Former Member Posted February 2, 2016 Share Posted February 2, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 3, 2016 Author Share Posted February 3, 2016 A few examples of wire benders there & I'm sure it gives a few ideas how to knock one up from bits in the shed. Speaking of sheds, not much time spent in mine tonight due to babysitting my kids. (I'm told by my wife that it's not babysitting when it's your own kids but I disagree!) Vicky was out visiting her Dad in hospital and then a committee meeting for the pre-school so I had to pick up the daughter from Brownies and be nice to her! Buttering her up for getting a doll off her! But I managed to get out around 10pm to do a bit more. First off though, for John, along with a new foamie from HobbyKing I recieved this today. Just over £2, quite rough in the moulding but damn that blade's sharp! Not sure how long it'll last but cuts just fine, in fact probably better than a new blade in a scalpel as it isn't dragged along the material to be cut so doesn't pull the fibres. Especially nice with glass cloth! Putting that to one side for later I got on with sanding the lumps off the cowl. It looks quite smooth but a quick scuff with sandpaper in a sponge block soon shows up the high spots. And bubbles that turn into dimples when sanded! After the cowl was completely sanded flat it was given a final smooth coat of resin and left to harden. Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 3, 2016 Author Share Posted February 3, 2016 After a coffee it was time for the fun part! The resin was hard enough not to be tacky so I made a start on removing the foam plug from inside the cowl. A small opening, about 2" was cut into the packing tape at the rear of the cowl and a McDonalds ketchup pot of petrol slowly dribbled over it. I use petrol because for some reason acetone has no effect on this pink foam! As the foam is eaten away I could start to get more and more petrol into the hole without it spilling out You can just see where the petrol has started seeping between the foam and packing tape Now it starts getting cool! About 50ml of petrol later... Just standing there watching it go! Finally the remaining pieces are small enough to grab with long nosed pliers and remove through the small opening, leaving the packing tape inside the cowl. And because the polyester resin won't stick to the plastic packing tape it starts to separate on it's own! Finally after easing the packing tape "bag" from inside the cowl and wiping it dry it can be tested on the nose. The moment of truth! The outside of the cowl is now pretty much smooth and the wrinkles you can see are on the inside. At this point it's quite fragile and bendy and the next step is to line the inside with more cloth and resin. I have done it this way around this time to try to reduce the amount of sanding and smoothing required after each coat on the outside of the cowl. Edited By Chris Barlow on 03/02/2016 01:34:04 Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted February 3, 2016 Share Posted February 3, 2016 You know some of those pictures look like something really revolting. The cowl looks good though Quote Link to comment Share on other sites More sharing options...
Martyn K Posted February 3, 2016 Share Posted February 3, 2016 That cowl is great - I agree. Mine will be a slightly different approach Martyn Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 3, 2016 Share Posted February 3, 2016 I've ordered my film n servos and forgot the cutter A few questions because I've never moulded a cowl, I thought you had to add extra layers within a certain time or is just roughing up good enough ? is there any danger of distortion when you start laying up inside the cowl because it creates heat and what about cleaning of the petrol ? just soapy water ? Looks good so far though John Quote Link to comment Share on other sites More sharing options...
kc Posted February 3, 2016 Share Posted February 3, 2016 My wire bender is just the same as Peter's except that it's not fixed to a bench but to a block of 4x 2 timber which can be clamped in the vice. ( suitable ends of 4x2 are thrown away all the time by builders ) Just as with the wire bender I think the fibreglass cowl sequence needs it's own thread so that anyone can find it in future. It's a magnificent example of how-to-do-it - thanks Chris. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted February 3, 2016 Share Posted February 3, 2016 I agree. What we need is for these Geniuses to write articles describing their techniques and have them uploaded into a MasterClass Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 3, 2016 Share Posted February 3, 2016 Posted by Martyn K on 03/02/2016 13:23:19: I agree. What we need is for these Geniuses to write articles describing their techniques and have them uploaded into a MasterClass Well you said you where doing a cowl Martyn, so start the ball rolling John Quote Link to comment Share on other sites More sharing options...
