wallyinoz Posted January 23, 2017 Share Posted January 23, 2017 Mashing the Bison together got my vacuform juices going... I have 2 vacuform kits left, models I really want in my cabinet - a Comet IV and a Britannia both in 1/72. (I bought both of these in the last 6 months) I pulled the Comet out and my mega big wet sanding board to sand the parts down to size, after a couple of hours of this I figured I would cut the Britannia out and sand that back as well seeing's I had the board out! I guess about 6 hours work to here, now I am going to have to think, build both at same time or one at a time? if one at a time which one first? I am gonna have to toss a coin. 12 Link to comment Share on other sites More sharing options...
stringbag Posted January 23, 2017 Share Posted January 23, 2017 Got me a front row seat for this one Wally. Good luck with them both Chris. Link to comment Share on other sites More sharing options...
wallyinoz Posted January 26, 2017 Author Share Posted January 26, 2017 Hiya Chris I hope you wont be disappointed! I have progressed with the Britannia fuselage, look, I am not declaring I am a fine modeller or expert or anything like that but as a few people have expressed interest in vac form projects I am putting in a bit of stuff that I have learned and maybe useful to others.. so number one,I like my vacform fuselages to be as strong as a baseball bat (slight exaggeration, rigid and strong will do) to this end I make bulkheads and position them strategically inside the fuselage I put in a box structure at the wing centre section to mount wing spars for a strong no-sag wing / fuselage joint. I used to make the ribs out of balsa and used epoxy but now I cut out plastic discs.. much much easier but for this need essential tools: a shape form thingamujig and a circle cutter. I dont know about you lot but I often find with many kits that the bulkheads often dont fit very well inside the fuselage sometimes you have to sand them down to close up the fuselage sides or sometimes they dont meet the other side.. not much of a problem with injected kits but big problem with vacforms. This may very well be due to my modelling ineptitude but I developed a "cheat" that helps me solve this problem. When the bulkheads are in and ready to join the fuselage halves I apply paint on the bulkhead edges push the halves together and see if and where the bulkheads touch the inside of the other fuselage half. If the joining surface area is not satisfactory I make what I call floating bulkheads.. a picture tells a thousand words: After making these I position the floating bulkheads in their frames (no glue yet), press the two fuselage halves together causing the floating bulkhead to slide in the frame and give a perfect gluing surface area, pull the halves apart run liquid cement in the frames and the floating bulkheads are now locked into the perfect position. Next liberal application of Tamiya liquid cement on the bulkhead edges and on the interior of the other fuselage half, push the halves together and tape up: After that has dried I use a paint brush to run loads of Tamiya extra thin cement down the seam which has been reinforced with interior doublers and tabs, I do a about 6 inches at a time to try and get the best joint possible.. for me it is never perfect I always require filler, (that is the nature of vacforms and the inept I am afraid) After doing this I put a steel edge on the fuselage top and saw that I had a little bump behing the cockpit where the bulkhead I made was as pushing the skin about 1 mm too high, I ran a saw down that section of seam (dremel with circular saw fitting) grinding a bit here and a bit there till the bulge disappeared. Now I am left with a little less than an inch long gap, I filled this with semi liquid dissolved plastic which I make with plastic shards and GP thinners, apply this to any gap the plastic welds itself together, sand and you wont know there was a joint there.. and it is as strong as continuous plastic 15 Link to comment Share on other sites More sharing options...
Bell209 Posted January 26, 2017 Share Posted January 26, 2017 You are an artist, Wal! Link to comment Share on other sites More sharing options...
Beard Posted January 26, 2017 Share Posted January 26, 2017 I've never done a vac-form, I have enough trouble with mainstream injected kits, but one day I will and this will come in useful so, I'm going to be following your progress. Link to comment Share on other sites More sharing options...
