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Old 10-23-2018, 05:04 PM   #1
eddie1987
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Carbon Wrap

So I’m looking at doing a carbon wrap for my Denton 120... I’ve decided on carbon sleeves from Soller .. any advice on which to get 3k or 6k... also anyone used a food saver as a vacuum for this application? Would this be sufficient , asking because I was planning to get a food saver anyways for my fillets .


Any advice on the carbon sleeve vacuum bagging process is greatly appreciated

Thanks


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Old 10-24-2018, 03:35 PM   #2
spearq8
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Re: Carbon Wrap

With sleeves it really is not so complicated to get a really high quality finish. For the Abellan, I think I used a 2.5" sleeve @3K. For the back area where it gets really thin, I used 2 sleeves and an extra strip of CF tape under the trigger guard (probably not needed)

I only did 5 Abellans with a CF skin, and like everything else, each time things were quicker and easier. The last time I did it took about 2 hours … first time a couple of days. On my first attempt I actually put the carbon fiber cloth even in the cavities of the lead ballast and the trigger pocket … that was just WAY too much work. Last version I just plugged those cavities with plasticine and cut the CF out. This saved about a days worth of work and I doubt the gun was any weaker. I did wax out the SS trigger guard and muzzle and screwed it in with the epoxy to get the CF really perfect there. I also put a taped up 8.5mm shaft to get the track really nice. In my case I had also changed out the trigger to a double roller trigger, so that covered up a lot of the patchy work I did to get the trigger fitted.


For the Vacuum packing, I doubt a food saver vacuum can pull hard enough to get a nice job done. But for sure you can give it a shot and it would work … just would need to spend more time cleaning up the excess epoxy that didn't squeeze out. I do use food saver type vacuum sealer for my handles … much easier than setting up the vacuum pump.

First you need to remove the trigger and all the SS parts and wax them and then tape them with electric tape. Pay careful attention to the front muzzle screws as even a little tension and they will break inside the wood … you don't want to have to do that it is incredibly difficult to get broken screws out of there. You then sand the entire gun with say an 80 or 120 grit and clean it up with acetone. This gives a good hold for the epoxy and CF sleeve. Then put a sleeve on the front and zip tie one end and then pull the sleeve through. It should nicely contour around your gun shape. Then slowly put epoxy and work it through with your gloved hand(use only very slow cure epoxy). The slow cure epoxy is usually very thin, but you can always use a hair dryer to make sure the epoxy liquifies and wets the CF really well. You then screw in the SS parts over the CF and put a taped up shaft in with shark fins up. Wrap all this with peel ply … then put a release film over the peel ply … and a breather fabric above that to suck up the extra epoxy to keep added weight to a minimum. Once you have all that you put in the vacuum bag and pull out the air. Once cured you just open it up and pull away the peel ply … maybe a very slight sanding of areas that need to be sanded. Peel ply leaves a fantastic finish that really takes the final coats of epoxy really well. To unscrew the SS screws you put a solder iron on each screw until it warms the epoxy and it will come out really easy. If the epoxy is not fully cured the screws will actually come out without heat. I replaced all the screws as it is just a PIA to clean the epoxy from them.

Sounds complicated and it probably is the first time, but after a couple of times it is really very simple and doesn't take up much more work than a normal sanding and epoxy finishing of a normal gun.
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Old 10-25-2018, 02:15 AM   #3
Diving Gecko
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Re: Carbon Wrap

Vacuum Bagging on A Budget

Hey Eddie,
I know you are not looking to invest in a pump but indulge me for a min...;-)
Thing is, I think this can be done on the cheap and it will give you a much better result. E.g. a discarded (free!) fridge compressor makes a strong vacuum pump and you might not have to do much to it.
I have one that I use for positive pressure to fill my airguns but it would def work for vacuum also.
The cool thing about rigging a vacuum pump is that you don't have to spend much on fittings and don't have to solder, weld or braze anything in place - there's no positive pressure trying to "explode" your parts. Also, vacuum pressure is maximum -14.5psi or -1 bar whereas positive pressure can go many times higher. This means that in a vac pump setup you can get by with plastic fittings and cheap hoses.
E.g. you could just get a barb hose fitting, a gauge, a three way valve, plumbers tape and some hose and you should be good to go.

One step up from that is a cheap vacuum pump that is often billed as being used for the refrigerator and AC service industry. I think they are used to evacuate the systems of air before filling them with the refrigerant gasses. They come in different sizes - bigger ones evacuate more air (higher CFM) - but they all pull a very, very good vacuum and the smallest version is more than enough for our needs. I'd think you can get one very affordably as many of these are now Chinese made and exported all over.

