Drilling CF

I want to drill a series of holes along the length of My CF boom for adjustments. The holes would be about .050" and about 1/4 to 1/2" apart. Has anyone tried this with negative results like the boom breaking or such?
Thanks
Don

I have drilled round sections successfully. I used a milling machine and careful setup to do it. Drilling by hand drill may be problematic. My booms did not seem to suffer from having small holes. The ratio of hole size to boom diameter will be a factor to consider. An .050 hole in a 3/8 boom may be OK but the same size hole in a .210 diameter boom may be risky. (.210 is a common size found in model airplane shops under the Great Western brand name).

Another idea for adjusting strings and things is to use a loose fitting sleeve that goes around the boom. Tie or CA glue the string to the sleeve. Use snug fitting rubber grommets on each end of the sleeve to fix the location of your choice. This is another quick and dirty solution that is widely used by EC12 guys in my area. If the grommets will hold on a 1200 sq. in. rig, they’ll surely hold the 600 inch IOM or US1. Take your boom to the hardware store and select appropriate grommets from their assortment.

I have drilled round sections successfully. I used a milling machine and careful setup to do it. Drilling by hand drill may be problematic. My booms did not seem to suffer from having small holes. The ratio of hole size to boom diameter will be a factor to consider. An .050 hole in a 3/8 boom may be OK but the same size hole in a .210 diameter boom may be risky. (.210 is a common size found in model airplane shops under the Great Western brand name).

Another idea for adjusting strings and things is to use a loose fitting sleeve that goes around the boom. Tie or CA glue the string to the sleeve. Use snug fitting rubber grommets on each end of the sleeve to fix the location of your choice. If you don’t have a proper sized sleeve you can just tie a couple of loose clove hitches around the boom or if you are feeling fancy use a turks head knot. This is another quick and dirty solution that is widely used by EC12 guys in my area. If the grommets will hold on a 1200 sq. in. rig, they’ll surely hold the 600 inch IOM or US1. Take your boom to the hardware store and select appropriate grommets from their assortment.

I have a milling machine and made a “V” block 4" long with holes every 1/4". I can just clamp it to the shaft and drill as many as I want. I’ve tested it on scrap but couldn’t decide if the arrow shaft would take it. I’ll give it a try now that I have your word that it won’t break.(grin) and use a wire clip held in place with an “O” ring. I have found an almost unlimited supply of arrows at the local archery club. As soon as the fletching gets a little bent they throw them out. We got a dozen from them the other day.

I tried the grommets and found them usually too tight or loose. If you found one that worked when you go back to get another few they have changed suppliers. Also if it was an adjustment that you didn’t change much the grommets seemed to glue themselves to the boom. Thanks
Don

For gripping round stock nothing, but nothing, beats the spring bowsers invented (AFAIK) by Gus Lassel ca. 1940. The first picture, from Mike DeLesseps’ excellent illustrations to the Yankee III book (shameless plug :-)) shows the idea as applied to the clew adjustment. It’s just a spring that you pinch open to release and let go to grip. Holds like crazy, infinite degrees of adjustment, no holes, no UV deterioration, just problem solved for once and for all. The same idea can be used for adjustable fairleads that can be slid around on booms to line up with deck rigging.

The second picture shows how easy they are to make from .035 spring stainless steel wire, available from Small Parts (www.smallparts.com). You need a mandrel about 1/16 to 3/32 smaller in diameter than your boom, and a wood block the same thickness as your mandrel and taped to it (1). You may have to experiment a bit to get the right size. Put a right angle bend in the wire and trap it in a vice (2). Pulling out and down, wind a three to three and one half turn spring and finish the ends to suit. Again, you may have to experiment a bit to get the ends lined up to the proper “pinch to open” configuration. The wire bending pliers sold by Micro Mark (www.micromark.com) are terrific helps in making all sorts of wire fittings.

Cheers,

Earl

Thanks for reminding me Earl, I’ve seen this before(probably on your site) and forgotten it. I’ll give it a try first because it’s non-destructive. I can always drill holes later. I’ve found it difficult to un-drill holes.
Thanks
Don

OK Earl what am I doing wrong? The first one I made will slide on the boom when I pull on it, so I used a smaller mandrel(drill bit) but now I can’t get the coil on the boom. I only had .031" wire, would that make the difference or am I just pulling too hard? I tied a sheet to one of the arms and pulled lengthwise and it moved too easily, I think.
Don

I’d try two things. One is to open up the smaller coil and put a bit of a “set” into it. The other is to use more turns. I’ve had problems before going below .035.

Cheers,

Earl

These items are often used on small engines such as Weedeaters, lawn mowers and small motorcycles. They are used as hose clamps. You can see larger iterations of these items on automobile heater hoses and such.

I have seen these used on RC boats and they are probably the best solution since sliced bread. The only drawback is that they work on round sections only. Hobby shops that cater to model aircraft guys will have a variety of wire diameters in spring steel. To hell with grommets, bowsies and beads. I’m going to the shop to make some of em. Bye

OK, for non-round sections, here’s “Springy Thingy (love that term) II” as used for clew adjustment on a Soling 1M. .035 spring stainless, sliding on a 1/16 round bracket. Kind of a lame picture, but I think you’ll get the idea. Wound around shaft, up and around to form an eye, back down again and around shaft. The tension here is not the coil but rather achieved bending the “legs” out so the “feet” are at an angle. As before, pinch to move, release to hold.

Cheers,

Earl

That’s neat Earl. I had not thought of doing it that way. Many of the things we learn from other modelers are most useful. :zbeer:

Just another idea from the late, great “Gus” Lassel. There’s a reason they called him “The Wizard of Wilmington [CA]”

Cheers,

Earl

Earl
Before I get myself in a knot trying to find the right sized wire. My clips side on the boom. I’m not sure if I’m pushing them too hard. Can you slide the clip on your boom by pulling(or pushing) it along the boom with your thumb? I can although it takes a little effort. I’m thinking that I’m just trying to make it too strong.
Thanks
Don

No, they don’t slide at all. They should be sufficiently small in diameter that they’re hard to get on, requiring pinching all the way open and twisting. What you describe is the way they should act when pinched open. I really think the problem is too small a wire.

Cheers,

Earl

Yea, I guess so. &%^*, Every time I turn around I need something that I can’t find here and everyone that has it seems to want an arm and a leg for “shipping”. I think “shipping” is their profit.
I tried the one for the Soling only I put it on the arrow shaft. It works well with the .030 wire and will be good for the outhaul because it has the height to reach the sail. I guess it binds a little better because of the leverage and two coils.
Thanks for your time
Don