Fiberglass Cloth or Chop mat, Is there really a Difference?

[jk13]

On a side note, other than cleanup looking like a total nightmare, I've ALWAYS thought a chop gun would be awesome to try/own.

We had a dry chop gun at the last place. Lay down or spray a heavy coat of resin and throw chop at it, then brush down and repeat...very much yes to the super messy.

[Wood]

On a side note, other than cleanup looking like a total nightmare, I've ALWAYS thought a chop gun would be awesome to try/own.

Just looked it up, that would be perfect lol... use it like a paint gun and call it a day lol

[yurvalentine]

Alright so I think I'm leaning towards the cloth and around the small curve I have, I'll break up the cloth for the extra strength...

Thank you fellas!!!

Break it up how? Chop mat is better for small pieces because you have strands in basically every direction to trasnfer weight loads, makes pieces a ton stiffer. Cloth is always only strong in the ply direction, which is why in the big time industry woven cloths aren't used that much. They usually just use unidirectional so it can be thinner and lighter, and will still have the same properties (except that it is prepreg, a whole different animal)

Basically, for this kind of work I prefer chop mat. You'll get more structurally sound parts.

[Wood]

Alright so I think I'm leaning towards the cloth and around the small curve I have, I'll break up the cloth for the extra strength...

Thank you fellas!!!

Break it up how? Chop mat is better for small pieces because you have strands in basically every direction to trasnfer weight loads, makes pieces a ton stiffer. Cloth is always only strong in the ply direction, which is why in the big time industry woven cloths aren't used that much. They usually just use unidirectional so it can be thinner and lighter, and will still have the same properties (except that it is prepreg, a whole different animal)

Basically, for this kind of work I prefer chop mat. You'll get more structurally sound parts.

Idk what I was talking about lol... but I'll see if my teammates have some extra mat I can use just for that part.. the rest is pretty much easy on shape

[Wood]

@ Yurvalentine

These were my old panels.. the new ones will be the EXACT shape but with 3 mids.. Thats what I meant by, there's not a lot of curves in my doors, just around the front part of the door...

[yurvalentine]

Well, here's my .02. If it were my project I would use chop mat for all of it. Stiffness and rigidity would be my preference over actual strength...I doubt they will be subjected to a whole ton of abuse where tensile strength will be a significant issue. But that's coming from industry training (in aerospace manufacturing, nothing car related). If you want to get nerdy about the differences I can go into that big time....it's what I do At the end of the day either should work okay, I just find I prefer working with chop mat. Plus it's cheaper. I've got a 125yd roll sitting in my garage because it's what I go for, and honestly it's dirt cheap.

Another thing to consider, again this is probably not a big deal, but try to lay it all up at once. If you want 8 layers of cloth mix up a big batch of resin and lay up all 8 in one go. When you let each layer cure you'll end up resin rich and you risk delamination because resin doesn't bond well to cured resin. I see tons of people (and I used to do the same) letting each layer cure....even if it doesn't need to be a strong part save yourself the time. And most definitely use a roller, air bubbles will kill your parts.

[Wood]

Well, here's my .02. If it were my project I would use chop mat for all of it. Stiffness and rigidity would be my preference over actual strength...I doubt they will be subjected to a whole ton of abuse where tensile strength will be a significant issue. But that's coming from industry training (in aerospace manufacturing, nothing car related). If you want to get nerdy about the differences I can go into that big time....it's what I do At the end of the day either should work okay, I just find I prefer working with chop mat. Plus it's cheaper. I've got a 125yd roll sitting in my garage because it's what I go for, and honestly it's dirt cheap.

Another thing to consider, again this is probably not a big deal, but try to lay it all up at once. If you want 8 layers of cloth mix up a big batch of resin and lay up all 8 in one go. When you let each layer cure you'll end up resin rich and you risk delamination because resin doesn't bond well to cured resin. I see tons of people (and I used to do the same) letting each layer cure....even if it doesn't need to be a strong part save yourself the time. And most definitely use a roller, air bubbles will kill your parts.

This is exactly what I needed to know!! Thank you!! I actually ordered my cloth, got a yd for $8 (4oz) ... I will DEFINITELY layup all layers at once.., that'll actually save me time in letting each layer cure because thats what I did previously

[yurvalentine]

Yup do it all in one go. What I always do is use plenty of resin, but when you get to the last layer roll it really good and use a squeegee to scrape off as much resin as you can. Reason being if you have too much resin (ideal ratio is 60% fiber 40% resin bu weight, but anything under 50/50 is considered good) the resin can crack, which can expand throughout the part and ruin it. Not fun.

Also once their done stick them in the oven if you can, or just get after them with a heat gun. 3 hours or so in a 300F oven post cure (let it cure for 48hrs or so beforehand) will do wonders for your part, and help prevent future warping from heat.

[Wood]

Yup do it all in one go. What I always do is use plenty of resin, but when you get to the last layer roll it really good and use a squeegee to scrape off as much resin as you can. Reason being if you have too much resin (ideal ratio is 60% fiber 40% resin bu weight, but anything under 50/50 is considered good) the resin can crack, which can expand throughout the part and ruin it. Not fun.

Also once their done stick them in the oven if you can, or just get after them with a heat gun. 3 hours or so in a 300F oven post cure (let it cure for 48hrs or so beforehand) will do wonders for your part, and help prevent future warping from heat.

Well I can't do that part, but I'm gonna use uv resin so the cure doesn't warp as bad!! But thanks for the resin to fiber ratio because thats another thing I learned thats necessary lol!!

[yurvalentine]

Even with a UV activator a postcure would still help. With larger stuff I usually just plast it with a heat gun for a little while, nothing fancy. It's just insurance against future warping from the summer heat.

Good luck, have patience. I love working with the shit but I know for a lot it's a job they hate