# Chopped fiberglass info

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#### MikeyDSlagle

My girlfriend got me a Binder Tyrannosaur for Christmas. My first Binder kit. For those who do not know, you build the fin can and remove it so that the fin to MMT joint can get a good fillet. Well, the instructions suggest chopped fiberglass for the internal fillets. I have been meaning to get me some anyway just never have. My go to source would be US Composites. But they are closed until the 2nd. They are hard to beat at 3.85/pound. Other sources have been $10+/lb. Would kinda like to get this project rolling. I did find some here: https://www.fiberglasssite.com/fiberglass-chopped-strands-1-4-5-quarts-5-lbs/ which is cheaper but 5lbs is quite a bit. And they want 20 bucks to ship it! Anyone have a cheap source for the stuff? Or alternative product. I have other stuff that I have used in the past and have never had any issues, but have never built a rocket to handle Js and the occasional K. I have some kevlar tape from Soller Composites. It is just basically a 1/2 strip of woven kevlar. I may be able to soak it in epoxy and lay it on the joint. Thoughts on that? Also, what is a good material/source for sewing my own harnesses. Sewing is so much neater than knots. So far I have uses braided kevlar (stuff I used in LPR rockets, just decided to sew with it) and the stuff that comes with a sewing awl. Good luck so far with both of those. And I am nearly out of both. I have looked at some other posts and went to various sites, I just don't know what size I need. Thanks Mikey D Last edited: #### Nytrunner ##### Pop lugs, not drugs TRF Supporter Exactly how necessary is the chopped fiber reinforcement? I've been wondering about this alot lately. I'm only L1 currently, but, in my senior year, my old college rocket team used straight Aeropoxy for the fin and ring bonds without issue on an M-powered fiberglass 4". #### timbucktoo ##### Well-Known Member Staff member TRF Supporter Global Mod Wildman sells chopped carbon fiber which is what I use for internal fillets. #### rms ##### Well-Known Member For the amount of chopped fibreglass you need, just pull some filaments from a scrap piece of fibreglass cloth and chop your own with a pair of scissors. #### dixontj93060 ##### Well-Known Member Use the Kevlar tape. It is a more than adequate substitute. #### Steve Shannon ##### Well-Known Member TRF Supporter I don't know how necessary the chopped fiberglass is, but if Mike Fischer recommends it I would be inclined to do it. If you have any fiberglass cloth you can just snip off some of the edge. You don't want much; it turns into the worst furball you've ever seen. Laying down Kevlar or fiberglass tape would absolutely work as well; just be sure to build a fillet first, then laminate the tape along the fillet. In a fillet the outermost layer farthest from the corner where the fin and BT meet contributes more to strength. Steve Shannon #### MikeyDSlagle ##### Well-Known Member I don't know how necessary the chopped fiber is, but it makes sense why it is used. The same thing is used in concrete on occasion. I remember using fibers about an inch or so long in some countertops and sometimes steps. And Mike suggests it. I don't have any cloth to make my own, but the local Walmart does, didn't even think of that, and my girlfriend is there now. So for just under 5 bucks, the chopped fiber problem is solved, once I chop it. I found out last night that Wildman sells chopped carbon fiber, good to know for future use. I'm gonna mess around with the tape and see what I can do with it. Probably be good for internals, but not the externals. Thanks folks. I'll start another thread down in tbe recovery section for the thread question. Mikey D Last edited: #### degreaser ##### Well-Known Member Look on ebay. You can find chopped/milled fiberglass and carbon fiber in varying quantities for reasonable prices. https://www.uscomposites.com/ is another great source for composites. #### Steve Shannon ##### Well-Known Member TRF Supporter I don't know how necessary the chopped fiber is, but it makes sense why it is used. The same thing is used in concrete on occasion. I remember using fibers about an inch or so long in some countertops and sometimes steps. And Mike suggests it. I don't have any cloth to make my own, but the local Walmart does, didn't even think of that, and my girlfriend is there now. So for just under 5 bucks, the chopped fiber problem is solved, once I chop it. I found out last night that Woodman sells chopped carbon fiber, good to know for future use. I'm gonna mess around with the tape and see what I can do with it. Probably be good for internals, but not the externals. Thanks folks. I'll start another thread down in tbe recovery section for the thread question. Mikey D Auto stores also sell woven and random stranded fiberglass mat right by their Bondo displays. Steve Shannon #### markkoelsch ##### Well-Known Member I believe that TRF user Rob Martinez is selling small containers of chopped glass, Kevlar, and carbon. #### MikeyDSlagle ##### Well-Known Member Look on ebay. You can find chopped/milled fiberglass and carbon fiber in varying quantities for reasonable prices. https://www.uscomposites.com/ is another great source for composites. Yes, I use US Composites a lot, mentioned that in first post. But thanks. Was about to order some from ebay, 3lbs for ~$26.00 shipped when I thought about the cloth at WalMart.

