n00bs Gonna Build a Carden

[gareth.ky]

For once something went smoothly.

The cowl is something I have been afraid to tackle. If you screw it up its kind of permanent. So far though its been a breeze. The fiberglass work is excellent, the cowl halves fit snugly together straight out of the box. I suppose there are pinholes in it somewhere but I cant see or feel them.



I made up the required 1 dozen blind nuts on plywood pads. The kit comes with some 1/8" ply for this but I have never seen a blind nut that short! The ones I get from Ace are at least 1/4" deep so I had to use 1/4" pads. I don't know whats up with that but that's how it is.



I taped the cowl halves together and marked the locations for the holes. The hardware is 6-32 and I used a 1/8" drill bit to drill the holes with a cordless drill. Slow speed works best. You need to get something under the part so you can press on it, I had this piece of scrap 2x4.



The two forward blind nuts on each side had to be shaped slightly so when the screws are tightened the cowl doesn't deform. Before gluing I took everything apart to wash it. Then I put everything back together and taped it as well. For gluing I removed one screw at a time so that nothing could shift. The screws got dipped in Vaseline and the epoxy was applied to the pad. then it was reinstalled before moving on to the next one. Every 15 mins or so I checked that all the screws still moved just in case.

I also had time to make some tools. I had this aluminum I-Beam that I turned in to an edge truer. It looks like a level but Home Depot doesn't know what its for! I put 120 Grit on one side and 220 on the other. Some scrap 2x4 with 120 grit paper is used for pushing the stock. Works great.



The next tool is a little block with a blade stuck to it, simple enough. This is for putting perpendicular notches in the end of bevel stock. The block was cut so that its perfectly square. This eliminates one of the most error prone parts of doing bevels; copying the center line mark from one side of the stock to the other. Really with a pen you line can be 1mm wide and if you are off by the line width on each face your off by 3mm on the other side. If you do that to two opposing surfaces then the accumulated error is 6mm. I think this was the source of a lot of my problems. If you get it wrong you cant see both sides of the part at once so you cant see how bad it is.

[mark786]

Gareth,
Short blind nuts are made and my Ace Hardware does not carry them either. They come in handy in a lot of areas around the plane so you will want to find a source. I found them at Lowes. They are typically sold in two different depths.
Mark

[gareth.ky]

Thanks mark786, If I could get 4 for around the canopy that would be excellent. I'll check Lows Today.

[why_fly_high]

Well? Are you getting a butt kicking or not? We need picks of the plane dry fit together ready to cover.

Dan

[gareth.ky]

	Quote: Originally Posted by why_fly_high
	Well? Are you getting a butt kicking or not? We need picks of the plane dry fit together ready to cover. Dan

I'm getting my butt kicked. Here is whats left to do:

• V-Stab, re-hinge and install
• Fit & Mount the Cowl
• Final Hatch Assembly
• Fit the Canopy
• Wheel Pants
• Control Horns

I think its going to keep me busy till the weekend. Covering can start on Saturday. Help is always welcome!

[why_fly_high]

Help!?!? I have to fly with OSU tonight, I have to attend a City Council meeting tomorrow, Wednesday I have to go to OSU for their presentation, Thursday I have to finish a stupid Pergola I started this weekend. Friday, Sat, and Sun I am in Wichita for the Engineering Contest. You may have earned a reprieve from the but kicking if you have it ready to cover when I get back from Wichita. Also, I'm not going to Little Rock. Looks like Houston the end of May. Git R Done!

Dan

[gareth.ky]

After lots of screw ups here my guide to beveling and hinging. This works and its repeatable, it requires a band saw and some tools you can buy or make for little or nothing. Its the "bevel before" method which I prefer because its faster and it allows you more chances to catch a screw up before the part goes on the airplane. Its the same method Walt outlines here with some extra bits thrown in. Lets get started...

#1 - True One Edge of the Stock

I'm using my edge truing tool build out of a 4 foot carpenters level. Its basically free to make if you already have a level. You only need to true one side because in the next step that side is going against the fence in the band saw. The other edge will be cut straight. Do both sides of the surface at the same time so the parts are consistent.

#2 - Cut Stock to Width

You want to cut the stock to some width that is wide enough to cover the surface your going to attach it to but narrow enough that the bevel will exit the side of the stock and leave a small flat patch on the side. You can see here I'm using a Feather Board to hold the stock to the fence. This one came from the Depot, is magnetic and really cool but also expensive. You can also make your own or get one from Rockler. Either way this little jig is a requirement, use a 2x4 if you have to. It will make all of the cuts in this process super consistent beyond what you could do by hand.

Quick note on the band saw blade. I'm using a 10 tooth per inch, thin kerf blade from Suffolk Machinery. They (and Walt) recommended this blade configuration for the sizes and types of wood we commonly cut when building a model airplane. It works great on aircraft ply as well.

When everything is cut give all the cut edges a quick sanding on the edge truer. You should now have a plank that has a perfectly consistent width all down its length and two straight parallel edges.

#3 - Mark Center

Use a good, fine pitched t-square or ruler to determine the center of the board. I was doing this with a mm ruler but that's not accurate enough. Use something with a 1/32" scale. I got this little engineers square from Rockler to do setup on the band saw but its also useful for this.

