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  #171  
Old 03-10-2012, 11:20 PM
stefanj stefanj is offline
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If my wood towers turn out as good as Jeff's I'll be happy.

The Dremel-assisted technique takes practice. In terms of true-to-roundness and smoothness, it definitely beats the hand-scraped technique.

Pretty much 1/4 of each dowel has to be trimmed off; the tips tend to taper in and the base tapers out. But this leaves enough dowel for the main struts, which is just fine.

After two or three tries I got the hang of turning out dowels tolerably close to .052" (as measured by the Semroc feeler gauge).

About a third of the sticks broke off and flew away . . . for the most part when trying to make the .041" dowels. The thinner diameter is much harder to achieve. In the five tries that did not break I got a few "close enoughs," one two-skinny, and one right on the ball.

You can see some of the final results on the Flickr page.

SO . . .

Any suggestions on how to handle the tank fairing?
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  #172  
Old 03-11-2012, 12:22 AM
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The way I did the tank fairing on my first build was to first make a couple of duplicates of the fairing to be used and then use the duplicates for practice.

To me, it turned out acceptable--but far from perfect.

Hence:
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  #173  
Old 03-12-2012, 01:02 AM
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Quote:
Originally Posted by stefanj
The Dremel-assisted technique takes practice. In terms of true-to-roundness and smoothness, it definitely beats the hand-scraped technique.

Pretty much 1/4 of each dowel has to be trimmed off; the tips tend to taper in and the base tapers out. But this leaves enough dowel for the main struts, which is just fine.



As my Dremel is not variable speed, I chose to do it by hand. I held a sanding block, the old fashioned wooden kind, with 150 grit paper on it in one hand and used my thumb to hold the dowel against the paper while twirling it with the other. I had one break and that piece is still bouncing around somewhere; I never found it. It is repetitive work, though. Sand a little, test it with the gauge, repeat.

If I had a better Dremel, I would think that trapping the dowel between two sanding blocks will yield a more uniform result.


Quote:
Originally Posted by stefanj
Any suggestions on how to handle the tank fairing?



Don't fear the FnF.

If I were to reengineer this kit, I would use a single cone and bevel the lower ends of the tank tubes to fit it.


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  #174  
Old 03-12-2012, 06:32 PM
stefanj stefanj is offline
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Well, the trickiest part of this re-build so far is putting together those little V-shaped cross-braces. Even with tweezers it is hard to line things up. I am going to try this:

Pin down the full-length dowel, with the end at the point of the printed V.

Cut down the end to make an angled matching surface.

Pin down another dowel at the appropriate angle; cut its tip and glue it to the first dowel.

When the joint is dry, make the cuts at the "top" of the V.

Repeat.

* * *

What kind of glue, and glue technique, have folks used on the fairing?
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  #175  
Old 03-12-2012, 07:12 PM
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Quote:
Originally Posted by stefanj
Well, the trickiest part of this re-build so far is putting together those little V-shaped cross-braces. Even with tweezers it is hard to line things up. I am going to try this:

Pin down the full-length dowel, with the end at the point of the printed V.

Cut down the end to make an angled matching surface.

Pin down another dowel at the appropriate angle; cut its tip and glue it to the first dowel.

When the joint is dry, make the cuts at the "top" of the V.

Repeat.

* * *

What kind of glue, and glue technique, have folks used on the fairing?



Have you considered building the tower with plastic rod instead of the wood dowels? You can get the rod already in the proper diameters and glue them together with CA. This might save the step of trying to get the dowels sanded round and in the proper diameters.
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  #176  
Old 03-28-2012, 03:02 PM
stefanj stefanj is offline
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I'm still working on cutting and gluing together tower struts. I've gotten pretty good at lathing out .041" (more or less) dowels with my Dremel. The hard part is laying out and gluing together such little pieces. I'm working on three towers at once, so the work seems to go on forever.

I ran into one really major annoying hitch. I finally got the tank fairing glued on. Not a perfect job, but with some filling and sanding it won't be too bad.

The problem is, the triangular bits have a slight concave curve to them as they go from the tail ring to the between-tank valley . . . while the root edge of the fin that fits over them is flat.

In other words, there will be a gap between the fin and the fairing. I believe the Semroc version got around this by putting a triangular balsa bit behind the rectangular "petal."

Any suggestions? Maybe glue some tissue or cardstock over the gap?
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