trim tab blocks

[sblair]

Hey everyone. I'm getting ready to bend the trim tab and elevator skin. What is a good way to produce the wooden blocks used in this process?

Just trace one of the ribs to get the shape?

Thanks,

Sean

 

[DaAV8R]

Bending Blocks

Sean,

I make several sets of blocks using progressively harder woods. I wanted to practice the bends with some scrap before attacking the real thing. I was getting slight deformation on the corner of the wood block when practicing resulting in a buggered edge for the real thing. Eventually I hardend the corner of the bending block with some cyanoacrylate otherwise know as CA in the modeling world. It is available at the local hobby or craft store. The glue is available in several thicknesses. The thin CA wicks into the wood and makes the bending edge very hard. If your prone to glueing your fingers together, you might want to pick up some debonding agent when you pick up your glue.

 

[sblair]

pattern?

Robert,

Thanks for the idea with the CA. I've used a little of it in R/C Aircraft, too.

To get the angle for the blocks...did you just use a rib and trace the pattern to get the angle?

Thanks again.

Sean

 

[papamike]

I'm there too, but I'm seriously considering installing a rib in the elevator instead of bending it. Still have to come up with a form to bend it to.

 

[SeanB]

Still looking for answer to pattern

I didn't seem to have much of a problem with these on my 10 build. In that case, you have to build two trim tabs and two close-outs on the elevators. I was fortunate to have the wooden forming blocks from another builder. Make sure you use double sided tape and enough clamping pressure.

 

[Transporter]

Pattern

I used a rib from the right elevator to make my blocks. Cut the outer and inner from one piece and flattened the surface on a sanding disc (could also be surfaced using a piece of sand paper on a flat workbench).

Robert's idea about using the CA to harden the edge is a good one.

A hard wood such as maple is another option.

Don't forget to radius the forming edge to allow for the bend.

Good luck,
Mike

 

[sblair]

Thanks

That's what I needed...thanks!

I just found the CA glue, too. Here goes!

 

[Mike Coady]

trim tab bend

Use as hard a wood as possible to make make your bending block from! I used a thick paricle board which the plans said was OK but the particle board broke causing the metal to shift...not good. Make sure to use the double sided tape on your bending block to the skin and that you have your setup clamped down very firmly. Go slow when you get to using your rivet gun if you use it. Good luck. HARD WOOD ONLY FOR BENDING BLOCK!

 

[sblair]

Will do

Thanks, Mike. I've got a piece of red oak that should do the trick. Got the double sided tape and good clamps, too. I'm minorly concerned about clamping too tight and creasing the skins.

Thanks,

Sean

 

[txnbuilder]

I used MDF

Sean,

I ended up making a little rib for the elevator (because I screwed up the bend by trying to use a piece of 2x4 as my bending form).

For the trim tab, I used 3/4" MDF. It came out great.

To make the form, I just traced the outline of the trim tab on the MDF and then used a jigsaw with a guide to cut it.

Here are some pictures:

http://rv7a.fabs-designs.com/2007/02/13/bending-the-trim-tab/

Good luck!

Luis

 

[sblair]

pics

I appreciate the pics, Luis. Looks like those turned out well for you.

Thanks,

Sean

 

[Mel R]

I struggled with the wooden blocks and used a hand seamer in the end with satisfactory results.

 

[MTBengel]

Good result using steel

I had a terrible result using pine blocks. I ended ordering a new skin for a second chance to get it right. This time I machined blocks out of 1" steel bar. In contrast to my first attempt, this gave an excellent result! The hardness of the bending die does appear to be the key factor. I'm going to order a new trim tab skin and redo that as well.

 

[RV7Guy]

First step!!

The first step should to immediately order a new trim tab. I think if there was a survey you'd find that 2/3rds of all kits sold ended up buying a second trim tab.

It has often been rumored that Van's makes little off the kits. The true profit comes in the parts we screw up.

Good luck!!!

 

[Smilin' Jack]

I bent mine and the results are not as pretty as those that have inserted ribs and flush rivet them.

I have looked at a lot of RVs and constantly those with ribs win hands down.

Mine is not a going to be a show airplane but I want it safe and well built and as well constructed as I can do.

Smilin' jack