Question for the community

REK · Mar 12, 2015

Hi everyone,

so recently I have been thinking on changing my strategy on making fiberglass tubes. I am thinking of using very light glass 3-4oz glass to make the glass tubes. It will require more wraps. I will be making these for those who dont have the time to make their own or for those who dont want to spend so much. My question to you all is what will you most often prefer, thin walled tubes or standard walled tubes?

Your feedback is most appreciated.

taiwanluthiers · Mar 12, 2015

Fiberglass is really strong, it makes no sense to make them so thick. I personally think those filament would fiberglass could be half as thick and still be strong enough for anything you could throw at it.

markkoelsch · Mar 12, 2015

What weave, what type of glass, are you using a post cure, and are you using vacuum bag or heat shrink tape to compress the laminate?

REK · Mar 12, 2015

markkoelsch said:
What weave, what type of glass, are you using a post cure, and are you using vacuum bag or heat shrink tape to compress the laminate?

The weave is going to be a 4 harness satin. There is no S-glass version of this super soft fabric so E-glass it is. When I make my oven, for sure I will be doing post cures. Again, once I make the oven I might use perforated heat shrink tape to compress the laminate.

REK · Mar 12, 2015

Im not gettig a lot of replies here, do I need to start this thread somewhere else? I'd really appreciate the feedback. So far one has cast their vote for thin wall tubes.

cwbullet · Mar 12, 2015

I think it is a good idea. I would be interested in seeing a demo or example.

Salvage-1 · Mar 12, 2015

Standard size ... Then it could be used as build, or as repair for all those 1,000's of standard sized rockets out there and flying that may someday need repair (or the ones that already need repair)

REK · Mar 13, 2015

cwbullet said:
I think it is a good idea. I would be interested in seeing a demo or example.

A demo in thin walls or standard size?

cwbullet · Mar 13, 2015

Thin walls or maybe comparison photos. I alway like to see what we are talking about.

REK · Mar 13, 2015

I laminated a tube from the 3oz plain weave cloth I had. A total of 7 wraps will give me a good 0.036" thickness. Thats about half the thickness of a standard tube. I will get pictures tomorrow when the tube cures.

Woody's Workshop · Mar 13, 2015

It has to do with cost in MHO. I have never done a glass rocket, but have layed 100's of yards on cars, vetts and boats. For me, I'd buy the cheapest standard size glass tube that I could. That I could fit ebays, nose cones and such to, for the cheapest price.
Hope this helps.

REK · Mar 14, 2015

Woody's Workshop said:
It has to do with cost in MHO. I have never done a glass rocket, but have layed 100's of yards on cars, vetts and boats. For me, I'd buy the cheapest standard size glass tube that I could. That I could fit ebays, nose cones and such to, for the cheapest price.
Hope this helps.

Im all about cheap. When it comes to the price set on filament wound tubes, it just runs through my head, why so much? I dont know if they use some expensive epoxy or something, but the glass is so cheap and also the hobby epoxies to these days can be used to most applications such as to Mach 3.

To the most part I've been selling hand made carbon parts for 50% below of that of a filament wound carbon tube. It is really a dung deal and in the long run. I can still benefit from it. You can expect me to sell these at a cheaper price that will save on money.

REK · Mar 14, 2015

Okay guys so here is the verdict on seven layers of 3oz plain weave glass. The OD came out at 1.584", this leads to say that more layers (just two more to be exact) to get it as close to 1.6", which I believe is the OD on the new thin wall filament wound tubes. Its a good thing I tested it first before using the satin glass.

ImageUploadedByRocketry Forum1426367683.231308.jpg

Here is a comparison photo showing the wall thickness compared to a standard tube (right tube).

ImageUploadedByRocketry Forum1426367768.146042.jpg

Night fliers eat your heart out, because this tube is a very great canidate for a night flier. It turned out very transparent.

ImageUploadedByRocketry Forum1426367829.448381.jpg

Well guys anymore questions?

The one thing I will update later on is the strength comparison. I thinned down Aeropoxy with 4 grams of lacquer thinner so right now the epoxy will take its time to reach its full strength. Of course later on once I make the oven, waiting wont be an issue.

