[IowaRV9Dreamer]

I'm about to have a set of false spars machined and before I have metal cut I thought I'd see if anyone else has a known good design that they'd like to share.

I'm planning to use "free fit" holes - my drill chart calls for 15/32 (=0.4687") for the big holes and 0.266" for the little ones.

The hole spacing is harder - I tried to measure my spar and it seems like Vans arranged the holes such that there is a constant amount of material (about 0.445") left between each.

If I work the numbers right (a big IF...), starting with one of the small holes, I get hole locations of:
Small hole: (0,0)
Big hole: (0.812,0)
Big hole: (1.726,0)
Small hole: (2.538,0)

Is this similar to what anyone else has done?

Thanks for any info,

 

[alpinelakespilot2000]

Dave-
If I understand you correctly, I think you are overthinking it. Put the spacer in the fuselage spar box. Mark the location of the bolt holes with a sharpie. Pull the spacer out. Drill oversize holes in the spacer. There's no reason those holes in the spacer need to be the size of the bolts. The only purpose of the spacer is to keep the spar bulkheads the appropriate distance apart. By the way... you don't need to drill all of the bolt holes in the spacer. Instructions say one or two bolts in the top and one or two in the bottom is plenty. In my experience, that was plenty.
Good luck.

 

[IowaRV9Dreamer]

Dave-If I understand you correctly, I think you are overthinking it.

LOL - I'm sure you are right! Engineering background & all that... The problem is I don't have the spacers to put in & mark... I'm going to have a student machine them at a local college. I thought it would be cool (for him/her and for me) to have the holes drilled at the same time. I'll probably make the holes another 1/16" bigger to allow for position errors & move on.

I'm also thinking about having the spacers stick out a bit with 2 threaded holes to allow for possible use as legs / wheels. Seems like an easy thing to do, but probably even more overkill.

I just thought someone might have a design already done for fancy machined spar spacers!

 

[alpinelakespilot2000]

I'm also thinking about having the spacers stick out a bit with 2 threaded holes to allow for possible use as legs / wheels. Seems like an easy thing to do, but probably even more overkill.

I just thought someone might have a design already done for fancy machined spar spacers!

Dave-Now I see why you want your holes to be right on and not too much oversized.

A lot of people do what you are contemplating (using the spar spacers as a place to attach legs for a fuselage stand). If you do that, just realize that you'll have to come up with a different way to fit your wings if you choose to fit the wings at home.

I'm using a rolling fuse stand/cart made out of 2x4's modeled on that of Bill Repucci. It has worked out fantasitcally so far. From rolling the canoe until getting it on it's own gear, it has been all I needed. Let me know if you have any questions about how we did it.

FWIW, I used three pieces of Baltic Birch or Apple-ply plywood (1/2" or 7/16"--or whatever they had) from my local woodworking lumber supply shop. When put together, the three pieces equalled exactly the dimesions called out in the plans. Further, and despite the thread I saw last week on this topic, I don't think the spacers have to be absolutely exact. Close or close enough work here, IMHO.