Pretty green flame Posted April 30, 2007 Share Posted April 30, 2007 Well, i'm going to try myself at making a couple of fiberglass mortars and one problem comes to mind. There are 2 possible types of resin for glueing together fiberglass. First there is polyester resin. The next thing is epoxy resin. Now both of these things work pretty well and set very hard. Which of these two will perform better (i.e. not fragment into sharp pieces) in an event of a shell malfunction. I've been told that polyester resin sets a bit more elastic than epoxy so my personal guess it the this is better but i'd still like some input from you guys here. So, which is better to use polyester or epoxy? Cheers Link to comment Share on other sites More sharing options...
Xtreme Pyro Posted April 30, 2007 Share Posted April 30, 2007 Well, i'm going to try myself at making a couple of fiberglass mortars and one problem comes to mind. There are 2 possible types of resin for glueing together fiberglass. First there is polyester resin. The next thing is epoxy resin. Now both of these things work pretty well and set very hard. Which of these two will perform better (i.e. not fragment into sharp pieces) in an event of a shell malfunction. I've been told that polyester resin sets a bit more elastic than epoxy so my personal guess it the this is better but i'd still like some input from you guys here. So, which is better to use polyester or epoxy? CheersIt is really hard to tell, you will always take the risk of the mortar tube exploding with a shell malfunction. They are both very strong and durable if i were you i would go with the polyester resin because it probrably won't shatter into sharp pieces and is very flexible, although epoxy resin would last a bit longer then the polyester resin, i hope this helps a bit. Link to comment Share on other sites More sharing options...
aquaman Posted May 1, 2007 Share Posted May 1, 2007 I agree with xtreme pyro. I believe the polyester would probably work safer for the mortar but then again the epoxy is harder and more rigid so it will probably last a little longer. Go with the polyester and just put a few concrete bricks in front of the mortar for just in case. Link to comment Share on other sites More sharing options...
Pretty green flame Posted May 2, 2007 Author Share Posted May 2, 2007 I see. I shall make one from each, polyester and epoxy, and put one of my cilynder shells upside down in it to see how they perform. Link to comment Share on other sites More sharing options...
aquaman Posted May 2, 2007 Share Posted May 2, 2007 There you go. Get pics, I'm kind of curious to see what they look like... Just do it in a safe area. Link to comment Share on other sites More sharing options...
asilentbob Posted May 2, 2007 Share Posted May 2, 2007 I have left over chems from making a surfboard in my garage and have thought about making a mortor before, however its so damn messy and stinky that i just keep putting it off. http://www.fiberglasssupply.com/ Where we ordered from. If you wanted to go really hi-tech you could make a kevlar or carbon fibre mortor lol. Link to comment Share on other sites More sharing options...
Xtreme Pyro Posted May 2, 2007 Share Posted May 2, 2007 I have left over chems from making a surfboard in my garage and have thought about making a mortor before, however its so damn messy and stinky that i just keep putting it off. http://www.fiberglasssupply.com/ Where we ordered from. If you wanted to go really hi-tech you could make a kevlar or carbon fibre mortor lol. A kevlar or carbon mortar sounds like a good idea, both strong and durable i might just try that . Link to comment Share on other sites More sharing options...
Pretty green flame Posted May 3, 2007 Author Share Posted May 3, 2007 I have left over chems from making a surfboard in my garage and have thought about making a mortor before, however its so damn messy and stinky that i just keep putting it off. http://www.fiberglasssupply.com/ Where we ordered from. If you wanted to go really hi-tech you could make a kevlar or carbon fibre mortor lol.A kevlar or carbon mortar sounds like a good idea, both strong and durable i might just try that . Get some Aramid, that's a kevlar/carbon composite, strong as hell, my father uses it on his model aircraft and this stuff is absolutely indestructible. Also, Aramid is also very expensive, IIRC it goes for around 40€ per square meter. Link to comment Share on other sites More sharing options...
deadman Posted May 3, 2007 Share Posted May 3, 2007 Both of those options would be very expensive. They are what poles for pole vaulters are used for. I've seen one break. It did not shatter, but was broken completely through. I guess it would have to be sort of rigid not to crease when bent by the vaulters. Interesting. Well since you are manufacturing your own, why not a rigind inner structure surrounded by a more giving material? How blast shields are made. Link to comment Share on other sites More sharing options...