REK · Mar 14, 2015

Motor fits in very nice. Once more check out that transparency.

ImageUploadedByRocketry Forum1426368375.373943.jpg

bobkrech · Mar 15, 2015

SinfulDarkLord said:
Im all about cheap. When it comes to the price set on filament wound tubes, it just runs through my head, why so much? I dont know if they use some expensive epoxy or something, but the glass is so cheap and also the hobby epoxies to these days can be used to most applications such as to Mach 3.

To the most part I've been selling hand made carbon parts for 50% below of that of a filament wound carbon tube. It is really a dung deal and in the long run. I can still benefit from it. You can expect me to sell these at a cheaper price that will save on money.

Commercial filament tubing winding machines are very expensive. Also commercial composites are expected to be made and tested to meet commercial specifications. Few hobby quality composites are, and most hobbyists probably don't need commercial quality products, and those that do may not realize it, nor have the knowledge and experience to determine exactly what they need.

Also commercial tubes and products are made by real businesses that are trying to make a profit, not simply reducing the costs of their hobby expenses. They are registered as businesses, pay rent, utilities and other business expenses. have lines of credit and pay taxes at business rates. They also pay themselves a wage they can live on. Few hobbyists do.

If you are doing all of these things, your expenses and therefore your prices would be comparable. Most hobby businesses fail within a year because the owners do not know how to price their products. If you don't pay expenses, taxes and yourself, then your going to be a lot cheaper than the competition, and probably loosing money on everything you make if you are "successful". You can live on the cash-flow of a new growing business for a while, but sooner or later you will realize that you never made a real profit, never paid yourself, and never brought in enough revenue to pay your bills. You stop filling your orders because you don't have enough money to order new materials to fill the orders and you get a bad reputation. This happens all the time.

If you want to start a small business I strongly suggest that you go to your local book store and buy a couple books on starting and running a small business. You will be surprised and educated on what it takes. If you pay someone $10 an hour, they have to generate revenues of at least $30 per hour or you're not being honest with your accounting practices. Similarly, if you are charging less than $4 for every $1 of material expense you have, you are not recognizing your costs properly, and most small businesses have to charge $5 for every $1 of material expense they incur to cover their costs and make a fair profit.

I'm not trying to discourage you from starting an enterprise but I am trying to make your efforts worthwhile and successful.

Bob

taiwanluthiers · Mar 15, 2015

I priced my business in such a way that for each dollar in material I use, I charge 10 dollars.

DizWolf · Mar 15, 2015

Thin is cool, as long as available couplers will fit.

thobin · Mar 15, 2015

Do what works, charge what you want, most of us do this for the love of the hobby not really to make money because lets face it, this hobby sucks for making a profit. When one vendor goes out of business two more will take his place. I have found most rocket hobbyists will not pay full price for an item (any hobby for that matter). Best you can hope for is price it for what people will pay. Unless you have a unique item you are stuck with market forces. In this day and age of the Internet you have to compete with a global market where everyone can undercut the next guy.

Dont do it to make money do it to help the rocket community and if you do make then woohoo bonus!

I like what I see sofar a what is the weight comparison?

TA

REK · Mar 15, 2015

bobkrech said:
Commercial filament tubing winding machines are very expensive. Also commercial composites are expected to be made and tested to meet commercial specifications. Few hobby quality composites are, and most hobbyists probably don't need commercial quality products, and those that do may not realize it, nor have the knowledge and experience to determine exactly what they need.

Also commercial tubes and products are made by real businesses that are trying to make a profit, not simply reducing the costs of their hobby expenses. They are registered as businesses, pay rent, utilities and other business expenses. have lines of credit and pay taxes at business rates. They also pay themselves a wage they can live on. Few hobbyists do.

