Scrap it or not?

[ajshyguy]

Hey,

Sorry I'm not posting this in the "the pepakura question" thread, but everyone kinda ignores it. Anyway I had a question for this pepakura and any peps I will do in the future. If my paper pepakura model has inaccuracies, can I sand them off when I harden it? or should I scrap it? I made a video explaining what I mean by this

[video]https://youtu.be/NbiusQPEKvw[/video]

thanks!

 

[clonesix]

Hi AJ, and welcome to the forum.

Pepakura, by nature, will have inaccuracies. You will only get so much compound curves from a 2-dimensional sheet of paper.


Also, white glue will work much better than hot glue, and you won't burn yourself. Give the model another try and it may come out cleaner, but you will still have the same issue with trying to turn it into a hardened piece.

 

[George]

Hi AJ and welcome to the RPF forum :thumbsup
The thicker your paper/cardstock,the smaller your chances of imperfections,but even with foam builds it remains a man made item.
Also,experience will rule out more and more imperfections as you get better.
Choose your method of preference and go for it :thumbsup

 

[Teddz]

Hi AJ,

to answer the question, I would harden it and continue. It looks fine to me.

A lot of what you showed can be and will be fixed once you start the shaping/sanding process.

I would remove any hot glue seepage first just to clean things up a bit. Maybe even cut some of the seams that are too far out of alignment and re-glue them. In the future, you may want to use a general purpose glue (like a rubber cement). This will give you enough time to make sure the joints of the pep line up as you're building it and won't burn your fingers. Then once the pep is built out, go over all the joints with a thin CA glue (super glue). This will not only help keep your pep together during the resin stage, but also give it a bit of rigidity. I did this process with a Star Wars Episode 7 stormtrooper helmet pep I did. Worked great. You can see the beginnings of the CA glue stage in these pics... looks like wet paper.

For those dents and wrinkles, once you resin coat (no fiberglass yet, just resin) the outside and inside of the pep and it's cured, you can use a heat gun to warm up certain areas of the resin to kinda massage it into place but that's only if it's relatively minor. Major dents and wrinkles should be taken care of before any resin touches the paper. What I saw on your vid won't really need any of this, unless the paper you used is too thin. The bondo will take care of filling a lot of the low spots and hiding the flaws of the pep.

Your biggest issue will be during the curing stage of the fiberglass. Since it's going to be thicker than the resin coat, it'll generate more heat. More heat means the resin coat gets a little soft and may start to warp the pep. An easy fix to this is to shore it up with some reinforcements - my go-to are Popsicle sticks held together with those black heavy-duty paper clips. The worst thing that can happen is it all warps. You may also want to glue that faceplate to the helmet for strength and cut it off after you've finished with the shaping/sanding process and are almost ready for paint. This will also make sure that the faceplate sits correctly and doesn't warp during curing.

Good luck with the build and post up some progress shots.

 

[clonesix]

Here is my opinion:

Let's use the photo above as an example of a pep'd piece that you want to turn into fiberglass, and discuss. Teddz' piece looks as good as most peps I see. Some are a little better, some a little worse, but that looks to be what most people would come away with, so I will use this for our discussion.

many of the builds that I read, describe a process similar to: 1) cover paper in resin. 2) Fiberglass the inside for stiffening. 3) use Bondo to smooth out the outside.


I don't like this process, as though we were trying to sculpt in Bondo. This requires a LOT of sanding, re-filling, more sanding, more filling, more sanding.....Until done. THIS IS MESSY, ITAKES A LONG TIME, and You have only a 50% chance of finishing something worth displaying.


Let me make a suggestion (not just to you AJ, but to all future pep'rs): once you have the finished Pep, and you want to turn it into a fiberglass piece, try this:

1) spray with lacquer to seal and protect the pep from moisture. Give it a few extra coats to stiffen. This is much better than brushing resin onto a fragile piece.
2) Reinforce the inside with resin, and add popsicle sticks or other material, so that the bottom sits flat, the diagonals are even, and even add some spay foam to stiffen the model.
3) At this point, you should have a model. NOT a finished piece, but a model, and we will treat it as any other model, we mold it.
4) This is known as a "Waste Mold, because it only gets used once. Hyrocal is a gypsum that is cheap and readily available. Silicone RTV will also do the job for this, but is cost-prohibitive.
5) You must create a dividing line for the mold. plaster is heavy, and will warp a paper pep if it was not sealed or supported well. Apply a thin coat and let set, so as no not crush the pep. next, add an additional layer of plaster, and reinforce with burlap.
6) Once cured, open the mold and remove the pep. The pep is destroyed here. So if you didn't do well on the mold, ALL you effort is for naught!
7) peel out the remaining paper pep, and throw away. This is where is does NOT matter if there were undercuts, or other "locks" in the model. because the model is destroyed in the removal, NOT the mold. (this is also true of foam models, they get broken out of the waste mold!)
8) Now, you have a plaster mold of a pep model.
9) You CANNOT lay fiberglass into an untreated plaster mold. So let the plaster mold cure for 1-4 weeks. (Plaster hardens in 10 minutes, but takes a full 28 days to fully cure)
10) Once cured and dry, the mold can be sanded of any high spots (low spots on the model) and modeling clay can fill any low spots in the mold. (which would be high peaks on the model)
11) Spray the mold with several coats of sealer, (Lacquer) and lightly sand in between coats.
12) spray several coats of PVA or comparable mold release.
13) lay fiberglass into mold. (It is ALWAYS my preference to use 2 layers of 3/4 oz matt, with a final layer of 6oz cloth - because if it is going onto your head, smooth is better than prickly!!!!!!!!!!!!!
14) Once the fiberglass has cured, (and this is a HARD one) smash the mold and break out your new model.