Pretty green flame Posted July 31, 2007 Author Share Posted July 31, 2007 So, yesterday i tried myself at making a fiberglass tube. The materials i used were 300g/m2 fiberglass mat and 2 component polyester resin. A sheet measuring 50x60cm was cut and a 45mm steel pipe was wrapped in waxed paper for easy removal later on. The fiberglass mat was spread out on the table and impregnated with 150g of resin (This was a bit on the dry side so 200g would be the optimal choice). The former was placed on the mat and rolled up. During rolling the rolled portion would be smoothed down with a paint roller to prevent bubbles from forming. When done i let the resin to set for 24 hours before taking it off the former. Due to the waxed paper the tube slid of very easily and the paper was also removed with no problems. Comments: Well i'd have to say the for a first try this went VERY well, the tube is rock hard. Overall there were 4 turns of fiberglass cloth on the former so the walls are 1.9mm thick which i think should stand up well for a mortar of this size. The only thing i'm going to change or improve is the final layer. After all of the mat has been rolled up one final turn of rowing is going to be rolled up for a smoother outer surface, also some fiberglass tape is going to be added at the muzzle for added strenght when the vacuum kicks in after the shell leaves the tube. A picture (The unpainted version, after it has dried i spray paint it with yellow paint)http://i15.photobucket.com/albums/a374/AVP2/Fiberglassmortar.jpg Link to comment Share on other sites More sharing options...
aquaman Posted August 1, 2007 Share Posted August 1, 2007 Glad to see that you actually made one. Looks good. When its finished let us know how it performs. Link to comment Share on other sites More sharing options...
Pretty green flame Posted August 12, 2007 Author Share Posted August 12, 2007 Hello again. I'm back with the results Over all i'd say it performed mighty well. 1st test: A 45mm canister shell was put in the shell and ignited from top (No lift charge invlolved). A serious explosion was heard where we were standing. Upon inspection the mortar revealed no injuries, no cracks, no fraying, nothing, as good as the day it was made. 2nd test: Another 45mm canister shell was placed in the mortar and ignited from top (again no lift charge). Another explosion was heard and the mortar inspected. No damage whatsoever. 3rd test: Beeing sick of the mortar actually working one of my friends made a black powder maroon on site. One way or another this mortar is going to blow. The maroon was placed in the mortar and ignited. An earth shattering explosion was heard. Upon inspection of the mortar no damage was noticed. 4th test: All of us beeing sickened by the fact that this mortar might not blow up we decided to put a 4g flash salute in it. Upon exploding the mortar was shattered into hundreds of smaller pieces about 1x1cm in size, very light and non lethal. Further inspection revealed 2 larger pieces, one beeing aroung 5x8cm in size. the other about 3x5cm, the largest one was found 5m away from ground zero which is in my opinion well withing the safe limits. And anyhow these two pieces were very light, so my guess is that they present a minimal health hazard as far as shrapnell goes. Another thing was observed, the mortar shattered only at the spot where the salute was. So only about 8cm high from the bottom. Please let me know what you think about using these. My personal guess would be that they are relatively sefe, but i'd like to hear some of your opinions. Cheers PS: The pics of the post mortem will be posted as soon as my friend wakes up Link to comment Share on other sites More sharing options...
Pretty green flame Posted August 12, 2007 Author Share Posted August 12, 2007 Here's the result http://i15.photobucket.com/albums/a374/AVP2/Fiberglassdestroyed.jpg These two pieces you see are the only ones that were recovered (apart from the tube intact tube pieces ofcourse), everything else was shreded into small snow flakes. Cheers Link to comment Share on other sites More sharing options...
hst45 Posted August 12, 2007 Share Posted August 12, 2007 PGF, great work, as always. Testing to destruction is a tried-and-true engeneering concept. And hey, if you get a good "BOOM" too, what's not to like. So overall would you say that fabricating fiberglass tubes is a good way to go? Your tube looks quite smooth and very professional. Again, nice job and thanks for the info. Link to comment Share on other sites More sharing options...
Pretty green flame Posted August 12, 2007 Author Share Posted August 12, 2007 Well i'd say that if you can not get pre-fabricated fiberglass mortars then making them your self is definetly they way to go. A bonus here is that you can make them in virtually any size you want and any wall thickness. If you are serious about using home made fiberglass mortars i suggest that you test one or two of them to see how they perform under the worst possible conditions, just to make sure. In the near future i will be making a 3" mortar and putting it through the same kind of test I did on the 45mm. So basicly trying to blow it up and seeing what it holds out. If this one also checks out i will be using them with confidence for all my pyrotechnics needs. Also, another thing to remember is that when making the first fiberglass mortar you should always write down the ammount of resin and dimensions of the fiberglass cloth so if the mortar is suitable for pyro use they you have a reference point from which you make all your other mortars of the same size. I think I don't need to mention that every size requiers different dimensions and resin ammounts. Cheers Link to comment Share on other sites More sharing options...
gods knight Posted August 12, 2007 Share Posted August 12, 2007 Can fiberglass be purchased at a hardware store/hobby shop? I like the results of those tests, and where I get my H mortars they are very expensive. Link to comment Share on other sites More sharing options...
