Strengthening Fiberglass-Bondo Question

memorysin

New Member
Hello!
Hopefully I don't get in trouble and that I'm posting this in the right place, I've looked on the forums and google-fu'd for the answer but I can't seem to find the information I'm looking for.

What I need help with is I am working on hammer__monster_hunter_pepakura_by_azeralpawn-d6mqrgh.jpg a monster hunter hammer. I want to resin strengthen it and bondo it, but it's completely sealed. How does one strengthen a sealed pepakura? Is it possible? Should I start over with it open?

Help would be appreciated, thank you so much :)
 
Yes, this is the right place to ask. :)

I think that the biggest problem is how to secure the head to the shaft so that the head does not fall off when you swing it.
There needs to be a rod/dowel and/or a pipe inside the shaft, maybe for this prop a section of PVC pipe with a wooden dowel snugly inside where the dowel is the handle and the pipe is exposed at the top section of the shaft.
If I had been you, I would have built the bulk of the head by cutting it out of construction foam because then I would just have needed a hole in the foam to glue the shaft into.
If you manage to reinforce the paper head then maybe the shaft could be stuck into a blob of Bondo inside the spike on top.

I would brush a few layers of polyester resin on it before taking it apart; maybe also layer some fine fiberglass weave at some parts.
Remember that Bondo adds weight.. and is brittle. It is mostly used for adding bulk and is not often a good choice for making something stronger.
If you do use construction foam, be sure to seal it with wood glue or epoxy, because it does not like polyester resin (which is also in Bondo).
 
Yay!

Thank you, I do have a support structure inside the handle that extends thru from the bottom of the handle and is attached to the top of the hammer, the only thing that's wobbly is the outer shell of the handle around the dowl inside the hammer it wobbles at the square juncture.

Construction foam? Like Eva foam? I don't have any experience yet with foaming, I'm new to Pepakura would you print the pep out without tabs that way?

What about fiberglass cloth on the outside? Does that work? I've also thought of cutting it open after a layer or two of resin and filling it with expanding foam?
 
If you were planning to bondo the outside to sand it to create detail then you could lose detail by fibreglass clothing it. If you already have your handle attatchment in place within the paper then you could try rondoing the inside.
You could cut a small hole in it, mix up a wet batch of rondo. 2 thirds fibre glass resin, 1 third bondo. You could go wetter it will set hard an isnt as brittle as plain bondo. Pour it in the hole and rotate the pep all over till its coated and keep goin till its set. If you put it down before its set the extra weight will push it in an it will set slightly warped. You could even do it in 2 stages, handle an head.
 
OH! I like that idea, I think I can do that. Should I resin the outside first and then cut it and do the rondo inside?

Thank you for all the advice/help, I appreciate it greatly.
 
OH! I like that idea, I think I can do that. Should I resin the outside first and then cut it and do the rondo inside?

Thank you for all the advice/help, I appreciate it greatly.

I would put your hole in first, just because its easier to cut than when its coated in resin. Make sure you have a recepticle that can pour into you hole ready to go. And be mindful that you might (probably will) git some drippage through your hole, so prepare for clean up. If you put in a second load after the first has set, you could have a solid model, which should well be strong enough to work on.

Edit: Meant to say cut hole first, then resin outside, then pour.

I used this method on my Big daddy Kick ass helmet, but i coated the inside with car wax first, this meant I could just literally peel the card off once it cured. You might still be able to do that but it would be harder as the resin may bond with the card.
The beauty of this particular method is that you're left with the first stage of bondo pretty much done, you just need to either fill or sand out the tab marks and you're nearly done. Easier obviously for a helmet than a sealed model. But might give you a few ideas
 
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Resin the outside, two medium - thin coats with no fiberglass cloth. When dry either cut a hole somewhere easy to repair or split it right in half and then fiberglass and resin the inside. Put it back together and clean up the damage from cutting with a little bondo. Check out the Mjolnir in my signature to see how I did exactly that.

Top cut off and inside fiberglassed:


Top back on and repaired:


Cheers.
 
With Rondoing How do you figure the hardener? Do you prepare the fiberglass resin with it's hardener and prepare bondo with it's hardnener then mix? Or do you just use fiberglass resin and it's hardener and add bondo to that?
 
With Rondoing How do you figure the hardener? Do you prepare the fiberglass resin with it's hardener and prepare bondo with it's hardnener then mix? Or do you just use fiberglass resin and it's hardener and add bondo to that?

The hardner for bondo and fibreglass resin is the same stuff, its an activator for the polyester.

Measure out your resin and filler into one container and mix thoroughly. Then apply the amount of hardener for the quantity of resin and also the right amount for the bondo and mix again.
 
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