If you are doing all of these things, your expenses and therefore your prices would be comparable. Most hobby businesses fail within a year because the owners do not know how to price their products. If you don't pay expenses, taxes and yourself, then your going to be a lot cheaper than the competition, and probably loosing money on everything you make if you are "successful". You can live on the cash-flow of a new growing business for a while, but sooner or later you will realize that you never made a real profit, never paid yourself, and never brought in enough revenue to pay your bills. You stop filling your orders because you don't have enough money to order new materials to fill the orders and you get a bad reputation. This happens all the time.

If you want to start a small business I strongly suggest that you go to your local book store and buy a couple books on starting and running a small business. You will be surprised and educated on what it takes. If you pay someone $10 an hour, they have to generate revenues of at least $30 per hour or you're not being honest with your accounting practices. Similarly, if you are charging less than $4 for every $1 of material expense you have, you are not recognizing your costs properly, and most small businesses have to charge $5 for every $1 of material expense they incur to cover their costs and make a fair profit.

I'm not trying to discourage you from starting an enterprise but I am trying to make your efforts worthwhile and successful.

Bob

Bob I respectfully appreciate the feedback. I am in no way discouraged or offended. The thing is I have no intention of starting a business. I am well aware of life's greediness when it comes to taxes. As I had stated, this is for those who dont have the extra cash nor the time to make a tube or any other type of composite.

I have great respect for filament wound tubes and I dont deny the price should be right since they use expensive materials. Once more the price can sometimes be overkill and thus the solution of a cheaper hand lay up works just as fine as a filament wound tube. It has been proven by many, so please no arguments there.

Thank you Bob

REK · Mar 15, 2015

DizWolf said:
Thin is cool, as long as available couplers will fit.

Thin walled couplers as well? I just remembered that there are tubing sized for me to be able to make couplers, but there is the problem that they have to be standard size to fit on the inside of the actual sized tubing. For example the standard ID for a 38mm whether it be thin wall or standard walled is 1.52", thus the OD of the coupler has to be close to that diameter to fit properly.

taiwanluthiers · Mar 15, 2015

I do wonder, how is Aerotech able to make high power single use motors (that uses filament would fiberglass as casing) that costs the same as reloads??

REK · Mar 15, 2015

thobin said:
Do what works, charge what you want, most of us do this for the love of the hobby not really to make money because lets face it, this hobby sucks for making a profit. When one vendor goes out of business two more will take his place. I have found most rocket hobbyists will not pay full price for an item (any hobby for that matter). Best you can hope for is price it for what people will pay. Unless you have a unique item you are stuck with market forces. In this day and age of the Internet you have to compete with a global market where everyone can undercut the next guy.

Dont do it to make money do it to help the rocket community and if you do make then woohoo bonus!

I like what I see sofar a what is the weight comparison?

TA

Just like you said, I'm doing this for the love of the hobby, not to gain extra cash. I really have no other tube to compare it with, but the weight on this tube at 36" long weighs in at 154 grams. Can someone help me in understanding the ratio? I used 3oz/psy cloth and I used 37" wide by 33.5" to make the 7 complete wraps.

REK · Mar 15, 2015

taiwanluthiers said:
I do wonder, how is Aerotech able to make high power single use motors (that uses filament would fiberglass as casing) that costs the same as reloads??

As Bob stated other industries use very expensive equipment. I dont know what Aertotech is using to make their filament wound tubes for casings. If their using expensive equipment too, then they are looking at something differently.

taiwanluthiers · Mar 15, 2015

If you're making stuff that requires very expensive equipment it may make better sense to outsource that work to someone who does have the equipment. Also you do want to charge what it costs so you can keep serving the community rather than having to shut down because you found you could no longer afford to pay bills.

REK · Mar 15, 2015

taiwanluthiers said:
If you're making stuff that requires very expensive equipment it may make better sense to outsource that work to someone who does have the equipment. Also you do want to charge what it costs so you can keep serving the community rather than having to shut down because you found you could no longer afford to pay bills.

I dont have any expensive equipment. Right now my mandrel is nothing but a bunch of 2x4's that has worked out nicely. Unfortunately I am having an issue with getting it to support one of my mandrels due to the fact that I only have centering rings to support the 38mm. I've been able to make the 54mm's, because I put it over the 38mm. The one I cant make is the 29mm's.