CHOPPED FIBERGLASS 1/4 INCH FIBER GLASS 3 POUNDS

Three pounds of this stuff is ALOT!

Auto stores also sell woven and random stranded fiberglass mat right by their Bondo displays.

Steve Shannon
Yep, they are usually higher priced than Walmart. And my girlfriend was at Walmart when I remembered them having it.

I believe that TRF user Rob Martinez is selling small containers of chopped glass, Kevlar, and carbon.
I think he does milled fiberglass and kevlar, and chopped carbon. Was looking at buying some of his kevlar and carbon at some point.

By getting locally and cutting it myself I avoided shipping costs and had it in hand same day. It was easy to chop. Pulled a few strands out and cut the stray parts with a rotary cutter. Then laid out the strands I remove and cut them as well. I really only needed a tiny bit, didn't know how little until I started mixing. Just a pinch is plenty. First batch was so thick I tossed it out, was afraid it wasn't wet enough. I have some kevlar mat I was going to try the same thing with, stuff just doesn't cut easy enough.

So I got it chopped, mixed and applied. Super easy.

Thanks guys.

#### Steve Shannon

TRF Supporter
Yes, I use US Composites a lot, mentioned that in first post. But thanks. Was about to order some from ebay, 3lbs for ~$26.00 shipped when I thought about the cloth at WalMart. CHOPPED FIBERGLASS 1/4 INCH FIBER GLASS 3 POUNDS Three pounds of this stuff is ALOT! Yep, they are usually higher priced than Walmart. And my girlfriend was at Walmart when I remembered them having it. I think he does milled fiberglass and kevlar, and chopped carbon. Was looking at buying some of his kevlar and carbon at some point. By getting locally and cutting it myself I avoided shipping costs and had it in hand same day. It was easy to chop. Pulled a few strands out and cut the stray parts with a rotary cutter. Then laid out the strands I remove and cut them as well. I really only needed a tiny bit, didn't know how little until I started mixing. Just a pinch is plenty. First batch was so thick I tossed it out, was afraid it wasn't wet enough. I have some kevlar mat I was going to try the same thing with, stuff just doesn't cut easy enough. So I got it chopped, mixed and applied. Super easy. Thanks guys. Good job! #### Nytrunner ##### Pop lugs, not drugs TRF Supporter I don't know how necessary the chopped fiberglass is, but if Mike Fischer recommends it I would be inclined to do it. I don't know how necessary the chopped fiber is, but it makes sense why it is used. The same thing is used in concrete on occasion. I remember using fibers about an inch or so long in some countertops and sometimes steps. And Mike suggests it. Gotcha. I've no doubt it strengthens the adhesives structure. I'm just trying quantify it a bit to judge whether the benefit is worth the increased process complication. Say for example, if the carbon fiber reinforcement gives a factor of safety of 5, but a properly applied and cured structural epoxy fillet gives a factor of safety of 2, I'd likely stick with a carefully done structural fillet. #### MikeyDSlagle ##### Well-Known Member I seem to remember reading somewhere (SEEMS like it, I may be wrong) that the joint is 25% stronger. No I can't quote the source, that is in my head for some reason. But it has to make the fillet stronger. I think of it like concrete with and without rebar. With rebar it is so much stronger, same principle. And it isn't really that much more effort. Well it is harder to apply, dont get me wrong. Try it on the internal fillets on one rocket and see what you think. Don't have any chopped fiberglass? Shoot, I'll send you some. It doesn't take much at all. Is it necessary though? No clue, this is a first for me. I was able to get me some kevlar trimmings today, will try that on the forward fins. Last edited: #### Rob702Martinez ##### Zip-Tie Oversight Committee TRF Supporter 5.50$ a jar of quality milled FG free syringe and 6 bucks to ship
Working on chopped kevlar, not the milled kevlar I sell but like the 1/4 carbon kinda chop. So far tests have been good, waiting for more.