The center mark on this face is for the hinge line. We need to mark the opposite face as well. That face will be glued to the surface and we need a center line to match up with the center mark we will make on the surface later. To do this quickly without having to measure again I made this jig that puts a perpendicular notch in the ends of the board. Just join the notches up on the other side with a line. You can see from the pic that its very accurate. Center is at 1 and 8.5/32 inches. Getting this wrong will skew the final placement of the parts and basically screw it up.

#4 - Do the Hinges

If your doing the Robart type pin hinges then you want to use a drill press and bore through both pieces of stock at the same time. I'm doing the Klett type hinges so I'm using the Hinge Slotting tool. A good top for using the hinge slotter is to take a razor blade and push it into the hinge line. then rock it from side to side to open up a pocket. This will guide the hinge slotter kind of like a pilot hole.

#5 - Cut the Bevels

Here I have the band saw set up to cut the bevel. Take the time to set up the saw so the fence is vertically square to the table. I check the table angle with my digital angle finder to be accurate. Do some test nicks in the end of the board until you are happy with how close the blade comes to the center line. You cant go back and do this again because the feather board trick wont work a second time. You want to get 95% of the material in one pass, leave just enough to sand everything smooth.

Because we have edge trued the board and because of the feather board this cut is going to be very consistent. Notice also that the piece we are going to keep is up against the fence. This will give a constant thickness of cut in the piece we are going to keep. Once the saw is set up right you can just flip the board over and do the other side. If you center line is truly in the middle you shouldn't need to make any adjustments.

Once the bevels are a few swipes with the block sander should be all that's need to clean things up.

#6 - Mark Center on the Surface

This is another step that can result in trouble. The best time to do this is right after you cut the surface free. If you use the bandsaw you'll have the surface and the stab/wing taped the shuck. The shuck can help support a straight edge to mark a line and also provides a square edge to put a t-square against.

If you don't have the parts in the shuck try putting the ends flat on a table. If you can, try and find the center about an inch inboard from the end. The ends are often slightly imperfect and can skew the center mark. Your going to need to copy the center mark up the ends of the surface as well. Once everything is glued together that's all you can see.

In either case use a good fine pitch ruler and check everything twice. This is really where I wish I had a tool or fixture to make this quick and easy.

#7 - Glue in Place

I use Poly glue for this. Only down side it the parts can move around on you while they set up. Use lots of tape but don't put and tension on the tape, it should just be snug. Tension has a way of moving things around when you turn you back.

#8 - Have a Beer!

[Dave_ORCC]

I like step #8 the best!!

Cheers,
Dave

[GERRY DALE]

Gerry Dale of DaleBuilt here! While phenolic horns have proven strong enough in most applications the horns now offered on the Dalebuiltgraphics and Carden website at made from G10 Epoxy glass and are 1/16" thick. They are many times stronger than phenolic. Thanks for the plug and they are now in stock here and at Carden.

[gareth.ky]

	Quote: Originally Posted by GERRY DALE
	Gerry Dale of DaleBuilt here! While phenolic horns have proven strong enough in most applications the horns now offered on the Dalebuiltgraphics and Carden website at made from G10 Epoxy glass and are 1/16" thick. They are many times stronger than phenolic. Thanks for the plug and they are now in stock here and at Carden.

No problem I'm glad they are available! This is something that has come to ARF's (e.g. Extreme Flight, Quiques airplanes and Comp ARF) and kits were left out. They have strength advantages, they are easier to install than a dowel and they have geometry advantages over threaded rod.

I need to get back to SWB, he has some 5" wide double arms to match the rudder horn for 1:1 geometry. That size is kind of rare.

[gareth.ky]

I got the V-Stab mounted to the fuse the week. I used some string to try and make it point straight down the fuse. Some serious foam and filler are gonna be needed to finish the job.



I liked Ken McGuire's / Terry Boston's idea so much I decided to rip it off. The stock location for the top ring mounts is on the side of the motor box. This makes it easy to adjust the ring vertically when your building but its permanently hard to get to the bolts. With this mod the bolts are easy to get to all the time. You just have to carefully set the height once.



You go through a bunch of sand -> test fit cycles. Seems like at least 100. The belt sander is really pulling its weight on this job. The top cowl ring shape isn't quite right. I had to add some "shoulder pads" to get it to fill out the cowl to the right shape. Some more cutting needs to be done to get the motor to fully clear the cowl. I didn't have to cut out nearly as much as I thought I might have to. I'm using 4mm bolts and blind nuts. Trying to keep everything on the airplane that will get used frequently down to one size.



All done shaping and the bottom ring is mounted. Those beefy spring clamps really helped. Anything with less grip wont let you test fit things. It's very snug.



I'm going the rout of tack gluing the parts in place and then later I'll go over the joints with Hysol. I tacked the hop first and then took it off so I could reach the bottom. I think it came out pretty well, just took the better part of two days.




Wont be long now till its all done. I'm waiting on some decent 3/8" balsa to show up at the hobby shop to fix the ailerons. Final fitting on the hatch needs to be done and that probably the biggest job remaining. Other than that its a few odds and ends and it should be ready to cover come Saturday.

[buttface]

NOOOOOBS , YOU GOT TO HURRY!!!!!!! They will beat you till bubbles come out your nose!