Howard...Thanks for the offer.
Is the new bridge on Coal Creek Parkway finished yet?
I have some FG props from "The Prop Shop" in Colorado, that I'd like to use for learning the technique. They have severe flashing around the edges, they're very thick, and they're about the color of rootbeer. I got them cheap at a swap meet. Anybody know if they'll work? They're supposed to have Hoerner tips, but that's not going to happen! They are sizes that I could actually eventually use.
So far, I've finished two Bolly 3 bladers and got a "Majik" (Mejzlik) 10.5 x 4.5 ready to use. I may have to revisit the first of the two Bolly's...the one that doesn't work. I haven't tried the most recently finished one yet. Maybe next weekend. The Mejzlik was impervious to a new Fox prop reamer, but it submitted to a real step reamer. The current need is for .3125" holes, to fit a Fox shaft extension. This reamer works SO much BETTER! If you need one, visit your local machine shop supply store. Maybe double or triple the price, BUT they can be resharpened for a lifetime of use...and made from tool steel, too.
1) I've got a Jim Lee prop scriber, and use it, once I ream the hole out to .251", with a real reamer in the drill press.
2) To cut off the excess diameter with a little to spare, I use the Dremel and abrasive cutoff disc...works amazingly well. I went to 11" dia. with these two Bolly 3-bladers, for a .46LA. Thanks to whoever recommended this!
3) I made a Delrin knob and pressed in a 1/4" dowel pin, to peg a blade template to the backside of the hub.
4) A template was made off one blade, with the tip shape desired. I used 1/32" plywood, and clamp it to the blade about 1" from the tip. I found one blade to be quite a bit narrower than the other two, so made the template and two wide blades match that one.
5) I don't have any of the "PermaGrit" tools that Brett mentioned in another thread on CF props. I guess McLendon's would have them. Do they come in various grits? What grits work?
6) My sandpaper selection is considerable, if not well organized. I started out using much too fine a grit, but soon was down to about 80 grit, followed by 180 wet or dry, then 320 wet or dry. I'm going for sharp LE & TE's. I won't be flipping these with bare hands, and I don't like a chicken stick. So, the "electric finger" is elected.
7) You already showed me how to repitch a prop. Now I have to figure out what the airplane needs, and the engine will tolerate. So far, I'm not keen on 3 blade props, but I didn't get to test the latest one. I changed back to the base prop, an 11.5 x 4 APC, with much improved performance.
I'm wondering about squaring the hub and blade tracking, mostly. It seems to me that tracking should be taken care of with hot water, like repitching. What I don't have is a way to check tracking. I could probably design and make something, but don't want to reinvent the wheel.
9) Have talked to Tommy Teamrace some about props, and it seems that the racers make props that works with almost no hand work and no repitching. Why don't we do that? They make a mold off a pattern, work on the product of that mold, then make a better mold. Repeating if needed, until they get a mold that makes a prop almost ready to use, after deflashing and balancing.
10) Tyrone is wondering when you're going to visit again!
Steve
Topic: Is there an online tutorial on finishing and tweeking CF props? (Read 1338 times)
