn't see at all the original LORD A. prototypes pieces he made for DF when he was working on the sewer project ?
It were designed to be the next resin set until dwarvenite took all over.
Each piece was 4x4 squares with some inserts to put if you wanted a door, a grid or a blocked passage. Modularity was preserved. I planed to cast it
I, for one, would love to see those original sculpts. Were they ever posted here for us to see?
I also would love to see those pics, the below pics are all I ever saw.

Image

Image

Image

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Re: Sewer request

Post by jchunick » Sun Dec 18, 2016 11:36 am

jackattack wrote:No, I didn't. Was it similar to the RotA intersection?

I wasn't talking about a 4x4 piece, I was talking about L, T, and X intersections like the original resin passage sets had. The T was 6" long in one dimension, and the X was 6" long in two dimensions.

I do remember (reading) that casting Dwarvenite is different than casting resin. Soft molds for resin are (relatively) cheap, and they can accommodate complex shapes like opposing concave forms. Steel molds for Dwarvenite are not, and they can't.

Just out of curiosity, are Dwarvenite dungeon passages cast as a single piece, or are they cast as multiple pieces that are joined together after being removed from the molds?
It has more to do with warping after the material comes out of the steel mold, from what I understand. That's what was happening with the 4"x5" patterned floor sections from KS1. When they were put into the water bath to cool down and solidify they would warp at that point. It was more a function of the more flexible PVC material being used. If, for instance, a stiffer ABS material was used there wouldn't have been any issues, such is the case in KS4.

One other aspect I'm not sure of is that I don't think metal frames were used originally in KS1 for the pieces to go into when being put into the water bath. Don't quote me on that, though. But you can see this is the case with the pieces in KS3:
Image
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Re: Sewer request

Post by jackattack » Sun Dec 18, 2016 10:06 am

No, I didn't. Was it similar to the RotA intersection?

I wasn't talking about a 4x4 piece, I was talking about L, T, and X intersections like the original resin passage sets had. The T was 6" long in one dimension, and the X was 6" long in two dimensions.

I do remember (reading) that casting Dwarvenite is different than casting resin. Soft molds for resin are (relatively) cheap, and they can accommodate complex shapes like opposing concave forms. Steel molds for Dwarvenite are not, and they can't.

Just out of curiosity, are Dwarvenite dungeon passages cast as a single piece, or are they cast as multiple pieces that are joined together after being removed from the molds?
Favorite Pieces: Chasms, 45 Degree Passages, River & Lava Banks, Ledges, Large Curved Walls, Elevation Arch

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Re: Sewer request

Post by jchunick » Sun Dec 18, 2016 9:47 am

HeroQuestFrance wrote:Then you didn't see at all the original LORD A. prototypes pieces he made for DF when he was working on the sewer project ?
It were designed to be the next resin set until dwarvenite took all over.
Each piece was 4x4 squares with some inserts to put if you wanted a door, a grid or a blocked passage. Modularity was preserved. I planed to cast it
I, for one, would love to see those original sculpts. Were they ever posted here for us to see?
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Re: Sewer request

Post by HeroQuestFrance » Sun Dec 18, 2016 5:27 am

Then you didn't see at all the original LORD A. prototypes pieces he made for DF when he was working on the sewer project ?
It were designed to be the next resin set until dwarvenite took all over.
Each piece was 4x4 squares with some inserts to put if you wanted a door, a grid or a blocked passage. Modularity was preserved. I planed to cast it

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Re: Sewer request

Post by jackattack » Fri Dec 16, 2016 8:48 pm

While that might be more convenient, those are large(r) and (more) complicated shapes that might not be possible as single pieces from single molds. Even if they were, they would essentially be recasts of multiple existing pieces, but less modular.

It is more likely that such pieces would be made by gluing multiple pieces together, which is something we can do ourselves.
Favorite Pieces: Chasms, 45 Degree Passages, River & Lava Banks, Ledges, Large Curved Walls, Elevation Arch

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Re: Sewer request

Post by lostpict » Fri Dec 16, 2016 5:03 pm

I would also like to see see prefab Corners, Tees, and cross-pieces that use fewer parts.
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Re: Sewer request

Post by iceycat » Fri Dec 16, 2016 4:15 pm

I'm actually not a fan of the design of the sewer sets. They're too many pieces. To make a rounded corner takes a half dozen pieces, that's just crazy. I also for the life of me can't understand why they have a different number of convex to concave corner pieces when you order them

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