The latter is what I used in my small vac setup, but I pimped it a bit with a small reservoir and an automatic pressure switch.
A reservoir means that if you do have a leak, the pump doesn't have to cycle that often and the pressure switch takes care of turning it on and off according to the target pressure and hysteresis you have set.

BUT you don't actually need a switch or reservoir or fancy fittings at all. If your bag is not leaking, it's totally OK turning the pump off completely after you've reached the vac pressure you want. The pumps tend to "leak" themselves so you would have to clamp down on the hose in between the pump and the bag. You can do this with a pair of Vise-Grips or even cheaper - just fold the hose back on itself a few times and hold the folds in place with tape. You could also just run the pump continuously until the resin has cured, but you risk killing the pump as they are not really rated for continuous running.

I do recommend buying a proper roll of tacky tape, the thick sealing tape, used for vac bagging. Also, you'd need some perforated release film and if you want to, a bit of vac bag film and breather material. I think you could use kitchen tissue as breather and possible drop film for vac bag - just test that it will release alright.

One note, though. Both the cheap AC service vac pump and a refrigerator pump are oiled. So, ideally, you need a bit of discipline in when you turn the pump on and off. Basically, you don't want a negative pressure pulling oil mist out of your pump and into the bag. I have a one way valve to help with this, but clamping the hose before you turn the pump on, and then releasing the clamp once the pump is at full vac, would do the same.
(Alternatively, if you do want a oil-less pump supposedly many (all?) of the Gast vac pumps are oil-less. They pop up on eBay at very affordable prices pretty often. The service kit for resealing is about USD 40 if needed, though - but you'd have a pro level brand name pump.)

Anyways, if you want to go this way, let me know and I can share more thoughts on how this could be set up.

Sorry, for this long-winded write-up but I do feel a lot of guys get dissuaded by their first few tries at composites and I feel like a vacuum bagging setup would go a very long way to reduce the pains.

Last edited by Diving Gecko; 10-25-2018 at 02:38 AM.
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Old 10-25-2018, 03:03 AM   #4
popgun pete
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Re: Carbon Wrap

For bulk long term storing soft items such as clothing in bags and then sucking the air out of them you see these vacuum cleaner attachments, would a vacuum cleaner do the job? Seems like a crazy question, but I thought it was worth asking.
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Old 10-25-2018, 03:03 AM   #5
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Re: Carbon Wrap

You need a vacum pump. Period. And the AC service ones work ok. And do not shut it off after getting a good vacum, as the seals will never be perfect and some air will leak in. You will have to leave it on. I did. Three times. For a 16h period each. The pump is just fine.

And regarding the material to be wrapped over the carbon fiber, there are already products out there that provide you the three required layers in a single product (peel ply, release film and breather). Much easier that way!

Mikel
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Old 10-25-2018, 03:05 AM   #6
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Re: Carbon Wrap

Quote:
Originally Posted by popgun pete View Post
...would a vacuum cleaner do the job? Seems like a crazy question, but I thought it was worth asking.
Not enough vacum. Need something more specific. Vacum cleaners pull a lot a volume with little negative presure. You pretty much need the opposite. Big volume is required only to degass some resins (poliuretane for molding) before dumping them into the molds, but for carbon fiber wrapping is not needed.

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Old 10-25-2018, 03:19 AM   #7
Diving Gecko
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Re: Carbon Wrap

Quote:
Originally Posted by Mikel_24 View Post
You need a vacum pump. Period. And the AC service ones work ok. And do not shut it off after getting a good vacum, as the seals will never be perfect and some air will leak in. You will have to leave it on. I did. Three times. For a 16h period each. The pump is just fine.

And regarding the material to be wrapped over the carbon fiber, there are already products out there that provide you the three required layers in a single product (peel ply, release film and breather). Much easier that way!

Mikel


Can't help this one as you are right about the rest, but plenty of guys manage to get leak free bags, period;-). It's not super easy, but it's certainly not impossible either. Even I have managed. Also, if you move onto resin infusion leak-free bagging is kind of a must (I am not doing infusion yet, though).
Granted, once you either have a switch or a pump which you don't mind letting run continuously - and you are doing wet lay up - you can get a bit lazy on this.
One last note, though - if you are intending to run a pump through the whole cure phase, I still think it would make sense to limit just how much you actually run it. With even very slow hardeners, I would think the resin has set more than enough after, say, 8-10H that it would be safe to turn off the pump? It could possibly prolong the life of the pump?

