dave665 Posted June 16, 2017 Share Posted June 16, 2017 Peter, Are the defects across the canopy or just on the front half? I'm wondering if the plug now has too sharp an angle where you have removed the windshield. Could your problems be with the shape of the plug around the canopy. Is it interfering with the smooth pulling of the sheet as the vacuum is applied? Dave 1 Link to comment Share on other sites More sharing options...
cati Posted June 16, 2017 Share Posted June 16, 2017 Try talking to roymatt on the cars topic. He or a friend pulls 1/8th car bodies etc in vacform so might be able to offer advice. 1 Link to comment Share on other sites More sharing options...
DMC Posted June 17, 2017 Share Posted June 17, 2017 Hi Peter, I am really out of my depth here with this calibre of modelling but I've done a little plunge and vacuum forming over the past year or so and have had good test results using baked clay moulds and styrene and PETG products from this supplier: http://www.stationroadbaseboards.co.uk/cart_plastic.htm He offers quality products, reasonable prices and quick service. The PETG is a product of Bayer MaterialScience and comes in .020 A4 sheets. Might be worth a try. I use clay (Sculpey) for my moulds because it can be baked and re-baked several times and can be polished to a very smooth finish without the use of filler or primer. Not for everyone, however. Cheers, Dennis 1 Link to comment Share on other sites More sharing options...
hairystick Posted June 17, 2017 Share Posted June 17, 2017 On 6/16/2017 at 7:37 AM, Pastor Rich said: Dunno, but the first person who comes to mind in the scratch build community who works on higher end processed and materials is Paul Budzik (http://paulbudzik.com/). He is a dentist by trade and uses a lot of medical tools and techniques in his approach to modeling. Just a thought. He is a member on this site too. http://www.britmodeller.com/forums/index.php?/profile/1058-paul-budzik/ 1 Link to comment Share on other sites More sharing options...
dave665 Posted June 17, 2017 Share Posted June 17, 2017 (edited) Peter, Could the small "bubbles" you've described simply be a dust problem? I believe petg sheet can be a bit of a dust magnet due to static. Especially after you have removed the protective film on it. Dave Thought... not sure if this would work... but try very gently heating one of your failed canopies with a heat gun. Heating the surface may help smooth out these bubbles. Equally it could melt the whole canopy if you over do it! Edited June 17, 2017 by dave665 1 Link to comment Share on other sites More sharing options...
airscale Posted June 17, 2017 Author Share Posted June 17, 2017 Hi folks Thanks for all the kind words of encouragement - I certainly need a lift as this is turning into an epic struggle (Man vs Plastic...) I was in a Dominos Pizza place the other night and noticed on their menu it said there were more possible combinations than there were people on earth.. I am reminded of that every time I try and vacform a canopy with all the different methods, tricks, gotchas and variables.. I have used all my PETG again still without success but have learned a lot on the way.. I also wonder if it is actully possible to vacform a canopy to the same clarity the sheet starts out at, but anyway I keep trying.. I have three kinds of defects: Bubbles - I know these are moisture and have managed to reduce to about 3 - 5 (from 50 or so) by reducing the temperature - this is an impossible balance between hot enough to form, but cool enough to avoid bubbles Patches - turns out these are trapped air and only occured with a super smooth polished plug/mould - bit like sticking a sticker and getting a bubble in the middle - the air has nowhere to go so it is a microscopic raised area which causes optical occlusions.. Wavyness - this I think is because the plug is now microscopically rough to allow the air to escape (dry sanded at 600 grade) I have tried plunge moulding - fail with bubbles and it didn't pull in and take the form properly, I tried a 20 thou white card vacform as a base on the master as said on a forum - fail it deformed & caused trapped air patches, I tried sanding & polishing - fail, the bubbles are in the plastic, I tried all manner of temperatures, grills, ovens and now have this dental tool for £95 off ebay (arrived in 3 days well impressed).. it has definately got potential as it works perfectly in terms of forming - it is just the material & outcome that is letting me down.. I have ordered more PETG from another supplier and m speaking with John Wilkes from Tigger vacforms tomorrow about helping me out - I have also emailed MDC and HpH in the hope of maybe doing a resin one as a commision.. by the time I am done the canopy will have cost the same as the rest of the bloody model.. ..in other news - i did try to keep my mojo going by doing the tailwheel doors - I had to remove the tailwheel well roof and move it deeper into the fuselage which was a horrible job with a dremel cutter right next to lots of lovely finished skin panels, but it worked out ok.. ..I also needed to make the tailwheel doors - seen here in one of Tony's lovely pics - note the tiny fairing at the bottom which I assume covers the very bottom of the wheel when retracted.. ..sketched out the door outline after embossing the fairing into the sheet first using a bit of plastic card with the female shape dremmeled out of it.. this is my last bit of 'good' litho that takes wire wool without turning red or blue so is very precious ..cut out the door shapes.. rivetted.. ..and shaped & started to add the internal framing.. ..thats it for now - I will sort the canopy one way or another, but jeez its the one bit of any build that ALWAYS causes me problems.. TTFN Peter 14 Link to comment Share on other sites More sharing options...