#### MikeyDSlagle

##### Well-Known Member

I use US Composites 150, the thick stuff. Mixing that with the chopped fiberglass/kevlar, will it saturate the fibers sufficiently or should I be using their laminating epoxy? Just a thought that came to me.

Thanks

#### Steve Shannon

##### Well-Known Member
TRF Supporter

I use US Composites 150, the thick stuff. Mixing that with the chopped fiberglass/kevlar, will it saturate the fibers sufficiently or should I be using their laminating epoxy? Just a thought that came to me.

Thanks
I wouldn't mix it with a resin that already has that much filler; in fact you may not really need it in that case.
I only use laminating epoxy, usually Aeropoxy although I seem to have built up a stockpile of West Systems so I'll switch to that and see how well I like it. With the Aeropoxy I can add whatever fillers I like, which leaves me in total control. I like that.

Steve Shannon

#### bill_s

##### Well-Known Member
An advantage of using chop when you just have regular epoxy is you can get it wetted out in the mix tray. I've also used chopped glass and Titebond or wood glue (last occasion : post CATO repair). I have a little roil of fiberglass tape I've been whittling away at.

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#### Rob702Martinez

##### Zip-Tie Oversight Committee
TRF Supporter
If you mix it in small batches, stir vigorously, you can generate a viel, if you would. The fibers overlap, cross in every angle, think of it as chopped mat FG but doing it as a wet layup with CF or Kevlar, chop or pulp or milled.

#### T-Rex

##### Ordinary Average Guy
TRF Supporter
Are chopped glass and milled glass interchangeable for our uses? or are they apples and oranges??

#### MikeyDSlagle

##### Well-Known Member
I wouldn't mix it with a resin that already has that much filler; in fact you may not really need it in that case.
I only use laminating epoxy, usually Aeropoxy although I seem to have built up a stockpile of West Systems so I'll switch to that and see how well I like it. With the Aeropoxy I can add whatever fillers I like, which leaves me in total control. I like that.

Steve Shannon
The epoxy isn't superthick. Probably like syrup. It is still pourable, squeezable, and syringeable. Not sure if that last one is a word, but you get the meaning.

An advantage of using chop when you just have regular epoxy is you can get it wetted out in the mix tray. I've also used chopped glass and Titebond or wood glue (last occasion : post CATO repair). I have a little roil of fiberglass tape I've been whittling away at.
So you are saying you don't use laminating epoxy? They stuff I have will be fine?

If you mix it in small batches, stir vigorously, you can generate a viel, if you would. The fibers overlap, cross in every angle, think of it as chopped mat FG but doing it as a wet layup with CF or Kevlar, chop or pulp or milled.
Yes. Using the 105 epoxy it turns into, what likes like, a small piece of wetted mat. Being my first time, I wasn't sure if this was normal. But I should have super strong internal fillets!

I haven't done fiberglass layup or used any kind of fiberglass cloth or mat in probably 12+ years. And that was on a larger scale in papermills. And was polyester resin based, I'm guessing because I remember Organic Peroxide. We didn't know a darn thing about what we were doing. We were given the mat, the chemicals and the task and told to do it. I had never done it before. Read some instructions and we got decent. Hated every second of it.

