Hi .
I wanted to know what's the difference between using reamer and drill bit when opening up a prop?Anyone ,please help

Mitty

Hi, Mitty.

A standard drill bit has only two flutes. A standard reamer the size of a propeller hole diameter normally has 4 flutes. Since the prop hole dia. is almost the proper crankshaft size and only needs a little material taken out, the only answer is a reamer. A reamer will NOT wander from the centerline of the prop hole, but will follow the hole religiously. A drill stands the chance of wandering off to one side or the other and is also much more likely to go thru the prop at an angle if you're using a hand drill. Of course, if the hole is running out or crooked, the prop will not run true and vibration will be set up.
ALWAYS USE A REAMER.

Jackster

Anyone having trouble reaming out the APC props? I have a fox and a tower reamer which go thru wood and Master Airscrew props like a knife thru hot butter, but can't get them to bite into the fibreglass APC. Am having this problem on both glow and electric props. Anyone found a way to get thru these without using a drill bit?

A drill used as most are may vary the hole size by .01-.02" making it sloppy on the shaft.
A reamer cannot make a hole only chase one. A reamer will hold the hole size within .0001" if used correctly. An industrial reamer has no pilot on the front to "religiously follow the hole" but will generally follow the hole made for it. All the prop reamers I have seen have a pilot to follow the original hole.

I prefer a tapered reamer. You can buy them at a good hardware store for probably $10 or more now. They center in the existing hole. They will do APC type props or wood easily.

Clair

Joe, it sounds like your reamers are dull. Hope you are not like some folks I see that just throw the reamer in the flight box and let it bounce off all the other tools in there. Not good for the reamer. With care, a reamer should last for many years. That said, some of the GP reamers I have seen come out of the pack a little dull.

B&B offers a drill bit that has the bottom of the bit ground down to be a pilot so that it will follow the original hole.

Ed M.

Bentgear, you bet they're dull, but they're brand new! Have tried shapening them with no results. Am going to have to get a drill with a pilot shaft, drill press, etc. Apc's are tough customers. The electric props are very brittle, and break at the hub with the slightest impact. Glow one's seem to be much more flexible.

A drill bit will rip through the material taking big bites. The reamer scrapes the material, taking smaller bites. It is easier for a drill bit to go astray of center vs the reamer, even in a drill press.

A drill press is of course, the best way to do drilling/reaming work. You can vary the drill rotation speed, which NEEDS to be slow for reamers to properly do their job. Also, a drill press and vise are necessary for holding the prop square, thus eliminating the possibility of non-perpendicularity of the hole being enlarged. A SHARP reamer is a MUST for it to do it's job in any material. If you need to, go to a hardware store or a machine shop and get one you know is sharp.

Jack

I agree with Jack....I always use the drill press. I want them straight,
and the hole enlarged to the perfect diameter. The drill press also
straightens out some "less than perfect" factory attempts to "knock"
a hole through the center of the prop.

I don't clamp them...I hold them by hand with a glove so they can
self center.

garch 22:
Reamers are not designed to cut quickly thru much materal they should just shave a little off with each pass.
The fast cutting action on the drill is what causes inaccuracy.
If you tried to sharpen the reamer by hand it is most likely no good any more. Sometimes cutters aren't ground correctly in a mass production process. The solution is to find someone with the knowlege and equipment to sharpen it correctly. A correctly sharpened and cared for reamer should last thru 100s of props.
I use reamers daily in toughened steel and they do wear out. Usually they can be touched up on just the cutting face and used some more. Plastic and wood will not wear the reamer as fast as steel nor will the size be as critical as I need.
A tapered reamer will leave a tapered hole not a pilot hole. The small surface will wear quickly and is a product of trial and error, not accuracy of tooling. The hole should be sized correctly as close to the propface as possible; usually in the sholder of the shaft not the threads.

Guys, I just received a new Fox reamer and guess what, it's doin the job just fine. Problem solved. The previous two, one from Tower, and one from Fox were very dull out of the package. Must have gotten some duds. In any case, thanks for all your input, always interested in knowing how others go about this.

try a reamer on a composite prop ha,,, well at least i know that Master makes one rock solid prop ...Blast two days and i'm still reaming I know its sharp cuts wood like butter apc props are a little slower but the master is by far the hardest material to get through... (well i wan not making head way so i pulled out the drill and ruined the prop...what a waste you just cant to it with a drill)gerrrrrrr

James,

I have a Metric prop reamer made by Fox.

I have used it on about 200 props and it had not lost its edge yet.
I do Bolly, APC and Master Airscrew propellers and many wooden props and carbon fiber too.

There has been talk in these pages about reamers made by lesser manufacturers, that cannot enlarge a hole in butter, after having done the first two props....