Martyn K Posted February 3, 2016 Share Posted February 3, 2016 I would but mine isn't going to be F/G (or balsa for that matter).. Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 3, 2016 Author Share Posted February 3, 2016 P osted by Peter Miller on 03/02/2016 08:20:27: You know some of those pictures look like something really revolting. The cowl looks good though This is my favourite! Looks like fresh brains! lol Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 3, 2016 Author Share Posted February 3, 2016 Posted by john stones 1 on 03/02/2016 12:19:03: I've ordered my film n servos and forgot the cutter A few questions because I've never moulded a cowl, I thought you had to add extra layers within a certain time or is just roughing up good enough ? is there any danger of distortion when you start laying up inside the cowl because it creates heat and what about cleaning of the petrol ? just soapy water ? Looks good so far though John There is a time period where the curing resin is giving off a lot of gasses and fumes which can effect the bond and finish of an overlying layer but generally as long as it's hard and cooled down it should be OK. Extra layers can be added any time in the future but as with any adhesive the substrate must be clean, dry and free of any contaminations. Scuffing the cured GF just provides a mechanical key to help the next layer bond to it. With only 2 layers of cloth and the fact that the top layer has been sanded this cowl is still very thin and flexible and will bend and crack if handled roughly. The heat during curing won't be a problem as long as the cowl isn't supported in a stressed or twisted position. What can cause a problem is if the resin isn't mixed thoroughly and one area of the cowl cures faster than another. Simple answer is to mix the resin thoroughly and only use one batch at a time! Most of the petrol (or acetone, depending which is used) is contained inside the packing tape "bag" removed at the end. There shouldn't be too much left as the petrol is added as it's needed so must of it should be in the goo! Any that escapes onto the cured resin will make it tacky again and must be washed of with water or just a wet cloth. To be certain the cowl could be rinsed in a bucket of water but don't do it in the kitchen sink for safety reasons! Have a go with it John. You'll soon be making cowls, wheel spats, undercarriages etc! Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 3, 2016 Author Share Posted February 3, 2016 Posted by kc on 03/02/2016 13:12:18: Just as with the wire bender I think the fibreglass cowl sequence needs it's own thread so that anyone can find it in future. It's a magnificent example of how-to-do-it - thanks Chris. I read about lost foam GF moulding when I was about 15 and had a go but only really succeeded in making a lumpy cowl and a lot of mess! Years later I spotted Peter Garsdens build blog for his PSS lost foam Tornado and decided to have another go for my Super Cub Cowl. Peter is at it again with another lost foam project, a slope soaring Jart L so there's plenty of threads on lost foam moulding already! Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 3, 2016 Author Share Posted February 3, 2016 Posted by Martyn K on 03/02/2016 13:23:19: I agree. What we need is for these Geniuses to write articles describing their techniques and have them uploaded into a MasterClass I'd be a genius if I could figure out a way to make money from it! I just learn a lot, either from other people of from experience! Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 3, 2016 Share Posted February 3, 2016 It's why I'm asking questions Chris I intend to thanks for answers. John Quote Link to comment Share on other sites More sharing options...
AndyD Posted February 3, 2016 Share Posted February 3, 2016 it would make a good advert for giving up smoking,better than the telly ad. Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 6, 2016 Author Share Posted February 6, 2016 Been busy over the last couple of days with babysitting and parents evenings at school so not much progress on the Ballerina. Just a few final bits making the cowl. A layer of cloth on the inside to increase the strength and some re-inforcing with glass tissue in a few areas i.e the chin, bottom of the cowl and rear opening where it will be screwed to the fuselage You don't want to use a lot of the tissue as it absorbs a lot of resin and is very heavy. It also becomes much harder and stronger than the cloth so I only use it where I need it! Tissue on the left & cloth on the right. Whilst the cowl was still transparent I marked the bulkhead position, exhaust header, rocker cover and glow plug positions and cut them out with a circular disk in a Dremel. I added 15mm to the bulkhead marks so the cowl will overlap the fuselage. You can also see the re-inforcing ban through the cowl. Remote glow plug marked and drilled, first with a 5mm drill the opened up with a tapered reamer to prevent the GF from tearing. The nose was also opened up for the prop shaft and cooling slot for the engine. Finally holes made for the low and high speed needles, drilled first with a 3mm drill bit, cowl fitted and positions checked, then opened up with a tapered reamer. The 3mm holes can be adjusted with the reamer by applying more pressure on one side when reaming the holes. Next photo shows the slots at the sides of the fuselage for engine cooling Total weight before paint is 41g and now looks like this when fitted Now for some wet & dry sanding, filler and primer! Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted February 6, 2016 Share Posted February 6, 2016 so when do you start taking orders for the glass cowls then Chris? Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 6, 2016 Share Posted February 6, 2016 That's a cracking job Chris Now you've got to somehow find a colour match though, so how you doing that, piece of covering taken for a paint match ? John Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 6, 2016 Author Share Posted February 6, 2016 A few options there John. As the dark green covering is Solarfilm I could use their paint range which is supposed to match. I could get a colour match by taking a sample to be scanned. I could paint it a contrasting cowl colour like silver or black or I could still use film over the primer, that doesn't sound easy! I might try covering it with film and if it doesn't work I can still paint it! Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 6, 2016 Share Posted February 6, 2016 3rd ones cheating. John Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 6, 2016 Author Share Posted February 6, 2016 Posted by Bob Cotsford on 06/02/2016 10:14:44: so when do you start taking orders for the glass cowls then Chris? £85 each! Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 12, 2016 Author Share Posted February 12, 2016 Posted by john stones 1 on 06/02/2016 13:32:10: 3rd ones cheating. John But very tempting! I had a bit of a go at covering it with film, more of an experiment but it didn't go so well! Even cutting a few intricate shapes in the film and careful planning how I was going to get around the compound curves I still had a few creases and the joints were a bit visable. So that idea has been scrapped, the cowl cleaned and some Solarlac dark green paint ordered! Meanwhile it has been 5 days since my last update and to be honest for 3 of them I've not done anything! The cowl has been sanded with 400g wet and dry and minor dimples filled with P38 car body filler, and sanded again ready for primer. The cockpit and boots have been sealed and painted on the inside too. That should help prevent the ply from rotting from all the mud they're going to collect! I've also added the cockpit coaming. This was done using one of my favourite model materials, the chamois leather cloth! I like it because it's very stretchy and supple and will conform to most shapes. It also smells great! I cut a strip of the cloth long enough to go all the way around the cockpit opening and about 20mm wide. This was coated with contact adhesive as was a 5mm band on the inside and outside of the cockpit opening. When the glue was dry to the touch one edge of the cloth was attached to the outside edge of the cockpit, keeping it a constant 5mm. A length of fuel tubing was placed around the cockpit and the cloth folded over and bonded to the band of adhesive on the intside of the cockpit. Because the fuel tuning is thicker than the balsa it forms a nice rolled edge. I also made a head rest by shaping a piece of 3/8 balsa and wrapping it with the cloth, bonded with contact adhesive again. The cloth is so stretchy it's easy to get a creaseless wrap around the curves of the head rest. The cloth was then trimmed back flush with the back of the head rest. This was then glued on to the back of the cockpit. The chamois leather takes paint easily and when painted takes on a stiffer, more leathery texture. Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted February 12, 2016 Author Share Posted February 12, 2016 Today I had a couple of new arrivals. Firstly, the ali spinner, which lines up nicely with the cowl and is quite pointy! And Beatrice, the Ballerina pilot! My daughter was quite pleased I wanted to use one of her dolls in my aeroplane untill she asked how it was going to fit inside the cockpit. "Her legs won't fit in" she said to which I foolishly replied "that's OK, I don't need her legs. I'm going to cut her off at the waist and glue her in" Needless to say the offer was rapidly rescinded and a visit to Ebay required! I have also fitted the wind shield to protect Bea's makeup! I cut a template from thin card after a bit of head scratching and tried it in position, trimming as I went until I had a shape that followed the edge of the coaming. The shape of the template was then transferred to a sheet of clear plastic and cut with scissors. I didn't get a photo of the shape before fitting it so have taken a photo of the removed protective backing! This was initially pinned in position with a couple of M2 nuts and bolts in the corners... the front edge was sealed with car bodywork fine line vinyl masking tape then superphatic glue was run between the screen and the cockpit coamimg. The masking tape prevents the glue from escaping! The glue has been left to set over night. Beatrice looks happy with it! Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted February 12, 2016 Share Posted February 12, 2016 That is a very, very smart cockpit. I do have some rubber cockpit surround that I use, nt got a lot left though. AS a tip. Dolls house companies sell super fine leather, not cheap but one doesn't use a lot. Quote Link to comment Share on other sites More sharing options...
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