Need some structure planting ideas from da group.

[Lemosteam]

Now that all of the background structures are lit and installed, it’s time to move to the foreground structures. The ground cover will be unsanded grout, and I am trying to develop a way to make a depression or uncovered area where the structure can drop into.

Here are the structures and their outline counterparts made of 0.030” styrene.



Below, I have the duplicate cutouts in place, and I am looking for ideas what the best way to adhere these false floors to the layout and still be removable to place the real ones down into the depression in the dried grout.

Here they are placed in their intended locations east of the canal:



Here they are placed in their intended locations west of the canal:

[milw156]

Latex caulk or canopy cement applied sparingly?

[Lemosteam]

Was also thinking Elmer’s? Or I have some really thin 3M double stick tape?

[MK]

Fun Tack or Blue Tack or however you call that stuff.

[nkalanaga]

Depending on what the layout base is, straight pins.  You might have to drill some small holes in the cutouts, but they wouldn't have to be precise.  Just stick the pins through them.

[NtheBasement]

Ditto, push pins or thumb tacks.

[Maletrain]

I need to do some of this, too, so I have been thinking about it.  But, I have not actually gotten to doing it yet on a layout. My experience comes from other hobby projects, so may not all be applicable.

My thinking on this is that the expendable duplicate bases are effectively expendable mold surfaces.  The unsanded grout is the material being molded around them.  And it is designed to stick hard to things like tile.

So, first I want to make sure that the molds are in the right place and rigidly fastened.  Second, I want to make sure that the grout doesn't stick to the sides/edges of the mold so that it won't get busted when the molds are pulled away.  Third, I want something to grab on the top of the molds to pull it up when the grout dries, so that I don't have to slip something between the grout and the mold to pry it out.

I am wondering if the 0.03" styrene is rigid enough to make sure that the grout does not get under its edge.  And, it looks like the base is foam, so I am wondering if thin pins are sufficient to hold the cutouts securely side-to-side as well as tightly down at the edges.

My thinking would be to make thicker duplicate bases with handles on top, use something like 3 or more 1/8" holes in the bases through which to push 1/8" pointed alignment pins into the foam, and weight the bases down with something heavy enough to keep them tight on the foam while spreading the grout.

On second thought, if you do use something like 1/8" alignment holes, you might be able to dispense with the lift handles if you have a bent metal pick that you can fit into the holes to lift the bases, once the grout is dry and the alignment pins are pulled out.

I am still thinking that the edges of the bases need some sort of coating to keep the grout from adhering to them.  If their sides are smooth, then a light coat of grease will probably do.  There are more expensive lubricating substances used for metal forming in hard steel dies, some of it dry instead of pasty, that you could use if you happen to have that type of thing on hand for other purposes.  Wax can also work, but I have had problems with regular paraffin being too hard to release easily.  Beeswax is softer, and also water soluble (which might be an issue with water based grout penetrating it).

That's all I've got.  I'm looking forward to learning from your efforts.

[peteski]

So the grout layer will be 0.030" thick (applied to the same thickness as the bases)?

Push-pins or small nails sounds like good idea to hold the bases temporarily in place. Or maybe use small dabs of Rubber Cement? It is weaker than Contact Cement.



I agree with Maletrain that adding more substantial "handles" would make it easier to remove the bases once the grout sets up.   The edges of the bases should be ideally perpendicular to the surfaces, or even add slight draft angle to them, for ease of removal.

Thinking some more about this, while I have no experience with grout I'm not sure that 0.030" layer of grout will be robust enough not to crack later on.

[ristooch]

Cabinet magnets? I admit it is a bit complex and more than you might do. Most cabinet magnets are large, and I was thinking the magnet would be in the structure with the metal plate buried in the "ground." That could be reversed, though. I just happen to have lots of them laying around from projects around the house so it became an easy solution.

Another way might be gluing some 1/8" round plastic rod inside the structure with a mating hole or tubing that would form the "female" end in the ground.

I have done variations of both of the above.

Velcro?

All of the above may be overkill in lieu of some water soluble glue. I would imagine even Elmer's white glue or Aleene's Tacky Glue would suffice.

[John]

LEGO?

[Lemosteam]

Thanks for all the great thoughts thus far!

The foam is 1/2” thick with a 3/4 plywood base. Now I am actually thinking about #6 or #8 pan head screws to hold them down. I don’t think that pins or tacks will stand up to the rigors of adding the grout. This will also prevent the worry of damaging the foam when pulling the “forms” because no adhesive would be used.

@peteski , The sanded grout in the background is about the same 0.030” thick and is quite durable and difficult to cut.

I was also thinking of wrapping the outside edge with blue painters tape before I grout. This will prevent the grout from sticking to the styrene.

I also think I might be able to use the edge of the form as a guide for a knife the separate the form from the grout and foam.

[BuddyBorders]

What about wrapping the base forms with SaranWrap? Then you could pull the bases and peel out the plastic wrap. The draft angle idea is good also.

-Buddy

[nkalanaga]

Or spray them with cooking spray.  It's designed not to stick to stuff, and is non-toxic.

[Maletrain]

Saran wrap does work, and leaves a much thinner gap than blue painter's tape when it is removed.  The nice thing about it is that it stretches tight and sticks to itself so that the overlap area can be thin, too.  And, it is easier to get the form out of the grout hole with Saran than with tape.

But, sticking it on the edge of a thin piece of plastic, and trying to not get any of it between the plastic and the foam, I think that Saran would be extremely "fiddly" to work with. 

On a thicker piece of material, such as a piece of 3/4" thick board, I think Saran would be a good option.

I am getting the impression that John intends to make the grout flush with the top of the 0.03" thick plastic bases. That does tend to avoid elevated lips of grout around the hole after the forms are removed.  But, if care is taken spreading grout around thicker forms, those lips will be thin and easily ground off with a wheel in a Dremel. 

[peteski]

No need to stick Saran wrap on the edges of 0.030" styrene.  Just use a larger piece of wrap, put the base on it, then fold the wrap around it (and maybe use some masking tape to hold the wrap on the top of the base. Basically gift-wrap it.     Since John is planning on using screws to hold the bases, the wrap on the bottom of the base will not be a problem.  I still think that filing a draft angle on the edges will be good to allow for easy removal. I still think that also filing (or sanding) a draft angle on the edges will be good to allow for easy removal.