Fiberglass experts, is it possible to make a tight 90* bend with mat? An example would be to wrap a box and not have the rounded corners or air bubbles on one side of the corner. If so, how? I'm new to this so don't have the tips and tricks down nor do I have an old body guy around to teach me. Kind of stumbling through this in the dark.
I wouldn't try to make the mat bend around the corner. That would probably be a disaster. A better idea would be to cut pieces for the box sides, and then fray the edges of those pieces. You can use a ruler or a pair of scissors (or whatever is handy) and scrape it across the edges of the mat pieces until they get all frayed and fuzzy. You want those frayed edges to interweave when you lay up the fiberglass. You may need to help the process along a little bit, by working the frayed edges into each other . For added strength, you can add a couple layers of cloth tape in the corners. That will also cover up the frayed mat, resulting in a smoother surface in the corner. I would suggest lightweight cloth tape, so it will follow the corner better.
Hope that helps!
[This message has been edited by Blacktree (edited 02-02-2017).]
I wouldn't try to make the mat bend around the corner. That would probably be a disaster. A better idea would be to cut pieces for the box sides, and then fray the edges of those pieces. You can use a ruler or a pair of scissors (or whatever is handy) and scrape it across the edges of the mat pieces until they get all frayed and fuzzy. You want those frayed edges to interweave when you lay up the fiberglass. You may need to help the process along a little bit, by working the frayed edges into each other . For added strength, you can add a couple layers of cloth tape in the corners. That will also cover up the frayed mat, resulting in a smoother surface in the corner. I would suggest lightweight cloth tape, so it will follow the corner better.
Hope that helps!
So you're saying two separate pieces where the frayed edges just kind of mix together at the corner? When all this is resined up will it hold together similar to wrapping the corner? I imagine it would be slightly weaker since there would be no continuous fibers wrapping around the corner. Not a deal breaker, just my curiosity speaking there.
Another option here would be to use vacuum bagging/infusion if you have access to the necessary equipment. I've seen some really tight radius corners done successfully using that method, but it requires certain equipment to do. I've had success on small parts just using my air compressor on small parts, but vacuum pumps aren't too expensive on the low end and should be fine if you're not trying to use it as an industrial piece. https://www.youtube.com/watch?v=VodfQcrXpxc That video is for carbon fiber but it's essentially the same process for all fibre types.
When you say "corner", do you mean the actual corner where the cloth has to bend in 3 directions or are you just asking about a sheet that is bent 90 degrees?
The 90 degree bend is very possible but a true corner where you are bending to cover 3 sides is not possible without some angled cutting.
I mean a 90* bend, not a true corner of a box type bend where I would be covering 3 different sides. I can't round off the edge at all but I am going to try the "fuzzing the edges and blending the fibersidea blacktree posted. It doesn't need must strength, it is mostly cosmetic.
Blacktree's suggestion is good. I might also suggest that you use the "lightest" weight mat you can get. I use 1/2oz mat that's like a veil. Easy to bend, but would require many layers. I also will cut the edges sharp on heavier mat (1.5 oz), butt them together, then reinforce the edge with cloth or veil, then more mat.
Bob
One last thought, the method used would also depend on whether you want the clean edge on an inside bend, or outside bend. You can always reinforce the side not seen, as I did on my side vents. Custom build
[This message has been edited by RCR (edited 02-03-2017).]
I cut off the end of my trunk lid and I'm molding it into the rear clip. Because of that I can't get to the back side. The piece is screwed down so the fiberglass won't be doing the heavy lifting of support, but it will be helping out and will have an edge. It won't be a cut you sharp 90*, think the sides of the deck, but it will be a very small radius since it will be a panel gap now.
You can do it but the best way is to use a mold, release agent, and vacuum bag it. All these things will produce the best results and are repeatable. Also to help with it you should use epoxy resin and not the polyester resins sold in auto stores. Most marine repair places will sell epoxy resins. The reason for using this resin system is working time. Epoxy resins have a much longer working time so you can get exactly what you want without the quick flash time. A lot of this stuff is expensive and I don't know your budget but some of it can be had cheaper off of eBay.