#### MikeyDSlagle

##### Well-Known Member
Are chopped glass and milled glass interchangeable for our uses? or are they apples and oranges??
I would think chopped would add more strength, seeing how (in my limited experience) it kinda forms a mat. No experience with milled, but seems like that would make more of a paste and not be as strong structurally.

Anyone ever used cotton flock? That's new to me. Well, all of it is new to me, but I don't remember seeing cotton flock before.

#### FMarvinS

##### Well-Known Member
I have used Rob Martinez's products with good success. The quantity & prices are excellent. If you search Robert on this site, you should easily find his contact info.

Fred,
L2, KG4YGP
ROSCO member

#### ksaves2

Too much chopped anything with too little binder (epoxy or whatever) doesn't add one iota in the strength department. I did chopped carbon fiber in laminating epoxy and tried to lay a fillet (on a modroc caliber project as a trial mind you)
and got randomly interspersed furballs in the fillet. Too much fiber and I don't think it adds anything especially if the orientation of the fibers is random.
Sure could add strength if one gets "everything" just right? Sure, maybe if one wants to practice a lot but unless one tests to destruction we really don't know if it helps. Where's "Doc" Drake Demerau when you need him? His rocket materials site had
some good test data for various materials but like everything Doc I guess moved on.

I've found that Proline 4500 or Duralco 4525IP does pretty good fillets in neat form so why pollute it with additives?

Ok, so I'm not a complete heretic. Laminating with cloth and rotating fiber orientation in layers is a different matter and is strength enhancing. No doubt about that. Random fiber orientation, I'm not so sure. Kurt

#### rcktnut

##### Well-Known Member
Too much chopped anything with too little binder (epoxy or whatever) doesn't add one iota in the strength department. I did chopped carbon fiber in laminating epoxy and tried to lay a fillet (on a modroc caliber project as a trial mind you)
and got randomly interspersed furballs in the fillet. Too much fiber and I don't think it adds anything especially if the orientation of the fibers is random.
Sure could add strength if one gets "everything" just right? Sure, maybe if one wants to practice a lot but unless one tests to destruction we really don't know if it helps. Where's "Doc" Drake Demerau when you need him? His rocket materials site had
some good test data for various materials but like everything Doc I guess moved on.

I've found that Proline 4500 or Duralco 4525IP does pretty good fillets in neat form so why pollute it with additives?

Ok, so I'm not a complete heretic. Laminating with cloth and rotating fiber orientation in layers is a different matter and is strength enhancing. No doubt about that. Random fiber orientation, I'm not so sure. Kurt

Beat me to it!! If your laminating use the correct epoxy, if your building use a structural/ adhesive epoxy. Use the right epoxy for building(all sorts of different brands out there) no need to add any sort of chopped this or that.

#### ksaves2

I forgot to add the 1/3rd, 2/3rds and full span lamination technique too. I had a cardboard tubed 38mm MD rocket with surface mount 1/8" plywood fins treated in this fashion blast through and destroy a Mayhem rocketry rail guide with
just a few paint chips in the fins. That's strong. Kurt

#### MikeyDSlagle

##### Well-Known Member
Too much chopped anything with too little binder (epoxy or whatever) doesn't add one iota in the strength department. I did chopped carbon fiber in laminating epoxy and tried to lay a fillet (on a modroc caliber project as a trial mind you)
and got randomly interspersed furballs in the fillet. Too much fiber and I don't think it adds anything especially if the orientation of the fibers is random.
Sure could add strength if one gets "everything" just right? Sure, maybe if one wants to practice a lot but unless one tests to destruction we really don't know if it helps. Where's "Doc" Drake Demerau when you need him? His rocket materials site had
some good test data for various materials but like everything Doc I guess moved on.

I've found that Proline 4500 or Duralco 4525IP does pretty good fillets in neat form so why pollute it with additives?