Pretty green flame Posted August 13, 2007 Author Share Posted August 13, 2007 Can fiberglass be purchased at a hardware store/hobby shop? Oh, to be honest i don't know. I found a store locally that deals with composite materials so that's where i get all my materials from. In hardware stores all I dound were fiberglass kits which were total and utter shit. So damn overpriced, 0.75square meter of fiberglass mat and a kilo of resin for 20€, damn, now I get a kilo of resin and 1square meter for 7.50€. Might be worth taking a look at hobby shops though. Most modern hobby airplanes are made from fiberglass so they might stock it. Cheers Link to comment Share on other sites More sharing options...
bmarley5780 Posted August 13, 2007 Share Posted August 13, 2007 Very nice trial run. On the topic of using carbon fiber for construction. When using carbon you need to use epoxy resin. The polyester won't adhere to the carbon well to give the moter the true carbon fiber strength that something like this needs. Link to comment Share on other sites More sharing options...
Pretty green flame Posted August 13, 2007 Author Share Posted August 13, 2007 Very nice trial run. On the topic of using carbon fiber for construction. When using carbon you need to use epoxy resin. The polyester won't adhere to the carbon well to give the moter the true carbon fiber strength that something like this needs. Thnx for the comments everyone. I would advise against using carbon fibre as a mortar material, sure it may be strong but it's expensive as hell, epoxy resin costs 4 times as much a polyester resin. Also, someone un UKPS forum wrote that cabon has some ceratin weaknesses when used as mortars but i can't find that certain piece of information right now. Anyway, it's far to expensive to be used as mortars. My calculations seem to indicate that for a 4" mortar you would need around 70-80€ worth of material. So 1.5square meters of carbon fibre cloth (provided it is the 300g/m2 type) and around half kilo of epoxy resin. While with polyester and fiberglass mat (300g/m2) you only get to about 8€ per 4" mortar. Link to comment Share on other sites More sharing options...
LGM Posted August 14, 2007 Share Posted August 14, 2007 What about copper tubing? It is fairly maleable so on the off chance that it does rupture all it will do is tear. Perhaps you could rivet the end cap on instead of soldering it so that it won't melt off, but I doubt that that would be a problem unless you are firing a lot of rounds in a short time frame. Link to comment Share on other sites More sharing options...
bmarley5780 Posted August 14, 2007 Share Posted August 14, 2007 I personally like the results of the fiberglass. Fiberglass is cheap, the polyester resin is also cheap. If you wanted to step it up just a tad you could get some carbon fiber tape and wrap where extra suport is needed. I have some CF twill leftover along with some epoxy to possibly do a trail, but right now I just want to focus on the "start"of my pyro. Link to comment Share on other sites More sharing options...
aquaman Posted August 14, 2007 Share Posted August 14, 2007 In the end it is still a metal that has mass. The copper tubing wouldn't tear it will rip to shreads and those pieces will travel. I say try to stick away from any type of metals for a mortar. Link to comment Share on other sites More sharing options...
Pretty green flame Posted August 14, 2007 Author Share Posted August 14, 2007 Aquaman, I agree, metal mortars are not suitable for hobby use, as one of my friends found out, he had a high velocity metal fragment fly inches above his head. This was about two years ago, after that he stopped making a certain type of device which includes some water piping and some end caps. Well anyway. Tommorow I shall be trying myself at making a 110mm fiberglass mortar to accomodate my 100mm shells. But I don't know what wall thickness to go for. I'd really appreciate it if someone who has a 4" fiberglass mortar would measure the wall thickness. Or atleast suggest a suitable wall thickness for a mortar of this size. I was thinking around 3mm would be enough. Cheers Link to comment Share on other sites More sharing options...
pudidotdk Posted August 14, 2007 Share Posted August 14, 2007 My 4" fiberglass is around 4-4,5 mm thick.It's actually quite hard to measure correctly, since there is a some sort of rim on the edge like this:http://www.skylighter.com/images/web_pictures/PL3183.jpg Link to comment Share on other sites More sharing options...
Chris Posted August 14, 2007 Share Posted August 14, 2007 Well anyway. Tommorow I shall be trying myself at making a 110mm fiberglass mortar to accomodate my 100mm shells. But I don't know what wall thickness to go for. I'd really appreciate it if someone who has a 4" fiberglass mortar would measure the wall thickness. Or atleast suggest a suitable wall thickness for a mortar of this size. I was thinking around 3mm would be enough. Cheers My commercial 4" gf mortars have a wall thickness of 1/8" Link to comment Share on other sites More sharing options...
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