Brodhead Pietenpol Association

Original Posted By: "Greg Cardinal"
I began cutting steel last night and I made my first Cabane fittings that willgo on the Fuse to hold the center Cabanes onto the fuselage. Drilled the holeswith a borrowed MicroLux mill so it is all accurate down to the .001 (sure makesit easy to just turn a crank handle ever so many turns to dial in a measurement!)I have been reading Tony B's chapter on fittings and have a few questions:He mentions having NO scratches on the steel, and to keep the edges of the steelrather sharp. I rounded the edges of the flat stock with the grinder. I hateto sound naive, but I am with steel: is rounded edges on the straps a problem?Polishing the faces of the steel: I bought a grinder that has 2 wheels- a roughand a fine wheel. BUT, the wheels are about 3/4" wide, and so I have used theside of the wheels to grind the round edges, otherwise I would get a series of3/4" marks all down the side, and would not be smooth or consistant. So, whatdo you use to polish the FACE of the part to prep it for the Zinc paint? I gotsome very small marks in the steel from filing the edges off of the holes Idrilled, so I'd like to polish them out. Nothing deep, just the standard scratchesin the face of the steel when you run a file over it.Also, when fitting these to the fuselage, I am assuming the 2 holes that are drilledin the fuse to mount these fittings (again, to hold the center cabanes tothe fuse) are drilled as such: the first hole at the bottom of the fitting isdrilled through the side strut leading to the top longeron, and the second holethrough the center line of the side of the top longeron. Is this correct?How far up should the 1/4" hole be above the top longeron to safely fit the cabanestrut?I am comfortable with the wood, but haven't found my sea legs yet with the steel.However, I DO have 8 new fittings that look pretty good, I just need to figurehow smooth to make them without over doing it!Thanks for the help. I feel these questions are a bit juvenile, but they causedme some angst last night whilst trying to fall asleep!MarkRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________

Original Posted By: "Mark Roberts"
Rounded edges on the steel fittings is no problem.Polish them using a Scotchbrite wheel on your grinder. It is especially important to polish the edges before you do any bending.When drilling holes use an undersized twist drill and use a reamer for final hole sizing.Greg Cardinal----- Original Message -----

Original Posted By: Ryan M

Original Posted By: "Mark Roberts"
Mark,You mention polishing, then mention you have a grinder with a fine and coarse wheel...Several things come to mind here. First, a "grinder" is a nebulous term. Youhave a grinder motor (?) with a couple of grinding wheels on it most likely. Those wheels, coarse and fine, 3/4" wide, are most likely aluminum oxide wheels.They are good for actually shaping parts you are making, as well as "polishing"to the extent of maybe removing saw marks (hack saw, contour saw, horizmetal cutting saw, etc) from the edges of parts before you polish them.In the big scheme of things, those things are pretty coarse and generally leavea scratch pattern deep enough to create stress risers. Which is how they canshape metal. Things that polish, for the most part, don't change the shape ofthe metal significantly. So, what Greg mentions is a "scotchbrite" wheel. It'll look quite like the wheelson your "grinder", but it's made of a propietary stuff that really is justa fine abrasive that will take out grinder marks. Probably not quite aggressiveenough to take out most saw marks. Does that make sense?Those scotchbrite wheels are about a hundred bucks, though they'll last for a dozenor so piets... You would mount it on your grinder, which is why I call "grinders"nebulous, because once you do that, it's kind of a polisher, ya know?Really, it's just a motor, what it does depends on what you have mounted onit.A quick safety note. Those gray aluminum oxide wheels aren't really meant to beused on the sides, though about everyone does. Just be careful and don't puta lot of pressure when using the sides. You can also use sanders to do the polishing you need for these metal fittings.They're called sanders because the most common use for them is to mount a beltof sandpaper and sand wood. However, you can get "sandpaper" in all sortsof configurations. Stuff specifically made to withstand the harshness of "sanding"metal, sufficiently fine, will do the same polishing as the scotchbritewheel. Sufficiently coarse, will shape metal easily.The most common sanders for this sort of thing is a little benchtop sander thatuses 1"x30" or 1"x42" belts, or one that uses a 4"x36" or 4"x48" belt, or onesthat use various sized discs. Aluminum oxide sanding belts are generally used for woodworking (and are reddish)but will work. Better (and more expensive) are blue ones made of ZirconiumOxide. Coarse ones are good enough to shape metal, really fine ones do a grandjob of polishing out saw marks and deep scratches left by the coarser belts(or grinding wheels).Google a company called Klingspor, or "the sanding company" for some great infoon sanding products. So, generally, and for a quick efficient job, it's a couple of steps. Cut outthe part (with some sort of saw). Do further shaping (files, grinders or coarsesanding belts). Use the same gizmo you used for "further shaping" to get rideof really coarse saw marks (or milling machine marks, whatever). Then usefine products (belts, scotchbrite wheels, or even really fine files) to justget rid of any obvious easily visible scratches.Keep in mind how you use any given method of sanding, or grinding (which are alsomerely methods of cutting) matters. A coarse medium applied randomly, willproduce a smoother surface, hence the effectiveness of random orbit (or dualaction) sanders. Although it's a bit deceiving. The size of the particle doingthe cutting really is the governing factor. But when applied randomly, therearen't really any long deep straight scratches. Pay close attention when you use a file. When used one way, there's an obviousscratch pattern left behind (bad for stress risers and eventual cracks), butused another way (as in drawfiling) a smooth surface is left behind. The goal of all of this is to NOT leave behind a scratch pattern that is conduciveto metal cracking with exposure to vibration (or while bending).If you keep that in mind, it makes more sense.Read this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Steel Fittings and Prep questions