Gondor44 Posted June 17, 2017 Share Posted June 17, 2017 I am hoping that once you crack the canopy problem you will never worry about it again. It's been a very steep learning curve but I am sure you will get the high quality result you are after. Gondor 1 Link to comment Share on other sites More sharing options...
dave665 Posted June 17, 2017 Share Posted June 17, 2017 Looks like you're making progress with the new vacform machine. 4 hours ago, airscale said: it has definately got potential as it works perfectly in terms of forming - it is just the material & outcome that is letting me down.. What was wrong with this canopy? Is it just that there are bubbles in the plastic? These are not just caused by moisture, you could be boiling the stabilisers out of the PETG sheet. You may be getting it too hot and too quickly. Let's hope your new supply of PETG won't have these problems. Dave 2 Link to comment Share on other sites More sharing options...
Pastor Rich Posted June 18, 2017 Share Posted June 18, 2017 Hi Peter, Perhaps try 400 grit sandpaper on your master with an eye on making a way for air bubbles to escape once you get your new PETG stock. It sounds like you are making progress and getting closer. But much more of this and you'll have to charge a subscription rate to follow this show! Maybe you can use the new found knowledge and tools to produce limited run products on demand via Airscale? Thank you for illustrating the tailwheel door construction so well! They are brilliant in their own right!! PR 1 Link to comment Share on other sites More sharing options...
hairystick Posted June 18, 2017 Share Posted June 18, 2017 Is there any improvement if it is "flamed"? A gas torch with a gentle flame can be used on certain plastics to improve them. Very gently moving the heat around at a distance, getting closer to the surface as needed. The edges of acrylic sheet which have been cut, can be "sealed" back up this way too. 1 Link to comment Share on other sites More sharing options...
dave665 Posted June 19, 2017 Share Posted June 19, 2017 (edited) On 2017-6-17 at 19:50, airscale said: I tried a 20 thou white card vacform as a base on the master as said on a forum I would say that 20 thou would be too thin a cover over the mould. You probably need 60 thou styrene to cope with the heat from 40 thou PETG. Alternatively you could glue the styrene to the mould. But I don't think you need to go down that route now that you have a resin mould. You probably just need to tweak things now. It does sounds like you are overheating the sheet. Try less heat for longer, increase the gap between the element and the sheet. The waviness and patches may be due to the sheet grabbing the undercut at the front edge of the canopy. It may be worth raising the back end of canopy and adding more draft at the front end to support the sheet more evenly as it is pulled by the vacuum. Found this vacuum forming guide (pdf) on Plastimach. Similar content to the guide by Formech on Paul Budzik's page. Dave Edited June 19, 2017 by dave665 1 Link to comment Share on other sites More sharing options...
CedB Posted June 20, 2017 Share Posted June 20, 2017 I hope you get the help you need on the canopy Peter and that it doesn't become your 'Moby Dick' (other forms of... no, stop it!) I don't think that having this done as a commission would detract from all the other amazing work you've done and, if it avoids you thinking "it's great apart from the canopy" then it will be money well spent. You can't be a master at everything surely? (In your case I'm not sure about that, actually) The tailwheel doors are, as usual, spectacular - amazing stuff 1 Link to comment Share on other sites More sharing options...
Pastor Rich Posted June 20, 2017 Share Posted June 20, 2017 Peter, One observation: Canopies on real aircraft are NOT crystal clear. They have distortions and deformities and even cloudiness. Some photos I see make me wonder how a pilot can see out! Yet once inside, the plex is usually clear to the crew and all is well. It seems a matter of perspective. I dare say that you are learning what Alexander Graham Bell felt like as he experimented time and time again to invent the electric light bulb. Your work won't change the world like the light bulb, but it surely does influence your peers to think more and more outside the box and engage in the process. That makes this space known as Britmodeller a better place. No matter the outcome of a given attempt, we are blessed to witness the triumphs and falls. No matter what, you have my admiration and thanks! PR 4 Link to comment Share on other sites More sharing options...
lunarhighway Posted June 21, 2017 Share Posted June 21, 2017 I agree with Pastor Rich, sometimes we attempt to make our models more perfect than reality, however the true quest is to make all imperfections in our models, intended or not, look like scaled down representations of real scratches and dents. I recently found plastic canopies can be sanded to the point where they're barely transparent and look rather ruined and subsequently using sequentially finer grits of sand paper (i use cheap nail care sponges of ebay) can be sanded and polished back to an immaculate shine also i find vacuum forming clear parts is a bit of hit and miss and provided you have enough material, it's best to make multiple attempts and pick the best ones. but once again, a very inspirational build! 1 Link to comment Share on other sites More sharing options...
