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Building tips and hints
The same questions keep coming up on the forum so it might be helpful to post your builders tips. Tell us about any homemade jigs or tools. And if you have the courage, tell us about your errors and how you corrected them.Potential construction pitfalls.
While building the Kitfox, I noted a few areas that can lead to problems later in construction, and a few areas that could have been a lot easier with just a little clarity.
I’m sure others have some great tips, so jump in here and share them with those about to embark on the journey.
There are so many things to cover it is not possible to put them all in a single post. Instead, I’ll add to it every few days or so. I hope you'll do the same.
Installing elevator bushings--- Reaming the elevator bushing sockets is tough. You can get the reamer in position but there is no room for a chuck handle. You’ll need a small wrench to turn it. That is a bit awkward. Try using a 1/4 inch drive ratchet with a square drive socket on the reamer. A short extension with a U-joint will give you room to turn the reamer and it will avoid turning the reamer in reverse. (Turning a reamer backwards will quickly dull it.) Some of my bushings were oversize and would not fit in the reamed holes. Put a sacrificial nut and bolt through the bushing and chuck it in a drill press. Hold a file against the bushing as it spins to reduce the size. To press the bushings in the stab sockets use a C clamp. Do not beat on the bushings with a mallet.
To drill out the 3/16 inch (0,187”) holes in the elevator and many of the fuselage tabs get a 24 inch long drill bit at Home Depot found in the electrical section. You can reach into spots not possible with a regular drill bit and motor. You can even flex the bit to drill around slight bends. The long drill bit is about $5 and invaluable for those hard to reach spots.
General tips on Hysol – Cheap veterinarian syringes make good applicators for Hysol. They can be purchased at most farm and ranch supply stores for about 50 cents each. They come in several sizes. The best ones for gluing are the type that use press on needles. The screw-on needle type nozzle is too wide to get in tight spots. To allow the thick Hysol to flow through the nozzle better, drill the tip to a larger opening. I buy 10 or so at a time and drill all the tips at once. Load the syringe using Popsicle sticks. To make nice looking fillets use a plastic soda straw dipped in denatured alcohol to smooth out the adhesive. Note on Hysol: Keep the lid closed as much as possible. The white colored part will granulate if exposed to air for extended periods.
Bonding preparation – Do not skip this step or your bonds may fail. Scrub all areas to be bonded with a Scotchbrite pad and clean with denatured alcohol. Especially clean and scrub powder coated items.
Flox or Micro balloons? What's the difference? -- Both thicken up the Hysol so it doesn't run or sag during application. Flox does not appreciably reduce the strength. Micro balloons add air and do reduce the strength. So use flox for strength where the glue might sag or run. Use micro balloons to make "Bondo."
Coming soon.... those $%^&* rudder torque tubes and how to deal with them.
John Pitkin
Greenville, TX
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Re: Building tips and hints
Great tips !!!!
Regarding the elevator bushing bearing stock. I cut mine to lenth and then put them in the freezer overnight. This makes them shrink and toughen up enough to allow them to be tapped into the metal bushing housings (I filed one end of the busings to bit of a point to help the process). Once, installed, I bored them out using a 12 inch flex-o-shaft on my drill. Drill bits with a 1/4" hex socket fit on the end of the shaft and lets me drill the bushings out to size.
Hope this helps
Roger
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When trimming fiberglass, stretch a line of blue masking tape along the scribe line. It’s easy to see and you can sand to the taped line after the rough cut is made. This works well on the seat pan, cowling, glare shield, windshield.
It's especially helpful when laying out curved cut lines like the cowling flange.
JP
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Those #@$%^& rudder torque tubes. --
The rudder torque tubes are quality products. Recent improvements have added gussets to prevent failures. However, getting them to fit and rotate smoothly can be a problem.
The tubes fit together fine until you add the bushings. Then things start to bind. Check the tubes for straightness. Also use a rod on the inside of the outer tube to check for welding sags or bumps.
A long rat tail file can help smooth the internal bumps. Some builders have reported success with a wooden dowel wrapped with sandpaper.
One of my torque tubes was badly warped. I finally stripped the powder coating and heated the weldment with a torch to straighten it.
spend some time on the torque tubes to get them perfect. Any drag on the assembly will be worse when you load it up with foot pressures.
John Pitkin
Greenville,TX
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Walking around the fuselage to get hardware from stock can require hundreds of trips. Why not bring the stock room to you?
I made this rolling parts bin from two wall shelving units bolted back to back. They are from Harbor Freight and set me back about $60 each on sale. I added a plywood top with fiddles to keep things from rolling off the top. On the bottom I attached four swiveling casters, also from Harbor Freight.