Original Posted By:> Mark Roberts
Not yet, but I'll take some. I don't have it connected to any stepper motors touse it as a CNC, but I am thinking about it. Wouldn't be too hard... But, forjust boring holes in a straight line, I am 'counting the turns' manually! :DI'll post some soon...aircamperace(at)yahoo.com wrote:> Mark do you have any pics of the MicroLux in action?> > > Ryan> >

Original Posted By: "Mark Roberts"
Wow! Thanks guys for the good replies. I am doing some further research on theScotch-Brite wheels mentioned and there appears to be a series of them. Not tobeat a dead horse, as I bet all of them would work well, but do you have anyidea which might e better at this on 4130 than perhaps another? Here are a coupleof links on amazon:http://www.amazon.com/Scotch-Brite-Mult ... ndust_3and finally:http://www.amazon.com/Scotch-Brite-Debu ... dust_3Read this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Steel Fittings and Prep questions

Original Posted By: "Billy McCaskill"
BTW, Thanks Tools for the very detailed help... I am off to look for stuff at http://www.klingspor.com/(Always wondered where the Klingons came from... This being the 46th anniversaryof Star Trek)Read this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Steel Fittings and Prep questions

Original Posted By:> n0kkj(at)yahoo.com
J...F...C... Tools=2C write a book or something . . . . > Subject: Pietenpol-List: Re: Steel Fittings and Prep questions

Original Posted By: "Mark Roberts"
Hey guys, slightly off topic, but I am really impressed and grateful to be a partof this list.... Let me BRIEFLY (I tend to ramble) explain:Looked for years to decided what to build. Didn't look at the support groups orlists like this to determine what to build, but I should have. I have a linkdirectly to this list that I use to log in. Tonight I had to log on via the forums.matronics.comsite and navigate to this group. On the way I slowly scrolledthrough the main page of groups to see what other groups are active. I hadNO idea that this group was far away the most active and helpful! Have you guysseen the difference in the amount of posts here versus the other popular builds?I was very surprised and very pleased.You know, it could be somewhat intimidating to see how much this forum is read,but you guys make it so comfortable to ask a question, and are so supportiveand non-cliquish that I haven't thought about asking a question or two. I'd liketo again say thanks for the help.So I'll be ordering a scotch-brite wheel soon. But until then, I sure appreciatethe advice and moral support. I hope I can afford a Brodhead trip next year!MarkRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Steel Fittings and Prep questions

