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Help with Centre Section Spacer

T

TimSPEED

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So I am sure I am over thinking this step, but when I get to this bit:

The F-804A-2 and F-804B-2 Center Section Sub Assemblies must be held in correct alignment while they are
being joined and while the fuselage is being assembled. Make two hard wood or particleboard spacers 1 7/16
(1.438) thick. The exact size of these spacers is not important, but the thickness is, as they will simulate the
spar as the bulkhead is fixed in its final position. Drill holes in these spacers to allow the installation of the NAS-
1304-50 1/4 close tolerance bolts. The holes in the spacer blocks may be oversized to allow the bolts to pass
through easily. This spacer will remain in the bulkhead throughout fuselage construction, until it is time to install
the wings. If you choose, make the spacer extra long so that it protrudes out the side of the fuselage. This
would allow for the future attachment of appropriate length legs for the fuselage to stand on while completing
other work on the interior.

I am unsure/unclear what is required.

What do they mean by make two spacers? One for each side, or one for top cap, one for bottom cap. And then when they say make it protrude out the side so you can use it as a support, it makes me think a single beam that is say approx 4' x 8" x 1/7/16" is what is best. But this is only one. And then given the precision asked for, how do we feel about the changes in thickness the spacers will undergo with the seasons?

Can anyone show mw what they did? I have tried a search on here to no avail.

Abd btw, merry christmas everyone.
 
Spacer blocks are to mimic the thickness of your wing spars to insure the opening stays wide enough to slide your wings into the fuselage.
They suggest making your spacers so they stick out the side of the fuselage 6 or 8”. Later, you can make a couple of legs to lift the fuselage off the floor by screwing a couple of 2x4s to those extended spacer blocks.
 
There’s several ways of making the spacers.
I have two bits of hard wood machined down to the right specs and they sit in the gap between the 2 center sections. Mine is the third RV-8 these have built.
Other people machine down metal spacers that fit where the bolts go. You can’t have a single bit of wood that goes the entire length as you need to access the centre of that section.
 

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Thanks @Jonnyb , that's the info I was after. So they don't/can't run all the way across. If each piece was about 14" long, is that long enough? Can't quite tell how long yours are.
Thanks again.
 
TimSPEED said:
Thanks @Jonnyb , that's the info I was after. So they don't/can't run all the way across. If each piece was about 14" long, is that long enough? Can't quite tell how long yours are.
Thanks again.
Click to expand...

I’m away from the shop at the moment but will measure them when I get back later.
 
FWIW, I made my spacers out of seasoned Red Oak. I planed them down to the exact thickness, drilled them out, slid them in place and installed the bolts (by the way, most recommend using hardware store bolts, not your good ones). When it came time to install the wings I had to beat the spacers out. The wings would not go in. With the help of Vans we were able to come up with a way to open up the slot and insert the wings. Here in Tennessee we have large swings in humidity that plus a hot shop in the summer time caused my blocks to shrink in thickness by just over 1/16" during the time I was building the center section.
 
Morepower said:
FWIW, I made my spacers out of seasoned Red Oak. I planed them down to the exact thickness, drilled them out, slid them in place and installed the bolts (by the way, most recommend using hardware store bolts, not your good ones). When it came time to install the wings I had to beat the spacers out. The wings would not go in. With the help of Vans we were able to come up with a way to open up the slot and insert the wings. Here in Tennessee we have large swings in humidity that plus a hot shop in the summer time caused my blocks to shrink in thickness by just over 1/16" during the time I was building the center section.
Click to expand...

I had a similar but less impactful experience here in sunny socal. I sized them on a milling machine and they were within 0.003” of the correct size. They shank about 0.01” over a year. They were within the Vans tolerance but it was disappointing. I don’t know. If I did it again I’d make 4 standoffs out of thick wall aluminum tube.
 
Ben Ellis said:
If you don’t have the right equipment or materials, these might be a good option: https://bullerent.com/product/rv-7-and-9-spar-spacers/
Click to expand...
Full disclosure, I haven't installed(or even built 😅 ) my wings yet, so TBA if I got the tolerance right, but here is the method I did for the spacing. I did DIY steel spacers similar to what Ben suggested (didn't know buying them was an option) and epoxied it into wood. The fuselage is basically done now and this is how I am supporting it until installing the landing gear.
 

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I glue two layers of plywood together. The combined thickness of plywood was slightly thicker than the spar and I had to shave it off to fit using a planner.

20191228_120631.jpg

Another advantage using the plywood was I could screw on a stanchion and place the fuselage on a platform so I could move the structure freely in the garage

20200113_113510.jpg
 
And good call about measuring your spars first. Mine came out about 0.2mm (0.007") bigger than the width called out in the destructions. I will adjust for it.
 
I used metal spacers I made myself, similar to bullers. I already fitted wings the first time. I was nervous but they fit snug but not tight, I believe instructions describe the fit. I was very pleased at my choice to not use wood. Like many tasks I have questions about. I read VAF posts and just get it done.
 
TimSPEED said:
And good call about measuring your spars first. Mine came out about 0.2mm (0.007") bigger than the width called out in the destructions. I will adjust for it.
Click to expand...
The fit of the wings was right on. Snug but there was no interference. If the spar block, wood or metal, was out of spec, you will have trouble. As matter of fact, after painting, there was a thin layer of primer on the wing spar top cap and I had to clean it off with acetone before it would fit. This was how tight the wing spar should fit into the fuselage.
 
I made some spacers on the lathe …. Wing spars fit nicely. Almost surprised that in the extremely critical area that Van’s doesn’t supply a factory built spacer .
 
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