As for the peel ply, I didn't mention it on purpose as it is not really needed if you are not going to do any secondary bonding. Not having it, in this case, is one less thing to worry about. But perhaps it is OK to have if you are going to apply a proper top coat on afterwards?


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Last edited by Diving Gecko; 10-25-2018 at 05:31 AM.
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Old 10-25-2018, 05:21 AM   #8
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Re: Carbon Wrap

Quote:
Originally Posted by Mikel_24 View Post
Not enough vacum. Need something more specific. Vacum cleaners pull a lot a volume with little negative presure. You pretty much need the opposite. Big volume is required only to degass some resins (poliuretane for molding) before dumping them into the molds, but for carbon fiber wrapping is not needed.

Mikel
I agree. I don't know how much vacuum a vacuumer pulls, but I doubt that it is enough.
Some people who do huge parts, like boat hulls or DIY aero parts start with a vacuumer just to evacute most the air in the bag and then switch to a proper vac pump for the real hard work.

As for how much vacuum you need for vac bagging, we haven't touched upon that and I know I spoke in favor of pumps which could pull a lot. Generally speaking, the more pressure, the more compaction of the fibers and the better a ratio of fiber to resin content you will get - this is all good. But you can actually pull too much resin out of a layup (depending on the resin viscosity, the perf film and cure time, I guess) if you pull full vacuum from the very start. I tend to pull about 50-70% and then once the resin starts setting I up the vac pressure. But I reckon some resins are thick enough you can probably pull full vac from the get go.
Just do a test on a piece of scrap first and all should be good.

Eddie, don't get scared off! Mikel is right, a pump will help you so much - and it's not really as hard as we make it sound.
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Old 10-25-2018, 05:29 AM   #9
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Re: Carbon Wrap

Quote:
Originally Posted by Mikel_24 View Post
You need a vacum pump. Period. And the AC service ones work ok. And do not shut it off after getting a good vacum, as the seals will never be perfect and some air will leak in. You will have to leave it on.
[EDIT]
Mikel
Come to think about it, I have some vacuum bags used for storing duvets, winter clothes, etc sitting in my closet chuck full of rubber bands. You know, the corny TV-shop kinda product with a Zip Lock-type zipper at the end and a small hand vac pump. Thing is, it has not lost pressure in months. I have used those same bags for smaller parts and besides not leaking and being cheap, the brand I have also releases really nicely. I doubt they make one long for a whole gun stock, though.
[EDIT] Oh, I just googled it and depending on the brand, they make them up 120-130cm long - so, diagonally, you might get as much as 160cm!

BTW, I hook it up to my vac pump - I only use the hand pump for when storing bands or duvets.


I think Majd mentioned, that Soller sells a bagging sleeve? That means less seams to seal and reduced risk of leaks.

Last edited by Diving Gecko; 10-25-2018 at 07:11 AM.
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Old 10-25-2018, 08:53 AM   #10
eddie1987
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Re: Carbon Wrap

Quote:
Originally Posted by spearq8 View Post
With sleeves it really is not so complicated to get a really high quality finish. For the Abellan, I think I used a 2.5" sleeve @3K. For the back area where it gets really thin, I used 2 sleeves and an extra strip of CF tape under the trigger guard (probably not needed)

I only did 5 Abellans with a CF skin, and like everything else, each time things were quicker and easier. The last time I did it took about 2 hours … first time a couple of days. On my first attempt I actually put the carbon fiber cloth even in the cavities of the lead ballast and the trigger pocket … that was just WAY too much work. Last version I just plugged those cavities with plasticine and cut the CF out. This saved about a days worth of work and I doubt the gun was any weaker. I did wax out the SS trigger guard and muzzle and screwed it in with the epoxy to get the CF really perfect there. I also put a taped up 8.5mm shaft to get the track really nice. In my case I had also changed out the trigger to a double roller trigger, so that covered up a lot of the patchy work I did to get the trigger fitted.


For the Vacuum packing, I doubt a food saver vacuum can pull hard enough to get a nice job done. But for sure you can give it a shot and it would work … just would need to spend more time cleaning up the excess epoxy that didn't squeeze out. I do use food saver type vacuum sealer for my handles … much easier than setting up the vacuum pump.

