Some of these props needs to have a lot taken out. The existing holes are very small.

I have been using a drill press and bits for years and have never had one not work or go wildly out of balance. Take your time and go slow, works great. I fly all the way up to 32" props.

The problem is with a straght hole that is drilled or step reamed crooked. The hole at the rear of the prop hub is the hole that APC centers during production. Here is a drawing of what APC is saying.

Gene, the normal old prop ream can be used in a good drill press. If you just knock out the piano wire handle then you can mount it in a press. My big one that is 10mm is already machined like a drill bit. Just run the press at slow speed. 10mm is usually for big props on gas engines from about 40cc so there is a lot of wood to remove from the bigger props. I still just ream them by hand. I have seen way too many props shift using a press and boogering up the hole. Part of my thinking is, what the hell, how many big props do I use anyway. I buy them one or two at a time. I reamed and balanced them when I had nothing better to do. When I was smoking it was simple, take a smoke break to relax and ream a prop at the same time. Maybe even have myself something cold to drink if it's the summer months. It isn't like I have a lot of big props on hand, they cost from a low of about $20.00 to about $40.00 for the engines I have on hand so it isn't like I stock pile 10 at a time. Don't over think it. A new ream is nice and sharp and makes short work of a prop. My reamer is in bad need of a stone but it still cuts nice and straight.
Charlie, I have those drill bits you are showing. They are made by Dewalt {Dewilt?}and don't cost a bunch if you get the set. They do get you on replacements. That tip isn't a step, it's a pilot so you don't need to use a smaller pilot bit. They are very aggressive bits and should be used with caution when drilling wood!!
Gene

I've used drill bits and hand reamers for the past 40 years. A problem arose when the prop shaft sizes got very large. The hand reamers were insufficent for the job. The larger drill bits, having sharp lips coming off the flutes, would dig into the material being resized. I went to adjustable reamers because they do not bite into the material as a bit will do. I do not have any problems with the adjustable reamers and you can size them within a range to fit your needs.
This video shows how to adjust them:
http://www.youtube.com/watch?v=qxxU0I_gvPE

I bought mine online, although not from the pictured source. Mine are manufactured in India and are relatively cheap and do the job.

Harbor Freight has an 11 piece set for $79.99.
http://www.harborfreight.com/11-piec...set-38577.html


Bob

Here is a 7 piece set with smaller sizes starting at 1/4 inch for $44.95:

http://www.amazon.com/Grizzly-H5938-..._bxgy_hi_img_b

Bob

Look what you can find when you start digging in boxes in the shop. I have a brand new great planes step reamer, even metric in size. goes to 10mm. Dumb me the wife was going to let me buy one. I should have taken the money then I could have gotten something else.[][][]
BTW, who is going to Toledo at the Weak Signal show. I am, I am.[8D]

Being a new guy on the block in the airplane section ( not to planes and RC.. ) i too over the years have drilled out some props with a drill.

Like to post this saying "for what it's worth"............

If you use a hand drill holding the prop against a block of wood or something simular (lot of work tables with shallow drill holes in them..) it will make the hole bigger.Is it going to end up Dead-on..............most likely not.Will it work on the plane,ya most likely if you don't care about proper balance (unless you drill the hole in the end of the prop )

But did want to mention a couple of things if this is the way you want to inlarge the hole.First would like to say some of todays drills are high speed,have a lot of power,and things can happen fast.If you are going to go this route...Wear a good glove that you intend to hold the prop with.Most of the time if you are going to just inlarge the hole a slight bit....what will happen if you don't have a hell of a good gripe on the prop and holding it tightly against something.........the drill bit is going to grab the plastic and run it up the drill shaft at an angle to where the flutes end and if you don't have a hell of a grip on it you will most likely be dripping some of that red stuff out of your hand or fingers.And in the end you have to ask yourself just how accurate can this new hole be.

BIGMIG

P.S. Been there and done this..........The old saying "live and learn" is not allways the way to learn.

I ended up using a reamer. The original hole on the prop was 1/4" I had to go to 10mm. My reamer started at 1/4" then it went 7mm, 8mm, 9mm and finally 10mm. It came out great. I did put it on a drill press so I could regulate the feed. It was a great planes reamer.

When you ream from the face of the prop balance on your right foot. when reaming from the backside of the prop balance on your left foot.
Chuckle chuckle

Tom

Dang!!! wouldn't ya know I did it backwards. Well that was OK because the engine runs backwards. chuckle, chuckle

Another thing about wood props and balancing them...buy props that have a similar grain on each end...they will balance easier...if the grains are vastly different, don't buy the prop unless you are ready to do some real balancing....just thought I'd throw that in.

To balance a wood prop I just use clear lacquer. I put the prop in the balancer and just give the light side a squirt or two. I only use wood props on my gas engines and went to Xoar props. They come pre balanced and require next to no work at all, even after reaming but I do always check them.