Niles Posted January 26, 2017 Share Posted January 26, 2017 59 minutes ago, wallyinoz said: I dont know about you lot but I often find with many kits that the bulkheads often dont fit very well inside the fuselage sometimes you have to sand them down to close up the fuselage sides or sometimes they dont meet the other side.. not much of a problem with injected kits but big problem with vacforms. This may very well be due to my modelling ineptitude but I developed a "cheat" that helps me solve this problem. When the bulkheads are in and ready to join the fuselage halves I apply paint on the bulkhead edges push the halves together and see if and where the bulkheads touch the inside of the other fuselage half. I wouldn't call it a cheat. You've discovered a fundamental technique that those of us who have to make two surfaces fit flush together frequently use. I'm a piano technician/rebuilder and when I'm making a new pinblock for a piano it's necessary to make the front of the pinblock fit precisely against the flange on the piano's cast iron frame that supports it. I use colored chalk rather than paint, which I smear all over the flange and tap the pinblock against it. The chalk transferred to the front of the pinblock tells me where I have to plane or file or grind it down. It's an iterative process taking several hours, but it's quite effective in producing the exact fit that is necessary for the piano to have tuning stability. Your floating bulkhead trick is very clever. I'll remember that and likely use it. 4 Link to comment Share on other sites More sharing options...
Niles Posted January 26, 2017 Share Posted January 26, 2017 1 hour ago, wallyinoz said: I filled this with semi liquid dissolved plastic which I make with plastic shards and GP thinners, apply this to any gap the plastic welds itself together, sand and you wont know there was a joint there.. and it is as strong as continuous plastic Yes, good thinking. I got the same idea about a year ago and chop up and dissolve the old sprues from kits in the industrial thinner that they sell now as a substitute for MEK. It's not as tidy to use as other fillers like auto body glazing putty and takes longer to cure, but it's the same material as the kit and is self bonding and welds everything together. Like you say it ends up like there never was a joint there. I call it "styrogoop". 1 Link to comment Share on other sites More sharing options...
wallyinoz Posted January 26, 2017 Author Share Posted January 26, 2017 15 minutes ago, Niles said: Yes, good thinking. I got the same idea about a year ago and chop up and dissolve the old sprues from kits in the industrial thinner that they sell now as a substitute for MEK. It's not as tidy to use as other fillers like auto body glazing putty and takes longer to cure, but it's the same material as the kit and is self bonding and welds everything together. Like you say it ends up like there never was a joint there. I call it "styrogoop". styrogoop it is! make a wikipedia entry! 1 Link to comment Share on other sites More sharing options...
Brandy Posted January 26, 2017 Share Posted January 26, 2017 Great thinking on the fuselage joints! I've used the chalk/marker/paint and press together to see where it touches idea, but the floating bulkheads is brilliant! I'll make a note of that one.... I had a dear friend, unfortunately no longer with us, who was on the Comet test pilot team along with John Cunningham (the two trained together pre war and were long-time friends even then). He also flew as Flight Engineer on the first Comet commercial flight to South Africa. He swore that the structural failures where not just because of square window apertures, but because the ADF aerial was added above the 4th window in a place where it was not designed to be, and the structure wasn't sufficient to have a hole there! Ian 4 Link to comment Share on other sites More sharing options...
stringbag Posted January 26, 2017 Share Posted January 26, 2017 1 hour ago, limeypilot said: but the floating bulkheads is brilliant! I'll make a note of that one.... Me too. Cracking idea. Thanks Wally Chris. Link to comment Share on other sites More sharing options...
wallyinoz Posted January 26, 2017 Author Share Posted January 26, 2017 10 hours ago, Bell209 said: You are an artist, Wal! butcher more like! 1 Link to comment Share on other sites More sharing options...
ROBOT Posted January 26, 2017 Share Posted January 26, 2017 watching with great interest, I' m in for a masterclass Session in vacform building !!! Thanks wally Link to comment Share on other sites More sharing options...
Covjets13 Posted January 26, 2017 Share Posted January 26, 2017 You gotta love a vac project, lovin the progress so far. Si Link to comment Share on other sites More sharing options...
aircraftkit Posted January 26, 2017 Share Posted January 26, 2017 Will be following this thread with interest ! Don Link to comment Share on other sites More sharing options...
Pete in Lincs Posted January 26, 2017 Share Posted January 26, 2017 Damn the popcorn, I've ordered pizza! 1 Link to comment Share on other sites More sharing options...