I tired blacktree's technique and it worked pretty dang well. Got a nice corner with plenty of structure for what I need. Mine was probably a rougher edge than a pro would have had, but that is why they invented sandpaper.
So now I have another question. How would you all tackle this area? Obviously this is just the driver side and the passenger side is the same. The tail lights stick out past the outer edge of the bumper, has a sharp corner edge while the bumper has the stock gradual bend corner, and there is a very large gap between the bottom of the tail light panel and top of the bumper. I imagine it will be a many step process, but what shape would you guys shoot for? I'm thinking take the pointed end off the tail light panel, and basically round that corner over from the vertical sharpie line to the front edge of the foam kind of following the diagonal sharpie line on the foam. After that build up the bumper below that a bit with some foam to match the shape above it.
As far as closing the panel gap. I like the height of the tail light panel so would rather raise the top of the bumper to close that gap. I also don't like the rounded off top edge of the bumper that I think was a carry over of the round trim. For that I was thinking that I would make a couple layer thick piece of flat fiberglass the width of the panel, cover it in packing tape, attach it to the bottom of the light panel, have the bumper mounted, build a box around the top and fill it with expanding foam. Then I can sand to shape and will have a smooth flat top that will be the height that I want for the bumper. Seem like it'll work or a waste of time? I'm down to my last couple quarts of foam and don't have any other projects I'll use it on so would rather not buy more just to take up shelf space.
Originally posted by mr_corean: ...but that is why they invented sandpaper.
YEP!
I'm glad it worked out for ya. As for the corner on the tail light panel, I see two ways to do that, depending on how you want it to look. You can either trim the corner of the tail light panel to match the bumper cover, or build up the corner of the bumper cover to match the tail light panel.
For the gap under the tail light panel, I would probably just extend the panel down. I say this, because the trim along the top of the bumper cover is a convenient place to have a panel gap. If you were to add material to the bumper cover to bridge the gap, then you'd have a body seam about 1/2" or so above the bumper trim, and that may look awkward.
For the gap under the tail light panel, I would probably just extend the panel down. I say this, because the trim along the top of the bumper cover is a convenient place to have a panel gap. If you were to add material to the bumper cover to bridge the gap, then you'd have a body seam about 1/2" or so above the bumper trim, and that may look awkward.
That would be true if I had any trim on the car. I have Archie's widebody on there that eliminates the trim. You can see in the third picture there is a body line between the rear fender cap and bumper that steps up an inch or so right along the forward edge of the foam. From there the bumper is straight across to the other side of the car. No trim on there at all. I don't think that stepping that line up another inch or so would make that big of a difference in the look. The reason I would like to do that is to keep the body under the actual lights the same until the line. If I do decide to bring the light panel down, how would you recommend I do that? Make a super thin strip and try to mold it in? The issue is that it is a full inch or so gap that needs filled so can't just build it up with a couple layers, but it's so small that I can't see trying to mold in anything very easily.
My mistake, wasn't looking closely enough at the photos. In that case, extending the bumper cover upward should be almost as easy as extending the tail light panel down. Pick whichever you prefer, and go for it.
If you do decide to extend the tail light panel down, it can be done fairly easily. You can use a strip of thin sheet plastic or aluminum flashing. Make the strip wide enough for the extension you want to make, plus an inch or two to overlap the tail light panel. Tape that onto your panel, and it will act as a tray of sorts to hold the fresh fiberglass while it cures. Also, remember to put some wax or some release agent on the strip, so you can peel it off after the fiberglass cures.
Just thought i would mention you can buy waterproofing for corners of bathrooms before the tiling is done which are 90 degrees they are designed to be fiberglassed into place.
[This message has been edited by Australian (edited 02-11-2017).]
Just thought i would mention you can buy waterproofing for corners of bathrooms before the tiling is done which are 90 degrees they are designed to be fiberglassed into place.
Thank you, sir. Went out and got some today. I think it will work well for giving me nice straight edges instead of just using the old Mk.1 eyeball. That doesn't work so well with my 2 lazy eyes.
Could also go to junk yard tip and cut some edging off old bat OR cut up some square side skirts from old ground effects that are outdated and nobody wants.
[This message has been edited by Australian (edited 02-15-2017).]