First, find out what the hole diameter is for the prop you are using, next find out the diameter of the prop shaft. Get a new drill bit the size of the prop shaft and take it to a grind shop and have them grind a pilot on the bit the size of the hole in the new prop. Use a drill press to drill prop and if you are drilling wood props set the drill press to is highest RPM and you will get a very clean hole with no wobble.

What?????????Pile, your taking a long walk in the woods son. you bore out the Prop to match the prop shaft, nothing more. reamers work just fine for wood...
drill presses are for glass filled...

I think one of the other problems if the flexibility of the props themselves. APC does flex, but when the reamer (or bit) goes to work it is firm enough to be bored correctly. When you use a Master Air screw it likes to flex or get pushed out of the way. When you remove the reamer it is still tighter than expected. I bought a $5.00 HobbytownUSA one (cheep I hear) and have had no problem in about 50 or so props. The composition of the props has a great deal to do with it. As for using a drill or drill press I go for the press of course and yes a hard clamp with low speed (very low). Even a slow turning prop can have enough force left in it to take finger tips off. How thick of a glove is required? I can't answer that, and just because it has never happened doesn't mean that it won't. An ER run for stitches can run well over $100.00, and a prop hand reamer as cheep as 5 bucks....makes the choice easy, at least on this camp.

Either way be safe.

Lefty

Unless you are planning on making a reamer assembly line, just stick with the darned hand reamer; it takes 1 minute.

I have a couple of Fox reamers that I have used for many years . No problems.

jess

I have always used prop reamers, but on my gas engines the hole needs to be 10mm to fit my DA 50does not go that big. I have a drill press and I got me a 10mm bit and I have a drill press vice. All you have to do is find a bit the same size as the current hole in the prop and then use it to line up the prop on the drill press vice and clamp it down good so ther is no chance of movement and then I switch to the correct size bit and drill it dead center. Works every time. Perfect. On small props my reamer will fit I use it so I don't have to spend the time to do all the other besides on my gas props I have to drill 4 mounting holes with the prop guide drill jig anyway so I go through the effort.

Norman Ross Jr.

Norman,

I have used a Fox reamer for ages now.
They also make [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXNL18&P=7]this reamer[/link] too, which will fulfill your needs.

If you want to use a drill bit in a drill press, go to a good tool supplier and tell them what you want. There are types of drills other than the normal twist drills we all have.

Do they make reamers or step drills in 1/2A sizes? I haven't run across anything smaller than 1/8".

George

If the reamer isn't reaming the material up to size, it's dull. A dull edge tends not to cut but skates down the hole, especially with soft materials like plastics, brass, bronze. That's why you're getting a small (tight) hole. The material may be tough, but it's being pushed out of the way rather than being cut. The reamer must be DEAD SHARP. The lead-in (the angled cutting edge at the start of the reamer) does the bulk of the cutting with the flute's cutting edges scraping out the hole and finishing the job. I've never had any experience with smaller sizes of CORE DRILLS, or if the even make them in the smaller size, but this would be another avenue to explore. A core drill has more than two flutes and is designed to follow an existing hole, and does the job nicely. You can find core drills and quality reamers at an INDUSTRIAL cutter shop. A reasonable supplier online is Enco (www.use-enco.com). If you don't buy the cheapest thing they have, I think you'll have good luck with their products.
It's been said (and rightly so) that the most dangerous machine in a machine shop is the DRILL PRESS. That's because it's the least respected. I've personally seen a person's finger PULLED OFF by a drill press. He was holding a part in cloth shop towel when somehow, it became entangled in the drill, and off came the finger wrapped in the shop towel. The machine didn't even hesitate while pulling the finger out of it's socket and off! You can take the advice of some and wear gloves to hold props down on a drill press bed, but I really wouldn't recommend it.

Futurase:

Your way of locating and drilling you holes may be close enough for your purpose but it is far from perfect. When I do it quick and dirty I do it that way too. Real accuracy takes more time and effort than this. A reamer is far more accurate on hole size and a piloted reamer is far more accurate on location.

Just the experience of a 30 year Tool and Diemaker and former Tool Designer.

MikeSell,
You are right. I just mentioned the down and dirty way to solve the problem and if care is took you can get it next to perfect or right at it. Yes, a tapered drill bit or even better a tapered reamer in a drill press is the absolute best way. Of course if you want to go whole hog you can use a mill or lathe, but 99.9% of modelers do not have one. Shoot, my Sears drill press even has some runout. Hey it cost $99 what do you expect. With your tenure in machine works you know as well as anyone the machine is no better than the person operating it. I just tried to give someguys a easy, cost effective way of doing it and be very accurate if they take their time. Not the absolute best way to do it.

Try taking a hand reamer and reaming out a 24x8 prop. It will take nigh on forever and is WAY too hard to do. Now a 12x7 ain't too bad.

Norman Ross Jr.