The bin rolls easily around the shop and it saves countless steps. I use the top shelf as a tool tray to keep reamers, taps and drill bits close at hand.
I labeled the bins with strips of white plastic electrical tape marked with a super fine felt pen. The tape just peels off when I need to relabel a bin. The bins hook on the shelves and are easy to rearrange for sequential part numbering and sorting.
Right now is it exclusively Kitfox parts and hardware. When the aircraft is done I'll have a nice roll around bin for the next project.
John
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When mixing small batches of Hysol, epoxy or two part fillers, I like to use paper cups. The hot drink type without the wax coating works best.
I cut the cups with scissors at an angle prior to use. the angle cut allows easier access for the stirring stick and keeps the product off my fingers.
If desired, I fold over the pointed high side and use it for a handle.
My favorite mixing paddle is a tongue depressor. I cut the end square with scissors so it will get into the corner of the mixing cup.
John Pitkin
Greenville, TX
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Those dang solvent can caps.
I’m sure everyone has used one of these cans with plastic snap caps. They are a pain in the cartouche to open requiring a screw driver almost every time. Soon the pry tab breaks off and it’s a bear to get the can open.
Push a drywall nail through the cap to make a tiny hole. When you need some thinner or solvent just pick up the can and squirt out what you need.
You can use the nail as a plug, if you like, but I found the hole is small enough to prevent noticeable evaporation even over extended periods.
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Paint runs? When I was restoring old cars, I would on occasion, get a run in the paint. As soon as I saw it, I put the gun down, get my 2" masking tape that I have attached to my hip, pull a piece about 10" long. Sticky side towards the run, make a loop in the tape(omega sign). Gently make contact with the tape to the middle of the run and let the tape splay out to the ends of the run. Gently reverse this by pulling slowly back. The tape will lift the run. Let it set up a minute or so then give one or two short hits from the gun. The fresher the paint, the more success you will have. Lion 8, form Southern N.J.
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RE: Paint runs and sags
Thanks Tom!!! (Lion8)
I have to admit, I didn’t think this would work as well as it does.
I decided to give it a try. I primed an empty Dr. Pepper can (we’re in Texas). I purposely sprayed until the primer ran, then pulled out a length of tape and mashed it onto the run. Much of the paint was picked up by the tape but it did lift the run. The surface didn’t look that great with a sort of mottled appearance , but it was flat. I waited a couple of minutes and hit it with a few fresh shots. To my surprise, the primer blended well and produced a usable surface.
So on to the next test… I shot some color on the can and made a saggy run. This time I let it sit for a bit as you might do when painting, not discovering the run until it’s almost too late. Out came the masking tape. It once again lifted the run and much of the surrounding paint. Without further prep I shot on a few short sprays and the paint blended and leveled out. Presto! The run was gone.
Just for fun I tried the technique with drywall tape instead of masking. It worked, but not as well. Something about the adhesive and sticky surface that makes masking tape the material of choice.
This is a great tip!
First photo shows the run area after daubing with the tape. Second photo is after re-spray. Not bad!!!
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Thanks for the nice review John. I hope I've redeemed myself for snapping at the McBeam's for not giving up drawings for an engine mount I needed. They,
you and everyone here at this site are nice people willing to offer some valued help. Hope everyone can use this tip
In my area, there is a family of Kitfox's and Avids growing. . -Tom from N.J.
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Setting Pop Rivets
Sometimes a pop rivet is a bit tight and doesn’t set all the way in the hole leaving the rivet head slightly proud.
Use a short length of brass tubing as a setting tool. The tube slips over the pop rivet shank A light tap with a mallet drives the rivet home without knocking the shank out the back side or damaging the rivet head.
John
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Wire ties
Sometimes you need to snug up a wire bundle to hold things in place, but have plans of adding more wires to the same bundle. I’ve tried leaving the ties a bit loose but that creates a problem of sloppy looking wire harness with loops and sags. If you zip the ties up tight to get a nice looking harness you must cut off the previously installed ties to add new wiring. That wastes a lot of wire ties.
I use a technique of temporarily installing wire ties backwards. That way the bundle can be snugged up for proper routing. There’s just enough friction to hold things in place but the tie can be loosened or removed for additional wiring.
Ties installed backwards may be readjusted dozens of times. I use yellow colored ties to remind me which ones are temporary and installed backwards or purposely leave the tail long to indicate it is a temp tie.
