I've got the 4 inch Truturn Ultimate spinner with the short shaft adapter on my 2.1 Moki. Does anyone know a good way to ream this baby without getting the hole off center? I could just grab a big drill bit but you know what happens....

....I just drill 'em hand held in a drill press. The larger
drill bit centers its self. Go real slow drlling out the
bottom, sometimes they will bite when the drill exits.

I used my prop reamer on my alum spinners. works fine.
d

A small Drill Press would be the ticket here. You could use the same size bit as the hole to center your piece. Another way is to run the spindle at a very low RPM in reverse (with the desired bit) and gentle bring it down and touch the part to find center than tighten things down. Most inexpensive Drill Presses don't run in reverse, so go to plan "A".


Happy Fly'n....

Dont mess with it. Send it back to Tru Turn and let them make the hole the right size. I think it costs less than 20 dollars and it will be right. If you do this yourself and miss even a little you will throw almost a hundred bucks in the trash because you wont like what it does to your airplane.

blabree

I apologize if my original post was not clear, I was referring to reaming of the propeller to fit the Tru-turn short shaft adapter bolt, not the spinner backplate. The backplate was already reamed to 12mm by Tru-turn. The problem is my prop reamer isn't big enough to ream the propeller out to the size necessary to take the short shaft adapter bolt. It is roughly 9/16 inch diameter and the propeller must tbe counterbored to take it. As I said in my earlier post, I could just get a big drill bit and get after it but I thought someone might know of a piloted reamer or counterbore that would work and keep the hole perfectly centered.

I asked the same question two different times. I never got the answer I wanted. From what I can tell, there are only four options:

1) Drill it by hand and take your chances.
2) Use a drill press and align the prop with various techniques.
3) Buy a custom drill with the tip and body ground to the exact diameters you need.
4) Use a service to drill your prop.

The answer I wanted was an off-the-shelf reamer with the proper tip and body diameters. In the case of an APC prop with a 5/16 hole, and an engine with a 10mm shaft, no such reamer exists. I did #1 and all seems well, but will eventually go to #3. I saw a link somewhere for custom prop drills for about $20.

Does anybody have that link?

It's on the tip of my tongue... I'm thinking that ?? B&B ?? carries a lot of gas engine items, among which are piloted prop drills: on a .375" drill bit the nose is ground down to .315" (5/16" to 3/8"). And other sizes.

I'm sure that many of the gas engine suppliers have similar drill bits.

Fox offers a 10 & 12mm reamer. It uses a 1/4" pilot, then is stepped to 10 then 12mm. $15 bux from Tower.

Bill Harris is right
I have three of the piloted drill bits from B&B. You still need a drill press and something to hold the work (your prop) so it absolutly cannont move. You wont be able to hold it by hand and do a good job. I have three paint stirrers to attest to that.

blabree

Contact B&B Specialties at (574) 277-0499.
See their prop drills at their website: WWW.BENNETTBUILT.COM/PAGE9.HTM

The Fox 10/12 mm won't work on larger APC props which have a 5/16 inch hole. Actually, I tried it anyway with a hand drill. The hole went off-center, but it balanced perfectly. Of course, I only balanced it along the blade axis. It seemed to run fine on my Saito.

Which brings up a good question. If you balance a prop with traditional techniques but the hole is off-center by .010-.020, will it run smoothly on the engine. Technically the answer must be NO, but practically speaking is it OK?

Thanks for the link Pilgrim.

The Fox 10/12 mm won't work here. The Tru-turn short shaft adapter is much larger than 12mm. I have had problems using the Fox reamer in the past. Reaming an APC 17x6 to fit my Moki 180, I got the hole off center. After careful rebalancing I got the prop to work. The problem is that these reamers are stepped but not piloted and you can get off center fairly easily. There doesn't seem to be any form of standardization beteen the engine and propeller manufacturers which makes propeller reaming a real pain in the a__ __. Anyway, I emailed Tru-turn and they suggested B&B specialties for a piloted counterboring tool.

Sounds familiar.