Original Posted By: JOSEPH SWITHIN
Quick follow up on the first post question that I didn't see addressed is placementof the drilled holes for the cabana fittings:Also, when fitting these to the fuselage, I am assuming the 2 holes that are drilledin the fuse to mount these fittings (again, to hold the center cabanes tothe fuse) are drilled as such: the first hole at the bottom of the fitting isdrilled through the side strut leading to the top longeron, and the second holethrough the center line of the side of the top longeron. Is this correct?How far up should the 1/4" hole be above the top longeron to safely fit the cabanestrut?Thanks again.MarkRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Sun, 9 Sep 2012 04:48:02 -0700 (PDT)

Original Posted By: "Mark Roberts"
Oh yea; here's another;7. did Graham build in any dihedral or washout? Thanks; PaulRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Steel Fittings and Prep questions

Original Posted By: "Chris"
Thanks Tools!Read this topic online here:http://forums.matronics.com/viewtopic.p ... __________

Original Posted By: "tools"
An exception I can think of is if you're making wood struts or something and designedthose fittings differently than original and need the hole a little furtheraway from the longeron or something. Also, there's a BUNCH of fittings on the plans for brace wiring where the holereally isn't far enough away from the fuse to allow putting in the clevis pinin the correct orientation (ie from the top) or easily. Knowing this ahead oftime and making them a tad longer (sometimes as little as a 1/4") would makea world of difference.Read this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Steel Fittings and Prep questions

Original Posted By: Ryan Mueller
kevinpurtee wrote:> When you take your hand drill and use a technique called "wallering" to get thebolts to go through...Man ain't this the truth! In all fairness, will probably have to "waller" a bitless though. waller (n. wall-er latin) 1. art of making bolts fit close tolerance holes sp. wallo, wallos, wallamos, wallas, wallanIs it too late to get this in the Tony B. glossary of homebuilding terms?Read this topic online here:http://forums.matronics.com/viewtopic.p ... __________

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Actually when I was working at General Dynamics, I learned that the correctterminology is to "Obligate" the hole, so that it's obligated to accept thebolt.Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Check out the RV-10 list sometime. What a bunch of whiners!Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----

Original Posted By: johnwoods(at)westnet.com.au

Original Posted By: "Chris"
Hey guys, slightly off topic, but I am really impressed and grateful to be a partof this list.... Let me BRIEFLY (I tend to ramble) explain:Looked for years to decided what to build. Didn't look at the support groups orlists like this to determine what to build, but I should have. I have a linkdirectly to this list that I use to log in. Tonight I had to log on via the forums.matronics.comsite and navigate to this group. On the way I slowly scrolledthrough the main page of groups to see what other groups are active. I hadNO idea that this group was far away the most active and helpful! Have you guysseen the difference in the amount of posts here versus the other popular builds?I was very surprised and very pleased.You know, it could be somewhat intimidating to see how much this forum is read,but you guys make it so comfortable to ask a question, and are so supportiveand non-cliquish that I haven't thought about asking a question or two. I'd liketo again say thanks for the help.So I'll be ordering a scotch-brite wheel soon. But until then, I sure appreciatethe advice and moral support. I hope I can afford a Brodhead trip next year!MarkRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________

Original Posted By: JOSEPH SWITHIN
I vote for this one!I bet they used it on sailing ships when thegronicle just refused to fit the binnicle gimp.ClifThe Early Bird may get the worm but the secondmouse gets the cheese.>> Actually when I was working at General Dynamics, I learned that the > correct> terminology is to "Obligate" the hole, so that it's obligated to accept > the> bolt.>> Jack Phillips> NX899JP> Smith Mountain Lake, Virginia________________________________________________________________________________Date: Mon, 10 Sep 2012 05:40:52 -0700 (PDT)

