Rib Question

[anthonyh]

I made a test rib in the jig and it came out really nice. I used left over spruce from my R/C builds and some lite 1/4" ply. For the test rib I stapled the gussets as I do not have my clamps yet. The rib did slightly stick in a couple of places but it wasn't difficult to remove from the jig. Overall I am happy with the results. Now all I need is the calmps and the wood to build the ribs.
Later!!
Anthony

[anthonyh]

Hi Guys,
I have finished up the jig and installed the vertical clamps. I will be placing my wood order this week. I am a bit unsure of the grade of plywood. I intend on ordering 90deg ply. I cannot find anywhere in the plans where it specifies 90deg or 45deg?
I will be ordering 90 deg 1/16" Mahogony for the gussets and 1/4 birch for the nose and tail pieces. If anyone sees an issue here please speak up.
Thought I would post a few pics of my jig setup. I have installed vertical clamps at each gusset location and an extra clamp at the tail and nose pieces. These clamps are just over $3 a piece. I cut the gusset shapes out of 1/4" stock to use between the clamps and gussets with the intention of making sure I have even clamping force across the entire gusset. From my experience with epoxy you do not want to have excessive pressure to squeeze out the epoxy you just want enough force to assure complete contact across the glue joint. The clamps are easily adjustable for the clamping force. I still need to build a clamping board for adding the gussets to the 2nd side. The jig may be a bit of overkill but it was fun to build
Later!!
Anthony

[anthonyh]

Another question:
Is there any difference in the quality of spruce between aircraftspruce and supply or from Wicks? One is considerably higher than the other. I don't want to get the wood and wish I had ordered from somewhere else.
Thanks!!
Anthony

[dougm]

When you clamp the gussets make sure you have pressure across most (or all) of the gusset. The gussets are thin and it's easy for the ends to lift a little if you have too much pressure at the clamping point and none elsewhere.

[anthonyh]

Thanks Doug.

If you look at the pics you will see the 1/4" think blocks I made the same size as the gussets. These will assure even clamping force across the entire gusset. Well that is the plan anyways
Later!!
Anthony

[anthonyh]

I finally took the plunge and ordered all the wood to build the ribs today as well as T-88. Looking forward to finally starting to make some real parts for the Hatz.
Anthony

[M Lightsey]

Don't over do the clamping pressure. It's a common mistake with epoxy to over squeeze it and force all the epoxy out of the joint. Resorcinal requires high clamping pressure, but epoxy only enough force any air out of the joint and keep the parts in "intimate contact". http://rgl.faa.gov/Regulatory_and_Guida ... r%2001.pdf

[anthonyh]

Thanks for the tip,
That was my reasoning for going with the vertical clamps over the common spring clamps. I can easily adjust the clamping force to prevent squeezing the epoxy out and starving the joint. From what I have read that does seem to be the most common cause of failure of glued wood joints on AC. The vertical clamps should be much easier to use as well.
I will post some pics of the jig in use once I start actually building something.
Later!!
Anthony

[Nick]

HI Anthony, I didn't see that anyone else mentioned this, so I'll say it, in case you're not already aware. When making your ribs, don't glue in the two inner upright members that are next to the spar slots. Otherwise you'll have a dickens of a time slipping them onto the spars. Those uprights are added, glued and gussetted into place after the ribs are slipped onto the spars and positioned. At least that's the advice I was given, and I'm glad about it. If you make all the ribs with all the uprights in place, you would have to put your spar plywood doublers on after the ribs were slipped on and then drill them, which would be a pain, if not impossible.

Nick

[Ebby]

I most certainly concur with Nick on his post regarding DO NOT glue the two uprights or gussets by the spars. I did glue them and it was nearly impossible to slip the ribs onto the spars. A rookie builders oversight on my part. I ended up removing them, installing the ribs and then reinstalling new uprights and gussets. A painful waste of time.