JP
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John, you stated "To press the bushings in the stab sockets use a C clamp. Do not beat on the bushings with a mallet."
Did you use the recommended Loctite 680 Retaining Compound? The tech info with that product states to apply to both surfaces and "assemble with high press rates". I have managed to install 3 of the 7 so far, but for 2 of the 3 I had to resort to a small hammer against a backing plate to get the final 1/8" or so. It seems the RC680 sets up really fast. No way would I be able to use a C-clamp fast enough. I used a Vise Grip 11R on my third one to get most of the way quickly after making sure the bushing/bearing was starting square. The aft center location looks like it will be really tough due to the decreased accessibility between the ribs.
I would be very interested in hearing your (and others) thoughts and experience on this step.
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I used threaded rod with nuts and washers on each end. No trouble at all.
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Stabilizer Bushings
Yes, I used 680 Loctite when installing the stab bushings. After reaming the sockets a few of the bushings were still very tight. I used a bolt and nut through the middle of the bushing to chuck it in a drill motor. Holding a file against the outside barrel of the bushing I removed a bit of material to have a nice firm press fit without forcing. [I have a lathe, but this was quicker]
I smeared the 680 on and pressed the bearings in using the c clamp method.
The suggestion to use threaded rod or bolt with washers and nuts is a great tip, too! I like it better in that it keeps the bushings aligned as they press into place. More than one way to skin an empenage!
The problem with beating on the bushings is they get deformed and will require redrilling and reaming back to size.
A note on Loctite 680... if you haven't used this stuff before you're in for a surprise. It is not like other Loctite products that set in hours. This 680 goo is FAST. You get about 15 to 30 seconds and in some cases less. It is also pretty permanent. Once set, it takes a lot of heat to break the bond.
JP
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A building tip I picked up somewhere that makes dealing with Adel clamps less annoying. Using pliers (or vice grips if you don't have a helping hand) to hold the clamp together put a small piece of safety wire around the base of the clamp. This tend to make the clamp loose enough to move yet easy to assemble. I recently swapped out the autopilot servos and they are mounted with Adel clamps which where a huge PITA. I put safety wire on the clamps before disassembling them and putting the new servos in was a snap.
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John,
Your right about the 680 setting fast!! :eek:
I like the bolt/nut or rod idea, but think I would be too slow with that, like I am with the C-clamp.
I am debating installing the bearing half-way dry and then applying the 680 to the two surfaces that remain exposed. Seems I could get it pressed on fully quickly enough although I would in effect have only applied 680 to one surface of each end. For what it is worth, Loctite specifies applying to only one surface for a shrink fit application (where the other surface will be heated prior to installation).
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Just a follow-up to my last post. I just talked with tech support at Loctite. They said that the working time for the 680 should be on the order of 10 minutes!!
They could provide no explaination for why I am observing significantly less, but did note that lower temperatures should allow more working time. My work area has been no more than 72 degrees for this though.
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Hello John, great bunch of tips. I am just setting up shop as I patiently wait for my kit. I have already jumped on your parts bin idea. There was one on sale that was already on casters and two sided at princess auto. The Canadian equivilant to harbor freight i think.
Just a quick question. You bring up the use of a drill press a lot in your posts. I intentionally bought the prefabbed parts option so I would avoid buying tools like that. Would you say if a person didn't have to fabricate all the parts that he should still have a drill press, table grinder/belt sander. etc? Here is a picture of the prefabbed parts I ordered.
http://www.kitfoxaircraft.com/images...%20-%20web.jpg
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I can't imagine building an airplane, prefabbed parts or not, without a drill press, belt sander/grinder, & a lot of other tools, although I suppose it can be & is done by some.
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Yes, you would be way ahead of the game if you had a drill press, even with the prefab parts. Wait until you try to drill a 1/16" hole thru the side of a 1/4" pin (x3) with a hand drill! There are many, many holes to drill that are much easier and accurately done on a drill press. It doesn't need to be a large industrial type, just a small bench top type is fine.
Jim
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Thanks for the quick reply. I'm not scared to spend the money on the proper tools. The major reason I went prefab was to save time since that is what I have the least of. I jsut thought I might not need it still. But now that I know I'll keep my eyes peeled for some good sales.
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Drill press tips
Having a drill press is in my opinion essential for building an airplane. You just can’t get the accuracy drilling even the simplest of holes with a hand held drill motor. Yes you need a hand held drill motor, too.
