My Fokker DVII Project - Page 107

Jeff Brooks · 25 April 2008, 05:53 AM

Quote:

Originally Posted by drrivah

Jeff-
Are you folks using T88 on the D.VII ribs?

-pete

Sorry I haven't been quick to respond ... I am trying to get into the prodution of the ribs, and that takes up my time. To answer your question, Yes .. T-88 is what I am using. I tried Resorcinol glue before, and between the brown/purple staining & the few poor bonds from improper mixing, I went with the T-88.

Quote:

Originally Posted by drrivah

Jeff:

Super job on the ribs. Do you plan stress testing on the prototypes?

-pete

Phil & I built a testing setup to load test some ribs we made before, but I put it off until the weather got better. We will do it soon. The reason for the testing is not so much to see what strength the ribs have ... Achim has already demonstrated that, but because I have a large amount of Mahogany ply that is the right thickness for wing ribs, and lighter than Birch ply. I want to see the strength difference. Plus it is good for Liability reasons too!

I spent last night making 3 more jigs to bend the capstrip ... each one can bend 5 pieces at a time, and now I am up to twenty in one night.

I also was up late cutting 6 sets of webs for ribs #3 & #4. Now I have twelve ribs to assemble at work tomorrow during the day.

zffltd · 25 April 2008, 07:04 AM

Quote:

Originally Posted by Jeff Brooks

The nice thing about this jig is the repeat-ability of the product. When I lay them together, they match pretty well.

I still have to trim the trailing edge so they are all 1200mm.

Jeff
What glue are you using?
Pavel

womenfly2 · 25 April 2008, 10:30 AM

Hi Pavel ... Jeff answered that question, see post above yours. You must have missed it.

WF2

Der Grüne Flieger · 25 April 2008, 05:12 PM

Jeff,

Are you seeing any grain seperation using the bending jigs? If so, I can make up a mating piece to them that will let us clamp the cap strips between the two with no separation.

I think the idea came from dogtail, back a few pages on your thread.

P

Jeff Brooks · 25 April 2008, 07:02 PM

The capstrip bending jig takes 5 1/4" square pieces at a time. When I start stretching the capstrip over the top of the jig, if one of the capstrip cracks, I just pull it out of the pile and put a new piece in it's place.
I find that some of the pieces have the grain in the wrong direction. That first cracking usually identifies the foul piece and usually means it will crack like that all the way from one end to the other regardless of what you do. So I just swap it with another and move on.
The rest are laying down nicely with little difficulty. I can set up twenty at night for the next day.
I have everything ready to assemble and glue 3 sets of #3 & #4. I plan to take Jig # 4 to work tomorrow and assemble all three sets. I estimate 30 to 45 minutes to assemble one set. So, with 12 hours on call, there should be enough to get them done. I will do #3 on Sunday.

Phil, If you can fine tune the jigs for #5 & #6, make the nose caps & stiffeners, I can get the rest of the materials ready for assembly on Monday & Tuesday!

Jeff Brooks · 26 April 2008, 08:18 PM

Well,
I only got three of the six ribs done today. my goal was to get all six of #4 rib done, but I ran into trouble with a couple of parts that needed tools I didn't have at work. So I took them home tonight and fixed them and I will finish the last three #4 ribs tomorrow. Monday I will do the #3 ribs. I forgot to bring my camera to take pictures, but I will bring it tomorrow.

Jeff Brooks · 27 April 2008, 06:33 PM

Hi all,
I only finished 2 of the three ribs I had planned to finish today. Vet stopped by in his CUB and gave a ride to my paramedic who has never been in a plane before. The guy liked it better than flying in the helicopter.
Then I had two calls back to back, so that took some of my time up too.
But I only have one left of this number rib to go.
Here is the table I set up at work to assemble the ribs.

You can see the spring clamps to hold the ends & other joints tight while the glue dries ..

here are 4 of the I have done.

Jeff Brooks · 27 April 2008, 06:39 PM

I have slowed down to make one rib per pot of glue, so that gives me 30 minutes to make sure everything is in the right place instead of rushing to get two ribs done in the same time frame. I make a glue teststrip for each rib. I put one together one at the begining of assembly and and one as the last thing glued.

Here is a closer image of the glue strips

Der Grüne Flieger · 27 April 2008, 06:53 PM

Jeff,

We need to talk a bit about this. Are you sure that you are not squeezing out too much glue by doing this? I think it is the right method, but I worry that there might be too much pressure with the clamps you are using. If you overclamp a glued joint you can squeeze out so much glue that it actually weakens it.

Could we do a glue strip test with the clamps versus a one with none? I'd like to make sure we are not setting you up for failure once you are up in the wild blue yonder.

Seems to me you've got the right idea here. Leave the bottom edge capstrip a little long and then you can go back and trim it off. I like this alot better than having the top capstrip go long. Can you use the clamp block I made up with the long cap strip??

Jeff Brooks · 27 April 2008, 07:28 PM

Actually, I have ripped a few apart because they didn't line up right and failed quality control. The wood came apart before the glue did.
I think that there is also enough glue on the plywood web to capstrip to hold as well as capstrip to nosecap.
I have two rejects available if you wanna tear it up and see. Maybe I should post a picture on the forum for the other folks since the question was raised.