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Help!
Drilling Falcon CF prop
A month ago I bought a Falcon 24x9 CF prop for my DA60. Drilled it out the way I have done successfully on many giant scale props over the years. My bolt alignment was off and an hour of attempting to fix it ended in frustration. I must have allowed the drill guide to slip. Oh well just wasted $80.
So I decide to buy another prop and let the pro's at Valley View drill it for me. Their bolt alignment is worse than mine. I cannot even drop the four bolts down with out the fourth binding - not even close. Needless to say I have an e-mail to them on what to do next. What is the deal with these CF Falcon props? I must have missed the memo on their special needs. My guess is that the hub material is so hard that the drill cannot drop/cut straight. Any suggestions? |
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I've drilled a dozen of them with a drill press and DLE drill guide. Nothing special that I can tell.
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I have also found it wise to pull the drill all the way out of the hole several times during drilling to remove the shavings as they get caught in the drill guide and bind the bit. Depending on how bad it is, and the price I may be interested in buying it from you.
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Shop Vac!!
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Quote:
The Falcons do seem to be a little harder (higher heat cure maybe) resin as I dont seem to get the imprint on the back over time, as deep as some other Carbon Props, and they seem not compress as much under use, as my prop bolts stay just about like I torqued them. I check them before every day of flying though. I've drilled about 5 of them now and all normal. Bill |
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Quote:
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Like several have mentioned, peck drilling to keep the drill flutes clear is important to keep the drill from loading up and walking off. That's with all props. A good, sharp drill will make it easy. Be sure to secure your drill guide to prevent it from moving. Drill from the back of the prop. After you drill a hole, drop a bolt, another drill, or a pin the size of the hole into place for added measure to keep the drill guide aligned. I haven't found drilling a Falcon any different than any other carbon prop. The hub is a little harder, but hasn't seemed to make a difference in drilling.
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I accurately drill 13/64 thru the guide but will increase to 7/32 after to allow a bit of wiggle room. When tightened down and compressed that extra 1/64 dissappears.
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I've drilled many CF propellers and there are a few things that make it easier to do. A drill press that has a table that is a true 90 degrees to the drill chuck is the first important thing to make sure you have before starting to drill a cf or any prop. I use the standard drill jig and as you start to drill, go through the cf skin carefully, slowly but not too slow or you'll dull the drill. Peck drill (meaning to drill like a 1/8" down and back the drill out to remove any chips before continuing to drill. By drilling too fast and or not removing the chips and debris as you go, this allows the drill to walk or drift out of alignment I carefully drill the first hole all the way through and the others a little more than halfway. Once you have done this, turn over the prop and place the jig with it aligning with the hole you drilled all the way through and use another same sized drill bit to use as a alignment pin and tighten down the jig. Finish with drilling the remaining holes to mate up with the first side you drilled.
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Hmmm...
Well I used a new bit and a DA guide. I slowly drilled down (no pecking) back to front. Have had no problems with Mejzlik CF they always came out perfectly. The folks at Valley View need to read this thread. Can I now hand drill and wobble or should I just ask for an RMA? |
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If you keep using a slightly larger bit the bolts should go through with no side loading. It's no big deal to have slightly larger through holes. That's all they are. The prop is held by the tension of the bolts and friction of the prop against the engine's prop hub. There should zero side load on the bolts.
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Cockeyed drilled holes that the bolts are forced through are the number one reason for busted prop bolts
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After I drill my 1st hole, I put a pin in.
locks the jig and prop together. Will not allow any rotation of the jig, which makes all the holes where they are supposed to be. |
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