First you need to remove the trigger and all the SS parts and wax them and then tape them with electric tape. Pay careful attention to the front muzzle screws as even a little tension and they will break inside the wood … you don't want to have to do that it is incredibly difficult to get broken screws out of there. You then sand the entire gun with say an 80 or 120 grit and clean it up with acetone. This gives a good hold for the epoxy and CF sleeve. Then put a sleeve on the front and zip tie one end and then pull the sleeve through. It should nicely contour around your gun shape. Then slowly put epoxy and work it through with your gloved hand(use only very slow cure epoxy). The slow cure epoxy is usually very thin, but you can always use a hair dryer to make sure the epoxy liquifies and wets the CF really well. You then screw in the SS parts over the CF and put a taped up shaft in with shark fins up. Wrap all this with peel ply … then put a release film over the peel ply … and a breather fabric above that to suck up the extra epoxy to keep added weight to a minimum. Once you have all that you put in the vacuum bag and pull out the air. Once cured you just open it up and pull away the peel ply … maybe a very slight sanding of areas that need to be sanded. Peel ply leaves a fantastic finish that really takes the final coats of epoxy really well. To unscrew the SS screws you put a solder iron on each screw until it warms the epoxy and it will come out really easy. If the epoxy is not fully cured the screws will actually come out without heat. I replaced all the screws as it is just a PIA to clean the epoxy from them.

Sounds complicated and it probably is the first time, but after a couple of times it is really very simple and doesn't take up much more work than a normal sanding and epoxy finishing of a normal gun.
Thanks for all the info Majd, i actually called soller and spoke to them. The guy was saying after you put on the sleeve to use heat shrink and cut tiny holes in the heat shrink (for it to get tighter squeeze) after that vacuum bag for about a minute then take the stock out and let it cure...

One question thought when you say screw the SS parts, trigger and muzzle. I'm doing this directly over the CF, so will have cut out the CF and then screw them in like the trigger.. thats the part that concerns me is mounting all the SS back on.

Also im using two sleeves right? one for the the main body of the gun (muzzle to say the trigger ) then a smaller sleeve for the rear where the gun gets really thin correct?

Thanks again for all the info
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Old 10-25-2018, 08:55 AM   #11
eddie1987
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Re: Carbon Wrap

Quote:
Originally Posted by Diving Gecko View Post
Vacuum Bagging on A Budget

Hey Eddie,
I know you are not looking to invest in a pump but indulge me for a min...;-)
Thing is, I think this can be done on the cheap and it will give you a much better result. E.g. a discarded (free!) fridge compressor makes a strong vacuum pump and you might not have to do much to it.
I have one that I use for positive pressure to fill my airguns but it would def work for vacuum also.
The cool thing about rigging a vacuum pump is that you don't have to spend much on fittings and don't have to solder, weld or braze anything in place - there's no positive pressure trying to "explode" your parts. Also, vacuum pressure is maximum -14.5psi or -1 bar whereas positive pressure can go many times higher. This means that in a vac pump setup you can get by with plastic fittings and cheap hoses.
E.g. you could just get a barb hose fitting, a gauge, a three way valve, plumbers tape and some hose and you should be good to go.

One step up from that is a cheap vacuum pump that is often billed as being used for the refrigerator and AC service industry. I think they are used to evacuate the systems of air before filling them with the refrigerant gasses. They come in different sizes - bigger ones evacuate more air (higher CFM) - but they all pull a very, very good vacuum and the smallest version is more than enough for our needs. I'd think you can get one very affordably as many of these are now Chinese made and exported all over.

The latter is what I used in my small vac setup, but I pimped it a bit with a small reservoir and an automatic pressure switch.
A reservoir means that if you do have a leak, the pump doesn't have to cycle that often and the pressure switch takes care of turning it on and off according to the target pressure and hysteresis you have set.

BUT you don't actually need a switch or reservoir or fancy fittings at all. If your bag is not leaking, it's totally OK turning the pump off completely after you've reached the vac pressure you want. The pumps tend to "leak" themselves so you would have to clamp down on the hose in between the pump and the bag. You can do this with a pair of Vise-Grips or even cheaper - just fold the hose back on itself a few times and hold the folds in place with tape. You could also just run the pump continuously until the resin has cured, but you risk killing the pump as they are not really rated for continuous running.

I do recommend buying a proper roll of tacky tape, the thick sealing tape, used for vac bagging. Also, you'd need some perforated release film and if you want to, a bit of vac bag film and breather material. I think you could use kitchen tissue as breather and possible drop film for vac bag - just test that it will release alright.