That's right, you did ALL that work to smash it on the ground




Now, what is left is a fiberglass copy of your pep. It is not as pretty as you would like, but you can now do the Bondo work on a solid fiberglass base.

I will NOT tell you that grinding and sanding fiberglass is any fun, but you are likely to have more success than trying to Bondo a paper model.





My advice goes down hill from here. If I were to make this model, I would do an intermediary step. I would pour plaster into my plaster mold, and produce a plaster model. Why? Because I can clean up a plaster model a LOT easier than a fiberglass one. The plaster can be shaped with chisels and sanding, a little filler and primer to get a finished model. ...and then you need to make another (finish) mold to create a clean helmet.



Those are my thoughts on Pepakura models. There is NO simple method to turn a paper model into fiberglass. It takes a few steps. The point that I wanted to drive home, if you are still reading this far, is that trying to Bondo a paper model is very time consuming and not the best choice for good results.



feel free to discuss amongst yourselves.

 

[Teddz]

WOW! That's a whole lotta work Clonesix. In the amount of time needed to let the plaster mold cure completely to lay up the fiberglass, a couple of matrix molds can be made and put into production along with having a finished master.

The Bondo stage of it isn't as messy and haphazard as some make it out to be. Is it dusty? Yea, but only if you don't own a vacuum. Is it time consuming? Yes, but so is putting peps together. I honestly don't like putting the pep together. The bondo stage for me is where it all starts to take shape. It's where the piece comes to life in my eyes.

As for the results garnered, it all comes down to how someone works, their skill level, time invested and level of OCD and/or perfectionism. If you know how to work your materials and put in the time, you'll get awesome results regardless if the material is bondo, plaster, foam, fiberglass or clay.

I will disagree with you on the "There is NO simple method to turn a paper model into fiberglass." statement... There is a simple way to do it and it involves coating the outside and inside with resin and then glassing the interior.
However, if you want a full on-just-fiberglass model, then no, there isn't a simple way to do it other than making a mold and laying up some glass in it.

Here's a couple of shots of the stormtrooper helmet after the 2 resin coats and 2 layers of fiberglass matting. No warping at all and it's very solid.

 

[blue2k]

The pep is just the starting support from, it is not the finished product. Don't worry about the inaccuracies the coating of body filler you add later can be sanded to the correct shape. After you have applied a coat of resin to the pep, you can heat it with a heat gun and when it becomes pliable again, you can manually pop out some of those dents etc.

 

[JPH]

It looks good. As others have mentioned, what you have is the bare bones. I use cardstock, then use clear packing tape or scotch tape on the edges. I tape my pep, I don't use any glue, and they hold up fine to adding resin.

Really, I'd move forward. Your eye for detail will pay off when you get closer to a finished product

 

[clonesix]

WOW! That's a whole lotta work Clonesix. In the amount of time needed to let the plaster mold cure completely to lay up the fiberglass

https://farm6.staticflickr.com/5786/21252418556_28da1beb9c_z.jpg

Wow, actually, that was a lot of typing. I didn't realize until after I posted.

Yeah, that is a lengthy process in order to go on the 'cheap,' as the OP seemed to be doing this for the first time. I, myself, would use silicone RTV for the waste mold, but it is still a WASTE mold and will be discarded after one use. The reason is to obtain a copy in a material that is more sympathetic than Bondo + paper.


The helmet is looking very nice, and there is a way yet to go. I hope to see progress shots.

 

[ajshyguy]

Thanks for the help everyone! I AM on a budget, so I'm leaning towards the regular resin, fiberglass, and bondo option. My cardstock is relatively thin for a cardstock (I blame wallmart) so I guess I'll just have to use a lot of supports to make sure it doesn't warp. I can't really think of any other way to reinforce it before resining. Although I will keep the plaster mold method in mind for any future helmets I might do. (I just haven't researched/know enough about using plaster to justify using it for the very first time on my pep)