Original Posted By: "Mark Roberts"
> To: pietenpol-list(at)matronics.com> > > Mark=2C> > You mention polishing=2C then mention you have a grinder with a fine and coarse wheel... > > Several things come to mind here. First=2C a "grinder" is a nebulous term. You have a grinder motor (?) with a couple of grinding wheels on it most likely. Those wheels=2C coarse and fine=2C 3/4" wide=2C are most likely aluminum oxide wheels. They are good for actually shaping parts you are making=2C as well as "polishing" to the extent of maybe removing saw marks (hack saw=2C contour saw=2C horiz metal cutting saw=2C etc) from the edges of parts before you polish them.> > In the big scheme of things=2C those things are pretty coarse and generally leave a scratch pattern deep enough to create stress risers. Which is how they can shape metal. Things that polish=2C for the most part=2C don't change the shape of the metal significantly. > > So=2C what Greg mentions is a "scotchbrite" wheel. It'll look quite like the wheels on your "grinder"=2C but it's made of a propietary stuff that really is just a fine abrasive that will take out grinder marks. Probably not quite aggressive enough to take out most saw marks. Does that make sense?> > Those scotchbrite wheels are about a hundred bucks=2C though they'll last for a dozen or so piets... You would mount it on your grinder=2C which is why I call "grinders" nebulous=2C because once you do that=2C it's kind of a polisher=2C ya know? Really=2C it's just a motor=2C what it does depends on what you have mounted on it.> > A quick safety note. Those gray aluminum oxide wheels aren't really meant to be used on the sides=2C though about everyone does. Just be careful and don't put a lot of pressure when using the sides. > > You can also use sanders to do the polishing you need for these metal fittings. They're called sanders because the most common use for them is to mount a belt of sandpaper and sand wood. However=2C you can get "sandpaper" in all sorts of configurations. Stuff specifically made to withstand the harshness of "sanding" metal=2C sufficiently fine=2C will do the same polishing as the scotchbrite wheel. Sufficiently coarse=2C will shape metal easily.> > The most common sanders for this sort of thing is a little benchtop sander that uses 1"x30" or 1"x42" belts=2C or one that uses a 4"x36" or 4"x48" belt=2C or ones that use various sized discs. > > Aluminum oxide sanding belts are generally used for woodworking (and are reddish) but will work. Better (and more expensive) are blue ones made of Zirconium Oxide. Coarse ones are good enough to shape metal=2C really fine ones do a grand job of polishing out saw marks and deep scratches left by the coarser belts (or grinding wheels).> > Google a company called Klingspor=2C or "the sanding company" for some great info on sanding products. > > So=2C generally=2C and for a quick efficient job=2C it's a couple of steps. Cut out the part (with some sort of saw). Do further shaping (files=2C grinders or coarse sanding belts). Use the same gizmo you used for "further shaping" to get ride of really coarse saw marks (or milling machine marks=2C whatever). Then use fine products (belts=2C scotchbrite wheels=2C or even really fine files) to just get rid of any obvious easily visible scratches.> > Keep in mind how you use any given method of sanding=2C or grinding (which are also merely methods of cutting) matters. A coarse medium applied randomly=2C will produce a smoother surface=2C hence the effectiveness of random orbit (or dual action) sanders. Although it's a bit deceiving. The size of the particle doing the cutting really is the governing factor. But when applied randomly=2C there aren't really any long deep straight scratches. > > Pay close attention when you use a file. When used one way=2C there's an obvious scratch pattern left behind (bad for stress risers and eventual cracks)=2C but used another way (as in drawfiling) a smooth surface is left behind. > > The goal of all of this is to NOT leave behind a scratch pattern that is conducive to metal cracking with exposure to vibration (or while bending).> > If you keep that in mind=2C it makes more sense.> > > > > Read this topic online here:> > http://forums.matronics.com/viewtopic.p ... 688#382688> > > > > > > ============================================> > > ________________________________________________________________________________Subject: Pietenpol-List: Re: Steel Fittings and Prep questions