For a budget minder builder a bench top drill press will do fine. Even the smaller ones in the 8 to 10 inch class will do 90 percent of the jobs. Prices at the import stores are under $80 for a small one. That’s a small investment when compared to the price of the aircraft. And… you’ll own it when the airplane is complete. Of course, a larger floor model will have the advantage of power and many more speeds. Floor models are about $250 and up. Fast spindle speed is not needed. Slow is better. Look for ones with slowest spindle speeds lower than 200 RPM.
Throat depth is not that important. Rarely do you need to drill in the center of a large piece. Most of the time you drill near the edges.
If your drill press is a smaller version, clamp or screw on a larger plywood table for added stability. It's amazing how just an extra foot will help support your workpiece.
Always bolt the drill press down to the bench or to the floor. I know it seems sturdy but the first time it starts to tip over when you are drilling is too much excitement for the average shop. It's easy to drill two holes in concrete floors with a masonry bit, slap in a couple of anchors [Hilti bolts] and your in business. If you decide to move the tool or wish to clean under it, just unbolt it.
Clamp a board on the drill press table as a fence and you can drill perfectly lined up holes in a row without the bit wandering. [Door frames and Plexiglas.]
Cut a “V” shape into a 2x4 to use as a steady rest for drilling tubing and rods. Always use a center punch for a starter divot when drilling rod stock.
If your chuck is a screw-on type (most of the smaller ones are) Use the drill press as a vertical drum sander. A 2 inch diameter sanding drum to fit 1/4 inch to 3/8 inch chucks is available at most woodworking supplies. It is perfect for smoothing edges on sheet metal.
Clamp a plastic coffee mug to the drill press column to use as a catch all for drill bits and the chuck key. A hose clamp or bungee through the finger grip works well.
LED flashlights make inexpensive work lights. They sell for $3 or $4 and come with batteries!
Keep some cutting oil in a used Visine bottle. Just a drop makes a huge difference in speed and a straighter hole, too.
Many drill presses have lousy drive belts that cause them to shake like ten year old washing machine. Replace the v belt with a Power-twist segmented belt.(Rockler.com) You'll be amazed at how quiet and smooth it will run. Pricey belts but worth it
A circular fly cutter for wood will cut nice large diameter holes in sheet aluminum. Make sure the metal is firmly clamped. Use a wood back up board, run at the slowest spindle speed and proceed VERY SLOWLY.
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Things not to do with a drill press...
Never leave the key in the chuck unless you like flying chuck key demonstrations. [yeah, I've field tested that, too.]
Do not use a sanding drum or end mills in chucks that use a MT or Jacobs taper mount, they will pop out when you least expect it.
Never hold sheet metal with your hand while drilling. The bit can grab the workpiece then slice and dice. [Ugly red color follows.] Always use a clamp or drilling vise.
I'm sure the readers have more tips.
John Pitkin
Greenville, TX
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The other power tool you must have is a Dremel tool with an assortment of cut-off disks, grinding and sanding drums, metal cutters, etc. You will use this tool endlessly.
Jim
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I ended up picking a used floor standing drill press for $200 I'm going to take up your advice and pick up a new belt for it to smooth out some of the vibration on the motor.
I do have a pneumatic die grinder which is the same size as a hand held dremel that I was planning on using. After I had $2000 bucks of eletric power tools stolen I've been slowly replacing my collection with air powered tools.
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Here's a tip to determine where to cut the hole in your lower cowl for the exhaust stack exit. The problem is a typical "Catch 22". You can't mount the muffler with an uncut cowl in place, and without the muffler in place, you have no idea where to mark the cowl.
Raise the tail on a stand and chock the wheels. Get yourself two pieces of PVC pipe, one that slips over the exhaust stack, and another small enough to slip inside the larger pipe and slide telescope style. Now, mount the muffler and attach the larger PVC pipe to the exhaust stack. Next, slide the smaller pipe downward until it touches the hangar floor, and glue it in place with a glob of hot melt. Now sliding the larger tube down out of the way, remove the muffler, reattached the cowl and slide the PVC pipe back up until it touched the bottom of the cowl. Draw around the pipe where it meets the cowl, and presto! You've got a perfectly marked cowl.
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Not a must have, but without a doubt the most frequently used tool I own is the expander wheel from Eastwood. It mounts on a typical bench grinder motor. It is very useful for deburring outside edges on tubing, fittings or sheet metal. I will also use it to debur holes in steel. The bands last almost forever and the older they are, the finer the finish on the metal. I've had mine for almost thirty years. Vhttp://www.eastwood.com/expander-wheel.html
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Aileron control rod protection
There are a few reports of seat pans cracking at the front lip. To prevent the seat from dropping and possibly interfering with the aileron push rod many builders install wood supports. The supports are sized to just touch the bottom of the seat pan. By bonding to the frame instead of the seat pan, control rod clearance can be checked when making rigging changes.
