n00bs Gonna Build a Carden

[gareth.ky]

Couple more shots:


The 1/8" hard balsa stiffer bits are all sanded down.

Made a cradle out of scrap foam so I could work on the wings.

Getting ready to razor plane the bevels.

[gareth.ky]

It makes a difference.

I bought a bunch of "Norton" brand sandpaper when this project started because... I was at Home Depot and it was there. I just ran out of the course (~150) grit stuff and had to go get more. I wasn't really happy with how often I was changing sand paper on the T-bar sanders. It seemed to start going bald in just a few minutes of use but i didn't really think much of it.

Man I went out and got me some real 3M sandpaper. The Norton stuff was a HUGE mistake. You would think something like sand paper would be easy to get right. Not so it seams. The 3M stuff is going strong, easily outlasts the Norton paper by 3-5 times. Its a small thing but every time I have to put fresh paper on a T-bar its a 20 minute ordeal. Gotta peel and scrape the paper off and soak it in goo-gone to clean up. Then cut new paper and stick it on with 3M 77. Big wast of time.

Do yourself a big favor and seek out the 3M sandpaper. I found 3M it at Lowes but not Home Depot.

When you think about it, bad sand paper is a great scam. You just put some clever marketing on a box of crappy paper and wait for the customer to come back. All my Norton paper is in the trash can. You couldn't pay me to use the stuff now. No more wasted time for me.

Another good trick is this Abrasive Cleaning Stick. It can get the crud off the sandpaper, belt sanders, sanding disks and the like so they cut like new. This really helps when sanding foam which tends to clog the sandpaper

[mark786]

Gareth,
When I first started I used to cut my own sandpaper and used 3M 77 to glue it on because I was just not going to pay the premium for the roll paper. Got tired of that and finally bought the roll. Now I have every grit roll on the bench and about 5 different bars laying on the table with different grits and lengths. It would be the best 5 bucks you ever spent.

http://www3.towerhobbies.com/cgi-bin...?&I=LXK321&P=0

Mark

[gareth.ky]

Thats a good tip! How is that stuff about peeling off the T-bar?

Anything you can do to make the sanding easier will pay for itself almost immediately. I used to think the T-bars were expensive. Now I would say you should have this as a start:
12" on 150 grit
24" on 150 grit
24" on 220 grit
36" on 220 grit

The 24" is the size I use the most. Smaller sizes are useful when you want to sand a smaller area. Larger sizes are good for big sheeted surfaces. Past 220 grit its probably better to stick the paper to a foam block. You are looking to smooth the surface at that point not shape it. 400 grit is my next step up. I'll do a pass with that and maybe some 600 before covering.

I'm finding that I put hanger rash on everything so I am holding off on the finish sanding until after all the work is done. All the nicks and digs are my fault. One of the biggest culprits was the T-bars. I was using the 3M Spray Mount adhesive and the ends of the paper would peel up. If you don't notice it will put some serious scratches in the surface. Now that I'm using 3M 77 thats happening a lot less.

I just seem to drop, scratch and nick everything at least once. Guess I'm just clumsy. I have a big cotton towel that I put all the parts on now. This cut down on the amount of dents in parts from grit on the table.

[mark786]

You have to try the roll stuff. Doesn't peel back but when you are ready to take it off it doesn't leave much to clean. I use to use 77 but had to always use adhesive remover to keep the build up down.
I think you will find that your final sanding will be good with 400. It will leave it as smooth as a babes butt. I agree with your other grits, that is about all I use is 220 and 150. You can take alot of material off with 150 grit.
Mark

[gareth.ky]

I haven't done a big write up on this phase of the project yet. I'm not really happy with the way it all went. Not that the results are bad, just that it didn't go smoothly and there were some mistakes made.

Speaking with Walt over in the ML 300 build thread he shared how he cuts his surfaces on a band saw. Thats the way to do it, everything else is less accurate and more work. I didn't have a bandsaw but I wouldn't approach this task again without one.

Part of me wants to do another kit just so I can apply everything I am learning building this one.

[why_fly_high]

Dude, I'll send you a kit with my bandsaw and we're set. I'll have to figure out which 40%er to send you.

Dan

[gareth.ky]

I should have borrowed your bandsaw!

I have a couple of parts where the center line of the bevel is not in the center line of the surface. I can't really figure out how this happened?!?! So on those parts the surface is is offset from the airfoil. In some places by more than the sheeting thickness.


AeroFAIL!

Hard to see but there is about 0 gap between the aileron and the wing. Everything thats sticking up is above the wing.

I've pretty much decided to do these over. 1 elevator and both ailerons are affected. The Rudder and 1 elevator are pretty nice.

The elevators are not exactly identical. At the root one is about 1/8" longer than the other. I don't know HOW that happened either. I had the parts in the shuck and over the plans when I marked them. The longer of the two also happens to be the one that came out pretty well.



I don't like having some 1/2 baked shido on my airplane.

[Neil4]

so you are going to get a new elevator half and wing panel and do it over again?

[Simpleton]

You can hit the glued on sand paper with a heat gun and it really speeds up the peeling off process, and comes off cleaner than just peeling it off at ambient temp.

[SunDevilPilot1]

Sandpaper Tip:

I buy standard 3M sandpaper but attach it to my sanding bar with carpet tape. incredibly strong tape that generally comes off without leaving it's "sticky" behind. A little "goo gone" will clean the bar in short order if needed.

SunDevilPilot

[gareth.ky]

	Quote: Originally Posted by Neil4
	so you are going to get a new elevator half and wing panel and do it over again?

no no, nothing that drastic! Just cut off the bevel material and do it again. This time with a bandsaw.