One note, though. Both the cheap AC service vac pump and a refrigerator pump are oiled. So, ideally, you need a bit of discipline in when you turn the pump on and off. Basically, you don't want a negative pressure pulling oil mist out of your pump and into the bag. I have a one way valve to help with this, but clamping the hose before you turn the pump on, and then releasing the clamp once the pump is at full vac, would do the same.
(Alternatively, if you do want a oil-less pump supposedly many (all?) of the Gast vac pumps are oil-less. They pop up on eBay at very affordable prices pretty often. The service kit for resealing is about USD 40 if needed, though - but you'd have a pro level brand name pump.)

Anyways, if you want to go this way, let me know and I can share more thoughts on how this could be set up.

Sorry, for this long-winded write-up but I do feel a lot of guys get dissuaded by their first few tries at composites and I feel like a vacuum bagging setup would go a very long way to reduce the pains.
I actaully found this cheap vacuum on amazon only $55
https://www.amazon.com/ZENY-Single-S...ds=VACUUM+PUMP

Its a 3.5 CFM single stage mixed reviews but mostly positive, this should be sufficient?
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Old 10-25-2018, 09:06 AM   #12
Diving Gecko
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Re: Carbon Wrap

Quote:
Originally Posted by eddie1987 View Post
I actaully found this cheap vacuum on amazon only $55
https://www.amazon.com/ZENY-Single-S...ds=VACUUM+PUMP

Its a 3.5 CFM single stage mixed reviews but mostly positive, this should be sufficient?
Very much so, this is exactly the type that Mikel and I mentioned - and the type I have. I have the smallest possible one as for our purposes, you really don't need anything else. It's actually also the kind that Easy Composites are re-branding and selling, like they do with a ton of their products and making it sound like it is very high end.
I am curious as to why Soller said only to vac bag for a minute? Sounds a bit odd. I guess, they feel it's just to add some extra compaction to the laminate and then the heat shrink will hold it in place after that. But honestly, if you have a vac bag setup it makes no sense to not just keep it in the bag until the part is fully cured.
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Old 10-26-2018, 03:57 AM   #13
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Re: Carbon Wrap

Quote:
Originally Posted by eddie1987 View Post
Thanks for all the info Majd, i actually called soller and spoke to them. The guy was saying after you put on the sleeve to use heat shrink and cut tiny holes in the heat shrink (for it to get tighter squeeze) after that vacuum bag for about a minute then take the stock out and let it cure...

One question thought when you say screw the SS parts, trigger and muzzle. I'm doing this directly over the CF, so will have cut out the CF and then screw them in like the trigger.. thats the part that concerns me is mounting all the SS back on.

Also im using two sleeves right? one for the the main body of the gun (muzzle to say the trigger ) then a smaller sleeve for the rear where the gun gets really thin correct?

Thanks again for all the info

I tried the heat shrink stuff and to be honest … it just doesn't work for spearguns. Maybe for pipe guns it works, but certainly not for a highly contoured shape that changes quite a bit from muzzle to butt pad like the Abellan. The shrink tape or sleeve simply doesn't shrink enough and you end up burning the tape trying to get it to shrink more … one huge mess! As for the CF sleeve, you only need one size sleeve for the entire gun … the 2.5" sleeve … it will expand and compress by simply pulling it our or pushing it in. You could get a smaller 1.5" or 2" size as well and do the back end alone and then do the final full gun with the 2.5" sleeve.

As for the SS parts, the Abellan is a CNC machined speargun, so there are a lot of little details to get the SS to fit perfect. To get a nice finish and fit with the CF, I found it best to screw in the SS parts so that the CF gets a perfect fit. I would wax the SS (release wax) and then put one layer of electric tape over the SS to make the epoxy clean up easier. I would also make sure I use sacrificial screws or a new set of screws after the epoxy. I like to screw the screws with epoxy as it gets into the screw hole and really seals it well with epoxy and protects this vulnerable area of the wood. For the muzzle area, DO NOT use the thin screws for the muzzle as they will break in the muzzle … just use small screws to just get the shape of the SS on the CF. You can use the long screws when you decide to put the muzzle on permanently … and again I suggest you use brand new high quality screws for these 2 screws as they might weaken when you pull them out. I am putting a lot of emphasis on those two long muzzle screws as I have broken them quite a few times and fixing that took longer than doing the entire CF skin of the gun! The front ballast cavity and the trigger area are really difficult to CF and best is to use plasticine and CF over that and then cut out the CF cavity. For the muzzle front band slot shape … I used the melt plastic pellets to shape and fill the muzzle. You need a right and a left side (not connected) so that you can remove it easy after cure. I find this give a beautifully contoured finish for the muzzle. Remember that you are adding about .3mm of height to your track … so maybe your trigger height needs to be adjusted a tiny bit after. One or two coats of epoxy in the trigger screw holes might be needed, but in all the guns I did it was not needed and I just got a much better fit as the original .5mm gap between trigger mech box top and shaft became .2mm (much better).
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Old 10-26-2018, 04:25 AM   #14
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Re: Carbon Wrap

