Modeling filler or resin?

[gavino200]

I'm looking for some kind of product that can fill small gaps and is easy to file/sand/cut. I'm working on a project where I'm fitting light guides into a structure made of foam and plaster. I'm cutting a small slot and fitting a light guide into the foam. However the edge isn't completely clean. I'd like to be able to fill the tiny gaps and then later work them to get a clean finish. Any recommendations?

 

 

[cteno4]

So what to use will depend what is next to the filler. If it’s foam right next to the filler on the surface you are wanting to be smooth and clean then I would use a foam filler so it will work similar to the foam next to it. ie

 

https://www.motionrc.com/products/beacon-foam-filler-8oz

 

https://woodlandscenics.woodlandscenics.com/show/Item/ST1447/page/1

 

or something like spackle if it’s next to plaster.

 

issue is like having a hard glue layer between two pieces of foam in that it tends to not smooth well between the soft and hard.

 

on the light guides, could you have the flat wall fixture inside be larger than the light guide and make the light guide round so you could just drill holes? Maybe just use large plastic fiber optic as your light guide and then a light figure (maybe 3D printed in clear or frosted) that’s larger than your fiber optic hole? Or even just mount your light fixture in front of a hole that’s backed by a 3 or 5 mm led if it’s within a short distance.

 

jeff

[gavino200]

3 hours ago, cteno4 said:

So what to use will depend what is next to the filler. If it’s foam right next to the filler on the surface you are wanting to be smooth and clean then I would use a foam filler so it will work similar to the foam next to it. ie

 

https://www.motionrc.com/products/beacon-foam-filler-8oz

 

https://woodlandscenics.woodlandscenics.com/show/Item/ST1447/page/1

 

or something like spackle if it’s next to plaster.

 

issue is like having a hard glue layer between two pieces of foam in that it tends to not smooth well between the soft and hard.

 

on the light guides, could you have the flat wall fixture inside be larger than the light guide and make the light guide round so you could just drill holes? Maybe just use large plastic fiber optic as your light guide and then a light figure (maybe 3D printed in clear or frosted) that’s larger than your fiber optic hole? Or even just mount your light fixture in front of a hole that’s backed by a 3 or 5 mm led if it’s within a short distance.

 

jeff

 

I've been using Spackle and foam filler. They're good for filling in holes and can be sanded smooth. It's much harder to work with them in a very small space. 

 

The "light guide" is also the actual fixture. This is my first round of experimentation with them. This "tunnel" is just a piece of scrap foam.  The paint is just simple grey latex paint. Not what I'm planning to do later. The purpose here was just to see if the idea would work at all. And to decide what kind of shape would work for the lights.

 

 

What I'm looking for is something to fill in the edge around these guides. Spackle and foam filler can't be cut with a clean line in this situation.

 

I can partially solve the problem by using masking tape and painting the guide proximal to the point where it protrudes. I can also let a small rim of painted guide poke out to look like the base of the light fixture.

 

This round is rough, but I think the idea has potential. The desired thickness is probably somewhere between the two shown here.

 

Edited February 25, 2018 by gavino200

[cteno4]

Gavin,

 

That is going to be a really hard gap to seal and finish. Corner gaps like that are really nasty and especially in your interior curved surface to try to finish cleanly. This is why I suggested to put a slightly larger light fixture over the light channel to hide any gaps between the light channel and foam.

 

jeff

[gavino200]

8 minutes ago, cteno4 said:

Gavin,

 

That is going to be a really hard gap to seal and finish. Corner gaps like that are really nasty and especially in your interior curved surface to try to finish cleanly. This is why I suggested to put a slightly larger light fixture over the light channel to hide any gaps between the light channel and foam.

 

jeff

 

Yes, I see what you're saying. 

 

I thought of a another possible solution, that I just did a partial test on. If I make sure to keep the light tube plastic perfectly rectangular (ie, parallel sides), then I can. 

 

1. Make an approximate slot. 

2. Place a dummy light tube that's longer than the real tube. 

3. fill in the gap with spackle, and let the spackle dry.

4. Back out the dummy. Sand the surface smooth. 

5. Then back in the final pre-painted tube.

 

I just did a rough test of this method, except wiping the spackle smooth, and backing in the tube (no dummy) without waiting for it to dry. It works pretty well.

 

I still would really like to find a filler resin, as described. I'm sure it would be handy for many projects.

[cteno4]

Yes that sounds like it would work. Experiment, I expect letting it set a while but not hard to where it will stick may work the best. Or try some mould release on them.

 

again trying to finish a corner gap joint like that in place is going to be tough, especially in your location. Lots of putties you could use, just getting it all cleaned up in a corner will be a challenge.

 

jeff

[gavino200]

2 minutes ago, cteno4 said:

Or try some mould release on them.

 

 

 

Great idea. Thanks!