Hewy Posted January 26, 2017 Share Posted January 26, 2017 I want to build my first vac form kit this year ,haven't got one yet but I'm browsing ideas. I'll tag along and pick up some tips , like it so far, Glynn Link to comment Share on other sites More sharing options...
corsaircorp Posted January 26, 2017 Share Posted January 26, 2017 Hello, I saw Bison, and my heart was pounding hard, what ?? a Blackburn Bison ?? I must buy it, I really like this UUUUH flying machine. But sigh sigh It was not this wonderfull piece of british engineering but a russian counterpart. Very nice job , thank for sharing and inspiring for my own vacu's Corsaircorp Link to comment Share on other sites More sharing options...
wallyinoz Posted January 27, 2017 Author Share Posted January 27, 2017 Hello vacuous followers (chortle , chortle) work progresses, difficulties abound eg: 1. this is the first vac form model I have built where the engine nacelles are separate units and not molded as part of the wing, this is good the shapes achieved are much better this way but it it does make a lot of work..each nacelle has to be treated like a separate mini fuselage. 2. with the inner nacelle slid onto the wing at the correct position the propeller would strike the fuselage (reciting the vacuform refrains under one's breath).. how to deal with this? the only viable option is to clip the prop blades 3. the main undercarriage mount will be in the wing, lucky I haven't glued the halves together yet! again I think these pics will save a thousand words: I am going to try and get some larger diameter brass tube for the exhausts the inner nacelles need to have their u/c doors cut out, then I have to build 3 more! 6 Link to comment Share on other sites More sharing options...
frankie Posted January 27, 2017 Share Posted January 27, 2017 Link to comment Share on other sites More sharing options...
wallyinoz Posted January 27, 2017 Author Share Posted January 27, 2017 Well it has taken all day (actually i did watch a bit of netflix.. I got so fed up with all the fettling!) but I have managed to build 2 nacelles and dry fitted them to the port wing, like I mentioned a lot of fettling was required to get them on. port wing and nacelles dryfit by wallycacsabre, on Flickr Now I have to do the starboard wing, fill the back of each nacelle with apoxie sculpt so I can shape and mount the jet pipe and exhaust, I'll have to shovel the bog in through the wing cutouts. The wings spars have to be shaved down from 12 mm to 8 mm to fit inside the wing (they are not glued in yet) Some useful tools that need a mention.. my trusty dremel and my multishape photo etch saw blades, these are worth their weight in gold. tools by wallycacsabre, on Flickr 4 Link to comment Share on other sites More sharing options...
aircraftkit Posted January 27, 2017 Share Posted January 27, 2017 Coming along nicely, Wal ! Don Link to comment Share on other sites More sharing options...
Brandy Posted January 27, 2017 Share Posted January 27, 2017 (edited) Lovely job so far! For the exhausts, could you use thin walled brass or plastic tube, squashed slightly flat, then cut the top off to the correct shape, and let the piece into the rear of the nacelle after removing the section your black arrow is pointing to? It should give you a nice thin edge and a good even curve.....just a thought. Ian Edited January 27, 2017 by limeypilot Link to comment Share on other sites More sharing options...
wallyinoz Posted January 27, 2017 Author Share Posted January 27, 2017 hi Ian, yes that is what I have done with the aerofoil shaped tubing ...pictures above.. unfortunately not quite enough diameter so off to the model shop tomorrow to get something bigger..as well as extra plastic card.. going through acres of it recently! Link to comment Share on other sites More sharing options...
stringbag Posted January 27, 2017 Share Posted January 27, 2017 27 minutes ago, wallyinoz said: hi Ian, yes that is what I have done with the aerofoil shaped tubing ...pictures above.. unfortunately not quite enough diameter so off to the model shop tomorrow to get something bigger..as well as extra plastic card.. going through acres of it recently! Hi Wally. Have a look at some aluminium tube as opposed to brass. It is much easier to manipulate and shape to form the exhaust outlet and you should be able to get the thin walled tube which will replicate the original more effectively. I found brass tube to be too thick for the job. Aluminium iseasy to cut as well by rolling back and to with a knife blade in the required position and you can get the round tube instead of the aerofoil section which will be easier yo alter to the oval shape. Chris. Link to comment Share on other sites More sharing options...
AdrianMF Posted January 27, 2017 Share Posted January 27, 2017 All good stuff here - starting to look like an aeroplane already! Regards, Adrian Link to comment Share on other sites More sharing options...
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