I'll soon be upgrading, still a cheap version, but it will help me in using all my mandrels with ease.

gltruett · Mar 15, 2015

At this time I would still like to see thick walled tubes as well as thin. Most of the nose cones I have now are for thick walled. Once those rockets become lost or destroyed they'll probably be replaced with thin wall versions and I'll prefer thin wall tubing.

bobkrech · Mar 16, 2015

SinfulDarkLord said:
Just like you said, I'm doing this for the love of the hobby, not to gain extra cash. I really have no other tube to compare it with, but the weight on this tube at 36" long weighs in at 154 grams. Can someone help me in understanding the ratio? I used 3oz/psy cloth and I used 37" wide by 33.5" to make the 7 complete wraps.

If your cloth weighs 3 oz. per square yard, and you are using 36" x 33.5" of cloth to get 7 layers that are 36" long cut, then the weight of the fiberglass in the tube is (33.5"/36")x(36"/36")x3 o.z=2.792 oz. = 79.14 grams. If the finished 36" long tube weighs 154 grams per yard, then the quantity of epoxy is 154-79.14 = 74.86 grams = 74.86/154 = 48.6% resin. That means the composite has more than 50% fiber which is considered a good fiberglass composite.
https://www.fibreglast.com/product/the-fundamentals-of-fiberglass/Learning_Center

3 oz. plain weave fiberglass fabric from ACP Composites is 0.0038" thick. The theoretical thickness of a 7 layer wrap is 0.0038 x 7 = 0.0266" thick. I would round this up to 0.004" per layer for thickness estimates for this material. Your fabric may be different, but if you're more than ~5%-10% thicker than theoretical for yuour fabric, you should try to improve your wrapping/compression techniques as excess resin does not contribute to strength.

You will find the articles you get when you google theoretical resin loading in fiberglass composite quite interesting. Downloading and reading them will be quite informative. Lots of pictures, drawings and plots. You don't need to be an engineer to read them either.

Bob

REK · Mar 16, 2015

bobkrech said:
If your cloth weighs 3 oz. per square yard, and you are using 36" x 33.5" of cloth to get 7 layers that are 36" long cut, then the weight of the fiberglass in the tube is (33.5"/36")x(36"/36")x3 o.z=2.792 oz. = 79.14 grams. If the finished 36" long tube weighs 154 grams per yard, then the quantity of epoxy is 154-79.14 = 74.86 grams = 74.86/154 = 48.6% resin. That means the composite has more than 50% fiber which is considered a good fiberglass composite.
https://www.fibreglast.com/product/the-fundamentals-of-fiberglass/Learning_Center

3 oz. plain weave fiberglass fabric from ACP Composites is 0.0038" thick. The theoretical thickness of a 7 layer wrap is 0.0038 x 7 = 0.0266" thick. I would round this up to 0.004" per layer for thickness estimates for this material. Your fabric may be different, but if you're more than ~5%-10% thicker than theoretical for yuour fabric, you should try to improve your wrapping/compression techniques as excess resin does not contribute to strength.

You will find the articles you get when you google theoretical resin loading in fiberglass composite quite interesting. Downloading and reading them will be quite informative. Lots of pictures, drawings and plots. You don't need to be an engineer to read them either.

Bob

Thanks Bob, wow not bad for a hand lay up. Once I make that oven I will use heat shrink tape with perforations to bleed out a lot of epoxy. That should definitely get it to a much better ratio.

Zebedee · Mar 16, 2015

In general (as a few have mentioned) it's going to depend a lot on what nose cones people can get that will fit. I believe most thin walled tubing is 0.04" thick (thin?) so if you match the ID you might shoot for that same thickness to also match commercially available NC's and other parts.

taiwanluthiers · Mar 16, 2015

Making fiberglass tubes for yourself by laying cloth over a mandrel is not the same as doing it commercially. When doing it commercially you have to make sure the diameter (both inside and outside) is consistent batch to batch and it MUST fit commonly available parts, otherwise nobody will buy it. It may require some trials and errors...

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