Ok, so I'm not a complete heretic. Laminating with cloth and rotating fiber orientation in layers is a different matter and is strength enhancing. No doubt about that. Random fiber orientation, I'm not so sure. Kurt
Fiberglass mat has the fibers ran in all sorts of random directions. It is used in many applications, boats, bathtubs, cars..it holds. The thinner stuff is held together with a binder that dissolves and you are left with just a bunch or random fibers. Getting it mixed may be tricky, but not difficult. First batch I mixed was, like you say, fur balled and useless. I wiped it off and tossed it.

Im not being a turd here, but I wasn't asking about Proline; have heard it is good stuff though. One day I'll try it. I was asking about chopped fiberglass in epoxy for internal fillets. More specifically sources for the fiberglass.

That being said, I appreciate your response and opinions. I will try Proline in the future, just not when I have other options either on hand or less expensive. I may even order some for my external fillets, still tossing ideas around for doing those. Gonna play with the chopped glass a bit and maybe lay down a root using it and use stuff I have to cover it. Just going to see how neat I can get my chopped fiber filled fillets.

Mikey D

#### Rob702Martinez

##### Zip-Tie Oversight Committee
TRF Supporter
Beat me to it!! If your laminating use the correct epoxy, if your building use a structural/ adhesive epoxy. Use the right epoxy for building(all sorts of different brands out there) no need to add any sort of chopped this or that.
Too much chopped anything with too little binder (epoxy or whatever) doesn't add one iota in the strength department. I did chopped carbon fiber in laminating epoxy and tried to lay a fillet (on a modroc caliber project as a trial mind you)
and got randomly interspersed furballs in the fillet. Too much fiber and I don't think it adds anything especially if the orientation of the fibers is random.
Sure could add strength if one gets "everything" just right? Sure, maybe if one wants to practice a lot but unless one tests to destruction we really don't know if it helps. Where's "Doc" Drake Demerau when you need him? His rocket materials site had
some good test data for various materials but like everything Doc I guess moved on.

I've found that Proline 4500 or Duralco 4525IP does pretty good fillets in neat form so why pollute it with additives?

Ok, so I'm not a complete heretic. Laminating with cloth and rotating fiber orientation in layers is a different matter and is strength enhancing. No doubt about that. Random fiber orientation, I'm not so sure. Kurt

Well I should probably toss the 50 LBS or so of composite material I have and stick to using the correct epoxy from now on. Its posts like these that deter the regular garage hobbyist from trying anything these days, or being creative or being successful at any small projects/goals. Structural epoxy is filled with fillers, just like the fillers the "every day" hobbyist can use.

When I start building actual aerospace components to be used in actual space flight, rather than just using LKQ processes as a standard on everything, I would probably follow the book. But for the everyday hobbyist it takes the fun out of what we do. Not everyone is on a quest for rocketry supremacy, nor has the time or resources to do all this fancy work. So we use what is available and what works time and time again.

rocket poxy with milled kevlar added.

aeromarine 300/21 laminating epoxy with 1/4 chop CF used for internal fillets, either inject or lay.

The problem people have is not that they used too much or too little material, its that you are using too much of your mixed material, to do the job. That is why it is sold in small quantities. Use the mind set of a little goes a long way and you will be fine on your ratios.

This survived a fall from about 800 feet where the main tangled the drogue, onto the playa, bounced at least 2x, 4in 12lb airframe and fins that stick out considerably far... Not bad for hobby/available epoxy and fillers, considering the structural joint did not fail but the g10 failed before the adhesive did. I am pretty sure I could build a comparable bullet proof MD rocket, using this stuff when I get into MD.

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#### Steve Shannon

##### Well-Known Member
TRF Supporter
I agree Rob, adding the appropriate fillers to a system epoxy, like West, or a laminating epoxy, like Aeropoxy, makes just as much sense. Ive got two gallons of West Systems resin, fast and slow hardener, chopped carbon in a couple different lengths, and a decent amount of experience building high power rockets. There's nothing wrong with using structural epoxy, but there's nothing wrong with adding the appropriate fillers to Aeropoxy or West Systems either.

Steve Shannon