---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Sat 10/03/20: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:16 AM - Re: W20 Bracket spec (John Wighton) 2. 01:56 AM - Re: W20 Bracket spec (D McFadyean) 3. 08:22 AM - Re: W20 Bracket spec (JonathanMilbank) 4. 10:10 AM - How much to sand for filler (n7188u) 5. 10:25 AM - Re: How much to sand for filler (n7188u) 6. 12:55 PM - Re: How much to sand for filler (timward) 7. 06:38 PM - Re: W20 Bracket spec (William Daniell) ________________________________ Message 1 _____________________________________ Time: 01:16:38 AM PST US Subject: Europa-List: Re: W20 Bracket spec From: "John Wighton" Use a minimum of 6061 T6, probably 2024 T3 will be readily available and gives slightly higher UTS. -------- John Wighton Europa XS trigear G-IPOD Read this topic online here: http://forums.matronics.com/viewtopic.php?p=498636#498636 ________________________________ Message 2 _____________________________________ Time: 01:56:48 AM PST US From: D McFadyean Subject: Re: Europa-List: W20 Bracket spec H30, I believe. But why not ask the Factory what they use now? Duncan McF. > On 02 October 2020 at 00:30 Brian Phillips wrote: > > > I am currently attaching the port flap to the wing on my trigear, I > find, for whatever reason, that the W20 bracket is too short by 12mm > when the flap is in its correct position. Rather than live with this > mismatch at the bolted joint, I will make up a new longer W20 bracket. > Does anyone know what grade and temper these aluminium brackets are made > from? > > Brian > Sydney, Aus. > ________________________________ Message 3 _____________________________________ Time: 08:22:03 AM PST US Subject: Europa-List: Re: W20 Bracket spec From: "JonathanMilbank" It's now 25 years since I built my Classic wings with the foam cores and I honestly can't remember the finer details, but are all the W20 brackets on each wing the same size, or are they made progressively smaller from inboard to outboard? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=498638#498638 ________________________________ Message 4 _____________________________________ Time: 10:10:03 AM PST US Subject: Europa-List: How much to sand for filler From: "n7188u" Dear forum members, I always had a question, never having a chance to see in person a properly done sample of how much you should sand a control surface layup before applying filler to the control surfaces. If you lightly scuff the surface with 80 grit all you get is minute dullness at the crest of the layup fiber bundles. I would say not even 10-20% scuffed. If you go more then you are indeed cutting through the fibers. but my understanding is that anything that is still glossy provides basically zero bonding strength. So what is that magical point at which you stop sanding and it is sufficient bonding for the filer. BTW, one time I spoke with a gentleman that happened to run the R&D department at Lancair during the certification of the Columbia 300. He told me they did extensive testing on how much to sand before a structural bond. He indicated that the highest structural strength with bonded components would be achieved by doing very detailed cleaning and then just using scuff pads to lightly scuff the surface. The resulting bonded structure was stronger than cleaning and sanding with coarse sandpaper until all surfaces are dull. Now, he explained we are not talking about the bond strength. He explained that what they tested is for the overall strength of the bonded structure and his explanation is that using coarse sandpaper damages the substrate layups and overall you end up with a weaker structure. Then he added they still ended up scuffing until dull in production because the FAA would not accept that just using scuff pads and ending with a surface that still looks glossy would be OK despite all the testing. I found the story interesting. Best regards, Chris Read this topic online here: http://forums.matronics.com/viewtopic.php?p=498640#498640 ________________________________ Message 5 _____________________________________ Time: 10:25:15 AM PST US Subject: Europa-List: Re: How much to sand for filler From: "n7188u" BTW, Rutan wrote in his booklet "Moldless Composite Homebuilt Sandwich Aircraft Construction" that if you wait until the epoxy fully cures "you will have to sand the fiberglass surface to a dull finish" Hence a lifetime of confusion for me. when we discuss this can we estimate how much dullness you want in terms of % of dull surface? Best, Chris Read this topic online here: http://forums.matronics.com/viewtopic.php?p=498641#498641 ________________________________ Message 6 _____________________________________ Time: 12:55:57 PM PST US Subject: Re: Europa-List: How much to sand for filler From: timward Hi Chris, My Air New Zealand painter who painted my aircraft Boeing White, said to go down to 180 grit only. Finer will cause a lack of bonding for the paint. Tim Sent from my iPad Tim Ward 12 Waiwetu Street, Fendalton, CHRISTCHURCH. NZ 8052 ward.t@xtra.co.nz 021 0640221 > On 4/10/2020, at 6:21 AM, n7188u wrote: > > > Dear forum members, > > I always had a question, never having a chance to see in person a properly done sample of how much you should sand a control surface layup before applying filler to the control surfaces. > > If you lightly scuff the surface with 80 grit all you get is minute dullness at the crest of the layup fiber bundles. I would say not even 10-20% scuffed. If you go more then you are indeed cutting through the fibers. but my understanding is that anything that is still glossy provides basically zero bonding strength. > > So what is that magical point at which you stop sanding and it is sufficient bonding for the filer. > > BTW, one time I spoke with a gentleman that happened to run the R&D department at Lancair during the certification of the Columbia 300. He told me they did extensive testing on how much to sand before a structural bond. He indicated that the highest structural strength with bonded components would be achieved by doing very detailed cleaning and then just using scuff pads to lightly scuff the surface. The resulting bonded structure was stronger than cleaning and sanding with coarse sandpaper until all surfaces are dull. Now, he explained we are not talking about the bond strength. He explained that what they tested is for the overall strength of the bonded structure and his explanation is that using coarse sandpaper damages the substrate layups and overall you end up with a weaker structure. Then he added they still ended up scuffing until dull in production because the FAA would not accept that just using scuff pads and ending with a surface that still looks glossy would be ! > OK despite all the testing. > > I found the story interesting. > > Best regards, > Chris > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=498640#498640 > > > > > > > > > ________________________________ Message 7 _____________________________________ Time: 06:38:23 PM PST US From: William Daniell Subject: Re: Europa-List: W20 Bracket spec Brian It looks to me as thought the lower surface of the flap is not aligned with the lower surface of the wing...or is it just how it looks in the photo? Will William Daniell LONGPORT +57 310 295 0744 On Thu, Oct 1, 2020, 19:49 Brian Phillips wrote: > > I am currently attaching the port flap to the wing on my trigear, I > find, for whatever reason, that the W20 bracket is too short by 12mm > when the flap is in its correct position. Rather than live with this > mismatch at the bolted joint, I will make up a new longer W20 bracket. > Does anyone know what grade and temper these aluminium brackets are made > from? > > Brian > Sydney, Aus. > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message europa-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Europa-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/europa-list Browse Digests http://www.matronics.com/digest/europa-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.