Good info, Majd! It's cool to have all this in one thread. I had been wondering about the heat shrink and it's great to have been saved the headache of trying it out.
I've mentioned it before - there are a dozen or so Abellans in the Chinese wild by now, and I have a friend whom I think I will help wrap one of his at some point:-)

Anyways, a few more small tricks for the OP:
- Consider applying a very light mist of spray glue (it's been mentioned before) onto the stock just before you "roll" the sleeve on (see next pointer).

- If you use spray glue, then it helps making a very simple tool to help with laying the sleeve and keeping it from sticking to the stock before you want it. Basically, it's just a round thin-walled cylinder just big enough to pass all the way down the stock. E.g. it could be a plastic bottle with both ends cut off or perhaps some PVC pipe. If you have a piece that's long enough for the whole gun stock, you could put the sleeve onto this "applicator tool", put the tool over the gun and then gradually pull the tool out and you will be able to control how much sleeve you lay down at a time. If you don't spray glue the stock you can just pull the sleeve on and fine tune it to no end, really.
Majd - do you roll the sleeve back on itself (like stuffing socks) before you roll it on? Do you use the spray glue?

- Most often sleeves are sold in a quite stretched state, so once you start making it wider, it shrinks longitudinally, so make sure you buy enough and don't cut your sleeves too short! E.g. if you buy one meter and stretch its width so that the fibers run at 45%, you might just have a 70cm long sleeve in front of you. Of course, on slimmer parts, you gain some, but just wanted to mention it.

- Get a slow or medium slow curing epoxy hardener and if you are in a hot climate do the lay up at the end of the day or in a colder room. This way, you don't risk the epoxy going off too fast - and if you do the layup as the temps are dropping, you reduce outgassing from the stock, which may lead to pinholes (the gun builders know this from coating the stocks). On that same note, epoxy is exothermic(?) meaning it heats up by itself and the heat can accelerate the curing way faster than you want. So, if you mix big batches of epoxy, then don't let it sit in a cup - pour it into something with more surface area, like a pot or plate of sorts.
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Old 10-26-2018, 04:53 AM   #15
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Re: Carbon Wrap

Quote:
Originally Posted by Diving Gecko View Post
Can't help this one as you are right about the rest, but plenty of guys manage to get leak free bags, period;-). It's not super easy, but it's certainly not impossible either. Even I have managed


I use stuff bought my resins, vacum bags, tacky tape, breather/peelply/release material, etc here: https://www.castrocompositesshop.com...ging-materials

The three ply material I am talking about is this one: https://www.castrocompositesshop.com...#/153-size-1_m

Totally recommended.

Regarding shutting off the vacum pump... Well. I tried. Tube vacum bag, tacky tape o both ends, etc. I set up a valve right next to the bag on the vacum line. Barb fittings and hose clamps. Tight.

When you have a good vacum the breather material gets translucent, showing that it is beeing squeezed against the object and absorbing excess resin. Well, as soon as I closed the valve (and shut off the pump), the breather material lost it's translucent-ness... to me it was an indicator that some air was getting in and I was loosing vacum. Could be through the seams in the tacky tape joints (most likely), or through the valve (unlikely) or barb fittings (unlikely as well).

I didn't feel comfortable with it and decided to leave it on.

Probably once it has gelled enough, you can shut it off no problem. As easy as leaving a leftover in a cup as a sample to check periodically how much it has cured. Keep in mind that resin in a pot gells faster than when spread out (increase in temperature due to the exothermic nature of the curing process)

Peel ply gives a nice texture. Some people like it as is to get a mate finish. I think it helps to mechanically bond the top coat if you aim for mechanical adhesion. I try my best to apply the topcoat when the previous layer is not fully cured (tacky) so you can still take advantage of the chemical bond (stronger)

Mikel
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