I installed supports on both sides of the control rod and on both left and right seats. The supports take most of the pressure off the front lip of the seat pan which should prevent cracking.
Even if the seat breaks, it will not contact the control rod.
John Pitkin
Greenville, Texas
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Wire Chase
Feeding wires from the instrument panel to the aft fuselage is a challenge. There is very little room in the center cockpit tunnel with few places to tie anything. Make a chase to keep the wires safely away from control cables and levers.
A sturdy and inexpensive chase is made from thin wall 1 ¼ inch pvc pipe. Make V cuts in the pipe where you needed to make turns leaving a small PVC “hinge”. The hinge keeps the pipe pieces aligned. The best way to close and bond the joints is to use 2 inch Polyfiber tape and glue it down with Polytack. The bond works almost instantly and it is hard as a baseball bat in about 15 minutes.
The 1 ¼ inch pipe has room for lots of wires and coax with room to spare. The inside is smooth without ridges so wires pass though with ease.
Make oval shaped openings in the pipe where wires need to break out of the bundle.
It's best to run the chase on the left side of the tunnel. You will need to dip down a bit to clear the seat pan and then com back up to just left of the rudder cable sheaves.
John Pitkin
Greenville, Texas
Here's the chase before installation. This one has five joints to snake around frame tubing. The opening int the pipe is for the trim control wiring.
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1 X 19 SS cable.
When routing Stainless steel cable though eyelets and guides the ends have a tendency to fray. Stop the fraying with a few drops of super glue on the end to keep the individual wires in place. Wipe the end after you apply the glue to smooth the wires.
To cover the ends of wires to guard against "meat hooks" use heat shrink tubing. But what do you do if you already have a ferrule crimped in place? A simple solution is to coat the exposed wire end with hot melt glue. It forms a nice smooth coating that can be molded when it cools a bit. Or simply heat the glue witha heat gun to smooth out any strings or blobs.
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Good tip John,
Another one that a few of us in the Phx area have used for a wire chase is the 1" drip irrigation hose. It is usually black with a blue stripe, very light and quite flexible.
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Re: Building tips and hints
Rib stitching is not too hard for itself: it is more or less a therapy IF you get the hold on it! And since there are several YouTube films on the internet (and the FAA-films, not to forget) i had lots of help from them.
But most of my learning-process was done on a practice-board: just tie your knots, starterknot, modified- and endknot - and see how it looks!!
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Learn a few simple knots, like a clove hitch, half hitch, etc. Get yourself a roll
of rib lacing cord, and free yourself those nasty nylon cable ties forever.
Much better way to tie wire bundles.
Here's a link to some pics, examples, etc:
http://www.aeroelectric.com/articles...able_lace.html
Jeff Hays
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Thats the way us professionals do it!!!!;)
Whats more when you get good at it it is quicker too and you dont cut your hands behind the panel!!!!
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I use an Olfa Knife to cut aluminum sheet. It works very well on the thinner aluminum sheets. I've actually used it to cut 12' lengths of .016, .020, .025, and .032 sheets. It's a tool for cutting countertops but works well for aluminum. I've used this tool to help build 3 homebuilts.
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That is a great tip...one that I have used many times in the glazing trade. To describe how the cut is made, take a straight edge and clamp it along the line to cut. Make several passes along the line until you guestimate you are about half way through. Then just bend at the score line a few times until it breaks.
This proceedure is used extensively to make straight cuts on plastic sheeting (plexi, acrylic, etc) as well.
Interesting how many of us picked up tips from the "ole timmers" years ago, made them a practice in our work, and never think to share with others as it just doesn't come up. Makes one wonder how many tips/techniques have been lost because of this.
Good thread :cool:
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Thanks for filling in the details Dan. I guess we all got little tips we can pass along. The is a good place to put them, isn't it?
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This is in reply to Jbonewitz suggestion on locating the exhaust cutout in lower cowling. I just tried his method on my SuperSport and it works perfectly for locating the exhaust pipe hole location. Everything works as advertised and is a very simple process. Thanks for the info.
Dick B
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Thanks to a suggestion from Dick B in KY , I just made the "Building tips and hints" a "Sticky" so it can easily be found now at the top of the General discussion page.
No need to use the search feature now if a new post hasn't been added under this subject heading in a few days.
Thanks to all who contribute their experiences so others may enjoy their builds and finished aircraft even more.:)