Joining Halves
10-24-2005 | 02:06 PM
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From: Swindon, UNITED KINGDOM
Joining Halves
Hi,
Up until now I have used tape or tow to join in the mould or in the case of smaller items that dont need the strength a bead of Hysol 4962 then clamp the haves together. I have noticed on a number of fuselages over the years that tape is not being used so obviously there must be an overlap of some sort, how much? Anyone have a user friendly method for this?
Up until now I have used tape or tow to join in the mould or in the case of smaller items that dont need the strength a bead of Hysol 4962 then clamp the haves together. I have noticed on a number of fuselages over the years that tape is not being used so obviously there must be an overlap of some sort, how much? Anyone have a user friendly method for this?
10-24-2005 | 02:58 PM
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RE: Joining Halves
Mikg,
Joining in the mold is time consuming but makes for a very strong/straight fuselage. I use both methods, both the overlap and the tape. Honestly, you end up with fewer voids in the seamline using the tape. The problem with the overlap (1/2 inch top of one mold side and 1/2 inch the bottom of the second mold size) is that even though you roll the built in seam down, it tends to pull the first layers away from the seam line. If you first trim both sides evenly, (after the epoxy has a good tack) and then make sure ALL of the seam line is correctly seated, and then join and roll a stripe of the saturated tape down it, I have found you end up with very few voids. The real trick here is the timing.. as in how tacky is tacky??? and being extremely careful not to pull away the preceeding layers of glass from the seam line. Only issue here is that you are indeed adding weight for no good reason. I have found this to be the most challenging part of laying up fuselages. If anyone has a fool proof/no void method I would certainly like to know about it..... I have found that experience is the best teacher here.
Good Luck,
Dan
Carolina Custom Aircraft
Joining in the mold is time consuming but makes for a very strong/straight fuselage. I use both methods, both the overlap and the tape. Honestly, you end up with fewer voids in the seamline using the tape. The problem with the overlap (1/2 inch top of one mold side and 1/2 inch the bottom of the second mold size) is that even though you roll the built in seam down, it tends to pull the first layers away from the seam line. If you first trim both sides evenly, (after the epoxy has a good tack) and then make sure ALL of the seam line is correctly seated, and then join and roll a stripe of the saturated tape down it, I have found you end up with very few voids. The real trick here is the timing.. as in how tacky is tacky??? and being extremely careful not to pull away the preceeding layers of glass from the seam line. Only issue here is that you are indeed adding weight for no good reason. I have found this to be the most challenging part of laying up fuselages. If anyone has a fool proof/no void method I would certainly like to know about it..... I have found that experience is the best teacher here.
Good Luck,
Dan
Carolina Custom Aircraft
10-24-2005 | 05:13 PM
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From: Swindon, UNITED KINGDOM
RE: Joining Halves
Hi,
Thanks Dan, you've pretty much expounded why I havent used this method, just thought it looks much neater, interesting you use tape wetted, I ease into place dry then wet and roll using purpose made tools, I suppose it what you personally get best results with that counts. Mike
Thanks Dan, you've pretty much expounded why I havent used this method, just thought it looks much neater, interesting you use tape wetted, I ease into place dry then wet and roll using purpose made tools, I suppose it what you personally get best results with that counts. Mike
10-24-2005 | 06:13 PM
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RE: Joining Halves
The goof-proof way to make overlapped (tapeless) seams is to use a removable joggle-gasket so that the overlap flaps are actually molded in. This is a level of complication that most modelers don't want to deal with.
Short of making these special mold pieces, you can still do the overlap method but it takes a lot of practice and details of the molds can make a large difference in how tough the job is. For example, if you have straight mold locating pins (like 3/16" music wire), then it can be nearly impossible. It's much easier if you have tapered locating pins (like hemispheres as an example), so you can bring the two sides together at an angle. The flaps are much less likely to catch and hang up on things this way. A picture would be worth a thousand words here, so I'll steal a diagram from the R&G user guide (http://www.r-g.de/):
Short of making these special mold pieces, you can still do the overlap method but it takes a lot of practice and details of the molds can make a large difference in how tough the job is. For example, if you have straight mold locating pins (like 3/16" music wire), then it can be nearly impossible. It's much easier if you have tapered locating pins (like hemispheres as an example), so you can bring the two sides together at an angle. The flaps are much less likely to catch and hang up on things this way. A picture would be worth a thousand words here, so I'll steal a diagram from the R&G user guide (http://www.r-g.de/):