CedB Posted June 21, 2017 Share Posted June 21, 2017 Seconding lunarhighway, only I use a Micro-mesh polishing kit. 1 Link to comment Share on other sites More sharing options...
hendie Posted June 21, 2017 Share Posted June 21, 2017 maybe take a look at this post... Jaguar Canopy 1 Link to comment Share on other sites More sharing options...
HOUSTON Posted June 21, 2017 Share Posted June 21, 2017 PHENOMENAL WORK. INSPIRATIONAL work indeed Peter. 1 Link to comment Share on other sites More sharing options...
airscale Posted June 26, 2017 Author Share Posted June 26, 2017 evening folks finally I am happy to report I have what I think is a working pull for the canopy lots of tries, and lots of fails, but I now have one which has one tiny bubble in a pretty remote spot and manageable imperfections - it is still not as good as you might see on the packaging for a BIC razor, but then I do not have a vacuum room to work in, ionised air supply, metal moulds or industrial kit... essentially, most of the problems are heat related - there is a very fine line between success and failure, and most different supplies of PETG exhibited similar issues - eventually I found a sweet spot on the vacform rig where a slower, lower exposure to the heat element gave a good enough result.# there is still some polishing work to do, but at least I can now start to build the frame.. ..it's not perfect, but finally it's good enough for me to carry on.. thanks for all the advice & support - its one of the things that make this place a great place to hang out TTFN Peter 20 Link to comment Share on other sites More sharing options...
neil5208 Posted June 26, 2017 Share Posted June 26, 2017 Congratulations, a very impressive result for all the effort 1 Link to comment Share on other sites More sharing options...
Max Headroom Posted June 26, 2017 Share Posted June 26, 2017 I'm glad you pulled it off. I know, I know, I'm getting my coat. Trevor (excellent result btw. Can't wait for the next instalment) 3 Link to comment Share on other sites More sharing options...
Pastor Rich Posted June 27, 2017 Share Posted June 27, 2017 A TRIUMPHANT DAY!!! TNZ wins at the America's Cup and you finally get a good pull to the canopy! Don't worry about "perfection" Peter. There is only One builder who is perfect. What you are building is artistry! That's why I enjoy following your work and feel blessed to be learning as you go. Congratulations Team New Zealand on your BIG win over Team Oracle. Congratulations Peter on a BRILLIANT OUTCOME for your canopy!!! HUZZAH!!! 1 Link to comment Share on other sites More sharing options...
hairystick Posted June 27, 2017 Share Posted June 27, 2017 22 hours ago, Pastor Rich said: A TRIUMPHANT DAY!!! TNZ wins at the America's Cup and you finally get a good pull to the canopy! Don't worry about "perfection" Peter. There is only One builder who is perfect. What you are building is artistry! That's why I enjoy following your work and feel blessed to be learning as you go. Congratulations Team New Zealand on your BIG win over Team Oracle. Like wise! That is a lovely canopy and wherever the "imperfection" is, I can't see it. A great win for TNZ! Especially as the boat was delaminating and slowly falling apart... Now, back to proper boats and none of this catamaran nonsense! 2 Link to comment Share on other sites More sharing options...
Pritch Posted June 27, 2017 Share Posted June 27, 2017 (edited) I think you're right about the problem being heat-related. That's why professionally produced vacform kits and canopies are produced with moulds made of resin mixed with aluminium powder. It has something of the heat-conduction property of metal moulds without the cost. Tony Edited June 27, 2017 by Pritch 1 Link to comment Share on other sites More sharing options...
Nigel Heath Posted June 27, 2017 Share Posted June 27, 2017 Looks perfect to me. 1 Link to comment Share on other sites More sharing options...
Ex-FAAWAFU Posted June 27, 2017 Share Posted June 27, 2017 6 hours ago, Pastor Rich said: Congratulations Team New Zealand on your BIG win over Team Oracle. Congratulations Peter on a BRILLIANT OUTCOME for your canopy!!! I'm confused. You mean Peter has been producing vacform parts for a 1/1 America's Cup boat? 4 Link to comment Share on other sites More sharing options...
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