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Old 01-30-2023, 11:29 AM
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Sakrison Sakrison is offline
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Bulkhead-to-Bulkhead vs. Joiner Strips

Many aircraft kits (and others) call for the fuselage sections to be joined "bulkhead to bulkhead." Like a lot of paper modelers, I don't like that method, and I don't trust it to create smooth, good-looking joints.

I make my own joiner strips by laying the fuselage part flat on a piece of scrap card and tracing the edge with a pencil, then cutting the strip about 1/8 inch either side of the pencil mark. I attach the strip to the section with the larger diameter, insert the floor (if needed) and bulkhead, and join the fuselage sections. And I always dry-fit the parts before gluing them to ensure a good fit.

In my experience, that forms a smoother joint than bulkhead-to-bulkhead, and it reduces the number of parts that need to be laminated and cut from heavy card.
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Bulkhead-to-Bulkhead vs. Joiner Strips-bulkheads-vs-joiner-strips.jpg  
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Old 01-30-2023, 12:42 PM
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Generally, I agree that joiner strips create seams that are smoother and cleaner, but….

My only real experience with a bulkhead-to-bulkhead assembly has been Ken West’s X-15A-2; I’ve built three, in 1/32nd and 1/48th. I quickly found the key was to get the bulkhead sized PERFECTLY and to make sure the adjoining bulkheads are EXACTLY the same size and shape.

The process usually involves cutting, fitting, trimming, fitting, sanding, etc. If the bulkhead is even slightly oversized (even fractions of a millimeter) it’ll “flare” the end of the model piece. Once that happens, you’re in trouble because you can’t shrink the opening back to its proper size.

Once I got Ken’s bulkhead’s to fit perfectly and glued them in, I then sanded the ends on fine-grit sandpaper to get them perfectly flat. When that was done, they fit together smoothly.
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Old 01-30-2023, 12:46 PM
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I use this methodology, too.

Thanks for these recent tutorials, which are very helpful.

Don
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Old 01-31-2023, 11:16 PM
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Sakrison Sakrison is offline
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Quote:
Originally Posted by dhanners View Post
Generally, I agree that joiner strips create seams that are smoother and cleaner, but….

My only real experience with a bulkhead-to-bulkhead assembly has been Ken West’s X-15A-2; I’ve built three, in 1/32nd and 1/48th. I quickly found the key was to get the bulkhead sized PERFECTLY and to make sure the adjoining bulkheads are EXACTLY the same size and shape.

The process usually involves cutting, fitting, trimming, fitting, sanding, etc. If the bulkhead is even slightly oversized (even fractions of a millimeter) it’ll “flare” the end of the model piece. Once that happens, you’re in trouble because you can’t shrink the opening back to its proper size.

Once I got Ken’s bulkhead’s to fit perfectly and glued them in, I then sanded the ends on fine-grit sandpaper to get them perfectly flat. When that was done, they fit together smoothly.
No question, either method can produce a good-looking model. Thank you, dhanners, for sharing your technique.
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Old 01-31-2023, 11:48 PM
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Thanks for the tip.
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Old 02-01-2023, 07:29 AM
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Nice discussion but in my opinion is that EVERY AIRCRAFT SHOULD HAVE STRUCTURAL FORMERS, no matter if it is with connecting strips or former against former. It is incredible that some models, such as Fiddlers Green and some Murphs models, have no formers with extremely complex fuselages like the PBY Catalina. I just can't understand why some designers get lazy after designing the model and develop no internal formers, let alone some precise and clear building instructions. I say this with all due respect.
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Old 02-01-2023, 09:33 AM
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Quote:
Originally Posted by Petestein View Post
Nice discussion but in my opinion is that EVERY AIRCRAFT SHOULD HAVE STRUCTURAL FORMERS, no matter if it is with connecting strips or former against former. It is incredible that some models, such as Fiddlers Green and some Murphs models, have no formers with extremely complex fuselages like the PBY Catalina. I just can't understand why some designers get lazy after designing the model and develop no internal formers, let alone some precise and clear building instructions. I say this with all due respect.

Broadly agree. I've had to write messages to designers asking how things are meant to go together, which way is up, etc. However, I know from experience that on even the best designed models the designer can never predict the exact thickness of the paper and thus the diameter of the former, with sub-milimeter tolerances being below the print resolution and thus the builder should always expect to have to trim formers. The other argument against complex 'skeletons' is the difficulty of getting fingers and tweezers in there to press glue joins together.


Anyway here's my solution to bulkhead joins: I glue the bulkheads together first, trim, then insert them into one of the skin sections so that the 'peg' can be perfectly fitted into the adjoining one. I do prefer glue tabs, but the bulkhead-to-bulkhead method makes sense for joining sub-assembles where you can't get tweezers in to press the join.
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Old 02-01-2023, 10:34 AM
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it is frustrating to find a model with great artwork but no formers and no instructions.
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Old 02-01-2023, 08:18 PM
Petestein Petestein is offline
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[QUOTE=Siwi;779381]Broadly agree. I've had to write messages to designers asking how things are meant to go together, which way is up, etc. However, I know from experience that on even the best designed models the designer can never predict the exact thickness of the paper and thus the diameter of the former, with sub-milimeter tolerances being below the print resolution and thus the builder should always expect to have to trim formers. The other argument against complex 'skeletons' is the difficulty of getting fingers and tweezers in there to press glue joins together.


I agree with you 100%. BUT you mention models WITH formers. Paper can also shrink and other factors which sometimes make former fitting not easy BUT FORMERS ARE THERE, one can sand them to perfect fit. Not difficult. Check, for example, the GELI, WHM and Schreiber aircraft, all with formers and are a real pleasure assembling them.
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Old 02-01-2023, 08:19 PM
Petestein Petestein is offline
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Quote:
Originally Posted by Sakrison View Post
it is frustrating to find a model with great artwork but no formers and no instructions.
I can't agree with you more. I prefer not to mention some brands or guys who design beautiful aircraft, extremely precise and accurate but trying to build them is a pain in the neck, only guesswork which is very frustrating.
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